Transmission Q:s - help me enlightened ones!!
 

Hi Again,

I have adjusted the "bowden cable" a bit on my 1984 500 SEL to make the shift pattern slightly less sporty. I have also adjusted the vacum modulater 3 notches clockwise in order to firm up the shifts a bit (as I have seen should be the correct direction by searching through different mails on this forum).

The reason for these adjustments was that i wanted the car to be less sporty and also to avoid shift flare when the transmission is cold.

The flare is only happening when the transmission is at lower temperatures for about 5-6 miles after which it is quite good.

After the adjustements I got the shift pattern right but the cold flare was slightly worse and dissapeared after the car warmed up when the shifts were slightly harder that before (although not bad in any way).

Is there anyone with enough knowledge on the list that can explain why the modulater adjustment didn´t reduce the flare? Is there some sort of temperature compensation on these older transmissions as is on the modern electronically ones? And last how do I determine if my vacum modulator is faulty or not?

Sorry about the long post but I´m a bit frustrated.

Our input is really needed.

Many thanks,

Mikael Westerberg
1984 500 SEL
Vanersborg, Sweden

There is a temperature controlled (60C switch) that softens the tranny shifts with a cold transmission to prevent overly harsh shifting. Drive gently til it warms up and you will be fine -- the alternative is severe hard shifting cold.

Peter

I recenty adjusted my transmission via the modulator to soften the shifts, especially during when cold, it did the trick. I would think that setting it firmer would make the flare worse.

Does a 380SEL have a 60c switch as well? Mine also flares when cold...

Hi Peter,

Do You know were the 60 C switch is located and how to troubleshoot it.

Many thanks,

Mikael

Hi Zeronero,

Did I understand Your mail correctly that the cold flare dissapered when You turned the T-habdle on the lodulator counter-clockwise?:confused:

Thanks/ Mikael

I'd like to know more about this 60deg switch. I never seen one and I can guarantee there is NO electronic control of shift strength in a 722.3 or 4 trans.

A shift flare would be taken care of in electronic transmission control by adapting the pressures and measuring the shift overlap. Without such capability some shmoosing of these defects can be had by the external adjustments. The problem is internal though and can only be camoflaged with the adjustments.

The original concept for modifying the flare was the right aproach in general. Real success comes from experience knowing which to affect most shift strength (modulator adjustment) or shift timing (control pressure adjustment).

Since the problem is really an internal defect (probably a leaking seal) all external repairs are a compromise. If it requires obnoxiously hard shifts to obercome or rediculously quick shifts, then it may be easier to just live with it till a real repair can be made. it won't hurt anything and could go years that way.

Yes turning it counter clockwise made the shifts smoother. When cold I experience the biggest difference. Before I adjusted it, it would slam into the next gear, push me to the seat, and jerk the car, now its smooth.