Rotational grinding when letting off gas after 35mph

Pinion angles should be 3 degrees or less. There should be 3 or less degrees on front pinion as well as 3 degrees or less on the rear. I'm not sure how to change the front pinion angle with out un-equal bracket heights, but in the rear different length or adjustable trailing arms would do the trick. Hope you get it straightened out.

 

Dont mean to thread jack, but do you think a 2.5 lift in the rear would cause the pinion angle on the rear diff to be significantly off? I’ve had a really faint rear diff whine at 60-68mph for a while now, and cant for the life of me remember if it was doing it pre-lift…wonder if that might be pinion angle….

 

First I don't know wtf is wrong.

But second he dropped his crossmember so stop saying he need a diff drop.

Pretty sure all bracket drops you cut and weld or bolt but cut regardless.

 

Not sure anybody said he needed a diff drop. But whether it was through that bracket, or through a traditional diff drop, it sure sounds like his front diff is no longer in the same position relative to the transfer case. And that sound like it might be the cause of the problem.

 

I'm Not sure about the cut and weld method, as far back as the the mid 80's a bolt in bracket was how they accomplished lift, with a lift that big, could be that the slip yokes are pulled out beyond max stability, any rate that's alot of lift and there's bound to be hiccups.

 

Could be, higher speeds amplify pinion probs, such as angle.

 

Couple people did.

Yes I agree its probably the problem but I got no idea how to fix it.

 

There is one way to fix it for sure.

 

I dunno if he can put back his old cross member. I'm guessing its long gone.

 

Ugh, that would suck. Maybe he could do a diff lift in the cradle its in, or however it’s mounted.

 

A good drop bracket lift kit should provide the necessary hardware to get the pinion angles and CV angles to within acceptable parameters.

Unfortunately, I've never heard anything good about Pro-Comp lifts.

@Oneal1234 might have to work with a good off-road or fab shop to improvise a solution.