jtrygstad

My teenage son just recently purchased a 1980 Euro S (during my absence!) It has about 120K miles and is in fairly good condition. Now it is a father-son project. The only glaring problem is that it will no longer reverse.

When he picked the car up, it had some difficulty backing up. The engine had to be revved a bit to get it moving backwards. Once in motion, it seemed to "grab hold" and do just fine. We thought that it might just need a transmission conditioner/additive to get things freed up such as a sticking valve, etc. We added a pint of Seafoam Translube and ran the car about 40 or so miles on the highway. Drained about 2 or 3 quarts of fluid the next day, refilling with new AT fluid. The drained fluid did not look or smell bad or show any metal albeit we did not pull the pan. Throughout the process, always maintained proper fill level (it was low when he first brought it home).

During the short period we have had the 928, the ability to reverse has gotten worse to the point it will not reverse at all. When it did, it would only when cold at which time it would lugged to engine down to almost stall. During the last time we had it jacked up for the last AT re-fill, we ran it through the gears. In reverse, the wheels would turn forward but could be stopped easily by hand.

Any ideas out there? Is it possibly a sticking valve or a loose band? Or worse?

A local Porsche repair/speed shop has suggested a power flush & filter change for $300 and a look-see under the cover. Does this make sense or does one go straight to a rebuild?

G Man

I'm no trans expert, but from the way you describe what is happening it sounds like the reverse bands are shot. I don'tknow if there is a way to tighten these or not. I'm sure there are others out there with more experience on this matter than me. Good luck.

mpesik

Hello jtrygstad .Unfortunate that you have a trans. problem. Have you replaced the filter? Might be somewhat restricted.Could be-sticking valves,oil pump,reverse clutch,worn clutch plates,worn reverse band. You could lengthen the pin with a shim to the B-1 piston.e.t.c. The biggest question is who will do the work and how ambitious you are.If you are willing to do more than scratch the surface, obviously you can go in deep and peer inside.If you will be doing the work yourself please let the forum know so I possibly could help in greater depth. Good -luck Mike.

Dennis Wilson

I wouldn't take it to the Porsche shop. The transmission is made by Mercedes, unlike the other Porsches. It may cost more than $300 but you wouldn't be pouring money down a hole for a "maybe" fix. BTW Walt K (on the 928 e mail list) is not far from you and may have a cheaper solution.

Dennis

Steve Cattaneo

Your car, with the 3speed transmission has an adjustable reverse band. Hopefully an adjustment can restore it. The procedure requires grinding a notch in the adjustment bolt. If you are mechanically inclined it’s easy to do, if not find a transmission shop that specializes in foreign cars, they should know the procedure, ask them. It’s obvious the Porsche shop don’t. A flush is not going to fix reverse.
If you think you can do it, let me know and I will post the procedure.

jpitman2

Assume its a 3 speed. Mine is slow to engage reverse, but I think its designed that way. I have been warned that reverse is weak, and it is NOT advised that you try to reverse up a steep slope, it will just let go - something about ungoverned pressure in reverse. ANyway, the book describes adjustment of the reverse band when rebuilding as adjust stop so that the gap in the bad ends is 3mm, usually when you screw bolt in in to bottom, and back out 1-3/4 turns. This bolt is on the RHS, very tight by the kickdown solenoid, locked by a 19mm? nut. You would need to pull the kickdown solenoid to unlock it, which will drain the fluid out. The bolt has its head broken off at build time, so you would need to cut a slot in it with a Dremel or similar to adjust it. I researched all this, but never did it, as I didnt want to drain and refill it, I just live with slow engagement. Visit www.mercedesshop.com forum for advice from MB people, they are good.
jp 83 Euro S AT 48k

jtrygstad

Steve C:

I am inclined to give a shot myself, would appreciate a description of the procedure. Thanks.

Mark Anderson

Before you adjust the band I would replace the 0 ring on the brake band piston. I have recomended this to many customers and it fixed the problem for them. This is espicially true if your problem is worse when the car is cold.

jtrygstad

How difficult is it to replace this o-ring and where is it located? Is it (brake band piston) the front servo?

V-Fib

No affiliation to the seller. I have these 2 and they are useful.
3 speed trans manuals

BTW, Jim's CD's have these included + much, much more. HTH

Mark Anderson

"How difficult is it to replace this o-ring and where is it located? Is it (brake band piston) the front servo?"

I have not done the job myself but it is part #008 997 354 5 and it is $2.88. It is located on the drivers side and can be replaced with the trans in the car.

jtrygstad

"No affiliation to the seller. I have these 2 and they are useful.
3 speed trans manuals"

I have purchased these and just awaiting delivery.


"BTW, Jim's CD's have these included + much, much more. HTH"

I am bit ignorant about these CDs; where do I get?

V-Fib

See the "Thank You Mr. Morehouse thread". PM or Email him.

Steve Cattaneo

Here is the link for the band ajustment procedure.




http://www.mastertechtrans.com/porsche/slkd/

goldknight

John, not that I wish you bad luck on fixing yours, just incase that dont work I have a 3spd. auto tranny sitting in my garage. yours cheap if you need it. May cost more to ship from Tacoma Wa. then one would like.

Thurston.