1979 300SD weird trans problem - PeachParts Mercedes-Benz Forum

cooljjay · #1 07-29-2013, 10:01 PM

Shifter bushings?

ROLLGUY · #2 07-29-2013, 10:24 PM

Quote:

Originally Posted by cooljjay

Shifter bushings?

I don't believe so. Something is happening hydraulically causing the problem, but what exactly, I have no clue.

ROLLGUY · #3 07-30-2013, 10:50 PM

Stretch? Anyone?

Zacharias · #4 07-31-2013, 01:18 AM

Normally I am about the last to offer transmission advice, but seeing as you seem to be getting an echo....

I have no idea if this behaviour is actually linked to the operating pressure, but I'll go with that for now.

You say you adjusted it a bit, did that make any difference to the shifting otherwise? If it did not, I wonder if the modulator is set way too low. How does it shift otherwise, firm or what I call slithering through the shifts (I hate overmodulated setups)?

If the modulator way off the correct setting, you will need many turns. You can either go ahead and just try one turn at a time, to see if anything changes. Or you can try to put a gauge on to test the operating pressure, to see if modulator adjustment is indeed the tree you need to bark up. To do that you will need to confirm which is the correct test port (there are probably three or more choices and they are apparently different on the later trans, so beware hooking up a gauge based on info from archive posts).

ROLLGUY · #5 07-31-2013, 10:32 AM

Quote:

Originally Posted by Zacharias

You say you adjusted it a bit, did that make any difference to the shifting otherwise? If it did not, I wonder if the modulator is set way too low. How does it shift otherwise, firm or what I call slithering through the shifts (I hate overmodulated setups)?

If the modulator way off the correct setting, you will need many turns. You can either go ahead and just try one turn at a time, to see if anything changes. Or you can try to put a gauge on to test the operating pressure, to see if modulator adjustment is indeed the tree you need to bark up. To do that you will need to confirm which is the correct test port (there are probably three or more choices and they are apparently different on the later trans, so beware hooking up a gauge based on info from archive posts).

I did remove the cap, adjusted the "T" in about a turn and a half, replaced the O ring, and put the cap back on. It is possible that I should have put 3 or 4 turns on the T, but it does shift firm in all the gears. I don't want it to slam into gear, but maybe more turns on the T tighter will make this weird problem go away, it may be worth a try. I am not sure when the fluid was changed last, but it looks newish....Rich