HTOB to External Slave Conversion

[Naumoff]

Jim and I have done the conversion on his Big Block FE with a TKO600.
He had a slip on McLeod HTOB and went to the Unique slave kit.
We did it at my brother's work with a lift so don't hate us for knowing somebody.
As with everything with our cars there no instructions so we documented it to help anyone who is thinking of doing this in the future.

The benefit is if there is an issue with the slave you don't have to remove the trans to work on it.

[Naumoff]

Step one.

To not hit the side pipes on the lift we had to cut some plywood blocks for spacers.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall040.jpg

If you don't have a lift skip this part:D

[Naumoff]

Remove drive shaft loop and drive shaft.

Shifter handle and boot.

Remove boot on trans and the shifter out of trans. Make sure it is in neutral to make it easy to re-install.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall033.jpg


remove 4 torx head screws. There are springs under the plates so be mindful of them.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall032.jpg

This will make it so you can pull the trans straight out and then down and easier to re-install the same.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall031.jpg

with the shifter completely out of trans.
http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall010.jpg


more later........

[Naumoff]

We disconnected the hydraulic line and put a 1/4" flare cap on the line from the M/C to keep the fluid from dripping on us.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall007.jpg

Put a jack under the trans and strap it down. Disconnect the trans cross member and remove the four bolts holding the trans to the bellhousing.
Slide trans straight back. Then drop it down and out.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall011.jpg

With a screw on HTOB there is a threaded collar that slips over the bearing retainer. It is pretty snug and it took some effort to remove.
We put some lube on the retainer and had to use a slid hammer hooked on the the threaded collar to get it off. It has two o-rings inside which holds it in place.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall008.jpg

This is after we got it off. It was all the way to the right. Forgot to take A picture before with the bearing on. Sorry.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall009.jpg

[Naumoff]

Jim's car is has the spacer for the stock Tremec input shaft and it looks like a McLeod diaphragm clutch.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall012.jpg

Jim made these nice trans guide headless bolts. Made lining it up to go back in easy.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall013.jpg

[Naumoff]

Test fit the new throw out bearing on the input shaft. Better to check it now.
Install the L shaped pivot point inside the bellhousing. Remember to install the four washers, two for each bolt, between the pivot and the bellhousing.(more on that later:o) The slotted side goes toward the trans shaft.
Put the clutch fork in through the trans opening with the wrong side facing out. Once in you will be able to flip it over then clip it to the pivot and clip on the new throw out bearing.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall014.jpg

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall015.jpg

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall016.jpg

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall018.jpg

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall019.jpg

[Naumoff]

The hydraulic line was strapped to the foot box. We had to remove them and then made a nice loop back over the top of the frame. This should be insulated to protect it from the heat. We looked at looping it under but it would have been closer to the header at the front of the foot box.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall020.jpg

Remove the bottom bellhousing bolt to the engine. There is a tapped hole in the block and the long bolt goes through the bellhousing bolt hole which is all the way through. The long bolt will go through even though you might think it won't just screw it through and then put the nut on it.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall022.jpg

Hook up hydraulic line to slave.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall039.jpg

Install trans

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall024.jpg

Caught Jim waxing :D

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall023.jpg

[Naumoff]

Install clutch rod and dust boot and adjust rod out to just have a little free play.
Install return spring (which we didn't have) too keep tension on the clutch fork to rod and slave.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall038.jpg

re install drive shaft and loop. Speedo cable and shifter. Top off the master cylinder and bleed clutch. Pump three time and then hold down pedal. Open bleeder and let the air out. Repeat this until no more air comes out with the brake fluid. Be careful not to get any in your eyes, painted services, etc., etc.

While your car is on the lift or jack stands start the engine and see if you can get it into the gears. If it does you are done. Check the free play on the clutch fork. You don't want the bearing riding on the pressure plate when you are cruising around or the engine is just idling.

[Naumoff]

We had some other issues and believe the clutch M/C is bad. It was not putting enough fluid into the slave to fully disengage the clutch pressure plate.

Also we boobooed when installing the pivot for the clutch fork.
We didn't use the washer that came with it for spacers. This was almost a full disaster as pulling the trans was a possibility. If we didn't have a lift and a welder it would have been. Trust me we had tried everything. We got the spacers on and the pivot bolted in but could not get the fork to clip on the pivot. Pulled the pivot back off and clipped it on the fork first but coldn't get the bolts back through. Pulled it back out and came up with the ideal to weld the nuts and the washers on the pivot. Slipped the pivot on the fork and install the bolts from the out side. Not fun but can laugh about it because we didn't have to pull the trans.
And you ask why the spacers are important. With out the spacers the clutch fork hits the bell housing and not allow the proper amout of travel.

Extra washers...........NOT! :eek:

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall036.jpg

After the weld. The washers are welded on the back side. It ain't pretty but it worked.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall037.jpg

[Naumoff]

Back on the ground and ready to be pushed. :D

I followed Jim home. He can fill in on anything I forgot and the rest of the details.

We hope this will help anyone who is considering doing this project.

It is a job that should take four hours. We only used hand tools.
The lift and trans jack helped a little. ;)


http://i229.photobucket.com/albums/ee99/Naumoff_photos/ClutchSlaveinstall041.jpg

[Jim Harding]

I must have thanked Tony and his brother John (owner of the garage we worked in) a dozen times. Guys, you need a friend like Tony when you need a hand. I could have sat in a chair drinking a cool one (ones!) and he would have been happy to do the whole job himself :D Hopefully his pictures and descriptions will assist others when they contemplate doing the retro external slave cylinder.

It appears (after everything we did) that the 3/4" master cylinder is not up to the job. Can't get complete disengagement of the clutch and still have some free play in the fork. Tony was once again searching for an answer and it appears others (on this forum) have had similar issues and have replaced the master cylinder with either a 7/8 or one inch.

