transmission mount, crossmember dilema

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May 16th, 2008, 09:51 AM
davids2toys

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transmission mount, crossmember dilema

In the process, of fabricating a drive shaft loop yesterday, my buddy noticed my shifter linkage is hitting the tranny cross member , first to second in particularly, also reverse.
I have a few questions. My tranny mount looks a little tired and I would like to replace it. I have a 428,toploader, Jag rear…is this something I could just get at an auto parts store or does it need to be special ordered? What do ask for?
As far as the linkage interference, it looks as though if I just added a few more washers between the mount and the tranny, it would be fixed, at present I have about ½ inch in washers on each side, if I added more washers, it would change the angle of the driveshaft, at present, my tranny is LOWER than the rear, so the driveshaft is going up hill toward the rear, is this correct? The pad that is welded onto the crossmember that the mount goes on is on the bottom of the crossmember, is this correct? It looks as though you could flip the whole crossmember upside down, putting bthat flat tab on top of the crossmember, that would bring the tranny up at least 1.5 inches, solve my interference problem, but I don’t thik it is correct. What is the proper configuration of these parts and what is the proper shimming procedure for the mount to the tranny.
I will try to post some pics, thanks guys, I appreciate it!!
There is also an excell;ent shot of my driveshaft in this thread,

http://www.uniquecobra.com/forums/showthread.php?t=5471 Post # 20

Regards…Dave
May 16th, 2008, 10:32 AM
pbrown

I don't know about the crossmember but I have a forum usage tip.

You can link to a single post. See the post numbers at the top right. Click on the number and the single post will open. When copy the URL from your browser.

http://www.uniquecobra.com/forums/sh...3&postcount=20
May 16th, 2008, 11:19 AM
davids2toys

Quote:

Originally Posted by pbrown

I don't know about the crossmember but I have a forum usage tip.

You can link to a single post. See the post numbers at the top right. Click on the number and the single post will open. When copy the URL from your browser.

http://www.uniquecobra.com/forums/sh...3&postcount=20

Very good, thanks.
It would not let me post that pic because it had already been posted in the past. Why is it like that, one picture could certainly be applied to many subjects...a definate inconveniance. Can that be changed? Is it something I can fix on my end?
Thanks...Dave
May 16th, 2008, 12:16 PM
pbrown

Go to Home > My Account > Miscellaneous > Attachments. You can use any of your past attachments (photos) in new posts.
May 16th, 2008, 12:24 PM
pbrown

Driveshaft

One comment in general about tranny, driveshaft, and rear ends. It is important for the tranny tailshaft angle to mach the angle of the pinion on the rear end. For example, if your tranny is angled down 10 degrees, the rear end should angle up 10 degrees. Imagine your car from the side. If there was a line through the tranny and another through the rear end, they would be parallel. The driveshaft angle isn't a big deal and long as you're two imaginary lines are parallel.

If you raise the tranny mount without touching the engine mounts then the tailshaft angle will change. You would also need to change the angle of the rear end to compensate.

There are exceptions. Sometimes a drag racer with leaf springs will point the pinion angle down a degree or two. The idea is that at full throttle the axle will wrap and everything will be is correct alignment.

I hope this all makes sense.
May 16th, 2008, 06:04 PM
scott h

my trans crossmember looks a little different than yours, but the flat plate is on top not the bottom, it came that way from unique. i have a tremec i don't know if that makes a difference. I believe you want some small degree/ angle in the alignment of your drive shaft in relation to trans and rear end to allow u- joint rotation.
May 17th, 2008, 06:38 AM
davids2toys

Quote:

Originally Posted by pbrown

One comment in general about tranny, driveshaft, and rear ends. It is important for the tranny tailshaft angle to mach the angle of the pinion on the rear end. For example, if your tranny is angled down 10 degrees, the rear end should angle up 10 degrees. Imagine your car from the side. If there was a line through the tranny and another through the rear end, they would be parallel. The driveshaft angle isn't a big deal and long as you're two imaginary lines are parallel.

If you raise the tranny mount without touching the engine mounts then the tailshaft angle will change. You would also need to change the angle of the rear end to compensate.

There are exceptions. Sometimes a drag racer with leaf springs will point the pinion angle down a degree or two. The idea is that at full throttle the axle will wrap and everything will be is correct alignment.

I hope this all makes sense.

I did not think the jag rear center section was adjustable at all! How is this done?
Also, if they are parallel lines as you explained, the driveshaft would be absolutely straight between the 2 points, I thought this was a no no!
May 17th, 2008, 06:39 AM
davids2toys

Quote:

Originally Posted by scott h

my trans crossmember looks a little different than yours, but the flat plate is on top not the bottom, it came that way from unique. i have a tremec i don't know if that makes a difference. I believe you want some small degree/ angle in the alignment of your drive shaft in relation to trans and rear end to allow u- joint rotation.

could you post a pic?
Can anyone tell me if the orientation I have at the moment is correct for my setup??
May 17th, 2008, 07:41 PM
JeepSnake

Dave,

My Unique Assembly Manual (about 2001 vintage) calls out Anchor PN#2258 for the Toploader trans mount. NAPA or similar should be able to cross reference.

