clunk when turning

[macdaddy70]

Good evening all. I have a 70 gmc c10 lwb with a manual transmission. I have recently noticed when starting from a stop and making a turn, there is a noticeable clunk in the rear of the truck. No issues after the initial clunk...it drives great but it does have me concerned. Does not happen when I am at cruising speed rounding corners and doesn't happen all the time when turning at a stop light. Mostly occurs when turning to the left...I do not recall it happening when turning right. I have checked u-joints and none have slack. Could this be an issue with the axle bearings or the differential itself. Any suggestions...?
Thanks for your help in advance. Hope everyone has a great Labor Day weekend!!!!

[saxart]

I would check the bushings in the track bar. This is the bar that extends horizontally from the rear axle.

[palallin]

Could in the rear end. This happened to me so many years ago that I cannot remember exactly what happened, but I ended up putting another rear under the truck. I didn't have the capability to set up a ring and pinion, and I couldn't afford to pay someone else to. The rear end was relatively cheap, and it fixed the problem

[FirstOwner69]

Is your rear end Positraction?

[Wrenchbender Ret]

I'm thinking like FO69. A positrack rear end will do that. If that is the case change the grease & put in an additive for positrac rear ends.

[macdaddy70]

it is positrack. if I remove the diff cover, is there anything in particular I should look for that is not obvious...missing teeth, loose parts, etc

[randy500]

Leave the cover on, add positraction additive, sounds like ur problem

[FirstOwner69]

Originally Posted by Wrenchbender Ret

I'm thinking like FO69. A positrack rear end will do that. If that is the case change the grease & put in an additive for positrac rear ends.

Yup. I first had the problem in a 1974 Vette (it felt like someone tapped the car in the rear end when I stopped for stop lights), then in my 2001 Wrangler and just a couple years ago in the 1999 Vette. The Wrangler and '99 Vette symptoms were most like the OP's. Changed the differential oil and added the additive. Solved all 3 problems. No reason not to change the oil too. Who knows how old it is? Just remove the cover, clean out any sludge, replace the cover and new gasket. Then add new oil and additive.

[NGN]

How's the hanger bearing , I remember a time back I had something that sounded the same and did the same and for a while, then I found it when it broke , the hanger bearing problem went away after the new was installed. lol Maybe check u bolts around the rear axle maybe one's a little loose , check the perch area were the U-bolts go through, one could be worn. I'm no expert just a thought.

[macdaddy70]

thanks for the responses. I will check these things this week.

[toolboxchev]

U-joint, Carrier Bearing, Shock Mount, Leaf Spring Shackle....