The present style Wilwood master cylinder (260-1304) is not available in sizes over 3/4 inch. So to stay with Wilwood, I'm going to a (Summit P/N) WIL-260-6766, at one inch. This is a physically larger master cylinder, with the outlet on the front end of the cylinder. Although clearance seems OK, I'm going with a 1/8"-27 NPT M/F 90 degree elbow (Summit P/N EAR-991401ERL) and 1/8" NPT male to 3/8-24 inverted flare female fitting (Summit P/N WIL-220-0628) which will connect up to the existing clutch line.

After this, all my hydraulic clutch problems should be behind me :cool:

- Jim -

Oh, on the waxing thing... doesn't everyone wax the tranny cross member before putting it back in?

[JeepSnake]

Jim - have you adjusted your clutch pedal stop DOWN? And have you adjusted your clutch pedal height UP? I bet that you're just not getting enough stroke on your existing MC due to adjustment in the pedal height and pedal stop. That happened to me - I've got the same slave and 3/4" master, and pedal adjustments cured it.

[will butterworth]

littleold wilwood mc,s are sometimes aggravating to work with.Have pull type wilwood slave cyl. and worked with it a while before figured it out and started working---then adjusted all of it--linkage and stuff---but thats all a challenge, good for the soul--if somebody else can do it we can too, snort around, huff and puff, I keep an old rusty bucket handy --kick it time or two --good rattle,gal upstairs hears it and she will leave me alone then.Slam a door--ye old professor Vernon von Studebaker has taught me a lot of things over the years.Will-alabama

[Naumoff]

Hey Zach,

We already did that. There was no pedal stop and Jim adjusted the pedal out so far that his knee is practically above the dash.
No pedal stop could have been the HTOB problem to begin with.

We have adjusted the clutch rod to where it has tension on the pressure plate.

It could be just a bad M/C.

I found this one post which was interesting by terrybieritz

Gary...

This isn't a direct answer and is only marginally relevant but I had issues with my Girling and finally replaced it. When I built my car the throw on the clutch lever seemed to be "just enough" to release the pressure plate. I had a Hayes "long" style pressure plate. I finally got it working but I just didn't think it was "right". I used silicone fluid from day one.

When I replaced my transmission recently the first clutch I bought was a CenterForce "diaphragm" pressure plate. Try as I could there wasn't enough throw in the clutch cylinder to release it. Two options were suggested. One...go back to the Long style pressure plate on the theory it requires less throw to release...and Two: replace the master clutch cylinder with one that has a larger bore...pushing more fluid which translates to more throw at the clutch cylinder.

I did them both. I bought a McLeod pressure plate, long style. I then bought a Tilton master cylinder with a 1 1/8" bore...the largest I could find. The combination did the trick! I can how adjust the lever to NOT have the throwout bearing riding the pressure plate constantly AND the clutch releases with minimal throw on the pedal.

The only down-side is it's a STIFF clutch! Oh well. It hooks up far better than the old combination. Maybe there's food for thought in my experience.

Terry


And Jim does have a diaphragm clutch.

[scott h]

did you use a pilot bearing? i am getting ready to reinstall trans (tremec TKO500) in a 351W. the trans shaft shows some wear indicating there may have been a pilot bearing but my new motor does not have one. maybe engine builder forgot?

[Jim Harding]

Scott, yep, there's a pilot bearing in there. But even if there wasn't, that would not give the same symptoms we're dealing with.
You'll definitely want to put in a pilot bearing/bushing before you stick in the tranny.

[weaver]

The problem is the diaphram clutch, we use a 3 finger clutch with a slave cylinder. to change the pivoyt point and get more clutch travel try installing a 1/4" shim between the fork bracket and the bell housing, this should fix the problem. Could you see where the HTOB was leaking, it might have had a loose line.

Alan

[Naumoff]

The problem is the diaphram clutch, we use a 3 finger clutch with a slave cylinder. to change the pivoyt point and get more clutch travel try installing a 1/4" shim between the fork bracket and the bell housing, this should fix the problem. Could you see where the HTOB was leaking, it might have had a loose line.

Alan

Alan,

I thought about that after I read some old post in the search I did.

That could be done but we have plenty of adjustment in the clutch rod and even had pressure on the throw out bearing to the pressure plate.
I don't think moving the pivot point out will change the amount of movement of the throw out bearing.
The fulcrum point of the fork would have to change to do that.
The diaphragm clutch is definitely a factor in this.
We are just not getting enough movement out of the slave.
The M/C could just be bad but changing to a larger M/C bore wouldn't hurt either.

Oh, and the HTOB was leaking from the piston seal.

[Master]

I had this same problem, speedway sells a external 7/8 bore push type slave cylinder. It will fix your travel problem.

[Jim Harding]

I'm putting this thread to rest!:)
Yesterday I swapped out the 3/4 master cylinder for a 1 incher and can now say that my clutch disengagement issues are a thing of the past.
As stated earlier in this thread, there is a compromise in that the effort to depress the clutch pedal has probably doubled. But I can live with that :D
- Jim -

[Naumoff]

Excellent!
See you on the road!

[rdorman]

Nice car Jim... where did you pick that one up? ;o)

Guys, once again I have to rebuild my wilwood pull type slave and I am sick of the things. Anyone know the part number, where to get the bracket etc to convert to a push type cylinder that mounts to the bellhousing? It is a toploader and it does have a diaphram clutch. Thanks!

[Master]

Rick, I used Alan's bracket that he supplies and switched to a speedway 7/8push slave.

http://www.speedwaymotors.com/p/1944,38_Push-Type-Slave-Cylinder.html?itemNo=slave

[ralphscott]

Nice job Tony and Jim on your documented swap. A picture is indeed worth a thousand words.

Ralph

[rdorman]

Rick, I used Alan's bracket that he supplies and switched to a speedway 7/8push slave.

http://www.speedwaymotors.com/p/1944,38_Push-Type-Slave-Cylinder.html?itemNo=slave

Thanks a lot!

