Gentlemen
My 2010 Chevy with duramax engine and allison transmisson makes a clunk sound when I release the brake pedal after stoping in traffic...As i release the brake pedal and move to the excelarator pedal i feel this clunk...Seems to have some sort of slack in the rear end or u-joint...Is this normal ??

Please let me know...thanks
Jerry

This may not be the rearend. Most of the time this clunk you are talking about is from not enough lube/grease on the yolk & splines on the output shaft on the tranny. You must pull the drive shaft to lube the yolk & output shaft splines. If you are going to do this yourself, there is a special grease used for this. You can buy OEM or what is called tacky grease which is red in color.
Good luck & keep us posted on your find.

Gob some grease on the splines on the yoke tht goes into the trans/transfer case and it will go away

It may also be the brakes. I am not sure about 2010's but if they have drums here is another thought for you.
My 96 Silverado did the same thing. Stopping it was fine. Take off and it would clunk. (here is where mine may be different) If I slowed down and stopped real easy (very little braking effort) it wouldn't clunk. When it did once I released the brake pedal, the truck would sit, then clunk and go. Or I hit the gas it clunks and would go.
I rebuilt the rear brakes. Everything but the e-brakes. Drums, shoes, springs, wheel cylinders. I don't have any pics but all 4 of my shoes were cracked. Other then that they looked fine. Got everything back together and wouldn't you know, hasen't done it since.
I would also agree though, the slip yoke will also cause this. I would try greasing that first. You can also check for play in the u-joints and differential.

Gob some grease on the splines on the yoke tht goes into the trans/transfer case and it will go away
It's a 2010..I'd just take it to the dealer and let them handle it. If nothing else, it'll be documented in case something related goes tits up down the road.

It's a 2010..I'd just take it to the dealer and let them handle it. If nothing else, it'll be documented in case something related goes tits up down the road.


So True, But I know that the job would be done, and done right.

The techs are over worked and underpaid, so to say I dont see a problem, or I did this or that and get an hours pay for 10 min. of nothing would be right up the alley.

To each their own, but I would not waste a day ob something that takes 10 min. to do.

Gentlemen
Thanks for the help...my rear end clunk felt upon taking off from a stop in traffic, turned out to be just what you said...the dealership greased the output shaft of the transmission and yoke of the drive shaft and the clunk went away...I was told that the clunk would not have caused any failure's...but it is sure nice to get the problem fixed...
Thanks
Jerry Mollere

Gentlemen
My 2010 Chevy with duramax engine and allison transmisson makes a clunk sound when I release the brake pedal after stoping in traffic...As i release the brake pedal and move to the excelarator pedal i feel this clunk...Seems to have some sort of slack in the rear end or u-joint...Is this normal ??

Please let me know...thanks
Jerry


most trucks do this IMO.

Gentlemen
Thanks for the help...my rear end clunk felt upon taking off from a stop in traffic, turned out to be just what you said...the dealership greased the output shaft of the transmission and yoke of the drive shaft and the clunk went away...I was told that the clunk would not have caused any failure's...but it is sure nice to get the problem fixed...
Thanks
Jerry Mollere


not trying to spoil the fix but it will be back after some miles.

Gentlemen
Thanks for the help...my rear end clunk felt upon taking off from a stop in traffic, turned out to be just what you said...the dealership greased the output shaft of the transmission and yoke of the drive shaft and the clunk went away...I was told that the clunk would not have caused any failure's...but it is sure nice to get the problem fixed...
Thanks
Jerry Mollere

I don't feel quite the same about this. When you think about it the clunk comes form a shock, i.e sticky output shaft coming loose. The next thing in line are the u-joints. Most stress is placed on the u-joints at start from a dead stop. Now add the shock from the sticking output shaft. Just think of the added u-joint stress in a few thousand mile of stop and go.
Just my .02 on the clunk.