Rear Brake/Axle Groan...

[f5fstop]

...upon heavy braking.

This is being rephrased....
The problem will be worked on Today, on my vehicle.
Appears to happen only with warm brakes and a heavy stop. Light stopping does not seem to cause the groan.
I'll keep you guys/gals informed.

[fourfourto]

Thanks F5.
Sounds like the same as mine,
funny thing this wekend on a 800 mile (total )upstate trip It was not that noticable,It could have to do with few complete stops but it wasnt as bad as last week with regular driving.

Remember I had my rotors cut and rear brakes replaced at 12K noise started again at 18K(dealer said normal) Im now at 20,000 miles.


Also Its not always a hard stop more of a consistent full stop

[Desert Dan]

I groan when in stop and go traffic too!

[Hmmm2]

Originally Posted by fourfourto

Thanks F5.
Sounds like the same as mine,
funny thing this wekend on a 800 mile (total )upstate trip It was not that noticable,It could have to do with few complete stops but it wasnt as bad as last week with regular driving.

Remember I had my rotors cut and rear brakes replaced at 12K noise started again at 18K(dealer said normal) Im now at 20,000 miles.


Also Its not always a hard stop more of a consistent full stop

X2!! Except I'm around 16.5 K with mine right now. My groan just came back .. intermittently. Now I come to a rolling stop .. I'm afraid to listen to that groan again. f5fstop .. what you have described is EXACTLY as I had described it ... EXACTLY! Can't wait to hear what you find out. I'm sorry your H3 has it, too, f5fstop .. but at least I(and fourfourto) will finally know the REAL reason once you get your answer!!

[f5fstop]

Ok, here it is and some may not like it......
Not the rear brakes, we checked them today, and all is well. Thought it might be the rear sway bar...Nope. Rear axle....nope.
Installed chassis ears*, drove around and we discovered an interesting thing; something we all know, but forget about...sound travels.
For some reason we don't know yet, when slowing down and suddenly stopping, and the trans downshifts into first, a metallic sound (sometimes a groan) is emitted from the transfer case and travels to the side, making it sound like the rear brakes are making a noise.
The vehicle is currently up in the air w/o a transfer case, waiting for a new one to be delivered. Once replaced, we will drive around some more to see if this is the noise.
If it was the noise, the case goes back to BW to root cause the problem...if there is a problem other than noise. This root cause will take time. In fact, it may take till next Monday to see if this solved the problem.
Now, was my noise the same as all other noises reported? Don't know, and really can't tell. I will say my noise this morning was more of a scrapping sound than a moaning sound, and that sound sure appeared to be coming from the t/case when using the chassis ears.

A regional rep has reported a groaning sound repaired on a vehicle by applying silicone lube to the stainless steel shims on the rear brake pads.

I'll keep you guys informed, but right now I have to suffer since the only vehicle available to drive was a yellow corvette convertible, and the temps are going to the 40s; so what good is it! I believe Friday I will switch it for a Crimson 2007 H2 that will be available that is in the test fleet, and they need more miles on it, plus some opinions on how it drives.... (Hear that DRTFYN?????)

(*A box with a rotor switch to tune into different circuits, has a head phone, and six leads that connect to different parts of the vehicle. So you can pinpoint a noise.)

[Hmmm2]

Thanks for the update, f5fstop. Am anxiously awaiting the outcome of your transfer case test. Thanks for explaining exactly how the chassis ears are hooked up. I had suggested to a dealer service mgr (upon your suggestion to me) that he use chassis ears on my H3 to pinpoint the sound. Do you know what he said? "With that type of noise, we couldn't put a mechanic under the vehicle while driving to hear the sound you're talking about!" OMG!!!! ()

Back to topic .. let us know as soon as you find out!! Thanks!

[f5fstop]

Originally Posted by Hmmm3

Thanks for the update, f5fstop. Am anxiously awaiting the outcome of your transfer case test. Thanks for explaining exactly how the chassis ears are hooked up. I had suggested to a dealer service mgr (upon your suggestion to me) that he use chassis ears on my H3 to pinpoint the sound. Do you know what he said? "With that type of noise, we couldn't put a mechanic under the vehicle while driving to hear the sound you're talking about!" OMG!!!! ()

Back to topic .. let us know as soon as you find out!! Thanks!

Tell them that's why H3s have a high ground clearance, to allow techs to ride underneath. That's why chassis ears were designed. Hard to have a mechanic ride around under a Corvette while checking for undercarriage noises.

[Ed Coryell]

Originally Posted by f5fstop

...upon heavy braking.

This is being rephrased....
The problem will be worked on Today, on my vehicle.
Appears to happen only with warm brakes and a heavy stop. Light stopping does not seem to cause the groan.
I'll keep you guys/gals informed.

I took my H3 in last week because it started making the same noise when I braked a little harder than just slowing to a stop. I had it in a couple months ago for a different noise that turned out to be the transfer case (that was discussed in another thread), and they replaced that at ~ 12 K miles. They had my H3 for 2-1/2 days, did the sound tests, spoke with the GM engineers, and determined that it's a design problem with the rear brakes. They said it isn't a safety issue and that the brakes work fine, but that because of all the complaints they've been getting about the noise (at least three more came in to my dealer in the day after I dropped mine off, plus others across the country), that GM engineers will be redesigning the rear brakes and will probably issue a recall when they've worked out the noise problem.

FYI - I also had the driver's door light switch replaced - the connection went bad in the middle of the night a couple weeks ago, turning on the dome light and setting off the alarm. It stopped doing it the next day (maybe there was some moisture in the switch?), but I asked them to replace it anyway.

I'll keep you posted when I find out more.

[f5fstop]

Those rear brakes are almost identical to half-ton pickup truck; can't figure out why, there would be a problem. However, I know who exactly to call on this one.

[fourfourto]

GM engineers will be redesigning the rear brakes and will probably issue a recall when they've worked out the noise problem.

F5 Any official word that gm engineers are working on this?


I know who exactly to call on this one.

Who?

[f5fstop]

Originally Posted by fourfourto

GM engineers will be redesigning the rear brakes and will probably issue a recall when they've worked out the noise problem.

F5 Any official word that gm engineers are working on this?


I know who exactly to call on this one.

Who?

Well, I thought I did, but it appears when I was off for three weeks, service engineering had a re-org in some of the areas. So, the engineer in charge of brakes is not someone I would call. However, from other sources, there is nothing spectacular about the rear brakes, basically a carryover design from another series.
But, I'm not done calling....

[fourfourto]

Well I just got a call from HCS manager susan,The hummer cust rep I talked to last week gave me wrong info,they will not do a repair without OK from field rep.I called dealer sevice and cancelled appt for friday.He will try again to get in touch with the field rep...Here we go again GRrr Grr grr


I guess its a matter of time(long time).I will just keep calling


F5 any new info on the brakes would be GR8 Thanks