For quite awhile, I've always had a slight flare on the 2-3 upshift. Did some research, but it looks like the k1 piston fix was on the early 80's models. I replaced the fluid and filter (yes, drained torque converter) awhile ago, didn't make much a difference. Fiddling around with the vacuum modulator and bowden cable seems to help a bit, but I feel it's not a quick fix. And I'm pretty damn sure I don't have a vacuum leak. Fluid level is correct. Car just went over the 200k mark. Perhaps it's really time for a rebuild?

And lately, the flare is getting worse. I can jump up 2000 rpm if the pedal is down more than halfway while cold. While the car is hot, the flare isn't quite as bad but it's still jumping 800 rpm or so. WOT upshifts seem to work perfectly fine. Any advice?

Just got the K1 kit for my W124...the 2-3 flare just manifested itself a week ago, but I don't want to wait until it gets really bad. The prolonged slippage will probably do some damage to the clutch internals...

...I tried refreshing the fluid as well but no dice. So I will do the install hopefully this weekend and post results. BTW, it's about $15 on PartsShop, so it's an inexpensive gamble if you are parts-throwing...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

It's getting worse. On the last mile home tonight, it wouldn't shift out of second gear. Not good. Takes forever to change gears. If I can get it to fourth, it's got no problem with highway cruising. Just a pain to get it there.