Clunk In The Drivetrain

[mfennema]

Just hoping someone can help me out here. I have noticed at times that when I am driving through town (under 35 mph) and I am slowing down lightly, then go directly to the throttle, the drivetrain will clunk. It almost seems like there is some play in the system somewhere and when I hit the throttle, it takes up that play and engages with the rest of the drivetrain. Is this normal? Is it something I should get looked at? The only problem I have with taking it in to the dealer to get it looked at, is that I can't always reproduce the issue.

 

It usually happens when I'm slowing down behind a car that is turning and then once its turned I hit the accelerator. It almost makes the truck lunge forward when it engages.

 

Any ideas? Thanks.

[Z71Adrenaline]

I'm not sure of the exact cause, but that was normal on all of my GMT-800s. My 2008 has done it once.. I don't think it's anything serious because I never had any issues in 300k combined miles on my old trucks.

[gaidin43]

Look at this thread... just started it 5 min before your post.

 

TSB for hard shifting

[alaska511]

His is not a 6 speed.

 

So far the condition he has is deemed normal by GM. There is a bulletin, I will find it, I have the same issue.

[mfennema]

My issue isn't a shifting issue either. The truck isn't shifting when it happens. Thanks anyways.

 

I would like to see that bulletin if you can find it alaska.

 

Thanks.

[2005LT]

I have this same "issue" as you do Mitch, just once in a while. My 2005 Silverado did the same. As Alaska mentioned, I don't think its anything to be worried about. It's probably just a tolerance thing with the driveshaft or something of the like.

[Chevymetal]

My 2005 does it real bad, feels like too much backlash between the ring and pinion. Having an aluminum driveshaft seems to almost amplify the noise too. I talked to a GM tech and he said the same thing, that its "normal".

[05silvycrew]

My 2005 does it real bad, feels like too much backlash between the ring and pinion. Having an aluminum driveshaft seems to almost amplify the noise too. I talked to a GM tech and he said the same thing, that its "normal".

 

 

same story here, i just try to ease into the throttle to avoid it.

[mfennema]

Thanks for the replies. Give me a little peace of mind!

[SparkySparks]

I had a similar issue with my truck, my service manager said some trucks don't have enough grease packed in around the slip yoke so they repacked the grease in mine which fixed it for about a month. I took it back and they ordered a new slip yoke and so far so good.

[Gryphon]

Yep, that damn slip yoke makes a hell of a racket when the grease works its way out. Mine has been clunking for some time and I just keep lubing it, and while it's nothing to drop the driveshaft and pull the yoke out to grease it I don't want to keep doing this every month.

 

That nickel plated slip yoke from GM is like $400 here! Anyone know of some alternatives? I've thought about having mine plated to get the extra couple thou coating on it to take up the slack (I imagine that's all the GM one does).

[ukrkoz]

I had a similar issue with my truck, my service manager said some trucks don't have enough grease packed in around the slip yoke so they repacked the grease in mine which fixed it for about a month. I took it back and they ordered a new slip yoke and so far so good.

 

DITTO!

just slide that driveshaft out, it's about 5 min job, pack inside youke splines with good grease, and be happy for about 7-8 mths. then do it again.

they "improved cost efficiency" by making those yokes out of rusting metal, and rust binds yoke to the output shaft.

so, unless you want to fork 400 bucks for a nickel plated one - which, knowing GM, i doubt will even solve the problem for long - just grease it.

[CapitalTruck]

They have a special grease for this, it's kind of pricey, but it's called "Spleen Grease" Its like 35 bucks for a tub, but supposedly it's really good stuff for this job.

[Sinkhole]

Just slide your but under the and give that drive shaft a good wiggle side to side to make sure there isn't a bad U-Joint.

[bradpell8]

Just slide your but under the and give that drive shaft a good wiggle side to side to make sure there isn't a bad U-Joint.

 

 

I have also found it is the rear brake drums that make the noise. Hwnever you slow down the front shoes are working the most all the weight is against them and when you reaccelerate the weight moves back. This sounds stupid but I had a 88 silverado doe the same thing. My 2002 silverado had rear disc brakes and it was fine then GM with there engineers went backwards and put drums back on in 2005 and my 2005 does that too. Nothing to worry about.