Hello all,
My '91 300E has been shifting relatively hard for a long time now. I have been trying to ignore it (too many projects and I am overly sensitive about these things anyway) but now I have a little free time... Fluid is full, fresh filter. Usually 3-4 is harder than the rest (sometimes it's 2-3, and yes I understand the 2nd gear start, it's definitely 2-3 sometimes), but all are harder than the '91 300TE we have. Not really bad, but noticable. The thing is, it seems to be in the back end...which makes me question the rear flex/diff. I have checked the rear flex disc, and it will need to be replaced in the near future, but it certainly doesn't look bad enough to cause the hard shifts.
Could the diff fluid be low? Is my tranny going? What else might be the prob? I much prefer to find these things before they get too out of control. If it is the tranny, diff or both, that wouldn't be too bad, as long as they give me a little while longer...(at least until I find my donor car for my manual conversion/ or a limited slip diff .)

Thanks for any insight .
Cheers,
-Matt-

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Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

Matt, disconnect your battery for about 5 minutes. This will reset your computer.

Reconnect the battery, and take a drive ..... if it's nice, and smooth for a few minutes, and then starts shifting hard again, then your problem is component related, and not your transmission.

If this is the case, see if you can get read out any diagnostic codes from the computer.

Computerized transmission on a 1991 W124 ???? Not sure about that.

Your problem is probably caused by your vacuum activated transmission modulator.
It is adjustable by removing the black plastic cover and turning the adjustment counterclockwise to make your transmission shifts softer. The modulator is located in the left side of the transmission. There is a vacuum line leading to it. Make sure it is tight and not leaking.
Do not adjust your modulator in large increments. Most of the time, only a few degrees will be enough to change the shifting performance.

exactly my point, this will verify that its something else causing his woes.

After resetting the computer, the car will run quite nice temporarily, and then revert to it's old ways...meaning it's not the transmission.

Next time read, before you argue

WLTORRES:
Please tell the world where you have found, seen or heard of a computer controlled transmission on a 1991 W124, 300E.
Some 2,000,000 W124 owners will be eternally grateful to you.

Jack a rear wheel free of the ground and apply a wrench to a lug bolt with the parking brake applied(be careful not to knock the car off the jack!). If the wheel moves forward and back under torque on the lug bolts, replace torque and thrust links in the rear suspension. Bad torque links cause sloppy handling and serious thumps and bangs back there, including on shifts.

Otherwise, inspect the vacuum line to the transmission. A bad vac line (or other cuase of a vac leak such as bad idle control valve hoses, etc) will cause hard shifts. I'd bet, if the rear suspension is OK and you don't have a bad flex disk, you have a bad vac line.

Check the flex disk, the front one only seems to last about 60,000 miles.

you should also check the differential mounts. They are on the rear subframe behind the diff, steel insert must be centered and not move much when the diff is jacked up. Bad ones cause a knock.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks for the info! I will check the rear end for play, it certainly handles a bit sloppy back there...I was just going to put in a tighter sway bar to pick up some of the slop....hadn't gotten around to checking some of the other components first.
I know all about the vac moduator on a diesel, I've never fooled w/ one on a gasser. Should act pretty much the same right? I'll fool w/ that if the rear is tight.
Cheers,
-Matt-

__________________
Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

If it is really squirrely on wet pavement in the rear, for sure it's the rear links. You are due, they go at about 150,000 or so in most cars. Not a bad job, let me know if you need them, there are some hints to help get the torque link in.

Vac modulators are the same, except the gasser is just a line from the manifold. If you have low vac for any reason, the tranny will shift hard. Another clue is throttle lag off idle -- if it hangs, then roars off, for sure you have a vac leak.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Yes, I also want to know how the computer controls the transmission on a 1991 W124

Please enlighten me

__________________
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

pesuazo
Ask wltorres.
He knows.
Instead of disconnecting the battery for 5 minutes as he suggest, maybe he could try this new gizmo from Microsoft. I plugs in the rear end....................................of the transmission:

drain the torque and pan, flush and refill with synthetic, you'll be very happy you did. I was very happy with the results on mine. Drained and flushed at 165k, still running like new at 190k. Even better results in the winter.

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88 TOY 4x4 putt putt w370k still putt'n...
92 300e old but clean
02 C320 sweet...