I am about ready to put my drivetrain back together after doing my batwing install.
http://forums.corvetteforum.com/c3-t...g-install.html
The rear end is level to the ground, just like it started, but only 1/2" higher. The engine/trans has a definite nose up/ tail down attitude, the driveshaft now has a front down/tail up attitude to meet with the now higher rear end. The low point of it all is the trans to driveshaft u-joints. In other words, right now I have a straight down hill line from the crank to the trans out put shaft, then an uphill angle from there to the rear end, and the rear end is level, measured at the strut rod mount. Should I raise my trans mount slightly to get everything into better alighnment? Does it even matter?
Bee Jay

 

It matters to the U-joints. Ideally, you want the crank CL and the pinion CL parallel (to each other, not the ground), but not concentric, so that the driveshaft is at the same angle at each end...



Doesn't matter which is higher, and we don't have to consider the diff rotating like conventional live axles. Hope that simple illustration helps.

 

Thanks. So if the engine/tranny is slightly nose up, the rear end should be slightly nose up?
Bee Jay

 

BJ:
I looked at you batwing retro ... just wanna say it all looks great! Merry Christmas.

-add- perhaps this too will help a bit ... but note where they make pinion angle distinction between race & street cars.

http://www.carcraft.com/howto/91758/index.html

 

yes just like it was drawn in the diagram

 

Maybe this makes it easier to envision...



Also, the optimum 2-3* angles are exaggerated above.

 

If I may elaborate a little on that diagram.... when I measure angles after doing conversions here I find it easier to do it by getting 3 angles.

1. get a measurement(angle) from the bottom of the tailhousing back near the end of the case itself. We'll call this " A "
2. Get a measurement from the center of the driveshaft tube(bottom side) and we'll call this one " B "
3. Finally, with the pinion yoke turned vertical and with a c-clip removed, take a socket that fits inside the yoke casting and directly on the u-joint cap and get a reading here. Cal this last one " C ".

Now take A-B= front working angle and then C-B= Rear working angle. It is these 2 working angles that we are concerned with. They should be equal but opposite in a perfect setup. They cannot vary by more than 1/2* and none of the angles measured can exceed 5*. Ideally, you'd want a " + " on the front working angle and a " - " for the rear working angle. Generally, we shoot for working angles in the +2 -2 or +3 -3 range when setting them up here and have never had any trouble or vibrations.



Richard
Tech Support

 

I had to raise my tranny mount 3/4", and raise the nose mount of the rear end 1/4" to get them parallel to each other. The drive shaft is almost parallel to the ground now, and everything appears much "straighter". I may have to get much more accurate readings later, but I am convinced that I am much closer to ideal now. Thanks for everyones help.
Bee Jay