need suggestions about pinion angle

[Wtfan18]

hey guys i finally got some free time to measure out my pinion angle this morning. currently the trans sits at a -2 degrees. which seems pretty typical... the rear end however sits at a +3 degrees. i know most say that the overall angle of the drive train shound usually be around -2 or -3 degrees correct? i already have a 4 degree shim in the rear and i still need to go another 5 to 6 degrees down! how the heck is that possible? can caltracs be used to adjust pinion angles? please send any suggestions you may have. current setup is a 4/6 bell tech drop with a rear flip kit. i need to figure this out because at 70 + i cant stand the vibrations and at 100 it feels like the drive train is going to vibrate loose... thanks all.

[r6z4o6]

So the back of you transmission points DOWN at 2* to the middle of the truck, and your rear end pinion points UP at almost he same angle. I would say it is correct then.(this pic kinda gives an idea, but it might be opposite)



The "equal but opposite" angle is ideal in most cases, i believe. The imaginary line going out of trans and out of your pinion "should" be PARALLEL. Especially when trying to iron out vibration. I dunno if we have gone over this with your truck, but is there vibrations when the truck is on jack stands? Have you scooched under the truck while it is running on jack stands and looked at the spinning drive shaft?

[Wtfan18]

So the back of you transmission points DOWN at 2* to the middle of the truck, and your rear end pinion points UP at almost he same angle. I would say it is correct then.(this pic kinda gives an idea, but it might be opposite)



The "equal but opposite" angle is ideal in most cases, i believe. The imaginary line going out of trans and out of your pinion "should" be PARALLEL. Especially when trying to iron out vibration. I dunno if we have gone over this with your truck, but is there vibrations when the truck is on jack stands? Have you scooched under the truck while it is running on jack stands and looked at the spinning drive shaft?

yeah it if was -2 and +2 it would be okay but is -2 on the trans and +5 on the rear end so its 3 degrees off. no i havent watched the drive shaft on stands i suppose i should huh?

[r6z4o6]

You should not replace or repair anything without verification of the problem. The more time you spend properly diagnosing the problem, the less money you will spend to fix it!! You have a one piece drive shaft, yes? Put the entire truck up on jackstands (so the rear tires will move. Don't use cinder blocks or you will need a new garage door :p) and start it up, put it into gear, and give it some gas!!! Get under there and look for a bent driveshaft, loose leafsprings, missing hardware, obvious stuff. Then take the tires and wheels off and do the same thing, hit the gas, does anything change?? Before you spend money on new pinion shims, you MUST be able to systematically cross every other variable off the list as NOT causing your problem. Bent wheel, busted belt in tire, loose bolts, etc. .....

WAIT a minute....

So if you took out your shims in the back, your rear end would be pointing almost 10* into the air??!? You've got a problem right there....

[Wtfan18]

okay okay i figured it out. my buddy and i totally goofed when we put the shims in. so i Shimmmed my transmission to right around 0 degrees and changed the shim and the rear end is now at -1 degrees and i can hit about 110 without any vibrations im hoping with a set of caltracs i can make it hold the pinion angle at any speed and i wont have any vibrations at all. thanks for the help guys. user error on my part lol. but Damn it feels good to really be able to hammer all of 3rd gear and some of 4th with 5th and 6th still free 8). 1/4 mile here i come

[r6z4o6]

LOL at the 3rd - 6th gear comment!!!

Don't forget videos!

Glad you got it fixed!!!

[Wtfan18]

haha oh you know it, youtube central. ive been waitin 2 years to run the 1/4 now LOL i just hope im not disapointed with the times i put up.