Tilton Flywheel-Clutch-Hyd. Release Bearing

[V8er]

I'd appreciate input from anyone who's had experience with Tilton Clutch-Flywheel assemblies, preferably the complete Tilton Flywheel-Clutch-Hydraulic Throwout package. But any input or tips on a particular aspect would be beneficial.

My FIA will be used primarily for spirited two-lane touring (read occasional non-competitive road racing), NOT long Interstate spans or drag racing.

I am mating a SBF with an estimated 460hp/450lb.-ft. to a Toploader. I would like to use a recommended Tilton OT-Series 7.25”, 2-plate Rally Clutch, Cerametallic disks, 157T Flywheel, Hydraulic Release Bearing.

1. Since the SBF has a 28oz. imbalance and the Tilton Flywheel is neutral balance, should I:

a. Add the 28oz. imbalance weight to the Tilton “neutral” balance Flywheel?

i. Weld the weight or tap and bolt in on?

b. Drill the opposite side to compensate?

c. Internally balance the engine using a “neutral” balance Tilton Flywheel and “neutral” balance Harmonic Balancer?

2. Is there any benefit or detriment to:

a. The Sintered Metallic versus the Cerametallic disks?

b. Are they equally safe from blowup?

3. Is there any benefit or detriment to:

a. The more expensive 600-series Hydraulic Release Bearing which is a simpler "bolt-on" the transmission item?

b. The less expensive 400-series requiring machining/modification to bellhousing/fitting to attach to the inside of the bellhousing?

4. Since a Tilton OT-Series clutch does not slip until the torque is 50% above the rated torque capacity, (making the rating rather conservative) should I:

a. Adhere to the pressure plate ratings or add margin capacity?

b. Consider the “High” or “Ultra-High” Pressure Plate Ratio?

5. Is this assembly:

a. As safe (“blow-proof”) as advertised?

b. Safe enough that I could use an original FoMoCo aluminum bellhousing?

[Aggressor]

In response to some of your questions:

I would have the entire rotating assembly (Including flywheel) precision balanced together by a good machinist. If you are off by only a a little bit when adding or removing balance weight, it can yield pounds of off balance rotating mass.

Your don't really have to go nuts on saving a few pounds. The car weighs in at say 2500 lbs. It gets to be a bit achedemic if your net power to weight ratio is 4.5 pounds per horsepower or 4.9. Either way it can be a wild crazy ride down the street. My car is quite a bit on the extreme side which is cool for bragging rights but looking back it was much more pleasant/fun to drive before the upgrades.

I would not want an aluminum bellhousing and fiberglass to be the only protection between me and the flywheel/clutch assembly. I used a Lakewood scattershield on my build as you never know when the spirited driving becomes high rpm stratospheric shifts to prove a point or just to pin your butt back into the seat for the thrill of it.
As Tom McCahill once said: "It's like being hit in the small of your back by a Louisville Slugger in the hands of Mickey Mantle"

- Geary

[TurnpikeBoy]

OK, let's try. (1) The flywheel must have the 28 oz. weight attached - usually the mfgr provides both 28 and 50 oz wts, and they screw onto the flywheel with included screws (2) Don't use a dual-disc clutche so really can't comment other than why the dual? - a single 10.5" will hold your setup with far more simplicity (3) simpler is better (4) what is the clutch rated for? - gotta believe it's way past what you're intending to put thru it (5) scattershields are good insurance no matter what the clutch mfgr says. Drag racing is the hardest app for a clutch, and since you say you're not going drag racing you could probably use the Ford housing. Just be aware it will offer you utterly no protection if something came apart in the clutch.

But I still have to ask - why a dual-disc? Just one opinion here....They're more complication than a typical single-disc by far, have had noise/grabbiness/harshness issues for a long time, and won't offer you any discernable advantage for your stated use.

[V8er]

Aggressor,
I have the complete engine in a competent machine shop (Vilas Motor Works, Bryan, TX) and intend to balance the entire assembly, my question is: Should I leave it external balance by using a 20oz. harmonic balancer and modifying the flywheel to effectively be 20oz. or try to internally balance it with "neutral" balance flywheel and harmonic balancer?

TurnpikeBoy,
Please note that I'm considering a Tilton OT-II Series 7.25”, 2-plate Rally Clutch, Cerametallic disks, 157T Flywheel, Hydraulic Release Bearing.

