M5 E34 3.8 1995 06 speed short diferential - The Unofficial BMW M5 Messageboard (m5board.com)

munhoz · 24th February 2002, 06:33

Is possible use diferential of m5 five speed in six speed car?

I think this diferential is more short, result 0 to 100 in lower times.

Alan Archer · 25th February 2002, 00:29

Yes you can....

I know a guy with a '93 3.8 (5speed)
who's basically done the oposite swap & put a 6speed
gearbox in HIS car....which is basically what you want
to do with the diff....

Yes the bottom ratios become closer...

No i've not bothered to calculate the new ratios (Mph/kmh/Rpm)

(though i did study 5/6th ratios with regards to top speed)

What i would say is that any gains in acceleration would be marginal against the clock...(and against your opponent !)
and would be negated by the additional need to change up more
frequently.

When i ran my car over the quarter mile last year
(with very accurate timing equipment )

I tried a few different tactics to get the best times...

Cutting to the chase when you get to the line you should be
approaching 100mph....you have two options (in a 5speed!)

1)grab 4th quick as you can just as you cross the line....

2)hold third and just hit the limiter PAST the line.....

Difference in time...a tenth of a second !!

All the good work is done off the line & in the gear changes...

That's why i haven't been worried about changing my cars ratios...

Regards,

Alan Archer

munhoz · 25th February 2002, 03:52

Tank you ...

I try intall this diferential.

Regards

Antonio

Mmm-Five · 25th February 2002, 14:31

Alan,

When doing quick 0-60, 0-100, 0-150 runs, how and when do you change gear?

Do you keep your foot to the floor and change at 6500rpm and change gear before the limiter cuts in - that's what I do on track.

Or,
Do you hit the limiter, lift off the gas and then change gear and plant the throttle?

Alan Archer · 25th February 2002, 16:14

You do neither !!!

In light of the fact that your car makes max power at 6900rpm

changing up at 6500 you're missing maximum power, hitting the rev limiter you're Halting acceleration....

Best compromise...(as our engines pull very well past 7000rpm)
is to change up JUST BEFORE the limiter...as close as possible,
ie:7100~7200rpm.

Not massive revs from the line (depending on traction..)

concerntrate on the revs not the speedo.....

and never attempt full speed gearchanges on a COLD GEARBOX.

Regards,

Alan.

Mmm-Five · 25th February 2002, 18:49

Sorry, couldn't remember where max HP was.

What I meant was exactly as you put it really, i.e. change up just after max hp but before rev limiter.

No full speed anything on anything cold, engine, gearbox, tyres, etc!

I agree on the revs for quick launches as well, I keep mine to between 3000 and 3500 for best traction - unless I just want to smoke someone behind me then 5000rpm works well!