Hey guys,

I've been chasing an issue for about 2 years now and can't find a decent answer or reason. My 1-2 and 2-3 shifts are quite harsh, kick in the pants kind of shift. 3-4 is fine 99% of the time. I've done multiple fluid changes, new filters, replaced the bowden cable and the modulator.

1-2 Shift: This is harsh at around WOT, the car starts in 2nd so I'm never down to 1 unless its heavy acceleration. I can live with this.

2-3 Shift: This is harsh at low/off throttle, basically I find this bad in parking lots. What happens is the car starts to shift, feels like its going to, pauses for a second and then slams into 3rd gear. Its not what I'd call a flare, its not slipping. It's just a pause. Under moderate throttle its absolutely fine.

Any ideas?

The harsh 1-2 shift is normal under WOT. In a programmed 2nd gear start transmission, you're on the kick down switch to force a 1st gear start and it will shift at much higher RPM.

The hesitation and rough 2-3 shift could very easily be a broken K1 accumulator spring. The part is cheap, easy to replace, and is well documented on this forum and elsewhere.

Anecdotal evidence time: My 300SDL drove like Helen Keller learning to drive stick when I got it. I found both K1 and K2 broken. Replacing them got the transmission shifting remarkably well despite it being very tired.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Haha, was just coming back to edit my post, K1 spring was replaced year and a half ago. First thing I did, but doesn't seem to have made any difference.

You may want to test governor and modulator pressure for your specific transmission part number. There is an ASTG manual floating around on the Internet that has all the testing procedures and values for the various different transmission part numbers.

How many miles on this car? If a high mileage example, you might try a bottle of the yellow Trans-X. If you have a bunch of varnish or sludge built up in the valve body it could possibly help. My SDL sat for a decade with old fluid in it. Transmission was absurdly rough when I put it back on the road, felt like it had a drag shift kit in it. Every shift was delayed and violent. Yellow bottle Trans-X helped a surprising amount. I'm not a believer in "mechanic in a bottle", but sometimes it's a band-aid that actually works.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Yeah I was thinking governor could be the cause, thought I had it figured out when I couldn't get it to upshift, figured the gear had broken but turned out to be an overadjustred bowden. I'll try and track down the test procedure.

The shop that adjusted the modulator did multiple adjustments to it, I was adamant they got it right so I don't think theres an issue there.