[Naumoff]

Thanks Ralph. We thought it would be a good thing to document the job.
It might not be the only way or best way to do it but it give you a good ideal of what it take to do it.


Rick, I am starting to become a firm believer in pedal stops even with an external slave. If you can over extend a HTOB you can over extend your M/C and external slave and do damage to them. Maybe not as dramatic as with the HTOB but there is still an awful lot of clutch slaves and clutch M/C failing prematurely. JMHO

[brfutbrian]

tony, every external slave cylinder ive ever seen has an internal snap ring that act as a piston stop that makes over extending impossible. ill bet an external slave has double the travel over an htob. later, brian.

[rdorman]

I always have throttle and clutch pedal stops.

[RJacobsen]

tony, every external slave cylinder ive ever seen has an internal snap ring that act as a piston stop that makes over extending impossible. ill bet an external slave has double the travel over an htob. later, brian.

I don't think over-extention is the problem. over-pressurization after the unit hits maximum extention is what blows the seals out.

[Naumoff]

I don't think over-extention is the problem. over-pressurization after the unit hits maximum extention is what blows the seals out.

Especially with the Clutch M/C. The Wilwood M/C from what I remember say to limit the travel of the pushrod. With out a stop you can over work the piston causing it to fail prematurely and slamming the piston all the way to the spring clip on the slave is not a good thing either.

So if the M/C is not sized properly to the slave you could have more problems. With a 3/4" M/C and a 1" slave you over work the M/C.
With the 3/4" M/C with out a pedal stop and a HTOB you blow the seals on the HTOB and over work the M/C.
If the M/C is 1" with out a pedal stop and the slave is 3/4" you could blow the slave and over work the M/C.
If you have a 3/4" M/C with out a pedal stop and a 3/4" slave you could over work your M/C.
I don't think you have more pressure in your clutch M/C as you have in your Brake M/Cs. The brake M/C pushrods don't travel anywhere near as much as the clutch M/C.


To much travel travel of the clutch M/C then I would say over pressurizing the slave is a factor. I wonder what the max pressure on slaves are. Probably not as much as the M/C.
Or all these parts they make are just total crap!;)
I am just theorizing:D

Rick,
What size M/C and slave are you running?



tony, every external slave cylinder ive ever seen has an internal snap ring that act as a piston stop that makes over extending impossible. ill bet an external slave has double the travel over an htob. later, brian.

I agree with you and this is exactly what could be the issue.
You also don't want to over extend your pressure plate either.

[Tony Radford]

I just replaced my MC and SC last night. I currently have a sack of wasted MCs and SCs. Over time, the fluid turns black and gritty for some reason or another. I had a small plate fabricated that pulls the slave away from the bell housing so that the rod is aligned with the cylinder as opposed to running a an extreme angle like before. The only way I've been able to get sufficient travel for my Ram long-throw clutch is by adjusting the pedal away from the floor. As a result, I think I'm overdriving the master. Recently, I could feel the master "stick" while I had the clutch pedal pushed to the floor. I reduced the travel last night, so I'm sure I'll have trouble getting the clutch to fully disengaged. When I pulled the master, the inside was coated with a black gritty slime. I may have to try this new slave. Can you get full slave travel with the standard master?

[Jim Harding]

Alan,
I'm answering your private email here because I couldn't attach a picture using that method. Also others may want to see what one looks like installed in the car, should they want to try this avenue.

The new clyinder is also made by Wilwood (Summit P/N) WIL-260-6766, at one inch. This is a physically larger master cylinder, with the outlet on the front end of the cylinder. Although clearance seems OK, I installed a 1/8"-27 NPT M/F 90 degree elbow (Summit P/N EAR-991401ERL) and 1/8" NPT male to 3/8-24 inverted flare female fitting (Summit P/N WIL-220-0628) which connected up to the existing clutch line. Here's a picture.

[Naumoff]

Looks good Jim.
Time will tell.
I also remember there is a spec from the clutch manufacturer about how much clearance is required for the clutch to be properly disengaged. Which I can't check with the stupid blow proof bell housing.
I think it was with a .050" feeler Gauge you should be able to slide in between the disc and the flywheel when the clutch pedal is pushed in.

I would still put a pedal stop and adjust it to where it gives enough movement in the slave to properly disengage the clutch.

Tony, If you have a 1" slave and a 3/4" M/C the manufactures say no, not with out over working your M/C.
I did a search on clutch slaves in this forum and came up with a lot of good info.

[Jim Harding]

Tony,
The pedal stop is still a part of this project, as well as a return spring and another adjustment for 'free play' at the fork. Right now, with the car parked on a slope, engine off, brake off, and in 1st gear, I can depress the clutch pedal about half way before some disengagement causes the car to move. However, this distance is not enough to shift into reverse with the engine running and not grind the gears. I have to press the pedal a good 3/4 of it's travel to get a smooth, no grinding shift into reverse. So a pedal stop will be adjusted for this distance, and then I don't think I'll have any more issues. Keeping my fingers crossed :D

[RJacobsen]

here is a link to the McLeod site with instructions for the set up of their HTOB. http://www.mcleodind.com/downloads/install_instr/McLeod_INSTR_1300BoltOn_WEB.pdf

[Tony Radford]

Jim, looking at that new master, I see the diameter of the part that passes through the bulkhead is considerably larger than the 260-1304. Did you have to drill it out or did it fit? It doesn't look like the hole is big enough on my car.

[Jim Harding]

Jim, looking at that new master, I see the diameter of the part that passes through the bulkhead is considerably larger than the 260-1304. Did you have to drill it out or did it fit? It doesn't look like the hole is big enough on my car.

