Clunk when hitting gas

[Wiscoburban]

On my 05 I keep getting a clunk when I first hit the gas from a stop and I can’t tell if it’s the trans or the rear end doing it. It’s been going on a while and doesn’t seem to affect anything else but it drives me nuts sometimes and I’m worried somethings going to let go soon. Any ideas what I should look in to?

 

[Curt]

Most likely a clunk caused by your driveshaft binding, a common GM issue in the trucks that share the shorter wheelbase SUV/truck frame (Tahoes, Yukons, Express Vans, etc.). I know it's a GMT900, but @BoxerPitMix has a nice write-up for GMT400s. The fix is to replace the slip yoke with a nickel coated one. You can check out the parts recommended in this thread, but double check they will work with your truck since we're talking about GMT400s in this thread: https://www.gmt400.com/threads/heres-your-fix-for-the-tahoe-yukon-driveline-clunk.30421/

 

[Wiscoburban]

Most likely a clunk caused by your driveshaft binding, a common GM issue in the trucks that share the shorter wheelbase SUV/truck frame (Tahoes, Yukons, Express Vans, etc.). I know it's a GMT900, but @BoxerPitMix has a nice write-up for GMT400s. The fix is to replace the slip yoke with a nickel coated one. You can check out the parts recommended in this thread, but double check they will work with your truck since we're talking about GMT400s in this thread: https://www.gmt400.com/threads/heres-your-fix-for-the-tahoe-yukon-driveline-clunk.30421/

Is it something I should fix to prevent other issues or not just a minor annoyance?

 

[Curt]

Is it something I should fix to prevent other issues or not just a minor annoyance?

Depends on how particular you want to be about it. If you plan on keeping your truck forever, then I'd fix it. But GM techs and engineers chuck this up to be a "normal" sound. I personally don't like the thought of a bind in the driveline, BUT it won't hurt anything. In the long, LONG run it'll probably take a toll on your truck in the form of crud being shoved in your slip yoke, accelerated U-joint wear from the constant jolting, accelerated bushing wear from the shock of the bind releasing in your rear end and transmission, etc., etc. But then again, I'm talking about 100k+ miles down the road of non-stop gas-brake transitions.

TL;DR: It's just a minor annoyance and you could leave it that way if you'd like.

 

[Schurkey]

Pull the (rear) driveshaft out of the trans or transfer case. Inspect for wear to the splines, wear to the bushing, and wear on the outside of the slip-yoke. Verify that the rubber output seal hasn't cut a groove into the slip yoke. Repair as needed. Polish-off any accumulated dreck from the exposed end of the slip yoke. Lube the splines on the trans/transfer case, and inside the slip-yoke using ATF or whatever lube the transfer case uses.

Put it back together.

That's all my '88 K1500 needed.