Engine/tranny Mounting angle?

gr8vet

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I didn't know any other way to ask this question.........

95% done with the T5 Swap into my 82. I did not reference anything on how the engine and tranny normally lay. What do you guys reference for correct mounting? i.e. is the bottom of oil pan level with frame? Engine angle backward 3 degrees off level??? Drive shaft run straight and level? Of course at this point I can swing the back of tranny up and down over 5 inches.

Hope this makes sense.

thanks
tt
 
I didn't know any other way to ask this question.........

95% done with the T5 Swap into my 82. I did not reference anything on how the engine and tranny normally lay. What do you guys reference for correct mounting? i.e. is the bottom of oil pan level with frame? Engine angle backward 3 degrees off level??? Drive shaft run straight and level? Of course at this point I can swing the back of tranny up and down over 5 inches.

Hope this makes sense.

thanks
tt
no. Dont level to the frame as a reference or you will be way off. Do a google or search old threads and read up on drive line angles, lots of info out there. You will need to measure the angle of your pinion also. Target for opposite and equal angles between trans/driveshaft and driveshaft/pinion but no more than 3 degrees.
 
Terry, I am interested to see what angle you achieve with the diff in this view:

drivelinealign2.jpg
 
Thus far:

Did not have to cut the drive shaft, going from a 700r4 to the T5.

First pass, if I let the tranny tail set hard on the cross member the tail shaft is at 3 degrees off plumb. At this point the drive shaft is at 5 degrees off level. I have no clue what the pinion is or how the heck to get that info. Measuring frame and some of the side castings on the pinion it is all showing level as it sets, accurate or not, no idea? I guess from my original question, what is the original pinion / tranny angle. Does the old tranny tail shaft set level or at what degree? (If it were not 22 degrees outside I would walk to my shop and get my assembly book, I'm going slap myself is all this info is in there.)

Now, If I jack the engine to level where the tail shaft is level/plumb, (now with a 2x4 under tail on top of cross member) then I get about 2 degrees or so on the drive shaft.

tt
 
Good Lord, how for the love of all that is good in this world do you ever drift the complete transmission into the pilot bearing? My friend Jeff and I dang near quit Corvettes and joined the local VW club after that. We could not get the bell housing to clear the floor and over the clutch. We did not approach this at an incredible angle if that is a key? We did try to come at it at maybe 15-20 degrees. Had to unbolt the bell, attached to engine, then somehow by the grace of God got the throwout bearing on and just shoved the whole dang thing on. Required some beating, cussing, more cussing, couple of breaks, and finally it pulled up. If the throw out bearing is to tight or too loose, God help me. You would think that Ford would have made it easier to mate their crap up to a chevy!

tt
 
Thus far:

Did not have to cut the drive shaft, going from a 700r4 to the T5.

First pass, if I let the tranny tail set hard on the cross member the tail shaft is at 3 degrees off plumb. At this point the drive shaft is at 5 degrees off level. I have no clue what the pinion is or how the heck to get that info. Measuring frame and some of the side castings on the pinion it is all showing level as it sets, accurate or not, no idea? I guess from my original question, what is the original pinion / tranny angle. Does the old tranny tail shaft set level or at what degree? (If it were not 22 degrees outside I would walk to my shop and get my assembly book, I'm going slap myself is all this info is in there.)

Now, If I jack the engine to level where the tail shaft is level/plumb, (now with a 2x4 under tail on top of cross member) then I get about 2 degrees or so on the drive shaft.

tt

Don't worry about the driveshaft angle. Let it be whatever it needs to be. Measure the diff on the yoke flange or one of the machined surfaces on the diff.
 
The tranny angle is the easiest to measure, you can simply use the starter mounting pad or any other machines surface parallel to the crank/transmission axis. The rear, like Larry says, measure the angle of the pinion, on your 82 the easiest spot to do that is right under the case, behind the cast in pinion mount. That whole underside is pretty parallel to the pinion axis.
 
I'm in the middle of an LSx, Richmond 6 speed conversion.
My engine/trans is at a 3 degree down angle in the back, driveshaft at 0 degrees, but my differential was 1 degree down in front. I'm guessing the rear rubber differential upper rubber mounts are a bit worn and crushed. I cut the front rubber mount and got the front up 2 degrees.
I'm hoping this is close enough. But I cant remember if the body could be lifted from the diff crossmember mount (68 flat style) without disassembling the whole rear end. Anyone tried to change out the 2 rubber mounts without pulling the whole rear end?
 
I'm in the middle of an LSx, Richmond 6 speed conversion.
My engine/trans is at a 3 degree down angle in the back, driveshaft at 0 degrees, but my differential was 1 degree down in front. I'm guessing the rear rubber differential upper rubber mounts are a bit worn and crushed. I cut the front rubber mount and got the front up 2 degrees.
I'm hoping this is close enough. But I cant remember if the body could be lifted from the diff crossmember mount (68 flat style) without disassembling the whole rear end. Anyone tried to change out the 2 rubber mounts without pulling the whole rear end?

If your old bushing is crushed and worn, a new bushing (thicker) will actually make the pinion point DOWN more. I have measured a few C3's without drivetrain mods and I'm finding that the pinion angle is about 0 to 1 degree down. All information I can find states that the pinion is supposed to be equal and opposite of the transmission angle.

My 68 was -.8 down at the pinion and, after disassembly and reinstalling, it is -1 degree. I would have to raise the front of the diff 1 inch to get 3 degrees up. At that point the yoke would be pushed through the tunnel!

