[W126 Coupe] Re: MBCOUPES Digest, Vol 16, Issue 8

[Richard Hesek]

To help me sort out exactly what is going on with the shifting on a 126
transmission (gas engine) I thought I'd post the symptoms and see what
any of you in the know think about what I am dealing with.

This car has the Economy and Sport switch on the shift gate and it works
fine in sport (first gear start) but I routinely run it in Economy
(second gear start) for fuel savings.

So, when starting out and accelerating I get smooth shifts with a small
amount of flaring between 2nd and 3rd and a smooth firm shift from 3rd
to 4th.  So, I'd say this is all within acceptable limits when compared
to the other 126 chassis MB's I drive.  Here is the problem, when I am
slowing down to say make a stop at a red light and the car is still
doing 5-10mph and the light turns green and I go from brakes to gas,
there is this long flair (pause) and then the car shifts fairly hard
into 3rd.

Questions does this sound like the modulator or the B2 piston having a
problem?  Regards,

Dick

specific to the MB sedan 126 chassis 300SE Euro

=============

Hi Dick,

 I don't want to appear to be nitpicking, but firstly the "S" is for
standard, not sport. And it won't make any difference whether you have
selected "E" or "S" the car will start in second gear in both. Unless you
have the actual first gear start module fitted. Or if you floor the
accelerator, this will drop down to first also. If you have the "E"
selected, this is automatically cancelled if you floor the accelerator
also.

As far as your shifts are concerned, I would guess at either the modulator
needs replacing and/or you need to check your fluid level. You certainly
need to check these first before you go any further onto the B2 piston
story.

Hope this is of some help.

Good luck,
Vance.
======================

   Dick,
  There are a couple things you should check before spending $$ replacing
parts.
 Fluid level and quality, control pressure cable adjustment and modulator
pressure.
  The slight flare you are getting between 2 and 3 indicates a high
modulator pressure. Adjusting the modulator to reduce this pressure will
firm up that shift. But the mod. pressure should be within spec.
The downshift behavior you are getting is usually caused by an improperly
adjusted control pressure cable. If you are coasting in drive @ 40mph, no
throttle, and move the selector to 3, does the tranny smoothly go into 3
without delay (< 1sec) ? Or, when sitting at idle, foot off the brake, when
you move the selector to D or R, does it slip into those gears smoothly
without delay (less than 1 sec) ?
  I suspect my modulator is shot since I get a real firm shift at 2 to 3
but I get proper downshifts since I know my control pressure cable
adjustment is correct.

There may be some differences in the Euro set up that I am not aware of.

Rick Hesek