Clunk "sound"

[coxfmly]

I promise this is the last one for awhile smile.gif

When I start to pull away from a light I can feel and hear a thud or clunk in the drive line.
I have talked to a rear end shop and they said it is my limited slip diff. They had me change the rear end oil and add the additives.

It seems that the hotter it gets the more frequent the sound. I usually pull away from the light softly due to this condition.

Every once in awhile I can hear the sound when I am about to stop.

[coxfmly]

A little more, I have change the center mount on the drive shaft. The trans and engine mounts are worn but not too bad.

Is this noise a common occurance with the rear end ?
The truck has 4:10 gears and is a 3/4T.

Could it be ?

Thanks Again

[MTTwister]

Asking the obvious - You've checked all the Universals for any play?

[coxfmly]

They are in good shape

[NH2112]

Does it clunk when you put it in drive, or only when you start to move? How much play is there between the pinion and ring gears? I like to jack the truck up and support it by the frame when checking U-joints, it takes and tension out of the driveline and lets you find slop you might miss with the axle on stands or the ground.

If it's a clutch-type limited slip, it could be worn out. What did the oil look like when you drained it? I'm not certain how to check limited slips, but I'd think that if you jacked up one wheel and tried to turn it it shouldn't turn very far before "locking up."

[Doug Towne]

IF you have the two piece driveshaft, the problem is most likely in the center splines. Over time a small ridge developes in the splines and the driveshaft binds. GM sells a special lubricant that helps (I don't know the part number), but I use Mercruiser U-joint and gimble bearing grease with good results. You can get it at most boating supply stores and it comes in small and large cartridges to fit most grease guns.