On mine I had to move space the trans mount up and then space the trans off the mount to get the rear driveshaft angle correct. It had a horrible vibration due to pinion angle. Hence by moving the trans up it also effected the front drive shaft angle. It has a mile vibration at 70-75 when t-case is in auto only.

 

Silly question, but why in the world would you need to use auto 4x4 at 70 mph in Texas??

I use it all the time here, but on snowy/icy roads.

 

When it rains on the occasion that it does and I live down a nasty road but i'm not driving 70 down that road anyhow.

Also when out playing in the twisties the main reason I dropped it.

 

I see. I get quite a bit more understeer(push) with my truck when I'm in 4x4 and driving hard in the twisties.

 

Mine does pretty much the same thing but if you go in low on a corner and really dog it through the apex it sure is a blast to drive. I've got 17" michelins until they get low enough on tread to put the denali 20's on. But they stick and hold pretty damm good considered they were never meant to be used like that on a truck.

 

Now, for drag racing you would go above 70 mph, what would be the lowest you could do then?

 

I'm 3/5 and have launched in 4 hi. Vibration goes away at 97 but it's a barely noticeable vibration.

 

The silver 2011 with the 5/7 should be making some passes in the spring. I think the track opens up around Mother's Day, but the schedule isn't posted yet.

 

Sorry to bump an old thread, but I'm at 5/8 with my ext cab 4x4...I get the vibration/rattle at anything over 60 when I release the gas pedal...tried shimming tranny and that moved the noise to 80+...tried 2degree pinion shim, no change...tried 4 degree pinion shim, no change...should I attempt a 6 degree? The noise is obviously coming from the back, it isn't CV's or differential...I did notice a little oily wetness on the rear end of the driveshaft...any solution??

 

I am running a 5/5 with no problems on my truck