Bucking under acceleration.

[keeponjeepn]

I have 89 mj 4.0 ax15 4x4. The motor runs fine. Under acceleration it is bucking and making a "waaa waaa" noise? Best way to describe it. It sounds like its coming from under neath me or rear of truck." It feels like my ring gears are oval shaped" if you could imagine how that would drive. It happens more at low rpms 1500 or under. If i put my foot into the pedal it feels a little more smooth. Just looking to b pointed in the right direction?

[HOrnbrod]

Have you crawled under and looked? Check the driveshaft and u-joints for slop. Check the gear oil level in your rear diff.

[Wounded_Fighter]

Mine seems to buck in first and second gear only if I don't give her enough gas... Hoping it will change when I switch injectors

[keeponjeepn]

1 hour ago, HOrnbrod said:

Have you crawled under and looked? Check the driveshaft and u-joints for slop. Check the gear oil level in your rear diff.

Ive been all under it. Fluids all good. Diffs,trans,tcase. It just recently started to clunk here and there while bucking. All u joints are good.

[keeponjeepn]

Well ring gear it is. Pulled diff. 3 teeth broke off 

[dvitha]

So you going to put a new axle under it or pay for a rebuild? Most will say get another if it is the dana 35. If you do rebuild it, make sure you take it to some one who can do it right. I seen people do the rebuild them selves and it whine like crazy then lock up in a few thousand miles, or teeth shred down the road. If you do, do it your self, take your time with the adjustment. It can take a day or two to get it lined up perfect.

 

Finding a cheap rear end that is upgrade from your most likely dana 35 would not be to hard to find.