Tony, you're very observant :D When I first tried to fit it through the bulkhead, it wouldn't go in. What I did was remove the rubber boot, install the master cylinder, (the hole was just large enough) and then refit the boot. Getting the boot on in that very limited space was a chore, but was doable. If that hadn't worked, my second thought was to ream out the hole, which after spending time and a few choice words refitting that boot maybe should have been my first thought :D:D

[Tony Radford]

Jim, I installed the new 1" master last night (like to have killed me working by myself to get the top nut that secures the master to the footbox). Now I can't get the leaks plugged. It's leaking somewhere in the concoction between the line and right angle adapter (like yours). I put teflon tape in the right angle where it enters the master and on the adapter where it mates up with the right angle adapter. I've torqued everything about as far as I can go and it's still leaking like crazy. How frustrating.

[Jim Harding]

Tony, mine is installed like yours. Although I've heard that NPT fittings "usually" don't require Teflon tape, I put two to three wraps on each of the male NPT fittings like you. I had a small drip between the adapter and the 90, but just snugged it down a little more and so far I'm drip-less :D Maybe you just need a little more snugging. :confused:

[Naumoff]

Tony,
Can you take a picture of it? How many turns did you get on the npt by hand before you put a wrench on it? It should go in at least a turn before you need to put a wrench on it. Could be cross threaded. I hope not. The flare fitting should not need any sealer or teflon.You should also be able to run the flare fitting up all the way by hand before it need a wrench on it.

[Tony Radford]

Well, I got too frustrated and the wife's leg was getting tired, do I removed the adapter and ran the line right in to the master. It still leaked up around the tubing and out of the connector. I just kept tightning until it stopped. I've still got a bit of air to bleed out. But I noticed that it now takes both feet to push in the clutch. I thought that with a 1" master, it would be easier.

[RJacobsen]

A 3/4" master cylinder with 1" of piston travel moves .442 cubic inches of fluid. A 1" master cylinder with 1" of piston travel moves .786 cubic inches of fluid. That is about a 78% increase. Thats probably pretty close to the amount of extra effort you are feeling. If your clutch pedal has a 6:1 ratio and used 6 inches of travel to move the slave 1" (assuming a 3/4" slave) with the 3/4" master, it now only needs about 3 1/4" of travel to move the slave the same amount. If you can measure the travel needed at the slave to disengage the clutch, you can calculate the proper sized master. I am not a math wizz but this is not that difficult.

[Jim Harding]

Tony, when I was looking over the room available to do the one inch M/C swap, I thought it would fit without the need for the 90 degree fitting, but worried that the tubing wouldn't be long enough to re-route to the front of the new M/C. Glad you got things together. And yes, my pedal is harder to push too, but it's not as hard as some cars I've had the pleasure of driving. ;)

[Tony Radford]

Jim, I ran a new piece of tubing. It's great being able to engage the clutch with a small amount of pedal travel. It's just so hard to push. I mean SERIOUSLY hard. But the clutch doesn't slip and the gears don't grind. Oh well, so it goes in the Cobra world!

[Tony Radford]

The 1" master is reducing the quality of my driving experience. I'm going out on a limb and replacing the 1" with a 3/4" master of the same series. It doesn't look like the additional travel amounts to much over the little master, but I'm taking the shot that it might be enough to give me acceptable clutch control performance. I talked to tech support at Wilwood, but didn't conclude anything of substance. I'm in the "try it and see" mode. It won't be the most amount of money I've wasted on a failed experiment. After all, I threw WAY more time and money at my Serpent Express vision.

[Naumoff]

The 1" master is reducing the quality of my driving experience. I'm going out on a limb and replacing the 1" with a 3/4" master of the same series. It doesn't look like the additional travel amounts to much over the little master, but I'm taking the shot that it might be enough to give me acceptable clutch control performance. I talked to tech support at Wilwood, but didn't conclude anything of substance. I'm in the "try it and see" mode. It won't be the most amount of money I've wasted on a failed experiment. After all, I threw WAY more time and money at my Serpent Express vision.

Tony,
Maybe you should try a Thigh Master.:D

Seriously, What is the bore size of your slave? just curious

[Tony Radford]

Tony, I don't remember. It's either a 3/4 or 7/8. The sad thing is that the slave has plenty of travel available. I just need a master that can supply sufficient fluid to make it work.

[Naumoff]

Tony, I can't see how more work the bigger M/C is over a 3/4". But if it works out for you with the 3/4" M/C let me know. I would buy the 1" M/C off of you.

:rolleyes:Maybe I should try Jim's first.:D

[weaver]

I installed a 1" for my silver car and you can't push the clutch, I ordered a 7/8" and will try it out. I will keep you posted.

Alan

[brfutbrian]

alan , youll like the results with the 7/8" mc. the pedal pressure and action is a big improvement over the mushy slow action with a 3/4"mc. enjoy , later, brian

[Tony Radford]

I just finished installing the large capacity 3/4" master. After fixing leaks about 50 times, squirting a bottle of fluid on the floor, headers and my body and going through the bleeding process for the 20th time this year, I have pressure. I tried the bench-bleed prior to installation and that got me no where. It's great getting the mushy pedal back. I need to do some adjusting before I know if it's going to give me enough travel (I lost interest before I got it adjusted). I'll do that tomorrow and report back. I really think that TV show - world's nastiest jobs - should do a segment on hydraulic clutch system repair. I need to go burn my clothes.

[Jim Harding]

I installed a 1" for my silver car and you can't push the clutch, I ordered a 7/8" and will try it out. I will keep you posted.

Alan

I guess all the possible combinations of clutch plate, m/c, slave, available pedal stroke/ratio, whatever, is probably the reason each of us has had different outcomes when it comes to doing things alike. My pedal travel with the one-inch m/c goes all the way to the floor as the slave moves to full travel. It is a rather hard clutch to push, but I don't find it that objectionable.

