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Serious problem, driveline jerk/clunk at 1/2 to full turn

37K views 21 replies 10 participants last post by  mdg 
#1 ·
The foz has a major problem.

When turning left or right on half to full lock there's a loud clunking noise and the car seems to jerk/clunk with it. Hard to explain really. It sounds like a CV joint failure but it's coming from the gearbox/rear diff area and you can actually feel the thunk through the steering and car seat/body. There is no noise or vibration when driving straight.

On the way home today I stopped at a services on the M1 and asked an RAC bloke if he'd have a listen while I slowly drove it in circles. His first words were 'Call your breakdown company'. He thought it was coming from the gearbox area. I limped home not going over 55mph.

Any thoughts?

mdg:icon_cry:
 
#2 ·
Re: Serious problem.

Manual or Auto?

Could just be a prop UJ..although that would be present all the time and not accentuated by the steering!

Possible front/central diff issue..certainly would be a suspect if the noise is louder while the car is turning and your inner wheel is rotating more than the outer!!

Check your G-box & Diff' oil levels..drain and inspect for rogue particles ...put car on four poster and check for awd rotation

Tapatalk from Galaxy S2
 
#6 ·
It looks your centrediff is the problem.
Try to drive with cold car in circle when the problem is not there, surtainly is it your centre diff.
Let someone else drive when hot drive in circle and look at the inside wheel when it is un-evenly rotating it sure is centre diff.

Could be caused by driving different tyrediameters front/rear or low tyre pressure on one of the tyres.

I had this 2 times with an Impreza Plus.
 
#11 ·
Sorry to hear your woes, Mike. Hope you get it sorted as cost effectively as possible.


Could be caused by driving different tyrediameters front/rear or low tyre pressure on one of the tyres.
perhaps a previous owner only replaced 2 tires and blew it up.. you will never know.
BTW this a BS reason for why centre diffs fail.

a) The vast majority of AWD drivers will replace one pair of tyres at a time - yet, AMAZINGLY, the roads are not strewn with 4x4s which knackered diffs.

b) The centre diff is viscous and pretty open so unless there is a massive difference in the rolling radius of the front and rear wheel, the diff will not have an issue with the tyres being slightly different.

c) The centre diff is not made of chocolate

...yes, I know Subaru state not to run with more than X mm difference between the front and rear tyres but they would, it gives them a get-out if a diff fails under warranty.

A locked centre diff will suffer from wind up if used on the road and this can certainly cause diff failures but not a diff as open as the Subaru ones.
 
#7 · (Edited)
#12 ·
The centre diff (nr.938913 in pdf)can taken out with gearbox inplace.
Exhaust partly removing / lowering the gearbox cradle and remove propshaft.
Than you can losen the bolts and take the centre diff out. When putting in a new/other diff check / correct the spacing.
Shiftlever has also be loosend.
It took me roughly around 3 hours to do it.
 

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#20 ·
Right. It seems to happen when the gearbox is warm. Done 2 shortish journeys and no noise/clunking.

If the diff does need changing, it's more than I'm capable of I think. That means giving it to a decent garage to do, and that'll cost much more that I'm willing to spend on it.

This could spell the end of the foz.
 
#21 ·
Gearbox change is not that hard TBH but it does help if you have a lift as maneuvering a heavy gearbox whilst lying on your back isn't the easiest thing to do. Can be done though.
 
#22 ·
I'd be ok with a full gearbox change as its just nuts and bolts, but I'd be lost if I had to open one up.

Can't understand why it doesn't do it when it's cold though.

Could it have something to do with the viscous centre thing?
 
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