I was driving my truck this morning, all was well for the trip i took into town to get fuel, Then i took off hard and began noticing a vibration.

I thought it was my new exhaust i just fabbed up possibly settling and hitting my rear axle.

Drove down the freeway, vibration got worse, but then with varied speeds it would go away.

Got off the freeway, back thru town, on my way home i punched it and she went, but then BOOM, and a grinding sound, also felt like neutral so i Knew i lost the drive shaft.


Any way the rear U - joint broke, actually the caps came off the housing yoke.

So i believe i need pinion/axle shims since i have Rear hangers and shackles.

What are you guys running with similar setups as mine???

( 2'' McG's drop spindles/stock keys front, Mcg's rear hangers, shackles, removed rear block.)

 

i just did mine but I'm 2wd mine was +6 or +7 so i did 8* shim so its at -3 or -4 they say thats best for drag racing

 

Thanks, who did you ask, McG's??

 

Tim, you need to measure your angles to figure out which shims to get. Every truck seems to be just a little bit different. Things like wheelbase, drop kit, trans/t-case length, all change things slightly.

 

nah i bought a angle finder and figured it out myself its pretty easy just make sure when you do it that the truck is on its wheels and not on a lift or jackstands

 

running a similar setup tim, 4/4 drop rear is a shackle and hanger as well and i ran 6 degree shims and have pretty much elimated any vibrations . most commonly 65-75 mph is where you notice it. i have measured a few other trucks and as said they are different from truck to truck but not alot usually within 2 degrees . 6-8 degree shims are the biggest you will find without stacking which is dangerous and when that much is needed the spring perch's should be re clocked . try 4-6* shims and you should be fine.

 

Thanks guys !!! , i have an angle finder, just kinda wanted to see thoughts/ what shims would cure the prob. Hey Roger how is your rear dropped? The same?
Man i appreciate the info mucho gracias!! LOL I think like you said since our drops are the same i will start with the 6* shims and go from there.

 

Block removed, 2" shackles, overload leaf removed, Cal-Tracs added. 4* shim for driveline angle correction, fat end forward.

Yours should be different since you have hangers also.

 

Did you need the shims with your changes? I am surprised. What did you encounter with your changes that warranted the shims? I am doing the same as you with the exception of removing the overload spring and didn't think I would have a problem.

 

At static ride height, I had 0*. Besides knowing that 0* is not good for u-joints, on a launch or when accelerating hard, pinion angle would go positive, and I'd get launch shudder or vibration, depending on speed. The 4* shim gave me a -4* driveline angle, and now there is never any vibration.