For a few months, my 1991 420SEL (W126) with 171,000 miles has been getting slower to engage into reverse, and now it has gotten to the point where I need to blip the gas a couple of times before it engages. Everything seems fine in forward gears - the fluid was changed at 150,000 miles (every 30K), and is at the correct level.

I have done a fair amount of searching, and found multiple references to an external adjustment of the reverse (B3) band, but apparently this doesn't apply to my transmission, which I believe is a 722.3 (??).

So, I am hoping you all have some suggestions:

- Is it really true that there is no external reverse band adjustment for this model?

- Is there any other form of adjustment that would help? I saw a post or two that talked about adusting the vacuum modulator, but isn't this mostly for forward gear shifting? If adjusting the modulator would help, how is this done? I see the modulator on the side of the transmission - is it basically a loosen and rotate? If so, which direction, and how sensitive is it?

- If none of the above are likely to help, what should I expect from a dealer repair - are there relatively minor adjustments that they can make, internal to the transmission, that are short of a rebuild?

Thanks for your advice and help.

rschleicher
1991 420SEL, 171,000 miles