Gerg007

Good morning! Time for everyone's favorite potentially expensive game, 'What's that noise?". This is on my '01 SS M6, for reference.

Well, first off, I have a loud stuttering sound that sounds like it's coming from the rear while I'm in reverse, usually giving it a generous supply of gas prevents this, but not always.

Secondly, I'f I'm on the throttle more than roughly 20% I start noticing a quiet, fast paced ticking/ vibrating sound (sort of like a card in a spoke ?) that seems to be coming from the area of the trans. It happens in all gears and worsens with the amount of gas I give it. However the sound seems to disappear completely around 3.5k RPM. You also don't hear it with your foot off the throttle or in neutral (regardless of rpm). I didn't notice this sound until after I changed my trans fluid (it's possible it was there before, though I may not have heard it since I drive with the window down primarily)

I've replaced both the transmission fluid (amsoil ATF) and fluid in the rear (M1 75/90) and both noises persist.

This car is going 100 miles to drill this weekend, so any insight is appreciated

WhiteHawk

The tick sounds like it might be an exhaust leak. The noise in your rear means it is time for a rebuild. The rear on my car sounded like that until it started making a groaning sound. Those are my guesses.

Time for some headers and a new gear in back!

-Geoff

Gerg007

You mean I have to replace the factory exhaust and gears? How horrible!

I suppose now that I think of it I can occasionally see some smoke from behind the engine if I rev it.

As for the rear everything looked to be in decent shape when I took the cover off, and the magnet only had a few small shavings.

WhiteHawk

To properly check the rear you need to do a gear wipe test - you put some goo on the gears and it will show you the contact pattern they are making. Also, you can check for play in the mounting of the differential - there should be virtually none.

My rear was making a ton of noise, and all it needed was a rebuild (new bearings, races, and shims). He used the same gears and posi unit, and now it is super quiet. The 3.23 gear which most of us have is discontinued, too, so replacing it with the same isn't even an option. Sometimes you end up having to get a new posi and/or gears, and that can get expensive. At that point you might be better off looking for a used differential - enough people still replace theirs with stronger rears that you caen usuall get them for $100-$200. Finding quiet ones is getting tougher though.

Doing the rears on these cars is as much art as it is science, so make sure you take it to someone who has done them before. If you want to drive up to Detroit, I have a guy up here who is the local guru, with 15 years of experience specializing in f-bodies.

-Geoff

97z28k&N

the smoke most likely has nothing to do with the exhaust system. What color is the smoke? if it is blue, than oil is being burned. If you see white "smoke" when the engine is cold then that is just the condensation burning off of the cold exhaust pipes.




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