surely 90% of the likelyhood of diffs breaking would be via dropping the clutch at high rpm and smashing through the gears?

Like the stock clutch being good if its not dragged surely the stock line can easily cope with 500-600bhp "IF" its not abused in drag conditions for example with 5k drops?

Sorry, couldn't resist any longer.

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If at first you don't suck seed, try drier grain.

I agree that it's normally clutch dumpings that cause the highest stress on the drivetrain. The only bigger stress would be axle tramp.

From what I've gathered, it's good practice to engage the clutch slightly while sat on the line to pre-load all the gears so backlash is taken up. This removes the 'impact' part of the stress when the clutch does finally come up.

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If at first you don't suck seed, try drier grain.

I am certainly hoping the standard 'box will cope with 500bhp on track. A rolling start would ease the strain on the transmission but as my car won't be doing NASCAR that rules that option out! I agree with Chris that if you take up the lash in the transmission on the grid then the shock loading on the transmission components should be significantly reduced. Using a plate type rear diff should help as the Torsen isn't really suited to circuit racing. According to Adrian the right/left torque split on the Torsen exhibits unpredictable behaviour on track. The plate diff fixes that.

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Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp