Pinion angle

[vortec350]

I have never had this problem but then again I did not swap an LS1 in mine either.I did lower the rear with shackles,and now have traction bars and the bars brought the ass end back up about another 1/2 inch or so.Never had an vibrations though.

[NITROUS]

vortec350, you'll be good for a 2/4 drop with no problems if you want to.

[farmtruc]

LOL, did i say that backwards, rearend down, trans up, actually 1-2 degs won't hurt.
sorry about that,
allen

[1BADC10]

Hear's an old thread that I figure I need to ask questions regarding this topic. I seem to have a similar issue with my truck. The thing is, I only feel vibration & hear driveline noise at speeds of 90+ I've gone up to 100, but am hesitant in doing so b/c of the vibration. Remember my thread about the busted trans tail housing? Problem still exists... just hasn't broken anything... yet.

Any chance pinion angle could be my issue as well? I had to haul a heavy couch & love seat for 80+ miles, and though my memory isn't the greatest, I've passed an 18 wheeler at 95. Problem is, I don't remember if the vibration was there or not.

Any ideas?

[GMCwantsLS1]

Funny thing on mine is vibration actually goes away at 100+. It is most noticeable at 75.

[Jewmont3]

<div class='quotetop'>QUOTE(GMCwantsLS1 &#064; Sep 11 2006, 06&#58;23 PM) [snapback]64752[/snapback]</div>

Funny thing on mine is vibration actually goes away at 100+. It is most noticeable at 75.
[/b]

I get a vibration around 68-73 or so...I have not changed my engine or tranny yet however I did replace the 10 bolt with a 14 bolt sf and had 4.10 gears and an eaton posi installed. The only other thing that was touched was the drive shaft was shortened and re-balanced...My buddy thinks its the driveshaft. I bent the stock driveshaft. This is an aftermarket steel one...allegedly...

[1BADC10]

<div class='quotetop'>QUOTE(Jewmont3 &#064; Sep 11 2006, 07&#58;54 PM) [snapback]64757[/snapback]</div>

I get a vibration around 68-73 or so...I have not changed my engine or tranny yet however I did replace the 10 bolt with a 14 bolt sf and had 4.10 gears and an eaton posi installed. The only other thing that was touched was the drive shaft was shortened and re-balanced...My buddy thinks its the driveshaft. I bent the stock driveshaft. This is an aftermarket steel one...allegedly...
[/b]

Well... I&#39;m on custom shaft #2. This one seems to have lasted longer, but vibration is still there, and I can&#39;t take off during the week to get it resolved.

[kwkenuf]

Have you measured your pinion and tranny angles? I have the same issue with both my swaps and I am working on the truck issue now. My vibration starts about 70mph and goes up to 76 then calms down.

I&#39;ve read that if you have a difference of 2 degrees or less between pinion and tranny you should have no vibration..... My tranny is pointing 5 degrees down and my pinion is pointing 3 degrees up. Theoretically I should be OK but in reality, no. I&#39;m either going to shim my pinion down or raise my tranny and try to fix this....

edit: Disregard what I&#39;ve typed above.... after reading this mess through, I&#39;ve got a serious problem with my math here... I gotta rethink this......

[kwkenuf]

Apparently I&#39;ve got to calculate the individual angles vs the drivesahaft then compare pinion and tranny angles. This article is a pretty good read. If anyone else can explain this, fire away&#33;

[1BADC10]

I had not measured the angles. I trailered the truck over to Driveline of Baton Rouge, and they measured everything. They told me I would be good to go. I&#39;m going to try to take a day off soon to drive it to them (they&#39;re not open on weekends... SUCKS ASS&#33, and have them ride with me. Before I do that, I want to measure, yet AGAIN, to ensure that the entire powertrain is centered, go back to FMS to ask about rear carrier, then have Driveline check it out.

I&#39;ll see if I can get some well lit pics to post, but measuring WILL be the best insurance.