[rismo]

Hi guys,

Nice thread, just to add some to the discussion, I have had the possiblity to analyse two ZF gearboxes with a AT diagnostic tool. Both came from a heavily tuned 335, one FBO mine was a FBO + RB's.

The FBO has 105000km and mine had 160000km tuned from it's birth.

The AT has memory that stores all kind of historical data, also a table with an operation temp range and the amount of time spend within each subrange.

I was surprised to see that the FBO, the car was never tracked, did not spend any time in the critical time range. Mine, a car that is tracked about 30 times on a racetrack (not 1/4mile), for more then 60 hours, did only spend about a hour within a temp range above the critical temp. (I thought this is is above 130 degrees celcius.)

Another thing I found was that the box temp is, during warm up, about 20 degrees celcius behind the engine temp, till the engine reaches 115 / 120 degrees celcius (Fully warmped up). The box requires a min temp of about 90 degrees celcius for max load, before that temp, high load is not recommend, so this means men should be carefull when you warm up your car, engine temp is not equal to the box temp, getting your engine up to 90 degrees is not sufficient for the gearbox.

Biggest problem for this AT is not the temp, it is the materials used for the clutchplates. Also for optimizing this box, real software adjustments are required. So far I have not found anybody outside BMW (Not ZF!) that has access to it and can adjust it.

In my gearbox, clutchplates 2-5 were completly gone. 1 and 6 in a pretty good state. This was after 150000km, while pushing the car most of the time.