vinyl_tien

Hi
I am new in here, I come from Taiwan, I bought a 1989 928 S4 auto 3 months ago, I had my auto transmission rebuild last month(because slip gear 2 to 3 ), after rebuild the trans, it still has slitly problem, slip gear 2 to 3 when drive in D mood(same situation), but in 3 gear mood, it will not. My tech man said that is because the trans valve body problem, but I don't belive him.

There is no any 928 user in my city, I have no way to compair it. I had read some artical here, it seem can use a MB 560SL valve body, is that true? MB parts is much easy to find in Taiwan.

Also I might have chance to get a GTS shell, can I install it only S4? I know the GTS is more wilder.

Thanks for you guys help.

PS.sorry about my poor english.

Jerry Feather

Your English is pretty good except I can't tell what you are referring to about the "shell." Is that the car body "shell" or something for or about the transmission? Jerry Feather

WallyP

Yes, it is possible to install the GTS shell on your S4 - but it might be more trouble and work than it is worth. The only way to do it would be to sit the two side by side and start swapping (exchanging) parts from the S4 onto the GTS shell.

You will need to check with your authorities before starting the project. They may consider the finished car to be the GTS, which can cause problems with taxes, registration, and so forth.

This will take a lot of time and effort., just to get wider rear fenders!

vinyl_tien

Hi Jerry
The shell I mean is 928 gts body.
I have a chance to get a 928 GTS wild body, but that is body only.no extra part left.

Jerry Feather

In that case, I would fully agree with what Wally has to say. The only advantage you might have is to first fully restore the GTS body with custom paint and everything else it might need, then fully restore or recondition or overhaul everything you take out of or off of the S4 before you put it into or on the GTS. You will end up with some kind of Hybrid 928, but which will be almost like new. The advantage is that you will have all of the necessary parts stored in the S4 in an orderly setting waiting to be removed and upgraded before you put them in the GTS. Jerry Feather

vinyl_tien

Hi Wally and Jerry
Thanks for your advice. It is almost AM 1:00 in Taiwan, My wife is calling me to bed, I will post some pictures tomorrow.
Many thanks!
Ps. Can any one help me with my trans problem, that is kind urgent.Thank!

jthwan22

How about getting a rebuild trans or new old stock. I saw a unused trans on ebay a while back. Transfering all S4 parts to GTS body is too much work just for the wider rear fender. If you like the look you can transfer the steel GTS fender to your car or get fiberglasss rear fender.

karl ruiter

I am having shifting problems with my S4 as well. I am thinking mine may be a B2 piston problem. Search here for B2.

Glen McCartney

If you are experiencing what seems like slipping only on the shift from 2-3, it may be the spring in the valve body that controls the 2-3 shift, a known issue. Do a search for 2-3 flare here. Your tech that rebuilt the trans should be able to find tech bulletins on it, the trans is a Mercedes Benz trans and the repair parts are M-B parts. If it is the problem it is an easy and cheap fix.

Tails

A few basics first to allow you to recognise the auto box fitted to your car.

Porsche designatioon is an A28.16 four speed automatic gear box.

The gear box were manufactured by Mercedes Benz for Porsche and the box fitted to your car is a MB 733.3 series auto transmission which is a 4 speed/6 bolt/large case.

You will find the MB number stamped on the side of the gear box casing along the horizontal joint face pan rail adjacent to where the large 6 bolt pan is attached to the bottom of the box.

There is a string of numbers stamped into the casing.
The 722 designates the type of transmission,
the next digit 3 (in your case) designates the model of the transmission,
the next two digits following on from the 3 designate the type of automibile or version number and is used to determine what modulator valve and the adjustment pressure is required, and
the last six digits in the string designates the MB serial number of the box.

The fault finding procedure enclosed in the Work Shop Manuals 38 - 112 Troubleshooting advises that the fault you are experiencing is as follows:

Condition:
Transmission slips during 2nd/3rd shift, or slip at first and then grabs hard.

Cause/Correction:

1.Check

Tails

I struck a fault in my previous post, so I have repeated it again with the missing items.

The gear box was manufactured by Mercedes Benz for Porsche and the box fitted to your car is a MB 733.3 series auto transmission which is a 4 speed/6 bolt/large case.

You will find the MB number stamped on the side of the gear box casing along the horizontal joint face pan rail adjacent to where the large 6 bolt pan is attached to the bottom of the box.

There is a string of numbers stamped into the casing.
The 722 designates the type of transmission,
the next digit 3 (in your case) designates the model of the transmission,
the next two digits following on from the 3 designate the type of automobile or version number and is used to determine what modulator valve and the adjustment pressure is required, and
the last six digits in the string designates the MB serial number of the box.

The fault finding procedure enclosed in the Work Shop Manuals 38 - 112 Troubleshooting advises that the fault you are experiencing is as follows:

Condition:
Transmission slips during 2nd/3rd shift, or slip at first and then grabs hard.

Cause/Correction:

1.Check modulating pressure, adjusting if necessary.
2. Check whether temperature orifice is installed (see removing and installing lower cover on page 38 -131) in WSM.
3. Replace shift valve housing.
4. Replace inner plates of clutch K1. Repair clutch depending on findings.

I would suggest that you take your car to a Mercedes Benz Auto Transmission Expert and discuss the problems and show him this e-mail for guidance.

Work through the cause and correction in the indicated order 1 through 4 and eliminate each condition by the correction.

The modulating pressure pressures for your vehicle are contained in the WSM, however, instead of driving the car up to the various speeds with the test pressure gauges attached, the modulating pressure can be adjusted and set at idle in "D". If there is no pressure at the modulating pressure port via an installed pressure gauge, it may be due to excessive clearance between the end of the modulator spindle and the modulatior valve assembly. This can be cured by adding a small shim into the the tube that the modulator shaft spindle fits into until there is oil pressure registering at the modulator pressure port.

Keep us informed of the outcome or if you require further assistance.

Tails 1990 928S4 Auto

Tails

Further correction.

Your gear box is a 722.3 series MB auto transmission, not a 733.3. Sorry about the mistake.

Tails 1990 928S4 Auto

vinyl_tien

Hi Tails,
Thanks, I will keep forward further info mation, after I talk to my tech man.
PS.
Here is some picture of the GTS shell.

vinyl_tien

I have thought buy a rebuild one from state, but I already paid rebuild charge, it still in the warranty times.
one of my friend said, he can ask his tech man to made iron fender for me. But I don't know the look will be, kind a little bit afraid about this idea.. Does any one have the GTS body diagram? I might ask him to do it like that.

namasgt

Do you know what year the shell is for?
Looks to be do able but how does your S4 look, if its a nice car I wouldn't ruin it to fix a beat up GTS. You can buy the shell and slowly put it together from gathering parts from ebay, rennlist or half off sales for used 928 parts. It wouldn't cost a lot since most of the interior is there anyway and seems like it still has some suspension parts left on it.

Good Luck