slow speed suspension clunking

kpanza · March 27, 2020

Add me to the list...seems to happen the most (or at least I can hear/feel it the most) when in reverse, or very slow speeds...happens every time I back out of the driveway, for instance. My truck has been sitting at the dealership for a week and a half because of leaking tranny, but I will see if they can try the above procedure with the u-bolt torque attempt. First thing I thought of was the spare tire bouncing around (like above poster said), not that. I even checked to make sure I hadn't left something in the bed...sounds/feels like something is moving around, definitely from rear of truck.

I only had the truck for 2 weeks before the tranny started leaking, but this noise/clunk was apparent right away. Anyone happen to know the appropriate torque setting offhand? My 5/8" u-bolts on my K5 axles are 140-150ft lbs...I know these will be metric bolts, but probably similar? I'll try it myself if they won't do it.

kpanza · April 14, 2020

So, just an update...got my truck back, but it's now leaking from transmission AGAIN...but while under the truck this weekend, I checked the rear u-bolt nuts...when I went to set them to 60 ftlbs, I had to crank on them almost a 1/2 turn! They were really loose! I backed them off, then back to 60, and then another 1/3 turn. Wow, They might have been 40-45 ftlbs from the factory?? Scary...

DogMom · April 14, 2020

My leaf spring squeak. I can spray lube on them at the plastic pads and that last a few days then starts squeaking again. Very frustrating pita. Dealer has looked at them twice and it’s the same answer. That oh we cleaned them and there’s nothing wrong.
They also want to give me ****** because I installed Air Lift load lifter 5000 air bags. Smh.
My rear brakes keep intermittently squealing and they said because I had painted my calipers red that may be causing it. Horse ******. My dealer sucks.
2019 Custom Trail Boss

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Air lift systems require a minimum 5psi in each bag at all times. When you're running unloaded it's still taking spring pressure off the leaf springs which in turn let's them run looser and allows them to move more than they would if the air lift wasn't installed.

If you throw about 250 lbs of weight in your bed, do your springs stop squeaking? Adding some weight to the bed with the minimum pressure needed to keep the bags from collapsing and pinching themselves might fix the issue. Granted, you may not always want weight in the bed but it would help.

Painting calipers often lead to over spray which hardens on the rotor so the brake pads can't get the same kind of friction as before. May try getting them resurfaced?

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ullose272 · April 17, 2020

My stealer looked at mine last week and said the inserts were the correct ones.
Said they cleaned between the leafs real good and it fixed the problem.
This weekend the problem returned.
I have Air Lift bags on the rear of my truck and they are giving me hell saying the bags are causing this issue.
I’ve added lots of air, taken all the air out, and had the pressure up to about 12 psi and various ranges in between and it will still squeak.
Every damn time I bring it in it’s not hardly doing it. I’ve found when it rains or there’s just a lot of moisture in the air, the springs tend to not squeak or not squeak that bad. I keep videoing when it’s bad but I guess that’s not good enough for them.
I’m sick of dealing with this ****** and ready to just fix the ****** myself.
They say I’ve technically voided my warranty because I’ve modified the rear suspension. SMDH
Screw it. I might as well go ahead and lift it more now.
My rear brakes keep squealing intermittently too and I’ve have videos of that as well.

Fyi if you got paint on the rotors it can cause squeaking because it embeds in th pad. When i worked at Les Schwab we used to paint calipers any time we put custom wheels on and the would come back all the time with squeaking brakes

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topgear1224 · April 17, 2020

go to a different dealer? for them to tell you to not bring it in while they research the problem is just crazy.

Trying to avoid buybacks.

Same way that they refuse to let me stay in the loaner until GM publishes a calibration update for my brakes being soft and not wanting to stop unless you put them to the floor.

Instructed me to break harder, earlier.

Wonder if they're going to cover the new pads, rotors, and tires it's going to need from all the ABS stops.

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Chad's Trail Boss · April 22, 2020

On 4/14/2020 at 12:24 AM, DogMom said:

Air lift systems require a minimum 5psi in each bag at all times. When you're running unloaded it's still taking spring pressure off the leaf springs which in turn let's them run looser and allows them to move more than they would if the air lift wasn't installed.