This 7.25”, 2-plate racing-style clutch is what is recommended for the nearly 500 lb./ft. capacity, extra torque. Since this is not an "OE" size (10.5" or 11") clutch, the usual/traditional rules don't apply. It's a simple but rugged, compact, lightweight system.

The Tilton 9 lb. Flywheel apparently is only available in a "neutral" balance so I'll either have to add the weight or internally balance the 351C. This is my dilema.

From the Cobra Automotive catalog:
Tilton Racing Clutches
"These small multi-disc clutch setups greatly reduce rotating weight and offer instant lock up with metallic lined solid clutch discs. Easy to maintain and almost indestructible, these Tilton button flywheel style clutches mount to a conventional automatic flywheel and allow you to use your stock bell housing and starter. A mechanical throw out bearing utilizing standard clutch linkage can be used with this Tilton clutch. Or, if you prefer, a more driver-friendly hydraulic throw out bearing can be used as well. The benefits of this clutch assembly are countless. No need for a heavy scatter shield, much quicker throttle response and increased braking capability because of reduced momentum when the throttle is lifted. The end result is more reliability while it feels like you have 50 more HP and bigger brakes! Clutch discs are easy to replace and these setups can be rebuilt at a fraction of the cost of a new one."

From the Tilton Site:

#66-302HORA or #66-302UORA
http://www.tiltonracing.com/content.php?page=list2&id=380&m=d#

600-Series Hydraulic Release Bearing
http://www.tiltonracing.com/content.php?page=hydraulic2 (http://www.tiltonracing.com/content.php?page=hydraulic2)

[V8er]

I meant to say "28oz. imbalance flywheel and harmonic balancer".

[mkassab]

V8er, I'm posting for Brent@b2motorsportsllc.com

From Brent: (copy and paste below... he's waiting for his membership to post direct)

That particular clutch package is basically overkill (in application and
price) for what your needs are.

A simple 10.5" diaphragm pressure plate kit would work just fine and they are readily available to handle 450, 550, or 650 hp. I can provide a RAM or McLeod clutch kit that will not need to have any type of exotic friction materials to hold 450-460hp. For just street driving on street tires, an aftermarket diaphragm pressure plate with an organic/organic disc will work perfectly. Keep in mind that the more exotic disc material that's used, the more chance of chatter and poor street manners. With just 450hp, there's no need in taking that kind of chance.

I would also advise against the use of a hydraulic throw out bearing. A conventional throw out bearing and clutch fork is much more reliable, unless you absolutely have no room for a fork. Keep in mind that if anything goes wrong at all with the hydraulic bearing (and at some point, it will), then it will require removal of the transmission and associated hardware.

To answer more of your questions:

1. If your budget allows, you can internally balance. What usually has to happen is that the crankshaft will need heavy metal to balance it.
This requires drilling a hole in the counterweight, then installing a slug of heavy metal and welding it in. Heavy metal (mallory) is very expensive. If you need a lot of metal, it can raise the balancing cost significantly. For a mild street application, there's nothing at all wrong with a 28oz or 50oz imbalance.

2. Yes...As stated above, there are many different flavors of clutch disc material. Organic is the most simplest and is usually what is found in most stock applications. Kevlar, sintered bronze, sintered aluminum, sintered iron, etc, etc, are "stickier" friction materials, made to hold larger amounts of horsepower. However, the risk of bad street manners increases with these materials.

4. Again, see above. There's really no need in such an elaborate clutch setup for a street car.

5. Any performance application deserves a blow proof bellhousing, and there are no flywheel/clutch combos that will guarantee that you will not have an explosion. With only a thin layer of fiberglass between the flywheel and your legs after an explosion, I would not trust my legs to an aluminum or cast iron bellhousing.

"an instant lock-up" is not something you want with a street car, as it's either on/off, with no slippage available. It would make it pretty miserable on the street.

[pgermond]

I'm probably going to get "Flamed" for saying this by some members, but I agree.... my experience (from watching friends with HTOB) has been that a conventional throw-out bearing and clutch fork are far less maintenance and problem free than a HTOB. IMHO, any time you have hydraulic fluid that close to a clutch plate you are asking for trouble.

