98 gmc Jimmy. About 7 months ago it started shuttering the right rear axel in reverse. No noises or vibration in forward gears. New axel bearings and axel about a year before shuttering started. Checked everything again. I drive Jimmy every day. Has not changed since it started.

 

Might need to pull the axle shaft to double check if the bearings are still good, and when you open the diff cover have someone rotate a tire to inspect the gears. Also don't forget to check your gear oil for any metal shavings or discolouration.

Another thing to double check is your driveshaft u-joints. The RR tire is the main drive tire in these trucks, and sometimes driveline issue symptoms appear to transfer downstream.

 

Thank you. My next thought was to replace the axel bearing again. They are cheap enough. I took it apart a few weeks ago and they seem ok. No flat spots or chipping. Rolled fine. And while in the air with no weight it will not duplicate issue. Feels like I'm running over railroad tracks while backing up in normal conditions

 

This is certainly not my area of expertise, but if the axles shafts are clean and not showing any abnormal wear, that doesn't sound like a failing bearing to me. Hopefully someone with more knowledge than me in this area will chime in.

 

Spider gears in the differential?

 

Axel bearing did not help but I had a new failure last week. I had to use 4 wheel drive to pull up a little hill where I parked for hunting mainly just so I wouldn't spin tires and tear the ground up more. Had to push 4 hi button 3 times and it went into 4 low. Pulled out to hard rd only 20 ft from where I started. It blew a fuse under hood and after replacing it a couple times I took encoder off to manually shift to 2 hi. I never done this before on this type of transfer case but it seemed I had to use a little more force than I thought it should. I'm wondering if something could be failing in transfer case telescoping to rr Axel. It started this Axel stuttering only in reverse last May. I drive it every day and it hasn't gotten any worse. I kept hoping it would completely fail or get bad enough to figure out the cause but it hasn't. The only thing that has changed is sometimes at lower speeds around 20 to 30 mph I get a wobble that feels like a tire separation and sometimes around 50 a vibration that's feels like out of balance tire. Swapped sides and put 2 different tires on and it didn't change. Trans input seal is leaking into transfer case now. Do you think it's possible for a gear to be moving on shaft in transfer case. A friend of mine told me about someone else that had that happen but I never seen it before. I am a very good industrial mechanic. I work on anything from tower cranes to toilets lol. I know I have driven this Jimmy over 12,000 miles with this issue. It just won't finish breaking to help me find it lol

 

It is very possible for a bad transmission seal to cause the transfer case to be overfull, which can definitely cause problems. I can't say that it's the source of your problem, but it may be worth investigating. Have you pulled the fill plug from the transfer case to see if it's over-full? Does draining some fluid change the behaviour? Is your transmission low on fluid if it's leaking?

 

The seal has been leaking. I drain it about every 1500 miles and fill trans. I put a used transfer case with 66.000 miles in and it did not change. Drives perfectly in forward gears. Only in reverse and rr wheel shutters . I could be wrong but if a transmission issue I think it would have torn up by now. I have replaced axel bearing twice after this started. New axels and bearings about a year and a half before this started. I'm going to remove parking brakes just to see. They look fine. But idk lol. I'm a industrial mechanic and I know there is a lot that I don't know. But I'm not all that big of a dumb *** either lol.

 

I have no metal . I wish I had taken a pic but the color of the gears looked dull. I recently took cover off to see if anything was on the bottom of housing. Very little to no dust. Could see what I thought was normal very fine dust. Not enough to measure. Very little. Also I didn't want to say but I'm dealing with a pituitary tumor in my brain. Sounds worse than it is. But treatment has taken a long time to start. I'm getting better now but still got a long road. It has effected my concentration and a bunch of other things. This truck is all I got. Dr's take my money. I'm going to be ok but struggling right now. I drive it every day. But I know I'm running out of days. I keep hoping it tears up but it keeps on going and I can't trust it lol

 

I hope I'm mis-reading your post, but are you saying that you don't have any gear lubricant in your axle housing? Where is this dust?