U-bolts loose - might want to check yours!

kpanza · April 14, 2020

After reading some posts about a rear "clunking noise" coming from the rear (which mine does), saw a bunch of guys citing proper torque specs for the rear u-bolts, as well as some talk about replacing the inserts between leaves, etc. I decided to check mine this weekend. The specs call for torquing them down to 60 ft lbs, then back off 1/2 turn, go to 60 again, then another 1/3 turn final. Well, when I went to check them, I started at 60 with the torque wrench, and had to crank at least 1/2 turn on all of them! That means they were well UNDER even the beginning value of 60, let alone the final value of somewhere around 80-90 ft lbs! Yikes. I haven't driven it yet after doing this, so I can't comment on whether it helped with the clunk noise, but not good having the rear axle held on at less than 1/2 the specified torque value.

I'd highly recommend checking yours!

hotrodz37 · April 25, 2020

I just checked mine and wow were they loose. I torqued mine to 60 and then 75 ft/lbs. We’ll see how it goes. I am getting a rumble on deceleration so hoping this might be part of the problem. Thanks for the heads up!

I also noticed the trucks I have gotten as loaners didn’t have the rumble and they didn’t have pinion shims but mine does. Pretty interesting.

Edited April 25, 2020 by hotrodz37

splatmatt · April 30, 2020

Curious, which plants were your respective trucks manufactured?

hotrodz37 · April 30, 2020

Curious, which plants were your respective trucks manufactured?

My truck was built in Mexico, and funny enough on a Monday as well. Lots of stuff wrong with it but slowly working it out.

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kpanza · May 1, 2020

Mexico as well, sadly...

splatmatt · May 1, 2020

I haven't had the "clunking" noise but my 2019 Chevy CC is built in the same plant in Mexico. Probably should check it.

I did find this TSB regarding the issue:

https://static.nhtsa.gov/odi/tsbs/2019/MC-10165102-9999.pdf

Edited May 1, 2020 by splatmatt

2019_Silverado_HC · May 4, 2020

I had the dealership check out the clunking noise coming from the rear when traversing sharp inclines. Picked it up and SM said they cleaned and lubed. No noise for a couple of weeks. I finally got around to crawling under the truck tonight to check the torque on the ubolts. First pass was at 60 lb ft. And not a single one was torqued to 60. Probably needed 1/2 turn to get to 60 then I torqued to 75. I will see what it sounds like tomorrow. Bottom line is you need to check your u bolts.

Bob Ross · May 5, 2020

Where are these U bolts located? Does anyone have a pic or can explain where these are so I can check mine?

Edit: if you are talking about the bolts for the leaf springs I just checked those and mine were not even at 60 ft lb. I tightened mine to 60, then 70, then 85 ft lb.

Edited May 5, 2020 by Bob Ross

2019_Silverado_HC · May 5, 2020

46 minutes ago, Bob Ross said:

Where are these U bolts located? Does anyone have a pic or can explain where these are so I can check mine?

Edit: if you are talking about the bolts for the leaf springs I just checked those and mine were not even at 60 ft lb. I tightened mine to 60, then 70, then 85 ft lb.

Did you have any clunking noises before tightening? Mine is better but not completely gone. I think I will tighten to 85 and see if any further improvement.

Bob Ross · May 5, 2020

3 minutes ago, 2019_Silverado_HC said:

Did you have any clunking noises before tightening? Mine is better but not completely gone. I think I will tighten to 85 and see if any further improvement.

I do have a clunking and I thought it was my rear end locker engaging and disengaging. I just tightened these down about 30 mins ago and have not driven it yet. But I do hope this helps

Ricomtzjr · May 6, 2020

I have something similar coming from the rear when slowly navigating the driveway, speed bumps, or uneven roads.

BlancoSilverado · May 6, 2020

~~Just called my local dealer, they said the torque for when adding the trailboss kit is 53ft-lbs for the ubolts.~~

I got no turn at 50ft-lbs and a couple of degrees when torquing to 55ft-lbs.

I am having another dealer look into it also just to make sure. I will have to re-torque again tonight

Other dealer sent me this, Thankyou Fremont Chevrolet.

NOTE: I have a regular 4wd(not Z71)

Edited May 6, 2020 by BlancoSilverado
Got great info

hotrodz37 · May 6, 2020

~~Just called my local dealer, they said the torque for when adding the trailboss kit is 53ft-lbs for the ubolts.~~
I got no turn at 50ft-lbs and a couple of degrees when torquing to 55ft-lbs.
I am having another dealer look into it also just to make sure. I will have to re-torque again tonight
Other dealer sent me this, Thankyou Fremont Chevrolet.

NOTE: I have a regular 4wd(not Z71)

That’s about what the first post said - curious what the exact final torque value is. Somewhere in the 80-90 ft lb range it looks like.

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Bob Ross · May 6, 2020

49 minutes ago, hotrodz37 said:

That’s about what the first post said - curious what the exact final torque value is. Somewhere in the 80-90 ft lb range it looks like.

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Makes me wonder why they wouldn't just put the final torque spec?