[weaver]

I agree with everything Brent said but if you are going to use the slave cylinder kit we sell (install) we recommend a 3 finger pressure plate, you can't get enough throw with a diaphragm plate.

Alan

[Justin Upchurch]

I am trying one of Forte's kits this week with the hydraulic slave and fork. I gave up on the HTOB after it started leaking again after a couple of years. Once I get this one in, I will let you know how it works, the pressure plate is a diaphram style.

Justin

[eliminator]

To each his own!!!!!

That's why we all dress differently.

Sorry guy's but the HTOB works just fine for me, and the one other car I built.

If you like the slave go for it. We have had pages of discussion on this topic. It's been a topic for 5 + years.

[weaver]

Some customers have had good luck with HTOB but we have had terrible luck with them, we sent the last one we tried back to McCleod 2 years ago and we haven't heard back from them, not even a refund or our bearing back. Standard Transmissions in Ft Worth has a 55 gallon drum full of bad bearings, they don't recommend them anymore.

Alan

[eliminator]

Alan,

You need me as your Purchasing manager....the squeaky wheel gets the grease!!!!

I know Maurice is capable of raising hell if necessary.:)

I will put them on my list at the Street Rod Nationals.

[weaver]

One of their best customers is Standard Trans, they couldn't get satisfaction either. We never could get anyone on the phone that knew the products, the old crew was replaced when they were bought out.

[V8er]

I've had good service in being able to talk to techs and help with putting together a package that will work for my application. Unfortunately, no one in our circle really knows much about Tilton button clutches, so there isn't any user input. Apparently, the racing world is quite knowledgeable about them, but not street/strip/street rod/muscle car users.

[B2 Motorsports]

There's nothing at all wrong with using a lightweight small diameter clutch. What's bad about the Tilton button clutches is that they are meant to be used on a lightweight flywheel or even an automatic transmission flexplate. When you take a 7.25" clutch kit, mounted onto a 5lb flexplate, you have no rotating momentum at all. Combine that with the fact that Tilton offers no sprung hub discs with street-friendly friction materials, their clutch would be on/off like a light switch with NO slipping whatsoever. As a result, you'd have to basically dump the clutch every time you wanted to take off and if you didn't have the revs high enough, you'd choke the engine down and kill it.

That's why there is no user input from the street/muscle car crowd...it's just not a street style clutch.

If you wanted a similar style clutch that's meant for the street, McLeod makes a real nice RST twin disc clutch that uses a 9" pressure plate and a manual transmission flywheel. The discs are also sprung hub, with organic materials. They are rated for 800hp, are light as a feather, and are very easy on the clutch foot.

If you need some extra input on how to package all of this together, give me a call. My specialty is dealing with the Cobra crowd. 502.759.1431.

[weaver]

I drove Bill Elliotts Cobra a couple weeks ago with a similar clutch and I damn near didn't get it off the trailer, when it released it took off like a drag car. The driver who has worked for Bill his entire racing career wouldn't even attempt to drive it. Ernie Elliott tried to get us to use one with our Nascar powered Cobra but his brother Dan who builds their transmissions and rear ends told us it wouldn't be good for the street.

Alan

[B2 Motorsports]

I bet it was a pain in the butt.

I don't even like driving cars with paddle style discs, even if they have sprung hubs. I make a fool out of myself everytime and look like I've never been in a manual transmission car before.

There's such a wide selection of aftermarket clutches, that it's very easy to find one to hold 550, 650, even 800hp without any bad street manners.

[V8er]

Alan,
I'd be intersted to know if Bill's Cobra has "sintered metallic" disks, which makes it a "racing" clutch with little more than being "in or out" of engagement, or "cerametallic" disks, which are a rally clutch. This is aparently a big difference in the ability to modulate the clutch. Also, was it a "high ratio" pressure plate or an "ultra-high ratio" pressure plate, which allows more pedal travel for disengagement and thus more ability to modulate.

[B2 Motorsports]

Sorry I missed your phone call.....call anytime....

[B2 Motorsports]

Paul, per our conversation earlier this afternoon...

McLeod says that the floater disc is sprung and the bottom disc is marceled. So both discs are engineered to absorb some vibration/harmonics/chatter.

