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GMFS MoPar/Air Force Crew
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5,457 Posts
Discussion Starter #1
Ok fellas, I am about to install 3 inch lift blocks on the rear of my '02 2500HD. I talked to someone today who told me that they put 3 inchers on the rear of thier older Blazer and it started wearing U-joints out real fast. Is there some truth to this (I understand the ideal that lifting the rear of the truck will change the angle of the driveshaft to the pumpkin and tranny) or is this a rare situation this guy is talking about? Thanks.
 

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GMFS MoPar/Air Force Crew
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5,457 Posts
Discussion Starter #3
dammit, I bet they are not as cheap as the $30.oo ones I bought at AutoZone, huh? Any info on where to get these angled ones at?
 

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GMFS slowest truck :read:
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5,501 Posts
if your only replacing your stock blocks and not stacking them, i wouldn't worry about getting the angled ones.
hds don't have blocks stock.

btw, you WILL wear out u joints sooner...but it shouldn't be considerably sooner. Get good joints, grease them good, make sure your angles are right, and ride on. If you have vibes, they KILL joints much quicker...ive had some last 3 months, ive had some last over a year and my shaft is MUCH more angled than most guys on here. You won't know if you need shims till you you get it lifted up and put weight back on it.
 

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GMFS MoPar/Air Force Crew
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5,457 Posts
Discussion Starter #6
10-4, thanks for the info fellas. I am going to get better joints like you suggested Nick. I think it will turn out ok 'cause the truck is pretty long so that helps out the angle some. I will check back in if any problems turn up.
 

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Install the blocks, figure out what angle (degree) your pinion should be at, buy a cheap degree shim (that will get you closest to your desireable pinion angle), install the shim, and you'll be all set.

I put 45k miles on my old truck with a 8-10" rear lift. I sold the truck with stock u-joints. It's all about the pinion angle.
 

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GMFS MoPar/Air Force Crew
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Discussion Starter #8
thanks for the advice, I am learning as I go.
 

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Is your truck crewcab or extended? Is it a one or two piece rear driveshaft?

I'm running a one piece driveshaft with 7" springs and no angle shims at all. They are not needed with mine. I ran 3" flat blocks, and 5" flat blocks also with AAL with no problems. The driveshaft is so long, the angles hardly changed. If figured mine all at with a protractor and it's all within specs. Given the 2 degree upward movement of the pumpkin at acceleration, you are allowed a 3 degree difference between the dshaft angles at the pumpkin and tcase. I'm only at a 2 degree difference with 7" springs. You'll be fine with your blocks.

If your local, let me know. I have some spare blocks and ubolts, but you'll probably want new ubolts anyway. Merkin Spring Works in Wilmington can custom make you any size.
 

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Bayou Surface Drive, LLC
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7,077 Posts
there is a thread about high speed vibs. read it they have good respnses in there to help yo get your pinion angle right
 

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GMFS MoPar/Air Force Crew
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5,457 Posts
Discussion Starter #11
Is your truck crewcab or extended? Is it a one or two piece rear driveshaft?

I'm running a one piece driveshaft with 7" springs and no angle shims at all. They are not needed with mine. I ran 3" flat blocks, and 5" flat blocks also with AAL with no problems. The driveshaft is so long, the angles hardly changed. If figured mine all at with a protractor and it's all within specs. Given the 2 degree upward movement of the pumpkin at acceleration, you are allowed a 3 degree difference between the dshaft angles at the pumpkin and tcase. I'm only at a 2 degree difference with 7" springs. You'll be fine with your blocks.

If your local, let me know. I have some spare blocks and ubolts, but you'll probably want new ubolts anyway. Merkin Spring Works in Wilmington can custom make you any size.
I have an extended cab short bed, and I believe my rear driveshaft is one piece. I am at work right now in Smyrna, but when I get out at midnight, I can double check. Thanks for the info on Merkin. I might be calling them when I go with bigger blocks. BTW, I live down in Camden by the Base.
 

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GMFS Enforcer
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3,568 Posts
I would return those A-zone blocks and get some good tapered ones. From what I have seen, the A-zone blocks are cheap aluminum.
 

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Yeah.... what freyguy said.
You'll probably be fine due to the length of your driveshaft. I had a mess of trouble when I lifted my K5 and had to get a new shaft made up and custom shims, but my driveshaft is probably close to half the length of yours. Send me or freyguy a pm and let us know if we can help.
 

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Mike D
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53 Posts
ive been lifted since last august and my ujoints have been worn out for a couple months now, not sure if the lift had much to do with it or not cause they are original ujoints and the trucks got 100k on it. guess ill see how long new ones last when i replace them.
 
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