If you throw about 250 lbs of weight in your bed, do your springs stop squeaking? Adding some weight to the bed with the minimum pressure needed to keep the bags from collapsing and pinching themselves might fix the issue. Granted, you may not always want weight in the bed but it would help.

Painting calipers often lead to over spray which hardens on the rotor so the brake pads can't get the same kind of friction as before. May try getting them resurfaced?

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Thanks DogMom for the input.

I do realize that the bags take pressure off the springs and I know that the minimum psi is 5. The Load Lifter 5000 bags are a convoluted style bag that wont fold over on themselves like Air Lifts old style bags did. They also have an internal jounce bumper that takes the place of the factory jounce/bump stop. It says in the instructions to run a minimum of 5 psi but also that running them a 0 would not cause damage because of the design and internal bumper. I actually run them between 12 and 15 psi for my what i consider "empty load" and here's why. I have the DECKED bed storage (220 lbs empty) with about 200 ish lbs of tools in the drawers. I also have an ARE MX Topper that's about 200 lbs. So my standard "Empty Load" is actually 600 to 650 lbs.

I figured out on my own, and then called Air Lift and confirmed that by installing the bags, the rear suspension only has about 2.5" of down travel now "instead of the about 4" factory" before the internal jounce bumpers in the bags will make contact and bottom out. With me running the bags at the recommended 5 psi minimum, my "empty load" would squat my truck to where the rear was only about 3/4" taller than the front. So it took up about 1.25" of the factory 2" rake the truck had. This looked great and almost level out the truck. The problem was that "unknowingly at the time" I then only had about 1.25" of down travel left in the rear until the bags internal bumpers would hit. I was feeling this in my everyday driving. So when I run the bags at between 12-15 psi this raises the rear back to the 2" of factory rake and then I have a full 2.5" of travel back in the rear before the bags internal bumpers hit.

When I spoke to Ready Lift about the bags travel I asked if the bags could accommodate an extra 1" of lift. They confirmed that the bags would still function fine. So when I replace the factory 2" lift block with the Ready Lift 3" lift block, that will then give me 3.5" of down travel in the bags before the internal bumpers hit. The truck stock had about 4" of down travel before the factory bump stops would make contact with the pads on the axle, so I will almost be back to factory travel specifications. This will in turn let me run the bags at a little less psi than I do now allowing the springs to take more of the weight and take up the 1" of rake that the Ready Lift kit will leave with there kit lifting the front 2" and the rear 1" up from the factory lift of 2" front and 2" rear. Adding the Ready Lift SST +2 Kit to a Trail Boss is like lifting a standard Silverado 4" in the Front and 3" in the Rear only leaving 1" of rear rake "taller in the back".

By the way, I've fixed my squeaky leaf springs and squealing brakes. Details will be below.

Chad's Trail Boss · April 22, 2020

On 4/17/2020 at 8:34 AM, ullose272 said:

Fyi if you got paint on the rotors it can cause squeaking because it embeds in th pad. When i worked at Les Schwab we used to paint calipers any time we put custom wheels on and the would come back all the time with squeaking brakes

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Ullose272. Thanks for the input.

I'm 100% positive I did not get paint on the rotors surface or pads surface.

I meticulously taped off everything with blue painters tape leaving only the surface of the calipers visible.

After painting I cleaned/wiped the rotors with brake cleaner just to make sure they were clean.

By the way, I have fixed the squealing brakes myself. Fix is below in separate post.

Chad's Trail Boss · April 22, 2020

So after getting nowhere with the dealer, I decided to fix the squeaking leaf spring/rear suspension myself. I also decided to fix the squealing rear brakes myself.

Here's the fix:

About 3 weeks ago I took the rear brakes completely apart. I did not disconnect brake lines so no bleeding involved. I just took the calipers off and took the pads out and wire brushed the nooks and cranny's cleaning everything up. I then sprayed brake cleaner on them cleaning them up further. I then reassembled using regular ole high temp wheel bearing grease. I put a light coat applied by finger to every metal on metal surface, ie. back of pads, where the pads are captured in the caliper, slide bolts, etc. Obviously I did not apply to friction surface side of the pads or the rotor. I put it all together and then moved onto the leaf springs.