I can't tell you without looking, but I want to think that the flat tab is on top of my crossmember. Don't quote me on that - I really would have to look.

No, having the transmission output centerline and axle pinion centerline parallel doesn't mean they point at each other. It means that their axial centerlines are parallel to each other in two separate planes. The idea is to have both driveshaft u-joints operating at exactly the same angle so that you don't get vibrations.

(I've got a cool sketch that explains this, but I can't get it scanned in as a file I can post here. Maybe I can get it to work tomorrow.)
May 18th, 2008, 06:54 AM
davids2toys

Quote:

Originally Posted by JeepSnake

Dave,

My Unique Assembly Manual (about 2001 vintage) calls out Anchor PN#2258 for the Toploader trans mount. NAPA or similar should be able to cross reference.

I can't tell you without looking, but I want to think that the flat tab is on top of my crossmember. Don't quote me on that - I really would have to look.

No, having the transmission output centerline and axle pinion centerline parallel doesn't mean they point at each other. It means that their axial centerlines are parallel to each other in two separate planes. The idea is to have both driveshaft u-joints operating at exactly the same angle so that you don't get vibrations.

(I've got a cool sketch that explains this, but I can't get it scanned in as a file I can post here. Maybe I can get it to work tomorrow.)

Would love to see the sketch, also, if you could take a peak at your crossmember to confirm orientation of the tab (top or bottom), would be great[thumb]. Are you big block, toploader, jag rear also?
Thanks
May 18th, 2008, 08:33 PM
twanita

hi david- you can shim the trans up a little more like maybe 1/4"-1/2" to get some clearance but not too much because remember you have side pipes attached to frame. jim
May 18th, 2008, 10:28 PM
Naumoff

David,
Your trans cross member is in the correct way. It takes the same trans mount as a 1967 Mustang with a 390.
The Anchor 2258 or 2253 is still a good #
May 19th, 2008, 04:49 AM
davids2toys

Quote:

Originally Posted by twanita

hi david- you can shim the trans up a little more like maybe 1/4"-1/2" to get some clearance but not too much because remember you have side pipes attached to frame. jim

I am shimmed about a 1/2 already. Also, I don't understand what shimming the tranny up has to do with the side pipes at all, my sidepipes are mounted to the outside frame rail, the tranny is mounted to the crossmember.:confused:
May 19th, 2008, 04:51 AM
davids2toys

Quote:

Originally Posted by Naumoff

David,
Your trans cross member is in the correct way. It takes the same trans mount as a 1967 Mustang with a 390.
The Anchor 2258 or 2253 is still a good #

Thanks a lot. Is my driveshaft suppposed to look like that( going up hill to the rear)?
How about the guys with the crossmember with the flat piece on top, are their cars wrong?
May 19th, 2008, 06:28 AM
JeepSnake

David, I haven't checked the cross member, but it probably won't do you much good. I'm a smallblock, T-3550 5-speed kind of guy. Didn't think about that.

On the sidepipes, the issue is that your trans mount height affects the forward-rear tilt of the entire engine & trans assembly. The side pipes are bolted rigidly to the engine and to the frame, so moving the trans mount around could put the side pipes in a bind. I imagine that there is enough play in the various bolt holes, though, that you could just loosen the bolts holding the pipes to the frame, adjust the trans, and be okay.

I'll try to get that sketch scanned in at the office today. Patrick, can I attach a PDF to a post for viewing, or do I need to try to convert to JPG?
May 19th, 2008, 08:59 AM
pbrown

Quote:

Originally Posted by JeepSnake

Patrick, can I attach a PDF to a post for viewing, or do I need to try to convert to JPG?

It needs to be a JPG.
May 19th, 2008, 09:26 AM
davids2toys

Quote:

Originally Posted by JeepSnake

David, I haven't checked the cross member, but it probably won't do you much good. I'm a smallblock, T-3550 5-speed kind of guy. Didn't think about that.

On the sidepipes, the issue is that your trans mount height affects the forward-rear tilt of the entire engine & trans assembly. The side pipes are bolted rigidly to the engine and to the frame, so moving the trans mount around could put the side pipes in a bind. I imagine that there is enough play in the various bolt holes, though, that you could just loosen the bolts holding the pipes to the frame, adjust the trans, and be okay.

I'll try to get that sketch scanned in at the office today. Patrick, can I attach a PDF to a post for viewing, or do I need to try to convert to JPG?

Excellent, thanks...talked to Maurice this morning, he said you can come up small bits at a time, heat up the engine then do some more. I am already shimmed 1/2 inch, I figure an 1/8" more, he did not see a problem!
My headers are mounted with a spring type/bolt apparatus to the frame.
Maurice said my crossmember configuration is correct and I should have a minumum of 7 and a max of 30 degrees pitch either way on the driveshaft angle. Anybody have a proceedurefor setting that up...I would think you would need a flat starting referance point.