I guess everyone will have to add the standard disclaimer to their posts - "your mileage may vary" ! :D:D

[Naumoff]

Mine works fine right now. Maybe I should leave it alone.
Trans shifts smooth and all seems right in the Universe.:D

[Tony Radford]

Well, I made a quick adjustment and took her for a quick spin around the neighborhood (weather is really crappy). I may be crazy, but the pedal seems much easier than even the original small 3/4" cylinder. The range seems much longer and I'm able to get good clutch travel. I need to go out and thrash it a bit to be sure, but so far all seems grand. It's truly amazing how much differences it makes on pedal pressure to go from 1" to 3/4". Absolutely night and day! I'm going to have to rent a warehouse just to store the pile of masters and slaves I've accumulated.

[Naumoff]

I wonder if an increase in line size for the larger M/C would help.

I know in refrigeration systems that you have High pressure high temp liquid from the compressor to the evaporator through a small pipe then when it goes through the metering device into the evaporator it drops to a low temperature low pressure liquid.

So I am wondering if a larger line would reduce the wall restriction(which it should) of the line and reduce the resistance at the pedal. The more I type and think of the flow charts for pipe sizes and pressure drops the more I think this could be the problem.

With the larger M/C you are trying to move more fluid through the same pipe. Does this make sense to everyone?

The more fluid or gas you need to move through a line from point a to point b the larger the line is needed at the same pressure. If you want to move more fluid or gas through the same size line the more pressure is needed.
It is not the Larger M/C that is the problem it is the same small line!

Tony, Don't throw those 1 inch M/C away yet!

Jim, I will pay for the parts to try this out on your set up if you will let me.

[Tony Radford]

I bought the tubing bender from hell for this latest change. It would be interesting to see if increasing the line diameter eased the pain.

[Slither]

I wonder if an increase in line size for the larger M/C would help.

I know in refrigeration systems that you have High pressure high temp liquid from the compressor to the evaporator through a small pipe then when it goes through the metering device into the evaporator it drops to a low temperature low pressure liquid.





Good observation Tony. Yes, the increase in size would help, since it would reduce pedal pressure.

The A/C system is a different process. It converts the liquid to a gas (in the evaporator), thus pulling heat from the evaporator core in the process. The compressor then converts it back to liquid form... or at least that is the idea.



So I am wondering if a larger line would reduce the wall restriction(which it should) of the line and reduce the resistance at the pedal. The more I type and think of the flow charts for pipe sizes and pressure drops the more I think this could be the problem.

With the larger M/C you are trying to move more fluid through the same pipe. Does this make sense to everyone?

The more fluid or gas you need to move through a line from point a to point b the larger the line is needed at the same pressure. If you want to move more fluid or gas through the same size line the more pressure is needed.

It is not the Larger M/C that is the problem it is the same small line!





It has been awhile since I last looked at my sophmore physics on Bernoulli's Principle, but it isn't so much that either is a problem... just a matter of physics.

The wall friction is primarily parasitic, as is turbulence and viscosity (though wall resistance goes up with the increase in size, the surface to volume ratio goes up faster, so it appears that it has less of an effect).

Since the larger piston moves more fluid (in order to get more travel from the slave), you require more pressure to accomplish this in the same amount of time. You are moving more fluid through the same size tubing, but it is the delta t (read change in time) while holding p (read pressure) constant that makes the difference. Or even better yet, the delta v (read change in volume) while holding t (read time) as constant (requiring an increase in p). You could use the same pressure on the larger piston as the smaller piston... it would not be a satisfactory shifting experience from the longer time perspective:eek:.

These are related through conservation of energy, where the pressure side is potential energy and the high velocity flow through the tubing (pressure drop) is pressure energy converted to kinetic energy.

The calculations are based on pressure, area, viscosity, time, etc.

Increasing the line would require more fluid volume overall, and increase the weight slightly, due to more metal and fluid.

If there is another disadvantage to a larger line, it is not coming to mind right now. I'll think about it later, if I get a chance.

[brfutbrian]

sorry guys. i hate to burst your bubble, but i think it would have a very marginal effect and it will actually be the opposite of what youre expecting. but it would be interesting to see what it would do. somebody should give it a whirl and find out. later, brian.

[brfutbrian]

before anyone actually tries this, consider that most likely youre going to have to modify the slave and the master cylinder. im sure the ports on both are pretty close to the same i.d. as the lines that you have now. without modification its not going to matter how big the lines are. later, brian.

[Slither]

sorry guys. i hate to burst your bubble, but i think it would have a very marginal effect and it will actually be the opposite of what youre expecting. but it would be interesting to see what it would do. somebody should give it a whirl and find out. later, brian.

Never suggested that it was either the right thing to do or even feasible, Brian, only tried to explain why it would have an effect/the results if done...;).

Not sure why it would work opposite, though. Can you help me understand?

Thanks

[Slither]

Where is Mr. Carlson on this one? We need a mechanical guy (read ME) to set us straight on it;):D[thumb]!

[Tony Radford]

I have to say that at this point, it looks as though the 3/4" large master is the ticket. I picked up a vacuum bleeder today and got the air out. Pedal pressure is less than the little 3/4" master, range is greater and the clutch seems to be perfect. I say "seems" because it's raining here today an I've only played around in the driveway. But the pick up point feels good and I can't feel the gears meshing - even going into reverse. So my conclusion at this point is that anyone unable to get sufficient range out of the stock master should find significant improvement simply by going to the large one and sticking with the same bore. I'm going to capitalize on this as a "feel good" moment.

[RJacobsen]

With the larger M/C you are trying to move more fluid through the same pipe. Does this make sense to everyone?

You are only moving more fluid with respect to an increase in movement of the slave. The larger master moves more fluid with less pedal travel, however the trade off is an increase in effort. Its all a matter of leverage, With a few measurements you can fine tune the MC size to fit your car. Tilton for example has the following Bore sizes available in there 75 series MC : 5/8", 7/10", 3/4" 13/16", 7/8", 15/16", 1", 1 1/8". If you know the travel needed at the slave to release the clutch, the travel available at the clutch pedal, and the clutch pedal ratio you can size a MC to fit. The larger line size would only help if the bore size at the fittings on the master and slave were also increased, but I think that it would not be noticable.

