Downshift clunk

[Bwoodkid]

What's up guys, picked up a 15' LT Z71 w/ 5.3 back in Dec. coming from a 2005 4 runner I had a bit of a lead foot with my Chevy. So far I have done two break stands and floored it twice. Truck has plenty of balls, I just hope that I haven't messed up anything. Only 3k miles. I hear a slight clunk when going down hill off the gas when tranny downshifts. What do you guys think?

[Daryl LBZ]

Sounds like a slip yoke clunk, but I didn't think these trucks had that issue...

Edited March 1, 2016 by Daryl Z71

[Bwoodkid]

Yeah, I mean it's not very loud. It's when I'm rolling downhill going about 25 - 30 in traffic. Couple guys at work say it's because there's no load. Shifts smooth when accelerating. I'm just being paranoid because of the burnouts, cmon if the truck can't get on it a couple times then what good is it right. Back to mellow driving now, just had to open it up a couple times.

 

Thanks for the reply!

[Daryl LBZ]

Yea I'm not real sure since I don't own a new one. Maybe someone with a K2 will chime in with a better idea of what it could be. I just know the slip yoke came to mind because it was so common before.

[f8l vnm]

Pretty normal I guess. I had it on my 14 and 16. Gm says it's normal. Lol.

[stevev]

Dealer claims it's normal. Mine doesn't clunk much going downhill, but rather on flat ground or going uphill and I take my foot off the gas, it clunks. I owned some F150's and they never clunked like this.

Edited March 1, 2016 by stevev

[Bwoodkid]

It's not too bad and only does it here and there, in a way it's good to hear that it's "normal" I was worried that it was something I did, driving like it was stolen a couple times.

[Nathan79]

Google "Chevy Clunk". Been a problem for years and years......

[stevev]

Google "Chevy Clunk". Been a problem for years and years......

 

a lot of the older complaints seem to related to the slip yoke and the clunk or "bump" you feel when coming to stop. A coworker had an early 2000's Silverado and I felt that bump everytime when riding in his truck when he came to a stop.

I think the "clunk" we are experiencing may be something different. My clunk noise appears to come from the front of the truck, like from the transmission or transfer case, not the rear end. It occurs either when letting off the gas or lightly cruising along and the truck downshifts and makes the clunk noise. Maybe it's just related to slop in the drivetrain or something? I don't hear or feel any clunk/bump when coming to a stop like the older Chevy owners...

[joeisalsocool]

I had the same thing for the first 1k miles or so. Most of my commute is slow and hilly, so it annoyed the crap out of me.
Came down to axle wrap. The leaves in the rear were slapping each other, making it sound like there were bowling balls in the back.
Torque all 8 U-bolts down to the recommended 78ft-lbs and you'll be good to go. Mine were at 10-15lbs each.

[stevev]

^already torqued them to 100-ft lbs and added the leaf springs clamps. Clunk noise is still there, although sometimes doesn't sound as loud.

[lockey14s]

"normal operating condition"... mines been that way since day 1. you just have to get use to the chevy clunk. roast those tires!

[Bwoodkid]

_{Thanks guys, Its hard not to get on it especially with the exhaust mod (Magnaflow) Am I the only one that thinks every truck that pulls up next to me wants to go?! lol. Told the little guy that he could drive it one day, so I better take it easy for now.}

[jonboy77]

I have just over 5k on my truck and I have been to the dealership over and opened a case with GM (that I have not had time to follow through with). I do not have the problem going down hill but I will tell you what I am experiencing. Maybe, its the same thing or at least try it out because if it is and you can replicate the noise if and when you decide to take it to the dealer. WHILE ACCELERATING (Above 25-30 and below 60) in whatever gear the truck is in RIGHT BEFORE it is going to shift I can let completely off the gas and when it downshift it makes a clunking sound. For example, while accelerating (normal acceleration or light acceleration) in town I let off the gas because the car in front of me is slowing down, stopping or whatever and I just have to let off the gas, it clunks downshifting. does not seen to do it in 1st or 2nd.

[Haus_Z71]

I had the same thing for the first 1k miles or so. Most of my commute is slow and hilly, so it annoyed the crap out of me.

Came down to axle wrap. The leaves in the rear were slapping each other, making it sound like there were bowling balls in the back.

Torque all 8 U-bolts down to the recommended 78ft-lbs and you'll be good to go. Mine were at 10-15lbs each.

 

Just tightened mine to 78. Some were around 30. Hope this helps, and thanks for sharing.