was looking up something to do with trikes yesterday, and thinking about car diffs that work best with car engines, obviously the 3.14 sierra diff is favourite, but bmw seem to have a lot of diffs with similar ratios

http://www.bokchoys.com/differential/GearRatios.htm

there's some 3.15 and 3.07 ratios is e36 and e46 3 series bmws, so would this make a good change (read, better available) to the sierra ones? or am i missing something about bec diffs?

[Edited on 10/2/11 by blakep82]

BMW diffs weigh more than most BEC kit cars.

Edit: because I'm retarded

[Edited on 10/2/11 by daviep]

how much do they weigh compared to a sierra diff though? i can't imagine they're THAT much heavier

They are heavier but better built and you can get a 3.15 with a proper LSD for £250ish. Caterham are now using them on all new cars.

was still thining along my F1 sidecar/trike idea, and it could be done as a trike, but would need 2 driven wheels at the back, and thought for a bike engine, those diffs have got to be better than the sierra ones

I have a 2.28:1 that'll be going in mine. Non lsd, from 330d, £150 from delivered from germany.

Weight is 40kg - heavier than Sierra by about 13 kg.

ATB

Simon

hmm, its quite a lot more, but i wouldn't say its enough to worry about it being tooooooo heavy. if it was literally twice the weight then yeah, but thats not bad i don't think. hmmm

The Jag unit I was gonna use was nearer 50.

Look at it this way, if I lose 2 stone (and I need to lose 4) I'll be quits on the diff weight increase.

Don't forget this is probably one of bmw's heavier diffs - I'm sure a 318 petrol would (probably) be similar weight to Sierra unit.

ATB

Simon

As above, bmw do what known as small/medium and large cased diff's.

I've a spare 3.15 medium case none lSD diff I can weigh for you over the weekend? Its the same as whats in my build except i've got the slippy version.