[V8er]

Well, I decided to go with the Tilton cerametallic 7.25" OT-II Rally ultra-high ratio clutch and Tilton 9 lbs. billet steel flywheel (not cheap) setup... mainly because I wanted to use a 157T aluminum bellhousing (I love the early look/hate the "blow-proof" look) after being assured by the the Tilton tech that "If it's good enough for NASCAR at 9000+ with aluminum bellhousings..." it's safe enough for me... especially since I plan to limit the RPM to no more than 6500. Seems reasonable with only a 7.25" clutch and low MOI.

I just received the flywheel and boy is it a BEAUTY! I'm looking forward to getting the clutch/pressure plate which are more reasonably priced. Stay tuned for pics!

[weaver]

you should go ahead and order your kit and build it over the winter.

[Justin Upchurch]

I agree, that way it is done for the Texas Spring meet, and just maybe Alan will make it down this year for the event. If he does he can bring me a hard top.

Justin

[Slither]

Hey Justin, just have Paul grab the hardtop when he picks up his car:cool:, then you can pop over to Weatherford... that's a lot closer for you than Gadsden[thumb]...

Do you ever see Kelly anymore? He seems to have disappeared:confused:...

[V8er]

Well, I finally have a 351C engine that has been balanced externally using a 28 oz. harmonic balancer and a Tilton neutral balance flywheel. Instead of being able to internally balance the crank, which would have taken an estimated (10) slugs of heavy metal, compromising the integrity, or replacing the crank with a $1700.00 new one, I chose to add offset weight to the flywheel. Actually, we decided to cut windows in the premium flywheel to lighten the opposing side. Now we can proceed with the remainder of the engine build, using Edelbrock heads and intake.

[B2 Motorsports]

Why didn't you just use a 0 balance harmonic balancer?????

[V8er]

I have a Professional Products balancer with removable weights but, without added counter-balance in the crank, you have to compensate with offset weight in the balancer and flywheel.

[B2 Motorsports]

What crankshaft, rods, pistons are you using?

This is a common setup, even with internally balancing the assembly.

The issue with this scenario is that if you ever change flywheels, have to replace the flywheel, or sell the engine to someone that doesn't want to run your clutch setup, there will be an expense in having to balance match the flywheels in order to make the assembly in balance again.

[Slither]

Questions for the mechanical engineers out there:

Does this compromise the integrity of the flywheel? Will those little webs stretch at 6 or 7K rpm?

I'd hate to see it come apart... :eek:!

[spd4me]

Does the clutch disk spin over the top of the slots?

[V8er]

The clutch is a Tilton 7.25" Cerra-metallic, 2-plate type which has a raised friction surface on the flywheel of the same size so it will not cover the area with machined windows. It is my opinion (and my Texas A&M machinist) that the tempered steel flywheel, which only weighs 9 lbs. before the windows were cut, shouldn't have enough mass at a limited 6500 RPM to be an issue, particularly with the ring gear to keep it all intact. I'd appreciate any opinions or theories.

[eliminator]

Hmmmmm!!! Never have seen that before.

[B2 Motorsports]

The clutch is a Tilton 7.25" Cerra-metallic, 2-plate type which has a raised friction surface on the flywheel of the same size so it will not cover the area with machined windows. It is my opinion (and my Texas A&M machinist) that the tempered steel flywheel, which only weighs 9 lbs. before the windows were cut, shouldn't have enough mass at a limited 6500 RPM to be an issue, particularly with the ring gear to keep it all intact. I'd appreciate any opinions or theories.

I think any piece of steel turning 6500 rpm is going to have enough energy to break anything that's cast aluminum. Cast aluminum is pretty brittle.

The Cup guys may run lightweight bellhousings, but their stuff is made by Quartermaster/Tilton and is usually made of magnesium. Their rules also dictate an enclosed clutch assembly OR a scatter-blanket around the bellhousing.

Also, if you've ever seen a flywheel explosion (I've seen the remnants of some cast iron flywheels that came apart), the ring gear doesn't always stay on.

I hope for your legs' sake that everything will be ok. After the aluminum bellhousing, there's only 3/16"-1/4" of fiberglass between the flywheel and you.

[Aggressor]

Time to invest in a premium scattershield.

[Slither]

There is an interesting thread over on CC that discusses this exact issue, and they posted this link. Check it out...

http://www.youtube.com/watch?v=vq5cjNhN_po


It is amazing what it did to the header:eek:!