Pinion angle and drive train alignment
 

Need a little help here setting up car. There is a lot of information out there and some of it contradicts others. Here is what I have:

Engine/Trans is at 4* tail shaft down...
http://i218.photobucket.com/albums/c...Picture072.jpg

Drive shaft is perfectly 0*...
http://i218.photobucket.com/albums/c...Picture074.jpg

Pinion is at 6.5* down...
http://i218.photobucket.com/albums/c...Picture077.jpg

Some sources say to only use the drive shaft and pinion while others say to throw the drive shaft out all together and use the tail shaft and pinion only. My opinion is that the tail shaft and pinion should be equal and opposite for a street driven car. (meaning that my tail shaft is pretty much fixed, so I need to angle the pinion UP 4*) this would put the center line of each parallel to one another. To me, this would reduce the vibration induced by the offset angles.

The other theory is that the drive shaft and pinion should have a -3* angle no matter the engine/trans angle.


What say you?

Proper angle
 

Angle of trans and pinion should cancel. 4 down at trans equals 4 up at pinion.

i am with you. pinion to be 1 deg different than tail shaft, i would set the pinion at 3 deg up.

probably going to hear a few different ideas.

Here's your problem. When you change your pinion angle from -6.5 to +4, your driveshaft is going to rise 4 degrees +or- UP towards the rear end. You are canceling out your U Joints BUT you must ADD your working angles. What I'm trying to tell you is your working angles are going to be approx. 7-8 degrees which are humongous for high speed. Everything I've read says 3 degrees is the max working angle for smooth high speed operation. I'm assuming this isn't a rock crawler. :D

What really needs to happen is for you to raise your tailshaft as far as you can reasonably to decrease your driveline angle. Trans/tunnel or Headers/floor clearance will be your first problem as most are designed for factory angle which is in the +or_ 4 range.

I found my car the happiest with unconventional angle of -3.5 drivline angle and a -2-3 degree pinion angle. That got my working angles under the magic 3. I've everything from equal and opposite to where I'm at now. If my car wasn't done, I'd slice the tunnel in a heart beat to reduce driveline agnle and reduce my working angles to 1-2 degrees. I'm an anal prick with tweaking cars....

Your type of body mounts, engine mounts, trans mount, suspension bushings will amplify vibrations once you get away from stock materials.

This is really confusing stuff and this is one of the best articles I've seen. They don't address what I'm telling you but we are lowering cars well past what they were ever engineered to do.
http://www.iedls.com/asp/admin/getFi...&TID=28&FN=PDF

+1 on todd. never throw out the ds measurement as the WAs are critical. also, buy a cheap digital level on ebay. my little 1x1 box was like 30 bucks shipped. it will do .1 degrees with a +/- .1 degree accuracy. way better than the one youre using. i find that style gets the needle stuck when its tipped sideways just a little. plus you can zero out the digital which takes care of some of the math. zero on the ds and put it on the other two. it will tell you those angles and theres no way to screw up the math.

+1 on the digital angle finder.

Craftsman has a nice one for $31 bucks.

item #00948295000

Darren

Maybe I am wrong here, but I thought the pinion angle was a total? So the -6.5 and 4 would be a total of a -2.5? Maybe I have this wrong?

I just bought one of those myself. It is a pretty nice unit, it does angles and percent slope. It is on sale right now for $29.99.

http://www.craftsman.com/craftsman-d...p-00948295000P