Hai gebissen

My '87 was built with LSD (220) but I have determined that it has an open diff now. There is a VIN sticker on the bottom of the case that reads WPOxxx924JS861111 which I take came out of an '88 (anybody know this VIN?)



Then there are these numbers stamped into the case:



Thanks for any help identifying this trans.

Eric

Dave928S

That VIN shows as an 88 with the G2813 Transmission, and also the 220 option limited slip diff. You may think you have an open diff if the plates in the LSD are worn out ... how have you checked?

Hai gebissen

Thanks Dave. Roger suggested it may just be worn. I only checked by spinning the right rear wheel with the car on the lift, and observing the left rear wheel to spin in the opposite direction.

What does the G2813 mean specifically?

Eric

Dave928S

G = manual ... autos have the A prefix
28 is the series for 928's
13 ... is the model number within the series

Examples to illustrate the progression .... my 82 S has a G2805 and the 95 GTS has a G2857

Highly likely the LSD plates are worn, but they're easy to check and rebuild with new plates to get them back to the torque spec again. You can see whether its a limited slip spool looking through the fill plug hole, and it's easy with the back cover removed. What you're seeing with the wheels is the behavior of worn out friction plates in an LSD or an open diff.

Hai gebissen

Thanks. I know not to assume things (because we know what that does) so I will investigate further as you described. Glad to hear it might still be LSD after all.

Hai gebissen

By the way, would this G2813 still have the 2.20 final drive?

Landseer

Yes it should be 2.2, unless swapped out during the install.


If you can remove the back plate , you can be certain if it has the LSD carrier or the open drive (in case somebody swapped it out previously).

If you are on a gravel hill, and start out, the open drive will likely spin a single wheel. The LSD will calmly move the car forward.


Here are a pair of earlier transaxles with back cover removed.
Your S4 will look similar beneath.
LSD carrier is on the right.

Hai gebissen

Score!

Ducman82

Greg brown has a great wrote up on replacing the discs for more grab

Hai gebissen

I am inclined to put new fluid in it and see what it does...good to know I have options to fix it as necessary...

Mrmerlin

since the wheel was spinning opposite while you turned the wheel,
then the friction plates are worn and should be replaced,
otherwise your going to waste 1 gallon of 90 wt to go back in and do it later

Hai gebissen

Roger that.

The never-ending project car...I just wanna drive it!!!

ROG100

See I do know something about 5 speed cars - not much but some 8>)

Hai gebissen

Yep, you called it. Thanks!

GregBBRD

Tough to imagine a limited slip so worn out that the other tire spins in the opposite direction....unless you are trying to spin the tire with the transmission in gear.