I put 100 psi in my air bags to take most of the weight off the springs. This allowed me to be able to easily pry the individual leafs apart and gain full access to the plastic friction pads. I placed a steel punch i between the leaves for safety while i performed this work. I thoroughly cleaned in between the leafs and on top and underneath the plastic pads. After all was cleaned, I put a nice coat of the same wheel bearing grease underneath and above the plastic pads. After all that I left the rear jacked up on the air bags and checked torque on the U bolts. In my opinion they were loose. I couldn't definitively find factory torque specs for the U bolts so I took them to 110 ft lbs. They seemed really loose as I was easily able to get about 1.25 turns on each nut before reaching 110 ft lbs. Nothing sounded or felt like they were being over tightened. This is not the first time I have messed with U bolts as I've lifted trucks in the past and I have a jeep I've custom built on leaf spring suspension.

Once I reached that torque setting I let all the air out of my air bags allowing all the weight on be on the leaf springs and re checked torque on the U bolts. They actually did tighten just slightly more to 110 ft lbs with them now holding the weight of the truck.

I then put the bags back to 14 psi and proceeded to check all mounting hardware on the Air Bags. Most everything was still tight from my installation. Nothing was loose to the point that it should be making all this noise as the dealer wanted to blame it on.

I then cleaned up everything and went for a drive.

The brake noise was completely gone and still is to this day. The rear suspension squeaking noise was I would say about 90% fixed at that point and actually the rear suspension felt more planted for lack of a better term. There was still a slight squeak that right at the beginning of any suspension movement. Thats what I would consider the remaining 10% at that time.

I drove it that week and everything was perfect now except for that 10% noise left.

The next weekend I did the only thing really left to do.

I completely removed my rear shocks and grease the bushings and steel sleeve that makes metal on metal contact with the mounting bolt. I thoroughly coated the bolt with grease and made sure the inside of the steel sleeve was totally coated with grease. I reinstalled the shocks and tightened them up to what I felt like they needed to be tightened to.

Success!!!!!!!!

That completely solved the problem and got rid of the other 10% of noise I was hearing.

The rear suspension is now perfectly smooth and noise free. I can now drive in and out steep driveway and it doesn't sound like I drive an ole 20 year old worn out truck.

The rear suspension articulates noise free and my brakes no longer make noise every time i go to a stop.

It quite sad I had to fix this problem myself but in a way I'm glad I did. I know its done right and tight now.

Hope this all helps someone.

Edited April 22, 2020 by Chad's Trail Boss

topgear1224 · April 23, 2020

So after getting nowhere with the dealer, I decided to fix the squeaking leaf spring/rear suspension myself. I also decided to fix the squealing rear brakes myself.
Here's the fix:

