07 GMC Yukon Mystery brake squeal Or Hub Chirp??

[Tray0625]

07 GMC Yukon SLT 4x4 5.3flex, 158K miles

Bought this truck rode hard and put up wet. No squeal when I bought it, but front rotors were warped, suspension clapped, rear brake lines clogged, brake fluid reservoir had green algae in it. This thing was in rough shape. No Squeal though!

I rebuilt the entire front suspension, put new brakes & brake lines in.

Got a squeal that started after rebuild that I cannot solve. Squeal is coming from Driver's front area.

Squeal only appears after everything has warmed up and been driven for about 10 min. Squeal will chirp over tiny bumps & when load shifts slightly. Squeal is prominent when turning left, and will dissipate when turning right, constant while driving straight. Squeal occurs at most speeds; 0-30MPH constant (not so much 35-55MPH), intermittent on highway at 70-85mph. Squeal gets louder under light braking, but deeper into brake pressure as you come to a complete stop, the squeal subsides. As soon as you start driving again, the squeal begins again.

To try to solve I have;
- cleaned/regreased caliper slider pins twice
- Replaced front brakes again (same manufacturer, assumed they were defective)
- replaced driver's brake caliper
- installed brake pad tension clips to pull pads away from rotors (like newer Toyotas use)
- used brake squeal stop silicone on brake pad backing plates
- replaced CV axle & hub
- Replaced CV axle & hub again
- checked clearances on brake dust plate and other parts behind wheel, and clearance is fine. I see no strange wear/rub indications on rotor.
- filed down brake pad retention clips/squealer clips, and even completely bent the squealer tabs backwards away from rotor
- pads do not seem to be dragging at all

I'm at a loss. Defective Strut assembly? Second new hub is defective too? WTF?

Your suggestions will be greatly appreciated. Thanks!

 

[Dustin Jackson]

@Tray0625 If the sounds occurs on flat ground when driving in a straight line I would think it is something with the wheel turning. Is my statement correct so far?

Have you been able to replicate the sound with the wheel in the air?

 

[Tray0625]

@Tray0625 If the sounds occurs on flat ground when driving in a straight line I would think it is something with the wheel turning. Is my statement correct so far?

Have you been able to replicate the sound with the wheel in the air?

You are correct, and I have assumed the same thing. That it has to be a part that is associated with rotation (hub, brake part, bearing, axle, etc). Especially since it only begins to squeal after everything has gotten to normal operating temp - it's as if there is something with a tight enough tolerance that when the parts are cold, they do not contact each other BUT once heat has expanded them ever-so-slightly, they touch and generate the squeal.

I have also been baffled that I have not seen physical evidence of it on the rotors or other brake parts.

I have not replicated the noise with the vehicle in the air, seems to need to be loaded.

I read on a different post of someone having a similar issue that they had a defective strut that "made a noise just like brake squeal". I may try it, just because I'm out of ideas.


***Perhaps another clue: When I first got the truck, I had a horrible clunk on the driver front. Previous owner had run over something (splash guards were sawzawed out, bumper had stress fractures in paint, etc. probably hit a deer or something). This prompted the full suspension rebuild. I replaced every part in the front end (except steering knuckles). Still had the horrible clunk. Found out the UCA mount had been bent open a bit, so the UCA was not properly torqued. So I bent the UCA mount back (it was only a slight bend) and then torqued the UCA to manufacturer spec. SOLVED, no more clunk.

I am curious how long the truck was driven with the UCA loose, Could have been for 100k for all I know.

Is it possible that tolerances got screwy from driving with a loose UCA for some period of time, and now that everything is back where it's supposed to be - I have a squeal due to improper wear somewhere?



I feel like a crazy person. I have owned, maintained, & fixed many vehicles. I've never had one stump me like this, or refuse to cooperate. It's been maddening.

 

[Geotrash]

You are correct, and I have assumed the same thing. That it has to be a part that is associated with rotation (hub, brake part, bearing, axle, etc). Especially since it only begins to squeal after everything has gotten to normal operating temp - it's as if there is something with a tight enough tolerance that when the parts are cold, they do not contact each other BUT once heat has expanded them ever-so-slightly, they touch and generate the squeal.

I have also been baffled that I have not seen physical evidence of it on the rotors or other brake parts.

I have not replicated the noise with the vehicle in the air, seems to need to be loaded.

I read on a different post of someone having a similar issue that they had a defective strut that "made a noise just like brake squeal". I may try it, just because I'm out of ideas.


***Perhaps another clue: When I first got the truck, I had a horrible clunk on the driver front. Previous owner had run over something (splash guards were sawzawed out, bumper had stress fractures in paint, etc. probably hit a deer or something). This prompted the full suspension rebuild. I replaced every part in the front end (except steering knuckles). Still had the horrible clunk. Found out the UCA mount had been bent open a bit, so the UCA was not properly torqued. So I bent the UCA mount back (it was only a slight bend) and then torqued the UCA to manufacturer spec. SOLVED, no more clunk.

I am curious how long the truck was driven with the UCA loose, Could have been for 100k for all I know.

Is it possible that tolerances got screwy from driving with a loose UCA for some period of time, and now that everything is back where it's supposed to be - I have a squeal due to improper wear somewhere?



I feel like a crazy person. I have owned, maintained, & fixed many vehicles. I've never had one stump me like this, or refuse to cooperate. It's been maddening.

It's not unheard of to bend a steering knuckle on one of these. A hard curb strike or an accident would do it. Since that's the one thing you didn't replace, it's worth looking at. Also is the CV joint possibly rubbing on the sway bar link? Is the outer tie rod touching the rim? A bent knuckle could cause the latter.

 

[Tray0625]

It's not unheard of to bend a steering knuckle on one of these. A hard curb strike or an accident would do it. Since that's the one thing you didn't replace, it's worth looking at. Also is the CV joint possibly rubbing on the sway bar link? Is the outer tie rod touching the rim? A bent knuckle could cause the latter.

I can try a knuckle, although is has aligned just fine. I would not be surprised if it was indeed bent, but it does not look to be just by eyeballing it.

CV joint is not rubbing, plenty of clearance. Tie rod is not touching the rim. Everything looks to be in the correct place.

 

[B-train]

Based on the 10 min driving info, I'd go after fluid expansion due to heat transfer. Maybe the slight increase in under hood temperature causes it, or some brake drag. Either way, I'd do a brake hose replacement seeing that you've done everything else. They can check-valve with heat and cause a caliper to drag. Try using an IR gun after a 10 minute drive and see how each side compares. If the noisy side is louder, then you have your culprit

 

[Tray0625]

Based on the 10 min driving info, I'd go after fluid expansion due to heat transfer. Maybe the slight increase in under hood temperature causes it, or some brake drag. Either way, I'd do a brake hose replacement seeing that you've done everything else. They can check-valve with heat and cause a caliper to drag. Try using an IR gun after a 10 minute drive and see how each side compares. If the noisy side is louder, then you have your culprit

I'll grab the IR gun and see what I come up with.

The rubber brake hoses were replaced, hard lines are originals. Still doesn't rule them out like the IR gun will though.

Thanks for the tip. I'll let you know what I find.

 

[B-train]

Just make sure to read on a dull surface - anything shiny will be a false reading

 

[Tray0625]

So I checked with an IR gun after driving, and the quiet side is actually 2 degrees hotter than the driver's where the noise is.

My gun was reading low battery, so I figured I would get a fresh 9V in it and double check just to be sure. Will update after I check with fresh battery.

Thanks