sullivs

I have an '02 C4S with 40K miles on it. My front differential is making noises like noisy tires. It is uniform, and goes up and down with vehicle speed. It is not a wheel bearing, and I cannot feel it through the steering wheel. It is louder now than it was last summer. So I'm assuming there is a growing problem with the differential. Whether it be a bearing or what-have-you.

If I assume the least expensive problem, does anyone have recent data or prices on replacing a bearing in one? Is this a dealer-replace-only item? I have seen some older comments on the List here about it, and was looking for some more recent information.

Thanks much,
Steve

SAM DACOSTA

Steve, the C4S making grinding noises in the front differential could be the 'viscous coupling' damaged. Have a shop check the front differential for any damage internally. I just replaced mine after a similar grinding issue. Have you had a 'smog check recently' by any chance? Especially when the noise first started?

sullivs

Sam, I have not had a smog check. Plus I don't really know when the noise actually started. It isn't that loud that all of a sudden I noticed there was a noise. Did you have to replace the entire differential? Or are there replaceable parts in it? Can you tell me what the costs were?

Thanks,
Steve

SAM DACOSTA

The only reason I asked about a smog check is that's how mine was destroyed. The Technician at the Smog Station did not realize this was a C4S (incompetent to say the least) and ran the car on a 2 wheel dyno, which caused the damage.

The shop that did my repair is also my personal local Porsche Indi shop and they do excellent work. The entire differential was not replaced but both front axles, the viscous coupler and some other parts were replaced. They checked for further damage elsewhere but found none. Total cost was $5K.

You need to take it to a Porsche shop and have them at least find out what issues you have, then you can determine the actual budget for your repairs. You really cannot use my repair as a gauge for yourself as you don't know if the same issue is within yours. They should be at least be able to guide you on an estimate after checking.

Topaz330ci

5K is kinda scary if you think of it.....

sullivs

Thanks for the details back. I'll do a little more investigating and see what I can find out.

Steve

SAM DACOSTA

I agree but what options do you have if you drive a C4S and the viscous coupler and axles were damaged? Parts as you can imagine are frightfully expensive and coupled with labor rates. If it were done at a dealership it would probably be closer to $8K. If the differential had been damaged, then that would have required a complete new differential as I'm told Porsche does not supply parts for re-building. (That statement was from a friend who's the Service Manager for Porsche in the Bay Area.)

Porsche ownership and repairs are kinda scary if you really think about it.

SAM DACOSTA

Good luck as you progress through this repair. Keep us posted as you find out more details. I hope it's not as bad as I mentioned for your sake.

wwest

Some time ago I came to realize that the C4 aspect of my '01 is so non-functional that should ANY part fail it will get REMOVED entirely.

SAM DACOSTA

Why is it non-functional? How would you remove it entirely? My questions are for information only, as I'm new to C4S ownership and your comments intrigue me.

Dennis C

I'm beginning to wonder if I've got an issue with my viscous coupling/front differential.

Just today, my C4S began to make a noise from the front end. It's intermittent, and I've only been able to replicate it a couple of times. It only happens when I'm coasting downhill in gear. It sounds a bit like a slipping belt, but from the front of the vehicle. If it makes this noise and I give it a little gas, the noise stops entirely. So far, I've only heard it in 3rd gear or in 4th gear.

Looks like a trip to my mechanic is in order.

Any thoughts? Does this sound like the front differential? FWIW, I had the front differential fluid chaged at my 90,000 mile service, which was two years ago.

Capt. Obvious

If your front diff goes out, you can usually find used ones on ebay for about $1000.

Or, you can just remove the AWD entirely. It's as pretty much as simple as removing the drive shaft, differential and then taking the CVs apart and removing the axles (and leaving the axle stubs in the hubs). A lot of the high horsepower Turbo guys do it.

Dennis C

I think I'd rather leave it intact. My preference would be rebuilding it if possible, but I don't know what's involved. I'll see what my mechanic finds.

seanmcr6

If you remove the dif/cardif from the front...wouldn't that mess up the PSM?

I am beginning to see the severe limitations of the 4 wheel drive system myself....but I love the wide butt

Capt. Obvious

Apparently, no. Quite a few people on the 6speedonline forums have done it with no side effects. If you do a search for "rear drive conversion" or something like that in the 996 Turbo forum you should find quite a few threads about.