vinyl_tien

Thanks~~ Working on it now..

Tails

When the B2 piston fails you usually loose all forward gears and retain reverse, so I personally do not believe that your porblems are related to the B2 Piston as you still have all forward gears. FWIW I do not believe that it is necessary to go into the action of the B2 piston and it application within the gear box at this juncture.

I have had a B2 piston failure and replace the B2 piston myself and all has worked satisfactorily ever since (The failure of the B2 piston is a known fact by MG as they have modified the B2 piston to a better design).

I wrote a report on its replacement of the B2 piston and posted it via 3 pdf files on this forum with pictures.

In addition, I was suffering from harsh gear changes and made up a union and pressure gauge and fitted it to the modulating pressure port and reset the modulating pressure to the correct specification value at idle in "D" and it now works as smooth as silk during gear changes.

Too low a modulating pressure will cause "flaring/slipping" between gear changes.

Tails 1990 928S4 Auto

vinyl_tien

Hi Tails
I just finished your report also show them to my tech man.That is amazing. I will ask them to replace B2 parts for me, then see how it work.
Thanks!

Landseer

Roger has also access to the parts and there may be new part numbers for those pieces, when I did it using Taills (excellent) writeup they had changed slightly.

There are a wide range of lengths of actuator pins possible for getting B2 clutch setting correct.

Setting modulation pressure with gauges and seems like an important step --- a rebuild should include this step and a new modulation valve. A little firmer modulation pressure adjustment might solve yours.

ROG100

Hi Tien,
I have the flair spring and B2 valve in stock and can add them to your order if your tech decides he needs them.
Roger

vinyl_tien

Thanks Roger, please receiver PM.
Here is the first tome my tech man replace for me, but I have no idea what these for.. Can any one tell me?