928 U.K.

i have been having problems with my 928 auto not selecting the correctly when driving for a while.I changed the oil and filter and it started working better but tonight i went for a drive and it felt like the clutch was slipping and then it would not move when any gear was selected.
Is the transmission bust or is there any other things i can check before it goes for a rebuild.

Randy V

Model year Tim?

Also, you start out claiming you have a 928 auto, then ask about the clutch.

Is it an automatic transmission or a 5 speed? Hard to tell by the way your post is worded.

John Struthers

Tim,
Check the Nichols site. I think Wally has posted replies to several threads there.
Might be the valve body. When you changed fluid did it smell like a burnt clutch-pac? If not you won't be out of the woods, but, it shouldn't cost you the firstborn.
LOL Maybe Wally will reply - BIG HELP.
Nichols site: <a href="http://nichols.nu/tips." target="_blank">http://nichols.nu/tips.</a> htm
Wish you the best on fixing this problem.

928 U.K.

sorry for not explaning. its an 84 s2 auto euro.when i changed the fluid it wasnt too bad and did not smell burnt however there was a bit of sludge in the pan about half a teaspoon full with some little fragments of plastic in it

thanks for your help

Hoyo

Dear Mr. Neeves.
Your in trouble.
Check out earlier posting, Dec.
I had the same problem on my 79 auto, 928s engine.
After a lot of sound advise, I decided on having the tranny rebuilt.
The mean machine has now been at the shop since 14 of Jan. (????????)
I took the 928 to the, supposedly best, auto repair shop. They claim they waited a while for a upgrade vent kit. Something to do about 928 tranny with 928s engine.(?????)
It was supposed to be ready last week but the guy have problems adjusting it all. Appears to be shifting alright until you stop and drive off again, then it starts in 2.
Anyway, im waiting.
Hope You are luckier than me.
In the mean time, Kayak building seemed like a good idea. Check out <a href="http://www.guillemot-kayaks.com" target="_blank">www.guillemot-kayaks.com</a>

" It's not a matter of where I am, it's a matter of when I am "

Erik Juhl

I thought the default behavior was it was supposed to start in 2, supposedly for fuel economy. After reading a few related posts on the Nichol's archive, it seems that people who don't care for fuel economy can either adjust their linkages or just do it manually. So maybe your Shark is really just good to go?

928 U.K.

when i put new oil and a new filter in the car there was hardly any sludge in the oil and the condition of the oil was pretty good and it smelt just like the new stuff which i have been told is a good sign.i am hoping that i can rectify the fault with the excellent advice from this board. the car is up on ramps at the moment and i am trying to check as much as possible like vaccums,modulator,gouverners cables and as many other things that apply to the auto tranny as possible. i spoke to an auto specialist and he said that it such a complex settup so many things should be checked before going for a rebuild.
any tips or ideas even the obvious would be greatly appreciated on this subject as i can not afford to go for a rebuild but i am learning a lot on this subject thanks to the contributers on this board

thank you

Tim
84 s2 auto euro

Hoyo

Erik.
You are quite right regarding the 2 gear start if we are talking 4 speed auto.
My 79 is a 3 speed and (I think) it is supposed to start in 1'st.

Tim.
I am sure Steve Cattaneo have the answer to Your problems.

Sincerely,
Geir

Steve Cattaneo

Hoyo,
Did your original transmission start in 1st gear, did you feel one or two shifts.
In 1979 280E,SE, CE, 300CD, started in 2nd, the valve bodies are calibrated different.
Is it possibly your mechanic use salvaged parts and instated the wrong valve body. Does your car ever start in 1st or does it say in 2nd all the time.

Thanks for the compliment.


Steve C
The Great White
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Hoyo

Hello Steve.
Good to hear from You. As You may understand, we do not have the greatest Porsche expertice here in Norway.

After thinking about Erik's reply, I became unsure if my car used to start in 1,st or not.
I was pretty sure it used to started in 1'st until now.

My mechanic said to me that the car was fine just after he had started it. Drove it for awhile, stopped, drove off again and it started in 2.
I read from what he told me that initially the car would start in first.
I must call him on Tuesday to find out.
He also told me that the valve housing looked fine when he rebuilt the transmission. Now he is thinking about changing the valve housing.

Sincerely,
Geir

Hoyo

....I am almost sure I remember 2 shifts, almost..

Hoyo

....or maybe, it was just one....

michael

Hi Tim -

Since you report that the fluid looked clean when changed there's at least a fighting chance that no serious damage has been done and that only adjustments are needed. Many owners have reported dramatic improvement in the A/T shifting charcteristicsby simply using the very highest quality fluid available.

It is very easy to under/over fill the tranny. The workshop manuals detail how to perform the fill properly. Nearly everyone seems to overfill the system the first time. And the A/T is very sensitive to the proper fluid level - it can slip when not at the correct level.

When you changed the fluid, did you also drain the torque converter? This is required to get all of the old stuff out.

Have you adjusted the vacuum modulator on the tranny? Turning it clockwise will delay your shifts and make them crisp - turning it counter clockwise will make them softer/smoother.

If you decide to take it to a shop, instead of going to your local Porsche dealer you may want to find an independent shop with a great reputation that works on MERCEDES. Even if they don't know it, they will be much more familiar with the 928 4spd auto transmission than your Porsche dealer! Porsche built the aluminum casing for the tranny, but the tranny itself was built by Mercedes (to Porsche spec).

Hope that's of some help.

928 U.K.

unfortuantly i hav no workshop manuals however i think that i did overfill the tranny as i put about 6 litres in but it looked o.k when i checked it over the next few days but yestrday after i was getting problems i checked the level and some spilled out of the plastic reservior.(about .5 litre)
where is the modulator?and what does it look like? so that i can try to adjust it

thanks for your comments

Tim

84 s2 euro auto

michael

Keep in mind that the modulator only adjust the feel of the shifts, not the shift points... that's done by the cable adjustment.

Wally posted this to the email list:
The handle is on the transmission vacuum modulator, which is one of the
several devices that adjust the shift quality for different conditions.
Get under the car (safely!) and look on the left side of the
transmission (driver's side in the USA). You should see a round (about
100 mm dia) drum-shaped object, with a small vacuum hose entering from
the top. It should have a black cap in the center. Pull the black cap
off. There should be a small bar across the center of the modulator -
this is the handle. Pull it straight out. Turning it clockwise will make
the shifts later and firmer. Turning it counter-clockwise will make the
shifts earlier and softer. Try a turn or two at a time, driving the car
for several mile between adjustments, to make sure that you like what
happens. Be sure to push the handle back in and put the cap back on.

Wally Plumley
928 Specialists