transmission adjustment? - PeachParts Mercedes-Benz Forum

Mooger · #1 11-04-2004, 09:46 PM

Hello,
I know this is not right but I dont know how to approach this problem. I did searches but I didnt find info specific to this situation. this is hard to describe - when I am at a stop in drive at idle the car still is pushing to go forward. the car actually squats a bit. if i put it in neutral it "relaxes". when I put in drive with the brake on it squats again. thats the best way I can describe it. seems like something needs to be adjusted. any suggestions and or references greatly appreciated- thanks very much for this forum.

Eric Eliel · #2 11-04-2004, 11:17 PM

Your idle should be around 650 RPM. Check that first.

redbaronph123 · #3 11-05-2004, 12:22 AM

isnt this supposed to be right?. i mean for an automatic transmission.. if you are in drive.. it is supposed to have the need to go forward. You really have to step on the brakes just to keep it from moving forward. If you release the brakes with the tranny in Drive, at idle.. the car will move forward (on a flat surface of course, or maybe downhill.. hehehe)... and if you do put it in neutral.. it should have that "lifting" feeling...

i would really think this is normal.. unless of course your being jarred whenever you engage to Drive.. then at that point i think you may have a problem.

i'm not really an expert, so correct me if i'm wrong, but that's how it is in my car. Unless i completely misunderstood the question. ???

Old300D · #4 11-05-2004, 10:35 AM

Sounds like fairly normal behavior to me. What car are you talking about? I understand the turbo engines have governors for the idle speed, but the non-turbos have a fast idle adjust. Maybe the fast idle cable is too tight. You may also have worn shocks that pronounce the squat - My 240D (with turbo engine) really wants to roll forward when stopped in drive, but shifting will not cause much, if any squat.

Brian Carlton · #5 11-05-2004, 10:46 AM

Quote:

Originally Posted by Mooger

Hello,
.....when I am at a stop in drive at idle the car still is pushing to go forward. the car actually squats a bit.

This is perfectly normal. All M/B will "squat" slightly when the selector is moved from neutral to drive.

Move the selector from neutral to reverse and you will find that the opposite is the case. The back end will "rise" slightly.

This is the body responding to the stalled torque in the differential.

Just be sure your idle is not too high. If the idle gets above 700, this phenomenon will start to qet quite noticeable because the stalled torque is greater.

The SD with the 617 exhibits this very profoundly with a 700 idle speed. It's barely noticeable on the SDL, 603 engine with a very high stall torque converter, and an idle speed of about 600.

boneheaddoctor · #6 11-05-2004, 11:05 AM

Quote:

Originally Posted by Old300D

Sounds like fairly normal behavior to me. What car are you talking about? I understand the turbo engines have governors for the idle speed, but the non-turbos have a fast idle adjust. Maybe the fast idle cable is too tight. You may also have worn shocks that pronounce the squat - My 240D (with turbo engine) really wants to roll forward when stopped in drive, but shifting will not cause much, if any squat.

My 300SD Turbo has a fast idle adjust on the dash and its Turbo..... I have good shocks and do notice the squat issue too, but it doesn't bother me.....I just wish these things didn't start in 2nd. Or there was a way to make it automaticly start in 1st. (and yes I bet that is a pipe dream because of how its engineered)

SD Blue · #7 11-05-2004, 11:14 AM

Sounds as if your rear differential mount needs replacing. My '84 300SD had the same symptoms. Once the mount is replaced there was no noticable "squat" or even "lift" in reverse. It is amazing what difference this $50 part will make.

Old300D · #8 11-05-2004, 12:00 PM

Quote:

Originally Posted by boneheaddoctor

My 300SD Turbo has a fast idle adjust on the dash and its Turbo..... I have good shocks and do notice the squat issue too, but it doesn't bother me.....I just wish these things didn't start in 2nd. Or there was a way to make it automaticly start in 1st. (and yes I bet that is a pipe dream because of how its engineered)

Maybe it's just the 617.952 that doesn't have the fast idle. I'm using the 722.117 transmission (from the 240D) and it starts in 1st gear. My old 300D had a 722.118 with mechanical linkage, and it would start in 2nd unless floored. I hated that too, I'm glad my 240D transmission acts like a normal unit. It has no mechanical link like a rod or cable - it seems to operate solely off modulated vacuum.

boneheaddoctor · #9 11-05-2004, 12:03 PM

Quote:

Originally Posted by Old300D

Maybe it's just the 617.952 that doesn't have the fast idle. I'm using the 722.117 transmission (from the 240D) and it starts in 1st gear. My old 300D had a 722.118 with mechanical linkage, and it would start in 2nd unless floored. I hated that too, I'm glad my 240D transmission acts like a normal unit. It has no mechanical link like a rod or cable - it seems to operate solely off modulated vacuum.

Mine also doesn't have a bowden cable it has a solid rod....but basicly the same thing I guess. My understanding is that adjusts pressure on the trans.... or I may be completely off target.

Mooger · #10 11-05-2004, 12:36 PM

ok, thanks for the input, MB's (and diesels) are a new animal to me. I want to check the idle but I dont have a dashboard tach. can I use the tach/dwell meter I have ? how should the engine sound iat about 600 rpm? also (i'm imbarrassed to ask but I just dont know) how is the idle adjustment on the dash is properly used. I have found that the engine starts much better when it is turned all the way CCW.

boneheaddoctor · #11 11-05-2004, 12:40 PM

Quote:

Originally Posted by Mooger

ok, thanks for the input, MB's (and diesels) are a new animal to me. I want to check the idle but I dont have a dashboard tach. can I use the tach/dwell meter I have ? how should the engine sound iat about 600 rpm? also (i'm imbarrassed to ask but I just dont know) how is the idle adjustment on the dash is properly used. I have found that the engine starts much better when it is turned all the way CCW.

No you can't use your tach swell meter, it relys on electrical connections being made and broken to count rpms, Diesel has nothing to hook that to.

Dashknob.....adjust it where it idles best and has least need to creep forward.

WANT '71 280SEL · #12 11-05-2004, 01:12 PM

Bonehead, sometimes my car flares between 3-4, how should I adjust that rod? Do you have an idea as to how much should be adjusted?
Thanks
David

boneheaddoctor · #13 11-05-2004, 01:38 PM

Quote:

Originally Posted by WANT '71 280SEL

Bonehead, sometimes my car flares between 3-4, how should I adjust that rod? Do you have an idea as to how much should be adjusted?
Thanks
David

I think the flaring is a vacume issue. Like all the 617 based models. Too much causes the 3-4 flaring and too little causes hard 1-2 shifting as I understand it. If you want to try to adjust that rod, write a note as to how much and what direction it was turned so you can put it back to original. As I understand it adjusting that requires taking haydraulic pressure reading on the transmission. My zero reference I don't have, the "C" clip was missing and it popped off the motor and surely vibrated out of adjustment before I found out last year. You could try 2 turn one direct and see iff it helps, if not return it to its zero refference then try 2 in the other direction....if no change put it back to zero reference and try measuring the variable vacume port on top the IP. I haven't done it so can't give you specific info. I will after I buy my mighty-vac.

When I first bought the car I thought it was a kickdown linkage......later I found out it regulats internal pressure on the transmission , basicl compensates for high throttle loads etc. Unless of course I have horrible misunderstood its function.