Need Help with B1 Piston W124 400E transmission 722.354
 

I am preparing the donor transmission for install tomorrow.

I built a tool to remove the B1 piston cap and removed B1 piston assembly.
Was easy.

Problem now is that I took the cap and B1 piston entirely apart except for the Teflon ring.

Cap and Piston are connected with a 10mm shaft and are 'secured' with a teethed washer (see pictures). That washer sits in the piston secured by a ring clip.


When I pulled the 10mm shaft out of the piston there was great resistance from the teeth of that washer but I could disconnect in the end.

But now I cannot get the 2 parts together again easily because the teeths of that washer (teeths are curved slightly towards the shaft-outward- and do not allow the shaft to enter).
But if I could get the shaft in with force how do I adjust the distance between the piston and cap?

I am not certain what to do but I need to do something (running out of time).
Worst case the pressure of the piston is not enough to push the piston towards the brake band.

What is the purpose of that design? I don't quite understand... maybe to restrict the return movement of the piston when the oil pressure drops and the springs push the piston back...but only a bit and not all the way?

Who can help?

Martin

Now I opened another transmission (also a 722.354 but a 92) and the set up is different here. B1 Piston has a rubber cup seal and there is no connection between Piston and Cap. Pictures attached


Also I found a note in a German manual that said something about a 1.8-2.0mm play... that has to be adjusted but I don't know what that means?

Who knows where that play has to occur and how it is measured? Is the play the distance the piston should travel from all the way back until B1 starts binding?


Martin

Now I got a manual from Andrew that shows the B1 in my case.
It seems to be an update for automatic set up the 1.8 - 2mm play.

here is the page

Pic 2 of your first post + manual pic. It is a self adjusting system like you are thinking. The teeth would grab the shaft in one direction but not the other. This would let the shaft continue to self adjust in the direction of wear but not the other way around. Free play is controlled by the groove on the cover side of piston. This 1.8 to 2 mm spec isn't something you can change, it is more of a worn part indication.

There is a snap clip 40a that you remove so the pin 37 c can come out of the cover. This way you will be able to assemble the toothed washer ( curved portion up ) from the cover side of the pin , install snap ring into the piston then put the cover on and press hard enough that the snap clip engages.

The end goal is to have the piston and cover close together after assembly. ( Per manual , don't pull it apart otherwise you will have to start all over again. ) Once the trans shifts, the piston will move away from the cover, self adjust but not fully return

I just did a complete edit of the above post, so go through it again if you didn't see this post before.

Thanks 97,

Andrew sent me that section and manual.

You are saying the same thing.

I am trying again to day to push that retainer apart to get the pin out.
It is hard in order not to destroy the retainer (you don't want that)

I find this not an easy process.

I'll let you know how I am doing today.

Martin

I have the pin out and parts in hand, finally.

In order to release the retainer clip from the pin you need a special tool that fits inside to push the 2 open arms of the 8-clip apart. I used a piece of 1.5mm sheet metal cut in a wedge form and rounded so it fits into the tight space, a screw driver didn't work for me.

My only concern is that the 12 teeth cup spring has lost some of the sharpness of teeth and won't do a good job now...

But I don't have a new toothed washer...meaning I have to live with it.

Also I am not sure about the teflon seal(it is not very smooth) ... but I might just live with what is there.

Martin

I ordered new toothed spring washer and retainer clips plus a new Teflon piston seal at Classic Center. They had to get these parts from Germany.

I installed these parts new in the B1 assembly of the transmission and it feels so much better. the new washer bites really well now while the old one was slippery. I guess the teeths are just not sharp any more with age and after removal. Mercedes has a note in their instructions to always change that toothed B1 washer whenever taking the piston/cap assembly apart.


Martin

To give you an update on the 400E donor transmission install.
The car is back on the road and it shifts nicely. transmission is healthy and I am happy with it.

Thanks for all your help.

Martin

Thanks for the thread update.