Marv

Not to hijack the thread, but are you suggesting replacing the OEM plates instead of installing an aftermarket Guards unit?

It seems the OEM LSD does not hold up well. Anyone know the difference in service life intervals between the OEM and Guards LSD?

I know my OEM unit is long worn out. Time to do something, but what?

AudiOn19s

The ramps determine the rate at which the diff locks and unlocks. What he's saying is the ramp rates are fine in the 996 so don't bother replacing them. 997 cars had different ramps that weren't as aggressive and many of those guys went to the same ramp rates that the 996 has from the factory as a performance upgrade. All of this can still happen within the stock differential housing for the car.

To be clear, when most people rebuild they are only replacing the disks and friction plates anyhow...but usually with the guard pieces not the OEM or cup pieces. I'd venture a guess that this is what 90% of the population does and it serves them well. Guard does offer a full billet differential housing but it's more than what most really need to have a properly functioning diff. The other advantage of rebuilding the internals of the stock diff with upgraded parts is that you can re-use the bearings that are already on the housing (assuming they are in good condition) which allows you to take it apart and put it together without any additional setup costs. If you replace the bearings or change the whole LSD housing you need to set backlash on the gears to avoid noises after install.

I've been on guard plates and friction disks only for the last 5+ years and they are still working great.

if you are a DIY'er rebuilding the differential is not difficult at all.

Marv

Thank you! That was very informative and just what I needed to know.

I am a DIYer.

Approximately what should I budget for plates and disks from Guards?

Techno Duck

black04

You're not "hijacking". this is all good information.
"Yes" I am saying per my experience and understanding of all the LSD threads, that it is not the LSD as a whole but the so-called clutch/plates/discs, whatever the proper terminology is, that are the problem. My car had a Porsche warranty rebuilt tranny installed the week before I bought my car, so I assume the LSD was rebuilt as well.

I am sure that the "how long does it last...?" answer is variable, depending on use. In my case, I basically only use the car on the highway and in the mountains. After 3 week-long trips in the the mountains, roughly 3000 miles, driving at 8/10ths, plus 4 track days, roughly 400 miles, i.e. 3400 "hard" miles, a total of 28,000 miles, the LSD was totally ineffective. (oh and there was that one time when I was abusing the car and I broke the spider gears ) I felt the difference immediately in the middle of a 22 mile run in the mountains on Arkansas Hwy 123

The tires had 50% tread and the alignment was fine. New tires did not fix the problem.

And as other posters indicate, the ramp replacement is optional. Maybe necessary for serious track-types only
And by rebuilding the OEM diff, one avoids the onerous clearance measuring process, which may not be doable by anyone other than the most experienced shops. i.e. everything about the OEM is GREAT, except for the discs/plate/clutch life, so why do more than that?

And yes, as a DIY'er I did the work myself, putting the car up on jack stands, no power or special tools, crawling under the car, delivering that 25 pound Diff-baby from the tranny-womb. Only dropped one wrench on my forehead. (I did make a wood-block clamp to hold the diff in a vise)

Techno Duck

I am thinking about doing the LSD rebuild myself. Ive got the tools and the equipment but honestly have gotten a little lazy the last two years or so. After buying the car, tires, toe links (front and rear, corner balance, bump steer and alignment, plus keeping my aircooled car budgeting is important . Seems like every evolution on these cars starts at $1500 lol.

AudiOn19s

Techno Duck

I should have the numbers Tuesday, shops been at the track since mid week.

I swapped the rears left / right. No change. Put about 100 miles on today...one hell of a car.

blomman

Check the ARB.
Mine was set one from hardest front, middle rear. The car felt loose in the rear.
Tighten the rear and loosen the front is the recipe.
Middle front, one from hard rear. Try this, Easy
/cheep start.

JarmoL

Also check the ARB links. You want to have them adjusted so there is no tension on the ARB when car is on level surface.

Techno Duck

Drove my friends '04 today and go figure his car does the same thing! I am guessing what i am feeling / not used too is just the dynamic of the car when lifting off the throttle. My friends car has a Guards GT rebuilt diff and about 20k less miles than mine. Maybe my '***-celometer' is a little too sensitive . I am calibrated from 15 years of driving torsion bar cars...

Also i did check swaybar preload. The shop that did the corner balance mentioned they had to disconnect the rear shock so they could turn down the collar for the sway bar mount to get the preload out. I also checked myself, the drop links can be twisted by hand with the car on level ground. No hint that it has any preload on it.

Ill stop trying to convince myself something is wrong and just drive the car now .

mistermct

Went back and reread your first post - can you clarify what you're feeling? Does the rear yaw into the turn (understeer) or the front yaw into the turn (oversteer) when you lift? And this happens in any corner but only when you lift?

tgavem

You should not be able to twist anything with the car sitting on the ground. Everything should be locked with lock nuts and have enough load so it wont move.

Techno Duck

mistermct

I'm starting to think it's just your sensitive butt dyno. I would absolutely expect that behavior from my car - any lift slightly increases the slip angle. This car is super sensitive to pressures and alignment so I would try lowering your pressure in the rear a couple psi more (i think you're at 35?) to give you more grip back there.. my conclusion was that 32-34 psi cold rear made for nice driveability. Anything higher and the back feels unsettled to me. Also a bit more rear toe may help... still waiting on those alignment specs to tell for sure...