loss of power when shifting

[joelj]

Hi guys,

I have a 280sl automatic. Since this is my first SL and have not had experience driving other people's w113, i dont know if the "loss of power" i am feeling is standard for this car or if there is something that would need adustments in my car.

It seems like when the car shifts from 2nd to 3rd the rpm really falls down (from 3500 to maybe 2000 rpm. Is this what is normal for this car or should I expect it to hold the rpm at around 3000 rpm

Thanls again,

Joelj

[TheEngineer]

This transmission uses a hydraulic clutch rather than a torque converter. (Ten Years later, even Mercedes saw the light and supplied automatics with torque converters.) I have always had the problem that the upshift 2-3 is rough, a clunking act, like popping a conventional clutch. It must be real hard on the driveline. If I drive the car hard, the transmission shifts up at much higher speeds and  then shift smooth. It also shifts very smooth when the transmission is cold, like for the first 10 miles or so. After the transmission warms up (to an estimated 160 degrees) I can only reduce the shifting shock by observing the tachometer and get off the throttle  momentarily at 2500 RPM, the shift point. Why is it that it shifts so nicely when cold and so rough when hot?
My friendly Mercedes dealer has no answer.

[Cees Klumper]

Something must be amiss with both your cars - the transmission in my '69 280 SL shifts really smooth almost all the time, certainly nothing like the symptoms you are describing. Sometimes the shifts are so smooth that they are not noticeable. I understand that there are a number of adjustments that can be made to possibly rectify your hard shift problems (modulator pressure, three-position solenoid switch, vacuum from the intake manifold and the like). Maybe worthwhile to really dig in yourself or have a knowledgeable mechanic look at the situation.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[rwmastel]

Joel,
You should go to the soon-to-be-organized Northern California event and drive some other W113's (owners permitting).
http://index.php?topic=2957

If you have the time & money, fly to Ohio and drive some cars here.
http://index.php?topic=2120

I would say your RPM drop between gears is normal.  With only 4 speeds, they cannot be close ratio.

TheEngineer,
I agree with Cees that you have a problem with your transmission.  People say "These old cars just shift rough.", but that's mostly because they are old and something is worn out, not because they were engineered to shift rough.  I don't have any educated suggestions for you, the only things I've heard of people doing for transmission problems is adjusting the venturi flap properly and replacing a rubber part that works with vacuum/pressure modulation.  Keep this thread active and someone good with automatic transmissions will help you out.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[J. Huber]

I tend to agree with Cees and Rodd. My transmission is original but has been fairly well-cared for over the years. And while there are certain scenerios where I get a clunky shift -- it usually shifts quite smoothly.


James
63 230SL