[brfutbrian]

Never suggested that it was either the right thing to do or even feasible, Brian, only tried to explain why it would have an effect/the results if done...;).

Not sure why it would work opposite, though. Can you help me understand?

Thanks

paul, it wasnt to say if it was right or wrong . all i was saying was i did not belieive it would have any great effect one way or the other (marginal). the reason i said it probably would increase pedal pressure is with a bigger line is it would increase flow rate into the slave. but it would be a good r&d experiment just to see the results. by the way i use 3 different size master cylinders in my car. 7/8 clutch, 5/8 front brake & 3/4 rear brake. no great formula to arrive at this , just r&d experimentation and seat of the pants feel. no science involved. rod`s explanation saved me a bunch of typing. thanks rod. if anyone wants to try it, im game to do the port modifications. later, brian.

[Naumoff]

before anyone actually tries this, consider that most likely youre going to have to modify the slave and the master cylinder. im sure the ports on both are pretty close to the same i.d. as the lines that you have now. without modification its not going to matter how big the lines are. later, brian.


That is easy enough to do. I think it is worth trying. I say doubling the line size will reduce pedal pressure.
The volume you are moving at the master cylinder to the slave will move quicker and easier. You don't loose the volume in the pipe as it full of brake fluid. With larger pipe diameter even with increase wall surface area you are moving more volume at a lower pressure.
I have to look up the physics of it but it works in the real world everyday.
I work with the numbers in sizing water and gas lines. :)

[Tony Radford]

I took her out for a spin around town today. It shifts well if I use all of the pedal. Pressure is very soft compared to the one inch master. I'm of the opinion that the 7/8" master is the ticket. This one will do me fine (until it self destructs) at which point I'll change to a 7/8". I think it will provide the right travel VS pressure ratio. If masters and slaves were collector's items, I'd be rich!

[brfutbrian]

That is easy enough to do. I think it is worth trying. I say doubling the line size will reduce pedal pressure.


shouldnt take more than boring out the port and tapping the bore with the proper pipe tap for the next i. d. size line. screw in a pipe to flare adapter and your good to go. id like to hear the results too. wanna bet a buck on the results? rod, you want in on this? anyone else? :) later, brian.

[brfutbrian]

tony, you may as well just go for the 7/8. youve invested alot of time and money getting your clutch to work the way you want it to work.you might as well add one last m/c to your collection. and get the results you want. you wont regret it. later , brian

[RJacobsen]

shouldnt take more than boring out the port and tapping the bore with the proper pipe tap for the next i. d. size line. screw in a pipe to flare adapter and your good to go. id like to hear the results too. wanna bet a buck on the results? rod, you want in on this? anyone else? :) later, brian.

I say no noticable change. The resistance to movement at the pressure plate is way more than the resistance from a smaller line size. Your on Brian. ;)

[brfutbrian]

rod, im already dreaming of what im going to do with the winnnings. maybe a couple of new chrome valve stem covers for my wheels. should have made it 2 bucks so i can get a complete set. how about you? bic lighter? bag of potato chips? you making the trip to gadsden next month? later, brian.

[RJacobsen]

I took her out for a spin around town today. It shifts well if I use all of the pedal. Pressure is very soft compared to the one inch master. I'm of the opinion that the 7/8" master is the ticket. This one will do me fine (until it self destructs) at which point I'll change to a 7/8". I think it will provide the right travel VS pressure ratio. If masters and slaves were collector's items, I'd be rich!

Tony, I did some math (now my head hurts), anyway this is what I came up with. If "useing all of the pedal" is a 7" stroke (just a guess) and you have a 6:1 ratio pedal (another guess but I think correct) and you change to a 7/8" MC, the stroke required to release the clutch would now only be 4.8". A 13/16" MC would need about a 6" stroke. The fluid needed to move the slave is such a small amount that what seems like a small change in cylinder size is more than one would expect. If you can varify the pedal stroke to release the clutch I can get more accurate for you.

[RJacobsen]

rod, im already dreaming of what im going to do with the winnnings. maybe a couple of new chrome valve stem covers for my wheels. should have made it 2 bucks so i can get a complete set. how about you? bic lighter? bag of potato chips? you making the trip to gadsden next month? later, brian.

Brian, after my last post I can't deal with any more numbers right now :D

[RJacobsen]

Brian, I won't be in Gadsden this year, I'm just going to hang out here with Phil G. I'll get you the address to send My check to.;)

[brfutbrian]

tony naumoff is the one you need to send your address to. im with you on this one. i was asking if you wanted in on an easy buck. you have been dealing with too many numbers. later brian

[Slither]

The fluid needed to move the slave is such a small amount that what seems like a small change in cylinder size is more than one would expect.

Keep in mind that increasing the MC size is an exponential function, as the area changes with the square of the radius. Notice that the travel on the 7/8" MC is approaching half of that for the original that you assumed at 7", and that is pretty significant[thumb]. Of course, this holds the slave travel constant.

We'll miss you this year Rod, as we will all of you who won't make it:(.

[Naumoff]

Hey guys I think I might have found something which can help explain the easier pedal with a smaller bore.

It came under Pascal's Principle.

The smaller M/C bore with a larger slave bore creates a mechanical advantage.

With a 1" M/C you would need to increase the bore of the slave to reduce the effort.
The result of the smaller bore M/C is a proportionately greater stroke which conserves energy at the pedal.

Mechanical advantage = D1/D2=A2/A1


I guess the trick is to get enough movement out of the clutch pedal to move the larger slave enough to disengage the clutch.
Which we were not getting from Jim's 3/4" M/C which could have been just a defective M/C which I stated it could be.

