I was told by a Porsche master tech that the easy way to check the viscous coupling is to jack up one front wheel then turn it vigorously. Within a few revolutions the force needed to rotate the wheel should increase, if the viscous coupling is working properly.
The front diff itself does not usually fail, the viscous coupling can wear out. The coupling is in the extension housing of the front diff. Where to get a new/better one, that I don't know.

 

I appreciate the comments/suggestions, and I'm planning to get it repaired and keep the AWD. I don't want to convert it to RWD. Found a few used ones at some Porsche Dismantlers from $1800 up to $4500. But they have a million miles on them, so it probably would be wise at the time to replace the bearings in them before installing it in your car. Priced out a new one at the dealer and it runs $8500.

So I received one constructive suggestion to contact California Motorsports about repairing it. Thank you 2fcknfst and lazarus. Any other repair shop suggestions from 996 owners?

Thanks,
Steve

 

Anytime.

 

The same front diff and viscous coupling is used on all 996 so it does not need to be from a Turbo.

 

So 996, Turbo, C4s & Carrera4 👌

 

I would worry that the ring and pinion might be ruined. I bet they are from bad oil and operating at incorrect tolerances. It might be best to just buy a used front unit.

 

@sullivs, this is local to me.

 

Thanks Docwyte, I will look into it.

Steve

 

Good price, cannot go wrong if you want an OEM.

 

I have the front diff from my 01 996TT sitting in my attic. I can replace the bearings and ship it to you if you want to save downtime on a rebuild.

 

Thanks for all the inputs. In my searches, I did find two shops that would rebuild Porsche differentials for a fixed fee with new bearings, seals and inspections. However, I did find a used one in CO for sale, and a Rennlister helped me secure and ship it to MO (thanks docwyte!). This diff had 30K miles. My trusty Indy shop installed new seals and fluids, and change the tranny fluid as well, then made the swap. I cannot believe how quiet it is, and now I can turn the radio down :-).

Now I have a spare differential, with a bad bearing or two, to store in my garage.

Thanks much for all the support,
Steve

 

No problem, glad it worked out.