W126 560 SEL trans shifts harsh

[LandYaghtLover]

So I went under. There is a new vacuum line installed. But the dial thing it attaches too looks like it *might* be factory. It looks like it turns to be adjusted? So I did. No change.

So what could be defective. I thought I recall reading about the trans shifts being vacuum dependent and a part failing. Pics?

[mbdoc]

With the engine running, do you have vacuum at the modulator on the drivers side of the trans?

[LandYaghtLover]

I will check. But its a straight line to the intake, so I would think so. The line is new and connections intact. Although odd that the line is new.

[rocky raccoon]

Simply having vacuum present at the input to the modulator is no guarantee that it is working. If you have a MityVac or similar attach it directly to the shift modulator and see if it holds a vacuum. If not, that is your problem and it needs to be replaced.

The part is inexpensive (about $35 as I recall) but was difficult to access on my 560SL without a lift. You may have more room on your car.

[LandYaghtLover]

If its the part the vacuum line goes right too, it seems easy to replace. Guess I will find out.

[rocky raccoon]

Yes, that's it. There will be almost no fluid loss when you remove it.

[rocky raccoon]

the new one, there may be a short period of trial and adjustment until you have the shift characteristics where you like them. Drive, adjust the modulator if necessary, drive, adjust, etc.

[LandYaghtLover]

Am I correct that adjusting it is as simple as moving that lever? If so and I am getting no change, I am betting its shot then. I will just replace it. I get parts at dealer cost, so no big deal.

[mak]

Any leak in a vacuum pipe end, or in a A/C pod will also result in harsh shifting as will a old & leaky modulator valve .

mak

[LandYaghtLover]

Where can I get a modulator. My usual parts guy where I get goodies at cost can not come up with one, even through his import channel.

[rocky raccoon]

on this site. Get Phil before he retires.