I really dont like how hard my auto tranny shifts in the low gears especially when co - PeachParts Mercedes-Benz Forum

spree17 · #1 01-12-2004, 08:39 PM

I really dont like how hard my auto tranny shifts in the low gears especially when cold. This is only noticable on the shift from 1st to second gear. Previous owner told me that was normal as do guys on another messageboard but it reminds me of a bad vaccum advance that I have fixed on other cars. Then when I looked up reviews on this 1993 190 the review mentioned a faulty transmission vaccum module. Does anyone have any information regarding this matter. My car drives like a dream on the highway but the tranny shifting from a complete stop stops are almost embarrassinly hard.

Any and all insite would be much appreciated!

stevebfl · #2 01-12-2004, 08:50 PM

There are a couple possibilities. The first would be engine performance. If the engine is lacking power during warm-up and requires more throttle then the other two factors are affected. Those factors are the control pressure cable and the vacuum modulator.

If the engine is right then I would make the trans shift earlier (lengthen the control pressure cable) and/or make it shift softer by backing off the vacuum modulator.

spree17 · #3 01-12-2004, 11:13 PM

thanks. the engine is perfect, How do I find the vacum modulator and adjust it? I'm pretty sure that is the problem.

I checked the fluid cold and it was way high then I checked it warmed up and it was a little above the max point. Would that make the first gear change rough. Its always rougher the colder it is. The rest of the gear shifts are fine.

Sid The Kid · #4 01-13-2004, 05:00 PM

I complained about the same problem today to my transmission mechanic. he said mercedes mixes aluminum with steel and with teflon and this combo leads to hard shifting in the first 4-5 shifts.

spree17 · #5 01-13-2004, 05:07 PM

mine shifts perfext except for the very first shift. My fluid is about an inch over teh max mark when checked on a level surface in a warmed up condition. I was able to siphon a tiny bit out today and already noticed an improvement. I dont know why I cant get this cheap siphon to work though. Took me 40 minutes and messy hands to get like 2 ounces out. It was a cheap hand pump siphon for $2

stevebfl · #6 01-13-2004, 05:32 PM

>he said mercedes mixes aluminum with steel and with teflon >and this combo leads to hard shifting in the first 4-5 shifts.

Well that explains it, who'd a thought.

brewtoo · #7 01-13-2004, 06:28 PM

Quote:

Originally posted by spree17
mine shifts perfext except for the very first shift.

You're not talking about the one-time delayed 2-3 shift when cold, are you?

spree17 · #8 01-13-2004, 06:59 PM

its a delayed first shift. Is that the 2-3 shift? It worse when cold but even happenss a bit when fully warm.

spree17 · #9 01-13-2004, 06:59 PM

I hate being so much of a pain to the board but this is really the only issue that stops my new (used) car from being perfect. This board really is great!

brewtoo · #10 01-13-2004, 07:08 PM

Click below and see if that is what you're talking about...

http://www.peachparts.com/shopforum/showthread.php?threadid=33150

spree17 · #11 01-13-2004, 07:22 PM

Thanks but thats nothing like it. my car shifts hard but not delayed like that. Just a harsh first shift that jerks your head a bit. It can be lessened if I dont step on the gas much

Sid The Kid · #12 01-13-2004, 07:36 PM

"Well that explains it, who'd a thought."
LOL

#13 01-13-2004, 07:46 PM

My 420SEL did exactly what you are saying. My mechanic tried to adjust the transmission (?) but the situation did not improve. He stated that the tras would have to be opened up and possibly rebuilt in order to address this proble. I know this doesn't help much but this type of issue is probably best left to the pros.

Sorry to not be of more help

#14 01-13-2004, 07:49 PM

My 420SEL did exactly what you are saying. My mechanic tried to adjust the transmission (?) but the situation did not improve. He stated that the tras would have to be opened up and possibly rebuilt in order to address this proble. I know this doesn't help much but this type of issue is probably best left to the pros.

spree17 · #15 01-13-2004, 08:05 PM

Thanks for the input but seems many people on various boards have made this problem disappear byt adjusting their vaccum modulater. I would adjust min except its impossible for me to reach it.