[Naumoff]

You are only moving more fluid with respect to an increase in movement of the slave. The larger master moves more fluid with less pedal travel, however the trade off is an increase in effort. Its all a matter of leverage, With a few measurements you can fine tune the MC size to fit your car. Tilton for example has the following Bore sizes available in there 75 series MC : 5/8", 7/10", 3/4" 13/16", 7/8", 15/16", 1", 1 1/8". If you know the travel needed at the slave to release the clutch, the travel available at the clutch pedal, and the clutch pedal ratio you can size a MC to fit. The larger line size would only help if the bore size at the fittings on the master and slave were also increased, but I think that it would not be noticable.

Rod and Brian are correct and I will buy you both a drink when we meet.

The size of the tubing between the M/C and slave would not effect the mechanical advantage of the smaller M/C.
With the same size M/C and Slave there is no mechanical advantage.
Hence the increased pressure at the pedal.

Paul,
Bernoulli principle does apply in my work but has little effect with a hydraulic system as it is Pascal's principle at work here.

Bernoulli's conclusion: the slower the rate of flow, the higher the pressure, and the faster the rate of flow, the lower the pressure.
Bernoulli published the results of his work in Hydrodynamica (1738), but did not present his ideas or their implications clearly. Later, his friend the German mathematician Leonhard Euler (1707-1783) generalized his findings in the statement known today as Bernoulli's principle.

Thanks for all the input as it helps to look at a problem from different angles and has saved me some money and effort. :)

[eliminator]

I have never seen so much written about such a non issue, amazing that only a few folks know how to set up and utilize a HTOB. If I had never owned or built a Cobra but was thinking about it, I would think again after reading all this just to get a clutch working.

Amazing I have been hearing this same stuff for 6 years about slave cylinders, yet it just keeps on going. Sorry guys but just give me the HTOB and someone that can set it up right the first time. They are a pretty simple device.

[Naumoff]

I have never seen so much written about such a non issue, amazing that only a few folks know how to set up and utilize a HTOB. If I had never owned or built a Cobra but was thinking about it, I would think again after reading all this just to get a clutch working.

Amazing I have been hearing this same stuff for 6 years about slave cylinders, yet it just keeps on going. Sorry guys but just give me the HTOB and someone that can set it up right the first time. They are a pretty simple device.

I agree with you to a point but this does not give me a headache as I like to know how and why something works. If I can understand it fully it makes it easy to set up correctly.

I have a HTOB and it works great. I will not put a larger M/C on my car to decrease the movement of the pedal to disengage the clutch because it will increase the effort a lot.


Now that I have an understanding of the the principle behind the bore size an how it effects slave movement and pedal effort it makes it easier to
pick the right parts for a specific application.

I hope others have been helped by this discussion.

Rick, Not everyone has been around here for six years and the cars have not change so I would expect the same discussion to come up over and over. That is what this place is for, I thought, so that newer member can get help from the people who have been around her for a while.

Peace :)

[JeepSnake]

I think the slave's accessibility is what causes it to keep getting discussed. People go to playing with diameters, strokes, etc. They also have an attitude of "Well, it's easy to replace, so I don't have to spend time on it..." I fell victim to that last year myself at Pigeon Forge - I should have realized that cylinder was on its way out since it was missing the dust boot and had lived most of its life in a salty environment (Miami). But, thankfully, it's easy to replace (at least with Ralph Long & Sandy supervising Butch, Dad, and me!).

It's a Ford vs. Chevy argument: both can work well, and both can break. While Rick would never give up his HTOB, I'd never give up my slave cylinder. Brian says "you guys," and I say "y'all" - both of them work.


Now, never being one to give up the opportunity to beat a dead horse...:D


Guys, whether you’ve got a slave or an HTOB, the line size is pretty inconsequential.

Since Paul asked for it, I’m reporting in with my official back of the envelope numbers. I didn’t stay at a Holiday Inn Express last night, but I am a PE of the ME variety.

First, some assumptions:
1) Driver pushes master through its entire travel, 1.43” for a typical Wilwood. This assumption should yield more flow than what the reality is.
2) Driver accomplishes this in 0.5 seconds.
3) Clutch tubing is 1/8 inch inner diameter (closest size in my charts).
4) Tubing length from master to slave is 3 feet.

Now, calculating for a 0.75” master cylinder using the above assumptions, you move an equivalent flow rate of 0.32832 GPM. At this flow rate in this size and length of pipe, you’re going to see a pressure loss of about 0.1415 psi across the pipe.

Calculating for a 1” master cylinder the same way, you move an equivalent flow rate of 0.58338 GPM. At this flow rate in this size and length of pipe, you’re going to see a pressure loss of about 0.4113 psi across the pipe.

So sure, you’ll have 3 times the pressure loss in the pipe with the 1” vs. 0.75” master. But, with the overall equation being vastly dominated by your clutch springs and the master vs. slave/HTOB, and with the difference all being in the sub-psi range, I doubt your leg is ever going to notice a change in tubing size.

[RJacobsen]

I think the slave's accessibility is what causes it to keep getting discussed. People go to playing with diameters, strokes, etc. They also have an attitude of "Well, it's easy to replace, so I don't have to spend time on it..." I fell victim to that last year myself at Pigeon Forge - I should have realized that cylinder was on its way out since it was missing the dust boot and had lived most of its life in a salty environment (Miami). But, thankfully, it's easy to replace (at least with Ralph Long & Sandy supervising Butch, Dad, and me!).

It's a Ford vs. Chevy argument: both can work well, and both can break. While Rick would never give up his HTOB, I'd never give up my slave cylinder. Brian says "you guys," and I say "y'all" - both of them work.


Now, never being one to give up the opportunity to beat a dead horse...:D


Guys, whether you’ve got a slave or an HTOB, the line size is pretty inconsequential.

Since Paul asked for it, I’m reporting in with my official back of the envelope numbers. I didn’t stay at a Holiday Inn Express last night, but I am a PE of the ME variety.

