Need help with trani mount/driveline angle

[corvette66]

I just learned how to insert pics, so i drew this nice little pic for all you
I need to know the proper angle driveline angle.

Anyway, my car was originally a 4 speed, but someone decided they needed a 700R real badly and cut the 4 speed trani mount off. So i fabricated one, but now i need to know the proper driveline angle. My drive shaft looks to be going up hill rather than down hill, so i def need some spacers to lift the trani up. But how much is the question. I had it where the drive line looked to be level or slghtly down hill, and the first run, i broke the U-joint under hard acceleration. (lota HP) So i really want to get this right. don't want to push it home again haha
thanx

 

[Hib Halverson]

The best way to solve this problem is to go measure another C3 manual trans car to find the trans mount bracket's postion in space.

The next best thing is to fab your new mount such that the angles at the diff and at the trans are the same measure say 1/4 to 1/2 deg, but opposite slopes, that is, if the driveshaft slopes up at the diff, it needs to slope down at the trans.

You can't eyeball this, you need a driveshaft angle measuring tool.

While you may have a driveshaft angle problem, most like you broke a u-joint because of torque load not an angle problem. If you have "lota HP" then you need the 2.5" drive shaft.

 

[big2bird]

The best way to solve this problem is to go measure another C3 manual trans car to find the trans mount bracket's postion in space.

The next best thing is to fab your new mount such that the angles at the diff and at the trans are the same measure say 1/4 to 1/2 deg, but opposite slopes, that is, if the driveshaft slopes up at the diff, it needs to slope down at the trans.

You can't eyeball this, you need a driveshaft angle measuring tool.

While you may have a driveshaft angle problem, most like you broke a u-joint because of torque load not an angle problem. If you have "lota HP" then you need the 2.5" drive shaft.

Yep. Get an angle finder at Home Dump. $10. Also, check that the tranny is offset 1" towards the pass. side.

 

[corvette66]

"Also, check that the tranny is offset 1" towards the pass. side. "

OK, yeah I was going to ask about that also, It naturally sat about an inch offset, and i wasn't sure if that was correct for it to sit that way. Great, one less thing to worry about. Are all cars like that, this is the only time i have noticed an offset on any car.

As for the HP, I figured the angle didn't have much to do with the broken U joint, since I have seen people run all kinds of weird angles (lifted trucks especially) But i thought I would check anyway. I have a very large yolk and a skinny shaft. So i had to get a special U joint that was 2 different sizes. The guy at the driveline shop told me that i was running the smallest size U joint they make on the shaft, but a Hefty size yolk joint, and i would probably break it with my engine. Sure enough. But really what were the chances of it breaking on the first shot!!! I couldn't belive it when it happened.

I hesitate to do any change because i would have to take the rear diff out to upgrade to a larger joint all around.

 

[JohnZ]

All '63-'82 Corvette engine/transmission mountings placed the engine so the axis of the crank/trans output shaft was oriented at 3* down from horizontal.

 

[corvette66]

uh, excellent. so as long as the trans shaft is 3* down hill, everything else will be correct. Now all i have to do is find a perfectly horizontal part of the chassis to measure against. any ideas?? The bottom flat part of the trani cross member is probably perfectly horizontal huh

If i could get the car sitt'n perfectly level, i could put an angle finder on the tail shaft.

???