Harsh Shfting?

[Haroundb]

Harsh shifting without any knocking sounds. So what could that be? Will that be gear mounting? Or will it be coupling (mine is torn and needs replacement)?

Any ideas? I hope it is not the gear needs to be fully replaced.

[symbolic95]

Check Vacuum modulator at the transmission with MityVac-get metal one from Sears,not cheap plastic.
my 300sd was shifting sooo hard it felt like someone was using a sledge hammer to shift gears,took modulator out,put it back with new o-ring ,now smooth like newer before.

[Eirik 400 SE]

hmmm. Could be the same as mine.. Shifts hard into 4th..
2nd and 3rd is smooth.. Gets a little worse when warm..
Not that it's that bad.. But a little annoying ..

[Haroundb]

What is the O-Ring?

[kingjoon]

Originally Posted by Haroundb

What is the O-Ring?

It is the part that goes into vacuum modulator and its a ring that looks alphabet O..buy a new parts to replace it and check the pressure of transmission fluid for adjustment of your modulater valve which looks alphabet T.

for adjustment check below link;
Transmission Vacuum Modulator Adj. - Mercedes-Benz Club of America Forums

[TasmanianDevil]

Originally Posted by Eirik 400 SE

hmmm. Could be the same as mine.. Shifts hard into 4th..
2nd and 3rd is smooth.. Gets a little worse when warm..
Not that it's that bad.. But a little annoying ..

Nearly the same except for gears; when on a highway its smooth as silk, kickdowns are perfect but when warm and in traffic it jerks forward when you let go of the gas pedal a bit and let it shift up. Nothing when its shifting down though weird but still not planning to open it up and rebuild it or anything.

Changed modulator, checked hoses, everything seems fine but above mentioned conditions still presist.

[cool]

check temperature throttle (#117 service shop manual), located on the valve body, that is after assuming you have already done all necessary adjustments of cable and modulator valve.

[Merc600sec]

Originally Posted by cool

check temperature throttle (#117 service shop manual), located on the valve body, that is after assuming you have already done all necessary adjustments of cable and modulator valve.

You want to explain this a bit more to this guy??

[cool]

temp throttle is a piece of plastic valve and a super fine (thinner than human hair) spring that is used in regulating the flow of ATF in the valve body based on temperature. If the ATF temp is still cool the valve opens full and when the temperature of ATF starts to increase it regulates/partial restriction to the flow of ATF on the MAZE of the valve body. That is one of the reasons why when the temperature of your ATF is still cool you have all the normal shifting and gets rough when the temperature increase, it is a form of abnormality of the transmission and must be attended to in order to avoid other damages inside the tranny.

Another reaction towards the absence of the temperature throttle is a slow shift from 2nd to 3rd gear, there is a slight gap between shifting from this gear ratio specially when temperature of ATF is hot.

[Eirik 400 SE]

Do you have a location on the car/gearbox for this ?
Or a part no at least. ?