First, some assumptions:
1) Driver pushes master through its entire travel, 1.43” for a typical Wilwood. This assumption should yield more flow than what the reality is.
2) Driver accomplishes this in 0.5 seconds.
3) Clutch tubing is 1/8 inch inner diameter (closest size in my charts).
4) Tubing length from master to slave is 3 feet.

Now, calculating for a 0.75” master cylinder using the above assumptions, you move an equivalent flow rate of 0.32832 GPM. At this flow rate in this size and length of pipe, you’re going to see a pressure loss of about 0.1415 psi across the pipe.

Calculating for a 1” master cylinder the same way, you move an equivalent flow rate of 0.58338 GPM. At this flow rate in this size and length of pipe, you’re going to see a pressure loss of about 0.4113 psi across the pipe.

So sure, you’ll have 3 times the pressure loss in the pipe with the 1” vs. 0.75” master. But, with the overall equation being vastly dominated by your clutch springs and the master vs. slave/HTOB, and with the difference all being in the sub-psi range, I doubt your leg is ever going to notice a change in tubing size.

Now lets calculate in the orfis size in the internal valveing of the individual Master cylinders in relationship to the inside diameter of the steel tubing and the max flow rate of the dot 3 fluid to dot 5 and the PSI of the muffler bearing clamp on ............ ;)My head is starting to hurt again

[JeepSnake]

Rod, after reading through the thread, I'm reminded of ME 571 (I think that was the number), "Industrial Noise Control." Taught at Auburn by a true-blue, old-style, somewhat absent-minded Brit by the name of Dr. Crocker. Only professor I had that still wore three piece suits to class on quite a few occasions.

Anyhow, after a full quarter of studying sound power, sound abatement, acoustics, etc., he turns to the class on the last day and closes his notebook. With the slyest of smiles, he said:

"Right. Now that is the way we perform our calculations and peform our work. However, when I am called to a factory to consult on how to make the work environment quieter, I generally start by simply placing plywood enclosures lined with foam rubber around the machines. Remember always to give this a try. See you at the final!"

What a hoot! After three months of intense math, the prof tells us to always start by throwing plywood and foam rubber at the problem!

[brfutbrian]

I have never seen so much written about such a non issue,

sure you have, how about the thread about needing an oil cooler thermostat, not to mention the one about how to bleed the bottom bleeders on wilwood calipers (no offense intended guys). normally i just like to sit back and chuckle and let the thread take its course. but i just couldnt resist chiming in on this. enjoy . later , brian

[Tony Radford]

If it was just about turning the key and taking a drive, this hobby would have died a long time ago. If every problem had a simple solution, each Cobra forum would be limited to two posts per day.

[brfutbrian]

tony, its all just part of the fun. as long as you arent tearing your hair out ,its all good. later brian

[RJacobsen]

I'll attempt to sum it up with this;
Bigger = shorter/harder
smaller = longer/softer.
all that from a 12th grade education:)

[brfutbrian]

all that from a 12th grade education:)

rod, same here. sometimes less is more :) later brian

[Naumoff]

Sometimes it takes more to end up with less.:D

Besides I love this stuff.

http://www.grc.nasa.gov/WWW/K-12/WindTunnel/Activities/pascalsprinciple2.GIF

Pictures help too.[thumb]

[eliminator]

For all you Rocket Scientist, GO FOR IT!!!

One note: It appears in years of observations on this issue, slave cyl. vs HTOB the slave cyl.tends to work better in small block applications and the HTOB better in big block (FE) applications. Although each system has worked with small and big block applications.

Big difference with a 11 or 12" clutch than the smaller small block clutches.

[brfutbrian]

rick, i thinks its just a preference choice, both cost about the same. both have pros and cons. both can work well if set up right, both can work like a nightmare if set up badly. sounds like good debate for the hampton parking lot. what day you showing up this year? tuesday or wednesday? we`re bringing a couple bikes in the back of the truck and going to do deals gap (tail of the dragon) with the car and the bikes monday and tuesday if youre interested and are passing thru (and anyone else too). later, brian

[RJacobsen]

[QUOTE=Naumoff;80364]Sometimes it takes more to end up with less.:D
QUOTE]

sounds like your thinking of running for some office Tony :)

[Naumoff]

[quote=Naumoff;80364]Sometimes it takes more to end up with less.:D
QUOTE]

sounds like your thinking of running for some office Tony :)


Is that an endorsement Rod? I could use a pay increase.:)

[eliminator]

Brain,

We will be down Wednesday evening around 3 PM. Butch is coming in Wednesday too...

See you then.

[brfutbrian]

rick, im looking to get into gadsden around dark on tuesday. see you wednesday. have a safe trip. tell butch not to forget my new differential. enjoy. later, brian.

[Tony Radford]

After a few dozen miles since the retrofit, I'm checking the "happy" box. Everything is working well clutch-wise. Pedal pressure is light, and disengagement is complete. One rear swaybar and I'll think she'll be perfect. I'm still able to make those 295 50 16s rub a bit on the fender wells in a hard turn.

[Naumoff]

Good deal Tony.
Full disengagement is all we can asks for. No grinding into reverse and the world seems like a better place.:)

[spd4me]

I was by unique a couple weeks ago and they were installing a new Wilwood master cylinder on somebodys car. I understood it to be a 1" dia. Push more fluid will give more throw on slave. I'm picking up one at homecoming.
bob

[Naumoff]

The pedal will just be harder to push.
Jim is good with his.:)

[Jim Harding]

The pedal will just be harder to push.
Jim is good with his.:)

I drove both my car and my F350 diesel dually yesterday and found the leg strength to push in the clutch pedal in each one to be about the same.
I was leaning towards taking Tony up on his offer to fund a 7/8 M/C for my car (Ginny pig ;) ), but with the current set up (1") the pedal travel needed to get complete disengagement requires the pedal to go to the floor. The smaller bore might be easier on the leg, but might not give the same results.
Like Tony said, I'm good (and happy) with this setup:shift: