In trying to troubleshoot a vibration I have put the rear on jack stands and wanted to view the driveshaft and u joints for any play. When the truck is put in drive without pushing the fuel pedal, the tires spin...stop...spin...stop with a clunk. Is this normal behavior?:help: :think:

Can anyone confirm this behavior as the locker mechanism engaging because the wheels are slipping? And therefore may be normal?

Anyone out there on this?

You are hearing the locking mechanism in the G80 rear. Absolutely normal

Vibration could be u-joints. How many miles on them?

Reineke- Just replaced u-joints last nite with 50k miles even though they were fine. Also had the driveshaft high speed balanced and it was fine.

RanaExcavating-Is the wheels spinning and stopping normal too? They actually individually stop spinning then start again. I thought the locker would only come into play if the wheels are spinning at different speeds and inducing the flywheel. If the truck is put in drive with both rear wheels up on jacks with no resistance, wouldn't they be spinning at the same speed?

Maybe bad wheel bearing in the rear causing one wheel to spin slower?

Is your gear oil level in the differential? You could take the tires off and turn the axles slowly to try to feel out a rough spot in the housing...

If there's more resistance on one side (as there usually is) only one side will spin until locker kicks in. Open diff sends power to side with least resistance.

The gear oil is level since I had a rear axle seal done within the last month and they top it off after changing the seal. As for feeling out a rough spot, how do you mean? Do you think it is normal for the wheels to stop spinning and start again out of phase when on jacks?
This afternoon I checked for play in the bearings by grabbing it at 12 and 6 and it has a little bit of play and a click/clunk noise when top is pushed in. Is that a bad bearing and/or needs to be adjusted?

Sorry a bit frustrated since I have been fighting this vibration for 6 months. I have replaced tires, shocks, then tires again( they screwed up mounting and balancing so 4 new ones), alignment, replaced worn lower a arm bump stops, u-joints and driveshaft balancing with no resolution to vibration.

Ockgator- when the locker kicks in will they both spin together? mine spin stop independent of each other.

So true.

My money would be on a Burr or Galled bearing; hand walk it like Reineke said, you should find it.

Good luck !

To feel for it, rotate it clockwise or counter and move it slow and try to feel for resistance.

Out of round/line wheel(s) ? ? ?

different air pressures?

Same air pressures.

Out of round? I don't know but this is the 3rd set including the originals that started doing it after about 35k miles. Alignment done.

Ok so I spun them feeling for resistance and did not feel anything. Although the lug nut and axle on one side was warmer than the other. I am thinking heat equals friction but can't feel it. I had a mechanic look at the truck and although he agrees that the vibration feeling is in the seat (which I thought meant it was in the rear) he thinks it is the tie rods. He thought there was slight play in the tie rods and thinks the vibration is resonating through the frame to the seat with minor bumps in the road. He suggests replacing tie rods and go from there. Any thoughts?

Idahofox- I reread your question on out of line wheels? When I read that before I thought it said tires. The wheels have only 0.002" runout.

Do you have two driveshafts or one ?

Have you opened the " Pumpkin " and " Eye Balled " the inside. There is a " Marker " somewhere, just have not found it.

Not tie rods, IMHO.

Good luck.

The gear oil is level since I had a rear axle seal done within the last month and they top it off after changing the seal. As for feeling out a rough spot, how do you mean? Do you think it is normal for the wheels to stop spinning and start again out of phase when on jacks?
This afternoon I checked for play in the bearings by grabbing it at 12 and 6 and it has a little bit of play and a click/clunk noise when top is pushed in. Is that a bad bearing and/or needs to be adjusted?

Sorry a bit frustrated since I have been fighting this vibration for 6 months. I have replaced tires, shocks, then tires again( they screwed up mounting and balancing so 4 new ones), alignment, replaced worn lower a arm bump stops, u-joints and driveshaft balancing with no resolution to vibration.

Adjust Both rear hubs................ again.............

Puffer- If you mean two piece or one, it's the one piece and it has been balanced with new u joints even though the ujoints were fine. It was out so they got changed.

Idahofox-I haven't opened the Pumpkin that is next, but need to get the gear oil and gasket first. Do I need some silicone too to seal it back up?

How do I adjust both rear hubs?

The pumpkin gasket is very soft, if you are carefull, can be reused. I prefer new. No extra sealant disired.

Hub adjust: Pull wheels/tires. Pull axles. Set aside.

The hub is held in place by an adjusting nut, the adjusting nut is held in place by a locking nut ( two nuts on the spindle ). Remove the adjusting nut; remove the key, tighten the adjusting nut to ~ 50 ftlb while rotating the hub, ( good time to check the quality of the bearing. Should turn smooth but tight. No rough or hard to turn spots). Back of the adjusting nut until there is Zero force on the hub ( finger tight or less ). There is a keyway that must align, finger tight the adjusting nut then backoff until the keyway aligns, install key and install locking nut. Intall axles with new axles seals/gaskets ( you can makes these ); tires on and test drive.

Good luck.

The pumpkin gasket is very soft, if you are carefull, can be reused. I prefer new. No extra sealant disired.

IIRC, no gasket, just silicone.:)

Picked up a gasket but can't find 4 qts of Mobile 1 75w90 at one store within 15 miles. A couple of places have 1 or 2. Seems silly to buy one at 4 different places! Will call another place tomorrow about 30 minutes away. Hopefully get to it some night early this week.

BTW If you hit the pax side rear tire it resonates in the hub like something is just slightly loose, any ideas? The drivers side rear just has a thud from the tire.