ja78911sc

My 1990 C2 trans serial # is G5003 "1" L03522. According to Adrian's chart (pg 581) in 1990 "0" no limited slip & "1" is limited slip. Based on this I have limited slip.

I spun my rear wheels while the car was in the air and the wheels spin in opposite directions.

Based on my search it appears my limited slip may be shot.

Can it be repaired with the engine/trans in the car?

If i continue to drive the car, will it harm the trans?

Parts cost--rough estimate?

Thanks,
Jim

Steve Weiner-Rennsport Systems

Hi Jim,

Sounds like your LSD is worn out and needs new plates.

The LSD can be extracted with the engine/tranny in the car through the side cover.

No harm if you delay doing this.

There are several rebuild options based on the configuration of your LSD ranging from simple plate replacement (OEM or Guard) to converting it from a 2-plate diff to a more robust 4-plate one.

johnsjmc

You will not make anything worse by continuing to drive it. The LSD unit can be removed and rebuilt with the trans remaining in the car.

ja78911sc

Thanks for the info !!!

ja78911sc

Really confused after reading my Bentley technical data without guesswork.

Page 02-5. The example in the book is a 1990 serial# and has "1" after the G5003. They claim "1" is a normal diff. Adrian's book says "1" on a 1990 is a limited slip diff.

Maybe my diff is standard?

Which is correct tech data without guesswork or Adrian?

Thanks,
Jim

Oracle

The LSD is a listed option in the hood sticker (or user manual). This is the official way.
As far as I know the 0 or 1 was a rule of thumb for those cars without records or sticker.
Also it is listed in the window sticker.

johnsjmc

I believe the #1 on the trans ID indicates originally built with LSD.

Ken D

According to PET, for MY '90, "1L" is open diff. "2L" is used with option M220 (locking diff).

ja78911sc

Checked my hood sticker and it does not list 220 as a option.

Any 90 964's out there with a 220 listed on the option sticker? If so, what is your trans serial # -- "1" or "2"

Thanks,
Jim

911porschefan

I'm a 90 964 C2, I have option code 220 but nothing after the G5003- in my warranty book. Can't check the car because its 2 hours away at my parents house in storage.

ja78911sc

Thanks Porschefan.

Considering the conflicting published info--I am still curious what other 90 C2 owners have for serial #'s and if they have the 220 option listed on the hood sticker.

Thanks,
Jim

johnsjmc

I might have been wrong thinking 1 meant LSD. Looking at my 993 service manual 1 is open and 2 is LSD. You should try calling a dealer The part dept should be able to tell you the fitted options based on the VIN.

The Race Line

I think that I can shed some light on this. The 1 means that you have a factory open differential, if there was a 2 then it would be a LSD.

As Steve said there are quite a few options out there for a LSD. Pricing is somewhat different depending on which one you go with. The GT Unit is a very good option and offers a variety of setups for the ramps as well as for the number of plates. You can also track down a good OEM unit and have it upgraded to use 4 plates instead of two. Or there is the OS Giken which has 20 plates and has been quite durable in Porsche cars. It really depends on your driving and your budget. You can also look into a torque biased differential as another option. Both GT and Quaiffe build them.

Keep in mind that if you change out the differential from an open to a LSD that you will probably want a pro to do the first install as the ring and pinion will need to be reset.

Let me know if I can answer any questions for you.

Erik Johnson
(303) 895-4828

MitchB

How much should someone expect to pay for a shop to install a factory replacement? I have a '92 C2 with the 220 option.

I'm in the same boat. My car is used only for street (albeit "spirited") driving, so doubt I can justify a more expensive option... But I'm open to being swayed by convincing arguments...

The Race Line

Mitch your car should already have a LSD, so in your case it would be too much of an issue. I would say maybe a couple of hours total in and out. Steve might have a better sense of the time involved. As to getting the plates replaced it depends on what you would like to do. If you just replace with stock plates it will not be too bad, $400 give or take, if you want to upgrade to more plates, I would give Matt over at GT a call he would be a better source on that upgrade than I am.

I hope that helps at least a little.

Erik Johnson