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Axle shims?

Skandocious

Skandocious

Post Whores Make Me Sick
19,083
663
California
So my truck has had a vibration that happens when accelerating from a stop, for quite some time... The truck has a 4" suspension lift and a 2-piece driveshaft, and I made the problem A LOT better by shimming down my driveshaft support bearing to make my driveshaft a bit straighter

DSC00889.jpg


but the vibration is still there... I figured I might try to shim my rear axle and point the diff up more towards the t-case... Anybody have experience with this? How many degrees would I need for a 4" lift and where can I buy them? Couldn't find any on summit...
 
surewhynot

surewhynot

Rep whores make me sick
13,843
821
Florida
Most lift springs come with shims. Did you get springs or blocks? Most likely a 2 degree shim will suffice. Lemme look to see where you can get them.
 
mrfixit

mrfixit

Chief Chaotic Engineer
8,334
171
Malfunction Junction, Fidelity MO -or- Mound City,
Will the 2degree shim increase the pinion angle sufficiently? He may need to have the axle mounts re-welded and even narrow the tranny mount for proper alignment.
 
surewhynot

surewhynot

Rep whores make me sick
13,843
821
Florida
You want equal but opposite angles at each end. So if your front joint is about 2 degrees down, your rear should be about 2 degrees up. With just 4 inches, 2 degree will be a good starting point. Vince is 100% correct, ideally you don't want any more than 3 degrees, but sometimes that is hard to achieve with a lifted truck.
 
surewhynot

surewhynot

Rep whores make me sick
13,843
821
Florida
mrfixit said:
Will the 2degree shim increase the pinion angle sufficiently? He may need to have the axle mounts re-welded and even narrow the tranny mount for proper alignment.
Click to expand...

I think it will be a good start because he isn't lifted too high.
 
mrfixit

mrfixit

Chief Chaotic Engineer
8,334
171
Malfunction Junction, Fidelity MO -or- Mound City,
short of being absolutely sure the truck sits level on level ground, yep. I have heard of guys using laser levels, but that's an investment lol
 
mrfixit

mrfixit

Chief Chaotic Engineer
8,334
171
Malfunction Junction, Fidelity MO -or- Mound City,
Skandocious said:
Yeah Tom is all that really necessary for only 4 inches of lift? I'll go take a picture of my pinion angle, you'll see its not that hardcore...
Click to expand...
Not if the shims handle it. You want the alignment to match what it was stock.
but sometimes the protracted length ot the shaft can do it too... It's designed to slide so far in, and you have it a bit further out now.
 
surewhynot

surewhynot

Rep whores make me sick
13,843
821
Florida
mrfixit said:
You want the alignment to match what it was stock.
Click to expand...

That is what most people miss when they lift a truck. Everything was engineered to work a certain way and any deviation from that way can be a problem.
 
surewhynot

surewhynot

Rep whores make me sick
13,843
821
Florida
Exactly. It's nice to see you did it right, instead of just using washers like some people do.
 
Fellro

Fellro

Moderator
Staff member
8,049
416
Iowa County, Iowa
You can get an angle finder, basically, it is a weighted needle inside a marked housing. Harbor Freight has them for certain, not sure where else has them. I have mine from my fabrication days, very handy for setting powertrain angles..
 

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