Transmission, Automatic

Hard Shifts

Hard Shifts

> 1) had to replace all or most the transmission oil lines, due to several
> leaks. But now, afterwards, even w/ adjustments the car still has a hard
> shift into 2nd or 3rd (can't tell), almost consistently now. The dealership
> is telling me that the transmission is a Mercedes and that they cannot get
> into it. But they do know that the "reading" should be 15 or so and mine is
> 9...say they have adjusted it as much as possible..(?) Have heard this hard
> shift can be caused by the transmission fluid used, and it merely needs
> replacing...any truth to this, or ideas about what else could be going on?
> The car was fine and ran corrrectly when I took it in...

I have spent a lot of time working through my tranny so I'll try to help. The thump of the tranny going into gear is likely due to a lack of shift modulator pressure. I can get you the instructions on how to hook a pressure gauge to accurately get the modulator pressure. I did this a couple of weekends ago. But, basically the shop manmual says shift modulator pressure should be 65-70 psi at stall speed in drive with the vacuum disconnected and 45 psi in 4th gear under hard acceleration. The first test can be done with the car in the air. The second can't :-)

There is a simple way to adjust this without getting into the tranny. It is to turn the shift modulator in 2-3 turns. This is done by prying off the rubber cap, pulling the little 't' handle and turning it clockwise and then seating it back. They should be able to do this while your car is on the lift, take it for a drive and adjust as necessary. If this doesn't fix it may require rebuilding your valve body. I had this done. Cost $225.


Kevin Berez (
'86.5 928S Auto Meteormetallic
'99 323i 5speed alpinewhite

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