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U-bolts loose - might want to check yours!

kpanza

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kpanza Enthusiast

kpanza

Posted
Posted

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! 

  • 2 weeks later...
hotrodz37 Senior Enthusiast

hotrodz37

Posted
Posted

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. 

hotrodz37 Senior Enthusiast

hotrodz37

Posted
Posted
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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2019_Silverado_HC Enthusiast

2019_Silverado_HC

Posted
Posted

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 Enthusiast

Bob Ross

Posted
Posted

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. 

2019_Silverado_HC Enthusiast

2019_Silverado_HC

Posted
Posted
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 Enthusiast

Bob Ross

Posted
Posted
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 Enthusiast

Ricomtzjr

Posted
Posted

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

BlancoSilverado Enthusiast

BlancoSilverado

Posted
Posted

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)

1365387892_U-Bolttorque.thumb.jpg.70f6095e54250ac795f8ee442be29af4.jpg

 

 

hotrodz37 Senior Enthusiast

hotrodz37

Posted
Posted
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)
1365387892_U-Bolttorque.thumb.jpg.70f6095e54250ac795f8ee442be29af4.jpg
 
 

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 Enthusiast

Bob Ross

Posted
Posted
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?

BlancoSilverado Enthusiast

BlancoSilverado

Posted
Posted
12 minutes ago, Bob Ross said:

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

From what i was told(fremont chevy), they are torque to yield bolts (not reusable). 

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