Rear Brake/Axle Groan...

[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? ()