Diff gone I think??

[high52kojak]

Just been out for a drive, encountered a nice 911 Turbo on the way, but anyway it has developed a serious vibration/clunk whilst off the gas, its loud and is easily felt through the car, its not there when I excellerate but as soon as I come off the power its there. I am thinking Diff? If the clutch is pressed whilst its doing it, it stops.
Ideas please anyone?

[BLUETHUNDER]

Sounds more like diff bushes have finally given up.

[high52kojak]

Hope so but it sounds and feels more serious than that, tootled home at 10 mph

[GreenV8S]

Could be bushes or a loose mounting bolt. If you catch it in time it may be very easy to fix, but if you ignore it you can easily destroy the diff housing leaving you with a very large bill.

[high52kojak]

Whats the best way of checking the bushes/mountings, will the unit be loose?

Thanks.

[ridds]

GreenV8S said:

Could be bushes or a loose mounting bolt. If you catch it in time it may be very easy to fix, but if you ignore it you can easily destroy the diff housing leaving you with a very large bill.

Yep, clunk coming off gas is 9/10 a bush or mount. Mine is forever working loose and has now elongated one of the holes in the offside wing plate.

Doubt the diff has gone, it's not a regular occurrence on these.

[high52kojak]

Anyone changed the mounts with the car just on axle stands? ie lying on their back, not with the car on a lift

[Brummmie]

My rear diff mount was in 3 pieces, get under the car and with a tyre lever give it a prize and see what gives. I made a thicker one as the standard one is bacofoil gauge!

Edited by Brummmie on Saturday 25th April 20:01

[high52kojak]

Was it the top mount Brummie?

[BCA]

Not common, but not unheard of, ours just became a very open diff - no noises.

[BGB autosport]

Maybe as the 911 came past you, his scissors fell out and got stuck underneth and are now causing the noise...






Will drop my stands off tomorrow mate.

[high52kojak]

BGB autosport said:

Maybe as the 911 came past you, his scissors fell out and got stuck underneth and are now causing the noise...






Will drop my stands off tomorrow mate.

Ha ha, your doing more than dropping the stands off, your doing the work on it

[brogenville]

high52kojak said:

Anyone changed the mounts with the car just on axle stands? ie lying on their back, not with the car on a lift

That's literally what I've been doing today- changing all bushes for poly, then replacing the rear mount along with fitting a new diff cover for good measure. Looks like bolts worked loose on my one too, then fatigue cracking got the better of the mounting bracket.

Removing diff with the car on axle stands isn't particularly bad, but trying to lift and manuvre he fker back into position whilst your lying on your back isn't fun. It's a heavy bd!

On the up side, gave me a chance to see that the diff internals look perfect.

[DonnyMac]

This could be a surprisingly cheap fix - when sitting on the drive dip the clutch through the biting point a few times, does this re-create the knock?

If so, it's the diff mount, clean snapped mine through, usual "argh, that sounds expensive", nope, very cheap indeed.

Fingers crossed.

[Brummmie]

high52kojak said:

Was it the top mount Brummie?

yes top mount, made extremely heavy clunking noises as the diff was resting against the chassis.



Here is before and after brackets

[high52kojak]

Hi, no bringing clutch to bite point doesn't recreate the sound, its a constant harsh vibrating when off the gas, not just a clunk when coming off the gas.

Where did you get your new bracket made Brummie?

[Brummmie]

high52kojak said:

Hi, no bringing clutch to bite point doesn't recreate the sound, its a constant harsh vibrating when off the gas, not just a clunk when coming off the gas.

Where did you get your new bracket made Brummie?

My fair hands, a truly bespoke piece of art i'm afraid!
The original bracket is not a great deal of money, but still made out of quality street tin, so didnt want to be back here again, but i have 500+ of torque at the wheels. In all fairness it was 11years old and it has had loads of harsh launches at various events, so was asking alot of it.

[high52kojak]

Yep its the diff mount, its all broke and bent, causing the offside drive shaft flange to rub on the chassis, hence the vibration/clunk. Going to be a long job, its taken me two hours to get the exhaust off!

Where is the best place to buy one from?

Fancy making me a new one Brummie??

[ridds]

If you do make one I'd be up for one too!

New business venture?

[brogenville]

I ust bught one from Raging Green. About 26 quid I think.