Hello. Im looking for some help narrowing down the list of suspects.
So the story goes:
Bought the car with bad reverse clutch seal, so eventually reverse has failed in a big way.
I pulled the tranny off and took it apart, the only damage was the exploded reverse clutch, I inspected all other clutch packs and brake bands and they were fine.
Decided to go ahead and rebuild it, I used genuine MB seal kit and MB valve body seal kit to satisfy my OCD. Installed new reverse friction plates, springs, spring plate and circlip. Same time replaced B1 brake band and some cheap plastic pieces. Measured all clearances as per assembly manual, everything checked out. Same time rebuilt engine top and replaced head gasket (had a small oil leak in the back).
If anyone interested I have a youtube channel with these videos.
Installed the tranny back ...
On first test drive it drove fine until the tranny warmed up, it started to slip on take off.
I thought it was the B2 brake band slipping, also a common thing to do in this case is to replace B2 piston pin with a longer one, they come in 0.8 mm increments.
So dropped the tranny and investigated. Measured the B2 band travel, 5.6 mm (spec is 5.5 -6.0 mm), on a closer look I found that the B2 piston clearance was a bit too big to my liking – 0.007”, so I got another piston and a new B2 brake band installed. Put it back together and installed back into the car.
On the test drive it did exactly same thing as before, as soon as it warmed up it started slipping on take off. As it drives it shifts better then before, no kick from 1 to 2, shifts up and down no problems, kickdown works OK.
I don’t know enough about the inner work of a transmission and how the transmission works in every detail, so Im lost. Need to come up with a plan for troubleshooting to narrow down on this problem.
So far I suspect:
1. Low oil pressure on warm transmission at idle?
2. Slipping one way clutch? I had it completely apart, except the actual sprag bearing. Looks like need to test if it slips in reverse as well?
3. Does anyone know what the spec is for 722.424 working pressure, cant find this info ?
4. How do I measure B2 piston pressure?

any help would be appriciated, as I really want to get to the bottom of this problem.