MagnusB

My car just developed a new noise, almost like I got a sports exhaust :-)
It only sounds when I drive and have the clutch engaged and I can feel it vibrating a bit in the shifter. If I don't push the throttle too much it kind of goes in &out just as if something was a bit loose and engaging/disengaging.

I'm worried it's the diff going to pieces but how do I diagnose this better?

Pac996

Any lash slack on and off the gas with a clunk coming from back there? I'd think if it were differencial then you'd have a little slack back there. Might as well try getting a look at your CVC boots and checking the oils. Also does it do the same in all gears helps figure where the problem is.

Macster

Diffs going bad usually make a lot of noise, a howl, whine, under closed throttle coast down.

Could be a diff, could be anything, but my WAG is a CV joint is going bad.

Good advice to check CV boots for any signs of trouble. When a CV joint starts to go bad it can heat up and sling away its grease and if one boot feels "heavy" with grease compared to the others...

If you can arrange to get the car lifted by its body lift points you can grab each half-shaft and tug and push and see if you can detect any play any looseness.

I'd be a bit careful about driving the car. I had a u-joint fail on a driveshaft and the driveshaft came loose at the tail end of the tranny and whipped around and busted the transmission. Ruined it. Lucky for me a dealer had just installed the new u-joints a few days earlier and the failed u-joint and transmission replacement covered by the dealer's service department warranty on the work.

Sincerely,

Macster.

MagnusB

Thanks guys.
I'll lift it up tomorrow and check the CV joints to start with.

The noise is in all gears btw, but more noise in some, also depends on speed.

Torontoworker

I've had a bad diff in both a CTS and a Camero and it sounds like a super charger winding up back there under power. Back off on the power the pitch of the 'whine' changes. Both cases it was carrier hub bearings. But it comes from the rear of the car and you shouldn't feel anything in the gearshift lever unless the rear end is about to explode. Could be clutch related, maybe the release bearing? I had something like this happen in a Mustang - the gear lever would be moving around as I went on and off the power - mainly in 3rd gear. Aside from a syncro issue the clutch needed full service and the release bearing was scrap metal and it did have a low and loud sound to it.

Macster

Another possibility is the dual mass clutch mechanism has failed. How does the clutch take up feel? Nice and smoooth or grabby with a clunk or any other odd symptoms?

Check the CV joints first.

You know unless you're going to fix it yourself you will still need to get the car to someone who can fix it and he'll want to do his own diagnosis.

In some cases it is better to just pack the car up on a flat bed and drop it off to have it fixed. I'm always a bit worried about self-diagnosis cause this subjects the car to more use when it is sick and this can cause more harm.

Sincerely,

Macster.

MagnusB

Checked the CV joints and they look fine.
The clutch has 50k on it with 30 track days and countless AX events. But it feels fine.
Took it to a shop for further inspection. Found that a transmission mount was bad. The shop will fix the mount and continue the investigation. I feel a big hole developing in my wallet.

kj217

any updates after changing the mount,,
i have a similar issue,, curious,,