It would be great if a couple of people could measure theirs, I think they might find that 0 is normal.
 
Alright guys, its in and driven! Who needs a dash and passenger seat! Man, it is sweet. Old vettes deserve a 5 speed. Shifts great, oh how nice to wind it out and let those pipes rattle. Setup was same as BlackBetty's, which made trial and error much less. Thanks Tyler!

I spent alot of time trying if nothing else just to learn what is what on this '82. After measuring the old tranny mounts and pinion I have a 1 degree down angle and the old tranny should should have been 1 degree also, maybe.

The T5 tranny was placed at the same shaft distance from cross member and the above proved to be true. This actually put the top of the shifter plate at the same level as the top of the tunnel, which is perfect.

BTW, with my front being lowered, this is probably why I am not at 0 degrees.

tt
 
The T5 is a direct swap from the 700R4, it's that way in 3rd gen cars too. Same driveshaft length and all.

Your car being lowered has no influence on the setup. You calculate the anges of the drivetrain relative to each other, that takes out wether the car is sitting level or not.
 
OK the differential is mounted at 3 points. there are 2 rubber bushings on the upper crossmember to the rear and one mount in front of the pinion, correct?
The front of the diff was down 1 degree. In order to get the angle to match the trans, it needs to be up 3 degrees. I cut the front mount so the front is up 2 degrees. If the 2 rear mounts were replaced with new, thicker rubber, wouldn't that bring the back of the differential down?
I'm in the middle of an LSx, Richmond 6 speed conversion.
My engine/trans is at a 3 degree down angle in the back, driveshaft at 0 degrees, but my differential was 1 degree down in front. I'm guessing the rear rubber differential upper rubber mounts are a bit worn and crushed. I cut the front rubber mount and got the front up 2 degrees.
I'm hoping this is close enough. But I cant remember if the body could be lifted from the diff crossmember mount (68 flat style) without disassembling the whole rear end. Anyone tried to change out the 2 rubber mounts without pulling the whole rear end?

If your old bushing is crushed and worn, a new bushing (thicker) will actually make the pinion point DOWN more. I have measured a few C3's without drivetrain mods and I'm finding that the pinion angle is about 0 to 1 degree down. All information I can find states that the pinion is supposed to be equal and opposite of the transmission angle.

My 68 was -.8 down at the pinion and, after disassembly and reinstalling, it is -1 degree. I would have to raise the front of the diff 1 inch to get 3 degrees up. At that point the yoke would be pushed through the tunnel!

It would be great if a couple of people could measure theirs, I think they might find that 0 is normal.
 
OK the differential is mounted at 3 points. there are 2 rubber bushings on the upper crossmember to the rear and one mount in front of the pinion, correct?
The front of the diff was down 1 degree. In order to get the angle to match the trans, it needs to be up 3 degrees. I cut the front mount so the front is up 2 degrees. If the 2 rear mounts were replaced with new, thicker rubber, wouldn't that bring the back of the differential down?


Moving the back of the differential down (by remounting the crossmember) will make the angle positive.

I am questioning whether or not C3's left the factory with the differential level. The few that I have measured are basically level and I can't raise the front of my pinion 1 inch required to make a 3 degree angle without the pinion punching a hole in the tunnel!


449b3d4f6f3220.jpg
 
I cant get the ROD trans any higher to minimize the angle, so I had to do something with the diff. I think both probably were at 0 degrees from the factory.
So I cut the rubber bushing on the front of the differential to raise it up but only got about 1-2 degrees up.
So my question is, if I replace the 2 rear rubber upper differential mounts to drop the rear, do I need to disassemble the whole rear end? Or can I just unbolt the mount and lift the frame to replace them?
 
Most, if not all engines and trans are installed at a 3-4 degree angle.

Separating the cross member from the frame cups usually requires a prybar. I suppose you could do it with the suspension in place but be careful, the pinion mount and the trailing arms are the only things holding the rear suspension at that point.

Not sure what you will use to reposition the cross member for the additional 1 degree. You will need a 3/8 spacer to make 1 degree. Maybe you could put 3/8 plate between the diff and the crossmember?

Thinking about this (as I'm typing), I would consider leaving it at 2 degrees. If the original installed angle was 0 degrees, your probably good.
 
I'll drive it and see if there's any vibration. BTW, I actually had the rear differential crossmember off a year ago when I went through the differential. I just cant rmember if there would be any issues with removing it with the whole rear end intact.
 
For what it's worth, a couple years ago I tried to make them parallel.
I loosened the diff crossmember at the rubber mounts, put a 3/8" shim between the diff and the crossmember to lower the back, cut down the front mount rubber to about 1/8" to twist the front up, and then re-tightened the crossmember. I then raised the tail of the trans about 1/2" also.
The closer I got to parallel, the worse the vibration got. I finally just put it all back to stock and the vibrations were reduced by 95%. What I get now is minor mirror fuzziness at highway speeds & that's how I left it...
Not trying to contradict anything, that's just the way it worked out for me.
 
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There could be a slight problem with the alignment when looking from the top or the bottom, a lot of these frames have some motor mounts issues, they become apparent when you install poly mounts, usually it's quite a struggle to get the bolt in on one side. These kinds of issues can mean the driveline is not pointing straight back. The thing is, you have to get that right too because its the actual vector angle that needs to be the same on both ends, so even if you get it right from the side view, if the other one is off it will still vibrate.

If the way you have it set up is vibration free, by all means leave it as is!!
 
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