Loud Clunk when shifting
#2
08-21-2006, 10:00 PM
RE: Loud Clunk when shifting
aharley1,
I had a similar 'clunking' up shift and sometimes downshift problem awhile back on my '87 560SL. Replaced flex plates and drive shaft carrier bearing as I was convinced that it was something 'aft as you call it. Well, surprise surprise...given the harmonics of our cars, sometimes where we think or feel the problem should be, it ain't.
In my case, it turned out to be the transmission vacuum modulator, the adjustable vacuum device located on the side/bottom of the transmission that is used to control the firmness or softness of shifts.
I don't know your skill with this kind of thing, buy mine is about a D. In my opinion, it took a very well qualified transmission tech to figure it out for me and replace the modulator as the internal diaphram had torn and would not hold vacuum. If on inspection/test, the modulator does hold vacuum, there is an adjustment port where the amount of vacuum can be changed. This is a pretty sensitive adjustment, and even my guy working with a new one, had to play with it a couple times before the car shifted as I like.
In short, unless trained in this stuff, I'd get the car to the best Trans shop around with a reputation/references as having worked on 107's and let them inspect/test for you. If an adjustment is all you need, they'll probably do that for free while talking you into a fluid change and filter...do it. If the part has to be replaced, it's around $50 for the Modulator and less than a 1/2 hour to install. Good luck and post how you make out-
Bob
I had a similar 'clunking' up shift and sometimes downshift problem awhile back on my '87 560SL. Replaced flex plates and drive shaft carrier bearing as I was convinced that it was something 'aft as you call it. Well, surprise surprise...given the harmonics of our cars, sometimes where we think or feel the problem should be, it ain't.
In my case, it turned out to be the transmission vacuum modulator, the adjustable vacuum device located on the side/bottom of the transmission that is used to control the firmness or softness of shifts.
I don't know your skill with this kind of thing, buy mine is about a D. In my opinion, it took a very well qualified transmission tech to figure it out for me and replace the modulator as the internal diaphram had torn and would not hold vacuum. If on inspection/test, the modulator does hold vacuum, there is an adjustment port where the amount of vacuum can be changed. This is a pretty sensitive adjustment, and even my guy working with a new one, had to play with it a couple times before the car shifted as I like.
In short, unless trained in this stuff, I'd get the car to the best Trans shop around with a reputation/references as having worked on 107's and let them inspect/test for you. If an adjustment is all you need, they'll probably do that for free while talking you into a fluid change and filter...do it. If the part has to be replaced, it's around $50 for the Modulator and less than a 1/2 hour to install. Good luck and post how you make out-
Bob
#4
08-21-2006, 11:03 PM
RE: Loud Clunk when shifting
aharley1,
You're more than welcome to print it out if you like. I just hope your mechanic doesn't react with...."so some guy read this, diagnosed your car over the internet, and you want me to do what with that"?
Egos being what they are, you may want to consider simply asking, "do you think there's a possibility that I'm losing vacuum at the trans that would cause this clunking"? or, "can you check vacuum at the modulator for leaks; I'm getting some harsh shifting"?
Good Luck
You're more than welcome to print it out if you like. I just hope your mechanic doesn't react with...."so some guy read this, diagnosed your car over the internet, and you want me to do what with that"?
Egos being what they are, you may want to consider simply asking, "do you think there's a possibility that I'm losing vacuum at the trans that would cause this clunking"? or, "can you check vacuum at the modulator for leaks; I'm getting some harsh shifting"?
Good Luck
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