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.

[fourfourto]

If it is the tranfer case making the noise the only way a dealer would replace it would be to do the sound test.
Do all dealers have this available to them.
If yours was bad will there be a record of the fix for the dealer to see.

[Hmmm2]

But .... if the groan is coming from the transfer case, does it mean that there definitely IS a problem where it needs to be replaced? I can just hear the Service Manager telling me, "It's not a safety hazard and doesn't affect the performance of the vehicle". But, fourfourto, how does that explain the feeling in the brake pedal that I get (and you, too, I think) as the groan is occuring? Yesterday I had the radio up high and when I came to a stop, I 'felt' it in the brake pedal. SO, I turned off the radio and brought it to a similar stop a block up. Sure enough, I heard it.

[f5fstop]

What we cannot determine is that your groan and my groan are the same. My groan actually started to turn into more of a metallic sound. The main reason GM is taking mine out in the service garage is to make sure nothing it tinkered with, and the entire unit, with fluid is sent to BW for teardown by their tech in their research lap.
I never felt anything in the brake pedel, but I heard this sound only when doing a heavy braking.
I guess time will tell, as of right now, it is still sitting in the garage and waiting for a new case.

[Hmmm2]

Originally Posted by f5fstop

I never felt anything in the brake pedel, but I heard this sound only when doing a heavy braking.

I don't hear mine as I roll to a stop or softly come to a stop. Mine happens (example) when I'm almost at the signal light and it suddenly turns red. I go, "WHOA! Red Light!" and hit the brakes. OR, as I'm going down hill and the light turns red at the base .. and I'm going 60-62 mph and have to hit the brakes. Just as I'm ALMOST at a complete stop from the hard brake, it groans. The problem is that you can't just drive along and brake when you have to leisurely ... you ALWAYS have the possible groan on your mind. I don't think that should be part of the H3 package, you know? ()

[fourfourto]

you ALWAYS have the possible groan on your mind


I know exactly what you mean

[f5fstop]

Just picked it up with a new t/case, and the groan/metallic sound is totally gone. Had plenty of chances to test it on the way home (MI stop/go traffic) and it is quiet as a mime in a mime contest.

I'll let everyone know when I hear what the results were on the teardown of the case.

[fourfourto]

F5 will there be any record of noise being related to the transfer case that a dealer could view.
Should I ask the dealer put a mechanic ear on my 3 to see were noise is comming from.
I dont think I will be making a appontment with the dealer for a couple weeks so maybe there will be some more info by then.

Im still not sure If its related to my brakes,
I will try to get a video /sound file from my camera this weekend and post it to see if it sounds like yours.
Thanks

[f5fstop]

I would suggest the tech put some ears on the rear of the brake shield where the park brake mounts, on the axle, on the spring (possibly a loose shackle) and on the case. He can then drive and switch between the different circuits to help locate the noise.
If it is found there are more like this, chances are a bulletin will be produced. However, they have to locate more of these and if it cures the problem, then likely a bulletin will be issued.
Mine might be the only one that has this problem with the t/case. Best way for me to describe is it starts out as a moan, turns to more of a metallic sound.

[Hmmm2]

f5fstop ... yours was a moan/groan that eventually turned into a metallic sound, as in metal on metal? Is that what you mean by metallic? So, the groan eventually disappeared, but turned into the metallic sound? I hope fourfourto can post a sound link .. I'm curious if it's the same sound as yours and mine.

I think I need to drive mine normally now and not be afraid to hear that groan. I've been pampering it at stops because I just don't want to hear that groan sound. I'm so tired of it. Maybe it needs to break down before someone will take it seriously. Thanks for the update!!! Let us know what happens after the t/case breakdown!! (Ohhh, congrats on having a quiet drive now! )

[fourfourto]

Hmmm3 try to also get a sound file of yours and list it on putfile.

I will get a sound/video clip tommorow afternoon and list it tommorow night.(Ive been waiting to take a day video)


That groan gives me chills right up my spine


F5 My brother said he might be able to borow a mechanic ear ,If he can get one I will inspect the noise befor going to the dealer.

[fourfourto]

Well I took 5 sound/videos.

Not really a groan from the outside more of a rattly springy vibrating type noise.

Let me know what you think opinions


the dealer said noise is normal


http://media.putfile.com/down-hill-r...de-brake-groan

http://media.putfile.com/downhill-left-side-brake-groan

http://media.putfile.com/brake-groan-tire-1

http://media.putfile.com/brake-groan-tire-2

http://media.putfile.com/brake-groan-tire-3

[H3PAC]

Could that noise be the anti-lock system?

[fourfourto]

Im not hitting the brakes hard enough for the anti locks to kick in.
Also I think the pump is up front.