The tranny in my new 1991 seems determined to get to 4th gear QUICKLY and stay there! I was being keen to take care of the timing belt--which is due for a post-replacement re-tension--but I pushed the go pedal down a good ways several times, and that old Merc wanted to let the engine do all the work--no downshifts for you.

A very recent maintenance invoice shows trans fluid checked.

I would describe the shifts as abrupt but not harsh--no smooth transition taking place between gears, and not much patience for hanging onto the lower gears when accelerating.

Sound normal?

I gotta read up on whether a Tiptronic can be retrofitted. I saw a post to that effect a few days ago. Some way to manually change the gears would make this engine much more fun. Before you MT guys come chiming in, my wife had to be able to drive this car. She can't come close to driving a stick, and she is not interested in being in a car (minivan) for any longer than it takes to get to the nearest shoe store, so she ain't learnin'. I get my 6MT kicks with my 997, but I couldn't help thinking--particularly given the lack of any response by the transmission to the throttle--that even an old Tip would make things a lot more fun.

Thanks,
Louis

 

Bowden cable needs adjust? or vacuum to tranny?

 

Nope on the tiptronic.... But much can be done to fine tune the shifting... and look up parallel kick down switch...and the "roger box" guys have learned how to row the gears pretty well

 

Thanks JJ. It sounds like I gotta get familiar with the Bowden cable, pressure control valve, governor, kick down solenoid, etc. I haven't been under a 928 yet, so it's all Greek to me at this point. I did see where one Rennlister had a bent bracket that led to less than full movement of a pressure valve when the throttle was depressed. Guess I need to start taking things apart under there.

Thanks JB. I'll look into the parallel kick down switch and "roger box." I need to talk to Roger anyway--assuming it's that Roger.

Louis

 

because Roger loves the automatic many refer to the auto as a Rogerbox...but simply stated once all the adjustments are correct you can force the trans to hold the gear you select....Porsche did "improve " the shifting on the late GTS "dynamic kickdown" as I recall involved a part throttle kickdown. At least one person has retrofitted that feature.

 

Thanks for the clarification. It'll keep me from calling up and asking, "Can I get me one of them roger boxes?" Akin to a snipe hunt. LOL

 

Be assured Roger would laugh with you ! A few minor adjustments , a parallel kick down and moving the shift lever lever will help a lot but the 4 speed later trans wants to start out in 2 nd gear..

 

Make sure your gas pedal hits and depresses the kick-down switch - it may need an adjustment, or sometimes the switch wears out and doesn't go-in smoothly.

 

Good to know. I did use the shift lever to get into 3rd a couple of times for passing and merging on the interstates.


I didn't go as far as the kick down switch because I was taking care of the timing belt, and everything else, given it was my first time in the car. I'll get a little more aggressive once I'm satisfied that everything is in proper order.

BTW, did you find that the GTS side mirrors reduced wind noise? I noticed a decent amount of wind noise seemingly from that area. Thanks.

Louis

 

I can't say they reduced wind noise, as I didn't have a back-to-back comparison. I had them installed before I picked-up the car from the shop that inspected it for me and did the initial round of repairs.

What I can say is that the GTS mirrors look better, but have less "mirror area" - you have to get used to them a bit.

There were rumors from Germany that they increase top speed by about 5 kph/3mph.


You can feel whether the kick-down switch moves smoothly with the car parked. With the engine off, depress the button with your hand to see how far it can move, and how smooth it is. Then depress the gas pedal all the way and see, if the button is depressed all the way as well.

 

I might look into those mirror some day--another possible project.

Even though it's been many years, I still think twice about depressing the gas pedal when the car is off. Until I went to college, starting a cold engine was an art.

I'll get under there and see what's up. Thanks again.

 

LOL! You are still thinking about carburetors.

But the 928 has a fuel injected engine - what should happen when the engine is off and no fuel is injected?


A few years ago, there were pictures of a 928 for sale, which had been converted to carburetors. I don't know, if it ever sold, but it is probably somewhere in 928 heaven now.

 

Another sufferer of Timbephobia! Join the club.

 

A parallel kick down switch is not needed once the Bowden cable is adjusted correctly. The trans shift point can be adjusted with the Bowden cable.

 

When driving the 87 Auto, I always start with the gear selector in 3 usually don't think a thing about it for in town driving. I only use "D" as an overdrive if I am at highway speeds. It probably explains my poor fuel consumption but the car is much more fun above 2500 RPM.