Transmission on 300SD

Hi again, this is Mia.
(Lots of questions, as usual).
Driving my 1984 300SD and loving it. Sturdy, heavy, solid, running over stuff and not even noticing it :) FINALLY gasoline got more
expensive than diesel again, whew :)
When the tranny's shifting from 1st to 2nd while I'm driving away from a stop light, depending on how hard I press the gas pedal, I may or may not experience a distinct 'jerk'. Sometimes I press the pedal just right, and it shifts smoothly. When I'm NOT stopping completely, like when making a turn, it never jerks.
My mechanic said the transmission fluid is a bit brown - could it jerk because of that?
Thanks.
Mia J.
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You can find out if you change it right away, also have the torque converter and filter changed, it's time. Brown oil is not good. Mobil1 synthetic costs a bit more but I feel it's worth it.
--

73
Hank WD5JFR

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I agree on this. I own a 1980 300SD. After renewing the oil, i adjusted the pressure that is used for changing gears. But if you're not expierenced, you should leave this for your mechanic.
On my car it made a hell of a difference.
Lamaeker

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Doubtful. Actually it seems to me that the jerk might be normal.
Basically this car is setup so that if you are very light on the gas you will see early and soft shifting, but if you gun it, you will see later/firmer shifting.
If what you are describing only happens when you really step on it, and there is no "flare" (ie the motor revs faster then the car is going), it could be normal.
Changing the tranny oil is probably a good idea if the car is new to you. Make sure the torque convertor gets drained also.
I also like mobil 1. Marty
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On Thu, 12 May 2005 10:58:33 -0700, Mia wrote:

Mia,
http://www.continentalimports.com/ser_ic20242.html
and
http://www.mercedesdismantlers.com/AutomaticTransmissionInformation.html
may be informative, if not actually helpful. A number of things I keep intending to do on these pages, but haven't quite got there yet.
Mine '81 (more or less) seems to run only in three gears, and the shift between the first two is decidedly firm - a quite solid thunk. When I accelerate a bit harder, the shift between those first two gears is smoother. The next upshift (between the top two gears) is always smooth. I'm still not sure I've found the legendary first gear.
Cheers,
Conrad
P.S. - if you like photoshop, you may want to play with the Gimp (www.gimp.org). It's a free download. Some folks actually prefer it to photoshop, but I think it's not so much a photoshop replacement as another nice tool to add to your graphics toolchest - and yes, it's written to run on *NIX platforms, but there's a very nice port to Windows.
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Typically the fluid color doesn't cause what you are seeing, but I would change it if it is brown.
It seems if one gets used to anticipating the shift and lets off the accelerator slightly, the shift is firmer. If you keep the accelerator down, it seems smoother.

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Comments from a 1980 300SD / 1986 SDL owner...
The transmission will start out in 2nd unless you smash the accelerator. The shift to 2nd should be quick and not very harsh. The vacuum actuated modulator on the tranmission should damp shift jerkiness at high RPM shifts. If you are feeling those I'd first check that the vacuum line is whole and connected to the modulator (and there are no vacuum leaks) That has made a big difference in the past. Changing the transmission oil is never a bad idea. That would be a good time to get the modulator set to the right shift actuation pressure by a MB mechanic.
If the transmission is older than 250,000 miles you may want to start planning to replace it and the torque converter both. Adsitco is still selling rebuilt transmissions for $1195 and TCs for $265 over the internet with a 2 yr / 24,000 mi warranty. I got the swapout labor done for about $500. I think this cost is very defensible for a car that you love. It doesn't take many new car payments to justify the repairs.

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