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1996 MB C280
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371 Posts
Discussion Starter #1 (Edited)
Hard Shift / Tranney Saga....

I had my transmission rebuilt about a month or two ago and is had all sorts of problems when I got it back. Included a hard shift between 2nd and 3rd. Most of the other problems have been resolved but this hard shift is lingering on...

I had asked the Transmission guy to come for a ride to determine what the problem was. So he did and he said that the problem wasn't in the transmission. So I took it to the shop and they checked over the car and said the only thing they see that was a problem is the differential and they showed me that there was quite a bit of play in the drive shaft (1/2 inch or so)

I got my car back today after having a used differential (in very good condition) put in my car. The hard shift is still there. It definitely feels better than what it was before (tighter) but there is still a significant hard shift between 2nd and 3rd.

Is is possible that they damaged one of the engine supports when they took the tranny out and put it back in?

Could the transmission also have a problem with a valve sticking or something? I did notice something else and that is if i'm starting out on a steep hill the car will seem to do what I call drop a gear. Where is starts in one gear and then there is a like a thud (you only feel the thud not hear it) and the car changes momentum.

What else could be the problem?

Any ideas?
 

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2001 CLK55 AMG, 2002 C32 AMG
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1,637 Posts
well, i believe we have talked about this before, and im just going to make sure. have you checked the modulator pressure? have you checked your vacuum going to the modulator? have you checked your kickdown cable postion? if all of this is done, then we will move on. it is very rare for the actual transmission or differential to go bad.

check out your flex discs? what are their condition? it sounds like you may have symptoms of bad flex discs.
 

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1996 MB C280
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371 Posts
Discussion Starter #3
Yes we have gone over this before but I have all the answers now :)

After the diferential was changed they took the car to the transmission guy who spent a morning adjusting pressures and making sure the vaccum lines are good. He said he did adjust it a little. That would tell me that the pressure is set correctly, the vaccum lines do not have any leaks, kickdown cable position was adjusted by him too.

Flex discs where replaced in the last year including the motor mounts & tranny mounts.
 

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1996 MB C280
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371 Posts
Discussion Starter #5 (Edited)
Ok here are the only two symptoms that exist now.

When starting off from 0 the car 'sometimes' drops a shift. Basically as it starts moving what feels like an up-shift occurs however at very low RPM like 1000-1500 or so. The sensation is sort of like on a standard when you push in the clutch and let it out again without changing gears where the car looses forward momentum for a very short moment (would be caused by gear change). This can usually be felt very easily when on a step hill trying to start moving from 0.

The other symptom is the hard shift from 2nd to 3rd. Now this ONLY happens when i'm in kickdown acceleration (full load / full acceleration) and basically it's the sound of metal banging against each other muffled a little due to cabin insulation. This happens when the change occurs from 2nd to 3rd. I have also had this symptom not quite so bad and much more sporadic but it has happened between 1st to 2nd.

The metal bang is joined by hard acceleration in 3rd. The sound is quick and occurs when 3rd gear engages (or so it would seem). I have not checked the RPM's shift points but I will do that next time I take it.

When I drive the car very cautiously and slowly it shifts smoother than butter to the point that you don't even feel the car shift.

I ask if they could have damaged the motor mount because they did have to take the tranny out and they said that it causes some extra weight on the motor mount since the tranny acts as a counter balance to the motor. Honestly it feels like something like that.

Any thoughts?
 

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2000 c230 kompressor
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373 Posts
here's a cheap solution, drive easy don't floor it, then it will shift like buter as you mentioned, hehe, still sound like the modulator pressure tho , just my 2 cents, good luck
 

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2001 CLK55 AMG, 2002 C32 AMG
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well, if it shifts fine under normal driving condtions, i would say your lucky :)

i was just wondering what rpm it shifted at when under the normal driving condtions, but i am also curious what rpm's it shifts at when at full load.

im assuming your modulator and kickdown cable are correct since you have great shifting under normal conditions.

what has your mechanic said about the problem now that it has stayed?

does your car actually upshift at the 1000-1500? or does it just feel like it? does your car have a w&s switch or any other switch associated with the transmission modes.
 

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1996 MB C280
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371 Posts
Discussion Starter #9
Ok so at really soft acceleration, like just enough to get going down a hill or something the car will shift between 1000-1500 rpm.

At normal acceleration it shifts around 1500-2500 depending on how much pressure is on the gas pedal.

I did not test the acceleration in kick down to see rpm's since it wasn't one of those drives.

I know a logical answer is to take it easy on the car, but that really isn't the point. I don't think the car had this problem when it came from the factory as I don't see people after paying the kind of money it cost for this car back then to be happy with a hard shift problem between gears.

