Hey guys, I took my 01 996TT today to the shop to get the wheel bearings replaced. I was getting a whirring/howling sound at above 40 mph and thought for sure it was the wheel bearing. A few hours later, I received a call from the shop and heard the dreaded "its not your wheel bearing, its your front diff." The owner gave me a few options, new diff from Porsche 4500, reman diff 3900, used/rebuilt diff 2100, or replace viscous clutch in diff for 1750. It's pretty much between replacing the viscous clutch or just going RWD. Does anyone have any input on what I should do? I've done a little reading on the RWD conversion, and that all you need to do is disconnect the front driveshaft, is that all you need to do? I don't care about the weight savings, I just need it be as easily reversible as possible. I live in California and the car rarely sees any rain and definitely no snow, I also have PSS9s, will I encounter any handling or drivability issues with the RWD conversion?

 

going rwd for you in CA is probably a good idea. there are many in here that have gone rwd. you can disconnect it and just run it like that. you can remove the entire unit and save 70lbs. Then you can wait till you find a spare up for sale at a more reasonable price than 2100 and replace it later. But your first two options should be totally out of the question, that is a ripoff.

 

Have not done business with this company but they are loacated just north of Los Angeles in the San Fernando Valley. http://www.laporsche.com/

Would not hurt to get a second opinion on your diff. since you dealing with big $$$.

Had a boost issue a while back and the stealer told me it was the DV's. Took it to my indy and turned out to be the MAF. How did they miss that one?

 

GO RWD!!! You'll love it.

 

Thanks for the suggestion, I'm actually in nor-cal. The place is also an indy and has confirmed it's the front diff (used a stethoscope and found the sound to be coming from front diff.)

 

Have you seen my post about the DIY diff repair?

https://www.6speedonline.com/forums/...ferential.html

How many miles you got on it? If you want shoot me a PM and if you ship it to me I can probably take a closer look at it for you.

 

I had same problem with the front diff and went RWD. Iam very happy with the decision but you cant just take the front diff off and be done with it. Its great that you already have PSS9 since you will need to adjust height of the suspension since removing the weight off the front will raise it. You will also need to get an alignment preferably as close to GT-2 specs as possible. It will also help handling to corner balance the car.
I had serious traction issues in first and second gears with my OEM sized PS2s and had to go to larger R-compound tires. You probably will not need to change tires unless your engine is significantly modded.
I feel my car handles better and is much faster since the conversion and I dont plan to go back to AWD.

 

Would simply pulling the front driveshaft even fix this? Won't the front wheels still be driving the front diff? If so the whirring might remain even with the shaft pulled :-(

 

I've seen your DIY and I wish I was as handy as you when it comes to stuff like this. Do you know if it's the bearings thats causing this noise? My mechanic is certain that it's the viscous clutch that needs to be replaced.

 

There is really no information out there (even for the dealerships) that tells you how to disassemble and reassemble the front differential completely and the specs and part numbers for anything other than the viscous clutch, an o-ring and shaft seals. I've worked with stuff like that before and wasn't afraid to tear into it. I'm not sure what's the millage on your car and if you ever ran the wrong diameter tires on there, but I can tell you that other than those two the viscous clutch really shouldn't fail that easily.

Since you though that your noise came from the wheel bearing than most likely it's one of the bearings in the differential just like in my case. When you use the stethoscope the noise carries throughout the whole differential case so it's hard to pinpoint what's causing it.

As far as the clutch itself I did some searching for you and here's what I've found:

http://www.autoatlanta.org/action.la...rds=10&-search

I believe the one for $650 is a used unit.

 

Laporsche are good guys. Caleb IIRC is the guy to talk to over there. I bought some used parts from them and they took care of me real good. They are also #1 in my book when it comes to packaging stuff.

 

Adam I have about 58k miles on the car. The wheel and tire package have only been on for about 10k miles and the rest of the time it has been running a stock wheel setup. My current wheel set up is 245/35/19 on a 8.5 in the front and 315/25/19 on a 11.5 in the rear. Does that sound like a setup that may cause diff issues?

 

Not sure as far as the wheels. If you do a search there is a thread that tells you how to calculate if the tires/wheels are ok for the differential as it involves pulling individual tire information from the manufacturers as different manufacturers might have a slightly different circumference on the same size tires.

As far as milage my car started having the noise issue at about the same milage.

 

That would be my impression as well. Would the issue be resolved if the driveshaft was no longer turning it, or would the fact that the front wheels are still driving it matter?