Got a strange coffee grinder noise coming from undernath the middle of the car on my '04 RS.

The higher my speed (ie: at about 70mph on highway) the louder it is. The noise is only there when i lift off throttle. Called Shep Racing (they did the diff rebuild back in '10). They seem to think it's ring and pinion wear coming from the transfer case.

Anybody had this problem? Like I said, it kind of sounds like a coffee grinder. Thanks.

 

Could be input shaft bearing, or TOB.

There is a bit of info on this here.
http://www.jackstransmissions.com/pa...-shaft-upgrade

I had the same "coffee grinder" type noise, and I have heard of quite a few people having this issue. I read a lot on here and eventually diagnosed my noise as being a failed input shaft bearing.

Some checks to do to rule out other things:
does it only happen when decel in gear?
press clutch while still in gear decel, listen.
while decel press clutch put in neutral, release clutch, listen.
while still, press clutch, listen.
you can rule out TOB this way.

Also, what clutch are you running? "Heavier" or multiple plate clutches can have excessive thrust load on the input shaft bearing, which can cause premature failure.

loud gear lash sounds could also possibly be from worn ring and pinion in the TC as Shep said.

The reason the noise is louder is because of the higher force load on the drivetrain causing more lash sound. (this occurred in my case as well)

I drove my car for about 10k miles with it making this type of noise until I was annoyed enough to fix it and have heard of people doing much more than that, if that's any consolation in terms of urgency.

 

I've driven my car well over 100k with decel noise. No biggie

 

Do you have a twin or triple disc clutch? Mine makes noise on decel as well, I have an exedy triple.

 

I get the same decel noise as you guys. My anxiety goes through the roof when it happens. I'm on a single disk (ACT HDSS) with HD pressure plate if that matters.

 

It's either the TOB or the input shaft bearing as someone stated earlier. Evo's have been making this noise since the 03's. It's a very common occurence. Just wait til your reverse idler gear assembly starts to get noisy. That will drive you insane.

 

it's not t-case? i have this noise, and an ACD reflash and it only happens when I'm in the track or autocross modes, not street