need a little help troubleshooting some rear end vibration. happens mostly when decelerating from 20mph to stop. feels like running over rough pavement, constant rumble and vibration until truck is stopped. happens in gear or out, on the brakes or coasting. almost feels like you can feel each of the gears turning when slowing to a stop.

there is a little vibration during acceleration around 37mph, but fades away quickly.

rear gear lube was changed last summer, replaced with mobil 1 75-140 syn. have checked fluid level, checks ok. fluid doesnt appear burnt, or glittery, no excess metal on filler plug.

u-joints/carrier bearing were also done last summer when driveline was re-tubed and balanced due to a dented tube.

appreciate any help or pointers, I'm unsure where/what to check at this point.

 

Decel shudder !!!!! HUMMMMM!!!!! Could it be a bad u-joint or center bearing? Could it be ABS on rear???? If you are in slight turn when occurs it could very well be anti spin differential needing the addative.

 

thanks for the reply. As noted, u-joints and carrier bearing were just done last summer, along with re-tube and balance of driveline. I guess its possible, but I would hope to get more than 1 year of service out of those parts.

I have had trouble with the rear abs sensor, and have pretty much written it off. the sensor has been replaced, twice in fact, but the abs light is still on all the time. has been like that since I bought the truck 3 years ago.

concerning the rear diff lube additive... i thought I did my homework, and read that the mobil 1 synth did not need the additive. i did purchase the additive from dodge, but never installed it since I thought it was not required. should I add it now? my only concern, and reason for not adding it was I did not want to cause problems with the limited slip clutches. i had read that if the additive was added and not needed, it could cause the limited slip to cease functioning properly.

thanks again for the reply, i can use any help i get at this point.

 

In regards to the Fluid used in a clutch pack style Limited Slip, if the fluid is not made for clutch style differentials or doesn't have the necessary friction additives. The loss of friction between the clutch plates will cause them to spin too much, overheat and fail. This is why people usually add friction modifier in order to keep their clutches "healthy".

If you want jack one rear wheel off the ground (just enough to be able to turn the wheel). Put the tranny in neutral and then go back and spin that the wheel that is off the ground. If your clutches are fairly good, and starting from a stop or a light push on the wheel. Your clutches should be locked together (meaning the wheel wont spin since is locked with the other wheel on the ground). Put more force into turning that wheel and it should eventually break free and spin. If you rock the wheel back and forth (locking the clutches) and then go to spin the wheel and there is no residence, your clutches are shot. If the wheel feels like it is locked and takes some force to free the wheel, the clutches should be alright.