Diff Is Gone

FTS · #1 04-18-2011, 09:46 PM

Well after only about 8500 miles, what I suspected from the difference of how the car is under hard braking and how one tire spins from going onto my drive way, the diff is pretty much toast.

So, I took it to the dealer to have them confirm it, which they did, and they offered to replace the clutch pack and rebuild the diff. The parts should arriving this week, we'll see how this ends.

PistolPete · #2 04-18-2011, 09:50 PM

What symptoms did you notice under hard braking?

Since the car is still under warranty I guess it make sense to have them repair it. Any thoughts on rebuilding it with aftermarket (GT Gears?) at some point?

FTS · #3 04-18-2011, 10:09 PM

No lock up in the rear and the car just jiggles left/right, just like the Cayman would

Actually it is a "wear item" just like the rotors, so normally they don't replace them under warranty. However, with so few miles they thought it is appropriate, which I agree and am pleased. I asked them if they can actually replace the clutch pack with the motorsport one, they are going to check and let me know.

A friend of mine had the very same issue with even less miles on it with his GT2 that already had GT internals. So, from a durability perspective, that may not be the solution either, although the GT2 puts out a lot more torque than the GT3. So, I will see what I can get from the dealer, and I will also talk with Levitas as he is an expert on diffs IMO. Mike will be out of town next few days though, at VIR with Bman and Trakcar

Their gonna have fun, while I am waiting at home for a diff

mooty · #4 04-18-2011, 11:38 PM

most likely dealer will not use motorsport part or guard parts.
but if you paid for the parts, they will do labor under warranty

FTS · #5 04-19-2011, 12:09 AM

That's what I am thinking too John. We'll see, they have very nice thus far, hopefully they'll let me know tomorrow. Also, I do not know how well they can do the labor part, but the tech seems to know what he is talking about, may be I should give them a try.

bman · #6 04-19-2011, 09:15 AM

Quote:

Originally Posted by FTS

A friend of mine had the very same issue with even less miles on it with his GT2 that already had GT internals. So, from a durability perspective, that may not be the solution either

Yup, stock diff was re-ramped and re-packed with Guard components. 16- track sessions (25 min each) and clutch packs had moved/worn. Initial performance was awesome but it was easy to tell when the discs were worn. Especially under braking. Ramps are fine. We just added more preload and couple of new discs. Hopefully the additional preload will improve durability.

bman · #7 04-22-2011, 12:31 PM

Repacked diff was awesome!

Car's a bit tighter now and has more understeer than I want but it's super stable under braking and when putting down power.

FTS · #8 04-23-2011, 10:16 AM

So, I guess with such a tight packing, you may need to alter how you use the throttle after your finish your trail braking? Do you know how Mike setup the lock ups?

bman · #9 04-23-2011, 10:40 AM

Quote:

Originally Posted by FTS

So, I guess with such a tight packing, you may need to alter how you use the throttle after your finish your trail braking? Do you know how Mike setup the lock ups?

Had to slow more in T1 to get it to turn in. Funny....I told the pro driver that I was having trouble with turn in and asked him to show me how to deal with it. He struggled too

Not sure what he decided on for lock up/ramp. But will ask.

mdrums · #10 04-23-2011, 10:57 AM

Quote:

Originally Posted by FTS

Well after only about 8500 miles, what I suspected from the difference of how the car is under hard braking and how one tire spins from going onto my drive way, the diff is pretty much toast.

So, I took it to the dealer to have them confirm it, which they did, and they offered to replace the clutch pack and rebuild the diff. The parts should arriving this week, we'll see how this ends.

Same thing here in my 2009 Carrera S with the Sport PASM suspension that comes with a LSD. I took mine to my dealer last year and they said my diff is fine and blew me off. I'm thinking of trying this again with them....and dumping some water out in their parking lot to show them my LSD is toast.

thoughts and opinions?

FTS · #11 04-23-2011, 11:00 AM

If they put the car on a lift and can turn one of the rear wheel with their hands while the other stays stationary, the diff is certainly gone, there cannot be an argument. My dealer, Tyson's Porsche in VA, has been awesome for the last 6 years, and they did the test without me telling them how to or had any arguments over the condition of the diff

The only thing we do not know is the condition of the ramps right now, we'll see sometime next week.

SH || NC · #12 04-23-2011, 11:32 AM

Quote:

Originally Posted by FTS

If they put the car on a lift and can turn one of the rear wheel with their hands while the other stays stationary, the diff is certainly gone, there cannot be an argument.

Are you sure that is the way to test it officially? Doesn't there have to be a load on the unit? I thought John (911slow) posted the process, and its done with the unit out of the car....? I could be mistaken.

FTS · #13 04-23-2011, 12:18 PM

Frankly, I do not know if it is sufficient of a test or not. I read John's process and I am sure it is the correct way, but who am I to argue with the dealer who found that the diff clutch pack needs rebuilding

SH || NC · #14 04-23-2011, 12:20 PM

No worries. Might as well ask them to install the cup clutch packs.

Trackrat · #15 04-24-2011, 01:04 PM

Sorry to hear Fatih, but it seems to be a replacement item.

Coming out of my rock-solid-under-threshold-braking GT3RS with Guard diff, my GT2RS is a squirmy worm and the back-end moving all over under hard brakes. Ugh. Hate to pop $1500 into it with only 1200 miles on the clock. Going to re-check toe first and see if that might be off.

Excess camber will contribute to instability under braking as well.