About 3 weeks ago I took the rear brakes completely apart. I did not disconnect brake lines so no bleeding involved. I just took the calipers off and took the pads out and wire brushed the nooks and cranny's cleaning everything up. I then sprayed brake cleaner on them cleaning them up further. I then reassembled using regular ole high temp wheel bearing grease. I put a light coat applied by finger to every metal on metal surface, ie. back of pads, where the pads are captured in the caliper, slide bolts, etc. Obviously I did not apply to friction surface side of the pads or the rotor. I put it all together and then moved onto the leaf springs.
I put 100 psi in my air bags to take most of the weight off the springs. This allowed me to be able to easily pry the individual leafs apart and gain full access to the plastic friction pads. I placed a steel punch i between the leaves for safety while i performed this work. I thoroughly cleaned in between the leafs and on top and underneath the plastic pads. After all was cleaned, I put a nice coat of the same wheel bearing grease underneath and above the plastic pads. After all that I left the rear jacked up on the air bags and checked torque on the U bolts. In my opinion they were loose. I couldn't definitively find factory torque specs for the U bolts so I took them to 110 ft lbs. They seemed really loose as I was easily able to get about 1.25 turns on each nut before reaching 110 ft lbs. Nothing sounded or felt like they were being over tightened. This is not the first time I have messed with U bolts as I've lifted trucks in the past and I have a jeep I've custom built on leaf spring suspension.
Once I reached that torque setting I let all the air out of my air bags allowing all the weight on be on the leaf springs and re checked torque on the U bolts. They actually did tighten just slightly more to 110 ft lbs with them now holding the weight of the truck.
I then put the bags back to 14 psi and proceeded to check all mounting hardware on the Air Bags. Most everything was still tight from my installation. Nothing was loose to the point that it should be making all this noise as the dealer wanted to blame it on.
I then cleaned up everything and went for a drive.
The brake noise was completely gone and still is to this day. The rear suspension squeaking noise was I would say about 90% fixed at that point and actually the rear suspension felt more planted for lack of a better term. There was still a slight squeak that right at the beginning of any suspension movement. Thats what I would consider the remaining 10% at that time.
I drove it that week and everything was perfect now except for that 10% noise left.
The next weekend I did the only thing really left to do.
I completely removed my rear shocks and grease the bushings and steel sleeve that makes metal on metal contact with the mounting bolt. I thoroughly coated the bolt with grease and made sure the inside of the steel sleeve was totally coated with grease. I reinstalled the shocks and tightened them up to what I felt like they needed to be tightened to.
Success!!!!!!!!
That completely solved the problem and got rid of the other 10% of noise I was hearing.
The rear suspension is now perfectly smooth and noise free. I can now drive in and out steep driveway and it doesn't sound like I drive an ole 20 year old worn out truck.
The rear suspension articulates noise free and my brakes no longer make noise every time i go to a stop.
It quite sad I had to fix this problem myself but in a way I'm glad I did. I know its done right and tight now.
Hope this all helps someone.

Since you performed what would be considered warranty work are you able to bill GM?

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ullose272 · April 23, 2020

Since you performed what would be considered warranty work are you able to bill GM?

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Hahahaha no

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Chad's Trail Boss · April 23, 2020

32 minutes ago, topgear1224 said:

Since you performed what would be considered warranty work are you able to bill GM?

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lmao. Yeah I wish. They wouldn't be able to figure out how to process the invoice. SMH Incompetent boustuds!

Ryguy · April 24, 2020

Chad thanks for that write up man, great info. Sometimes you just gotta get your hands dirty.

JAP90 · April 25, 2020

I have a 2020 AT4 with 900 miles on it. You all are discussing a squeaking sound, but mine is a clunking sound in the left rear. Sounds like a ball rolling around in the bed. It happens at low speed, when turning (loading or unloading the LR), when going from drive to reverse into a parking spot, and when going over small bumps. It's gradually getting worse.

The same SB 19-NA-129 mentions squeaking and clunking in the rear end. I took it to a dealer and they acted like I was an idiot, so I left.

I'm somewhat mechanically inclined, and my intuition tells me it's the leaf springs or the LR shock. Anyone had luck fixing the clunking sound?

Kchampagne · April 25, 2020

4 minutes ago, JAP90 said:

I have a 2020 AT4 with 900 miles on it. You all are discussing a squeaking sound, but mine is a clunking sound in the left rear. Sounds like a ball rolling around in the bed. It happens at low speed, when turning (loading or unloading the LR), when going from drive to reverse into a parking spot, and when going over small bumps. It's gradually getting worse.

The same SB 19-NA-129 mentions squeaking and clunking in the rear end. I took it to a dealer and they acted like I was an idiot, so I left.

I'm somewhat mechanically inclined, and my intuition tells me it's the leaf springs or the LR shock. Anyone had luck fixing the clunking sound?

I agree with you. Mine is clunking, not squeaking. The dealer is replacing my leaf spring. I would try a different dealer.

Chad's Trail Boss · April 27, 2020

On 4/23/2020 at 10:55 PM, Ryguy said:

Chad thanks for that write up man, great info. Sometimes you just gotta get your hands dirty.

You bet man. I was really getting frustrated with my truck and the dealer on this crap.

Now that I finally said screw it and fixed everything myself, I am totally pleased with the truck and my BP is lower not having to deal with the dealership.

I know the whole situation is not right but as you say, sometimes its better to just get your hands dirty and deal with things yourself.