S2 diff

[jonk]

Right, straight to the point... According to my local backstreet mechanic my differential is knackered. Not surpising after 160k miles I suppose though the rest of the car is cracking and it still drives beautifully. I'm presuming this will be expensive? It does hum at higher speeds 50mph plus, though gear change and clutch action is fine. Very small oil leak on the diff too. Bearings shot is what I'm thinking. Any experience or words of wisdom guys?

Many thanks

 

[chrisg]

i would politely suggest that its the diff bearings not the dif itself that is the issue. The main expense is dropping and replacing the box itself rather than actually replacing the bearings (needs a porsche specialsit to get the preload correct). Ring promax and ask for aquote ?

other option = 2nd hand box, but could be just as bad ?

 

[jonk]

Thanks Chris. By box do you mean gearbox replacement?? Hell's teeth...that will be a mother of a job. I would have thought the diff bearings would be separate though of course the transmission my have to come out for access. Porsche shop in Halesowen is near so I may pop it into the workshop there for a diagnosis.

 

[GC8]

Yes, get a better mechanic. A 50+mph hum is nothing to worry about.

 

[robwright]

ORIGINAL: GC8

Yes, get a better mechanic. A 50+mph hum is nothing to worry about.

Or some thicker boot carpet [] Seriously check your boot carpet for sound deadening underlay on the back of it. It does a lot for quietening down the boot.

 

[jonk]

Ok thanks all. Specialist knowledge really helpful. He claimed there was play in the diff itself. So, do I understand it that all high mile 944s hum from the rear(!) at higher speeds?

 

[pauljmcnulty]

So, do I understand it that all high mile 944s hum from the rear(!) at higher speeds?

All 944s have a surprising amount of noise from the back, it was an issue at the time they were new, let alone compared with the decades of NVH reduction we're used to now.

I'd get a specialist to check it, but try a few other cars for noise as well; comparing yours to some other owner's cars is often very reassuring. []

 

[david924s]

Or pop it along to a local PCGB meeting and have someone with another 944 have a listen to it, sometimes the words "not a problem mine does that" can often alleviate many fears.

 

[NeilW]

I had a drum/groan noise on my S2, which was traced to diff bearings. The volume increased with speed and off/on throttle conditions. My specialist was able to swap the outer bearings without dropping the 'box and was therefore a cheap repair. It made a world of difference to the driving experience though!

 

[jonk]

Thanks all. The symptoms above ^^ are spot on to what I am experiencing. I'm close by the Porsche shop in Halesowen this afternoon so may well swing by and speak to one of their workshop guys. Can you remember a ball park figure regarding replacement of the bearings? I have also taken out the spare wheel and added carpet to the wheel well area which may improve matters in the car. Whilst there is a hum, I wouldn't say it is unduly distracting yet, just not silent, but by the sounds of reports from experienced owners, many were never silent from day one....

 

[NeilW]

I don't have receipts at hand but from memory c.£200. That probably breaks down as 2 hours labour plus bearing part cost.

 

[JamesO]

Another thing to mention is that the gearbox is not a big job to drop and re-fit. Removed mine in roughly an hour on ramps on the driveway, so labour at a garage with a Lift, transmission jack and air tools shouldn't be bad.
Also I don't see how its possible to replace both diff carrier bearings without dropping and splitting the box.
One side can be done easily on the car by taking the side cover off but to do the other side the diff has to come out.

 

[bmnelsc]

I've no experience with this repair but seems to me that you should be able to extract the diff carrier from the open side - otherwise - there would be no way to measure and adjust shims on the sides of the carrier without taking everything apart again. Replacing the closed side bearing race would be tricky but I suppose a long drift and a steady hand could work it in straight. I would think they would be driven in like a front wheel bearing race rather than heated and pressed so it seems feasible to replace those without a complete tear down. If its any of the shaft bearings, then agree - the box must come apart.

 

[Lowtimer]

Unless the noise is changing rapidly as you put miles on, it is highly unlikely to lead to a sudden catastrophic failure over the next month or so, so I think you can safely get a second opinion from one of the recognised specialists for the transaxle cars: Promax, JMG, Hartech, etc. Whereabouts are you?

 

[JamesO]

ORIGINAL: bmnelsc

I've no experience with this repair but seems to me that you should be able to extract the diff carrier from the open side - otherwise - there would be no way to measure and adjust shims on the sides of the carrier without taking everything apart again.  Replacing the closed side bearing race would be tricky but I suppose a long drift and a steady hand could work it in straight.  I would think they would be driven in like a front wheel bearing race rather than heated and pressed so it seems feasible to replace those without a complete tear down.  If its any of the shaft bearings, then agree - the box must come apart.

I must admit I didn't try to take the diff out without splitting the case as I couldn't see how you could get the crown wheel past the pinion gear without pulling it out of the way first. Also I still have to clean the destroyed oil pump drive gear from the gears.
When/if I get round to putting new bearings in and buggering about with shims, I will report back as to if its possible or not.

 

[jonk]

Thanks for all the suggestions. At the moment, I'll just have to keep my eye (ear!) on it. Haven't noticed it getting much worse, but at motorway speeds, there's definately something whirring quite loudly that shouldn't be. I noticed today that it does stop when coasting out of gear. Still the diff bearings do we think?? Lowtimer, to answer your query, Bromsgrove, South side of Birmingham towards Worcester.