Also after all the money i've put into it regarding the drive train it should be working perfectly.
 

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1986 190D 2.5 5 Speed
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608 Posts
Ok so at really soft acceleration, like just enough to get going down a hill or something the car will shift between 1000-1500 rpm.

At normal acceleration it shifts around 1500-2500 depending on how much pressure is on the gas pedal.

I did not test the acceleration in kick down to see rpm's since it wasn't one of those drives.

I know a logical answer is to take it easy on the car, but that really isn't the point. I don't think the car had this problem when it came from the factory as I don't see people after paying the kind of money it cost for this car back then to be happy with a hard shift problem between gears.

Also after all the money i've put into it regarding the drive train it should be working perfectly.

If it is pedal dependent, I would still fiddle with the kick down cable. I would try loosening it based on your symptoms. Michael
 

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2001 CLK55 AMG, 2002 C32 AMG
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do you have a vacuum gage? do you know where your modulator vacuum line goes into your intake manifold? if so, tee off there and read that vacuum that is being applied to the modulator. do you hear any hissing from the engine bay?
 

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1996 MB C280
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Discussion Starter #16
Ok guys I was out today and had a bit better chance to test the car. Under full acceleration (kick down) the car accelerates religiously to 4500 rpm and changes gears consistently all the way to fourth (I did this test twice with the same result both time). I didn't catch the speeds it did this at and I didn't have enough road to test again.

I did notice that if I slightly let off the throttle just before the change to 3rd (around 4000 rpm) the hard shift doesn't occur. I know this is most likely due to the change in load but maybe a clue.

At various softer accelerations with the pedal at different positions the shift rpm's vary. If I hold the position of the pedal all the way through the gears it will shift at the same rpm through the gears.

Would the sensation of the car dropping shifts at lower speeds have anything to do with this?
 

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2001 CLK55 AMG, 2002 C32 AMG
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well, there might be one more thing that you can adjust, however i dont really know too much about this adjustment myself. i kind of found it by accident and i havent really found any information that tells you to adjust it or how to adjust it. also, i dont even know what the component is called. but it kind of goes back to one of my earlier questions you didnt answer.

is there a switch on your transmission, well around your shifter for different modes of your tranny? i think this was only on the electronic ones, but i could be wrong...

on the tranny, well at least on mine, on the passenger side there is a red box type thing, and above it there is a green one. i think the red one is for the modes, but i dont have modes so there is nothing attached. and then there is a green box like i said, which has a small adjustment screw/nut on it which is white. my upshift delay from 2-3 use to always shift at 3500 rpm... no matter how hard i was pressing the accelerator and it would be a very jerky shift. and it was always on the first shift, or amybe the second one as well, but once it warmed up it never did it again, it was the upshift delay function. well i adjusted this screw/nut which is very hard to get to and used it to bring my upshift delay point down to around 2k. im not sure where this is supposed to be set, but it seems right lol. however now with my bowden cable set to where it shoudl be set, my car too seems to shift at around 4500-5k, not really at redline like i imagine it should or maybe even used to do. im not sure if adjusting this will help your problem, but maybe your transmission guy know something about this adjustment which may help me as well :p any information would be greatly appreciated.
 

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1996 MB C280
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371 Posts
Discussion Starter #18 (Edited)
Well I'm sorry to have not gotten back sooner to this thread. I thought it would be good to update you guys on the situation.

Here are the problems I'm 'still' having with the transmission:
- Hard shift from 2nd to 3rd
- Under light load the clutch slips when changing gears
- Feels like it awkwardly changes gears sometimes when starting out (more so on hills and it basically feels like an instant loss of power like it up shifts but at a really bad time)

The problems mentioned above are not consistent this makes it hard to diganose but I took the car back to the transmission specialist and left it there for a couple days as he had requested. Basically he told me that he took the brain out and cleaned it up (don't ask what he meant by that because I don't know) but he said that this would include a cleanup of the valves.

I got it back and the problems mentioned above existed but were significantly softer but this was a full rebuild the transmission should be perfect not "almost". It's not right that it hard shifts in any gear or that is makes weird shifts.

I know they have played around with every adjustment that exist on the tranny and related to the tranny. It still has the same symptoms, granted they are much softer and much less noticeable however I still know they are there and I still feel them.

I will be going away for a month in August so i'll be leaving the car with my regular shop. They said they will either get the transmission guy to rebuild it "AGAIN" or they will simply replace the tranny on their bill.

liquidusculade: My car does have the swtich but it's only E or S (Winter or Summer) but it's controlled via vacuum.

Sounds like a good shop to me :)
 
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