Diffs.. What to do?

[spookypt]

Hi all, just looking for some suggestions.

After my 2nd Diff failure in 3 Nats events (diff, clutch, diff YAWN) its time for a serious change towards reliability. Having discussed at length with BDR USA it seems the race cars are putting out too much for the little beemer mid case diffs to handle. I understand BDR USA have had a failure recently also. I have 3 options currently, none of which are all that great.

First off, for those of you unaware my rear is essentially a BMW M3 E36 rear end, centre and cradle. All the pick up points are exactly as per BMW. All Backdrafts essentially run this set up. The perfect ratio for my car based on most of the tracks we run at is 4.27. I know this is short but due to such a tall first gear in the Jerico 4sp box anything longer and I fry clutches. Most will have witnessed how its hard to idle around the pits. In fact it doesn't idle full stop. The problem is the shorter ratio you go the weaker in effect they get and I have a pinion gear with no teeth left due to it's size for racing not being up to the task.

My options so far are....

1. Rebuild another mid case diff with 4.27 ratio and have another in the trailer for swapping every 3 meets. Crap idea I know.

2. Do a subframe conversion to accept the Ford 8.8 diff. There is a company in the USA called Vorshlag who make a retro fit kit . They put LS V8's into E36 BMW's. The problem with this conversion is new 1/2 shafts, drive shaft mods etc etc and you can only source 4.30 ratio's which is close enough I guess.

3. These guys Home Page do a conversion kit where they modify the cradle of the BMW mid case diff to suit the larger Beemer large case diff. These centres have a 210mm R&P and are set up to run into the 800HP range. Again, I'd need new 1/2 shafts etc etc but on the down side the larger diff centres used in the BMW 750il V8 and V12 BMW sedans don't come in a 4.27 ratio. Only the 4.10.

Its a bit of a chicken and the egg scenario. Some will say look at your GB selection too as that tall first gear is killing it. Currently at WP Park I wind through the gears 1st to 4th 3 times during one lap.

It all needs sorting out but I'm not sure what the best way to go is without almost ripping out and starting again from scratch!

Any thoughts, advice is appreciated.

Spookypt