How to change pinion angle?

I'm trying to align my drivetrain and fab a crossmember support for my T5.
I'm measuring with a protractor and a weight tied to nylon fishing thread.
I'm using the horizontal rib of the differential and the gearbox and the driveshaft itself as measuring surface.
All measures done while frame at 0° (measured that at underside of the sides of the frame).

So Far I have the engine 3° backward, as usually recommended, my driveshaft 1° backward, and my differential pretty much level.
So if I could tilt my differential upward 4° I would have the engine and the differential on parallel planes and good hope to get the driveshaft level.

How can I change the pinion angle?
The only way I can see so far is by getting the differential bushing thinner.
I installed energy suspension poly bushings, and the new bushing was the same thickness that the previous one.

You don't need to rotate the diff 4 degrees the other way. Having the trans tailshaft down and the diff pinion down is fine for phasing the ujoints. It is also fine to have the pinion up equal to the tailshaft down but its pretty much impossible with C3's (without hitting the tunnel).

This is close to what you have:

I had the same issue with my Richmond 6 speed.
trans tail 3 degrees down, driveshaft at 0, differential was down 1 degrre in front.
First shim the trans tail as high as possible.
Then I cut the rubber front mount thinner. I saw another pic on here of someone re-drilling the mount that connects to the diff too.
I got mine matching within a degree, no vibration problems.
Check out this thread:
http://www.vettemod.com/forum/showthread.php?t=3177

I cut my diff poly bushing to get the angle where I needed it to be. ...and don't confuse the angles as you're looking at trans and diff from the same side and flip the protractor.... don't take much to get it wrong ("angle down" vs "angle up")

BBShark said:

You don't need to rotate the diff 4 degrees the other way. Having the trans tailshaft down and the diff pinion down is fine for phasing the ujoints. It is also fine to have the pinion up equal to the tailshaft down but its pretty much impossible with C3's (without hitting the tunnel).

This is close to what you have:

Click to expand...

This is surprising to me, I thought diff and trans had to have the same angle, not the opposite angle. If so I could put shims on the diff bushing to make it point downward even a little more and have 3° on both side.
Someone please confirm this because it goes opposite way of all I've read on the subject so far.

Garys 68 said:

I had the same issue with my Richmond 6 speed.
trans tail 3 degrees down, driveshaft at 0, differential was down 1 degrre in front.
First shim the trans tail as high as possible.
Then I cut the rubber front mount thinner. I saw another pic on here of someone re-drilling the mount that connects to the diff too.
I got mine matching within a degree, no vibration problems.
Check out this thread:
http://www.vettemod.com/forum/showthread.php?t=3177

Click to expand...

Shimming the trans tail as high as possible gives me clearance issues with the parking brake cable. It'd been cool to keep the trans at 3° down, I would only have to notch the passenger side of the trans tunnel.
If I get you right what you tried to achieve was having the whole driveline almost level, isn't it something you usually try NOT to achieve?

denpo said:

This is surprising to me, I thought diff and trans had to have the same angle, not the opposite angle. If so I could put shims on the diff bushing to make it point downward even a little more and have 3° on both side.
Someone please confirm this because it goes opposite way of all I've read on the subject so far.

Click to expand...

Take a look at this post by 427Swede. It give a link to driveline information that describes the arraingement that I have described. Phasing crrectly is not dependant on whether the angle is + or -.

http://www.vettemod.com/forum/showpost.php?p=89716&postcount=66

Also, remember that you have a side to side angle also (pinion is offset from tail of trans).

I ended up with the trans about 3 degrees down in back. I got the diff almost 2.5 degrees up in front. Driveshaft angle was flat at 0 degrees.
Do a quich search for "driveline geometry" pretty much everyone, including transmission sellers, reccomend the trans down and the diff up at equal angles and the driveshaft within a certain range.

Garys 68 said:

I ended up with the trans about 3 degrees down in back. I got the diff almost 2.5 degrees up in front. Driveshaft angle was flat at 0 degrees.
Do a quich search for "driveline geometry" pretty much everyone, including transmission sellers, reccomend the trans down and the diff up at equal angles and the driveshaft within a certain range.

Click to expand...

That may be true, but on the C-3, the 3rd member is stationary, and does not move up and down like 99% of most vehicles.