cosworth turbo touring lsd -help!

[fuzzy]

hi folks, ive got two limited slip diffs from a 325 sport and one from an e30 m3,one will be fitted to my cosworth powered touring that is producing around 330-340 bhp ,its a job ill be doing myself and im wondering how i work out what gear ratio they are and which one would be the best for acceleration rather than top end speed, ive still not got the car back from the garage that is fitting the engine but im expecting it anytime now. any help would be appreciated on the lsd front,thanks

[lentec]

I think if you markup then turn the input flange and count the number of turns it takes to rotate the output shaft 360deg that will give your ratio!
The one that has the most turns will be quicker accel but less top speed
The other will have slower accel but more topo speed

Corect me if im wrong im going from memmory

[Simon13]

well the sport diff will be 3.91, and the M3 is 3.15 or 3.25 one of the two.

They should have tags on the diff on the back plate, clean it with a wire brush and the ratio's will be stamped on them

The M3 one will give long long legs in each gear, but will be a bit slower acceleration wise, but will give u a wicked top speed

The sport diff will make it really rip in a straight line but u will top out at about 130-140mph. and the range in each gear will be alot shorter if u get me?!

Cos uve got over 300bhp i would put the M3 diff on as it's so powerful u don't need a diff with acceleration in mind.

just my opinion!

i expect with that power the LSD's won't last that long! but they are tough so let us know how it lasts!

What gearbox is it running? an E30 one?

[Andy335Touring]

It depends on your gear box ratios

[fuzzy]

its running with a borg warner t5 rwd gearbox from the sierra cosworth with a one off propshaft

[M3Compact]

its running with a borg warner t5 rwd gearbox from the sierra cosworth with a one off propshaft

The T5 runs a .84 5th gear iirc, MT75 is .8.

A 3.91 diff' should be fine imo, can't see a problem with it handling the torque either.

I use a Cosworth rear flange with an adaptor on my Compact prop' Fuzzy, (for various complicated reasons.)

When it came to fitting, the flange fouled the (E30) beam due to the tight clearance which I'd overlooked. The beam had to be removed and modified. (Major annoyance. )

[markybumpit]

hey fuzzy, ive got myself a m3 diff ratio 3.25.1. ive been reccommended this one as the sport ones it would be difficult to keep the power down and be very twitchy, where as the m3 one would be a lot more usable power. cheers mate keep me posted.

mark

[Toby_Unna]

well the sport diff will be 3.91

or 3.64 from an older sport

The T5 runs a .84 5th gear iirc, MT75 is .8.

A 3.91 diff' should be fine imo, can't see a problem with it handling the torque either.

well i don't think it will be fine unless i'm missing something

my 5th gear is 0.81 and my diff is 3.91
and even with just 220 bhp first gear is useless even for a full-on standing start. it will pull 2nd easily on tickover. so i essentially have only four useful gears which is a complete waste

picking up a 3.64 today, which will be an improvement i hope

[M3Compact]

well i don't think it will be fine unless i'm missing something

my 5th gear is 0.81 and my diff is 3.91
and even with just 220 bhp first gear is useless even for a full-on standing start. it will pull 2nd easily on tickover. so i essentially have only four useful gears which is a complete waste

Depends what you want it for, the T5 has 'proper' gear ratios. (2.95 first, 1.94 second)

325i boxes have a 3.83 first gear and the 'Sport' boxes have a 3.35 first gear.

The 2WD Cossies used a 3.65 diff with 15" wheels as standard, so his 3.9 would be better than his 3.15 or 3.25 imo.

[fuzzy]

well if i wasnt confused before i certainly am now!!! i think the majority favours the sports 3.91 lsd ,so ill try that one first and see how it works out, thanks for the help folks,all i need now is the garage to get their fingers out and actually finish fitting the engine and im ready to get stuck in!!!!!