345 Diff - The Unofficial BMW M5 Messageboard (m5board.com)

apk1013 · 12th October 2004, 16:59

I hear great things about the diff, but does it really improve the times or just the buttometer???

Andrew

SC'dKellenersM5 · 12th October 2004, 17:06

it actually does both... members here on the board swear by it.

the butt o meter says that things are going a bit faster but times really are a bit quicker...

Are you looking for a dinan 3.45 because i have a completely unused diff that im swapping out for a koala motorsports quaiffe. It was installed on my car sometime in april but the car has not moved in nearly 10 months due to my supercharger install.

mr_bock · 12th October 2004, 17:21

I have the Dinan 3.45 gears and love 'em. Acceleration is very quick and some of the stress is taken off of the running gear. However we all know about the weak stock clutch. I do not track my car so I can't say if times are improved. My guess is that the times would not improve because you will most likely need to shift one more time in the run and that would cost you a bit.

Stop light to stop light, the 3.45 gears are the way to go!

SC'dKellenersM5 · 12th October 2004, 17:27

I think the diff is great for any situation but you bring a good point Mr Bock. The extra shift that might be required in the quarter might negate some of the gained speed.

If you are not timing the car you will certainly notice an improvement.

ELEVENS · 12th October 2004, 19:07

An extra shift might be likely under many conditions, such as on the street or certain autocross or roadrace courses, but I doubt that an extra shift would be needed in the 1/4 mile. With the factory gears, the car has just been shifted into 4th gear when you hit the traps. It's so close, I actually tried to make it through the traps in third gear. With my car's redline at 7450, I came within 50 yards or so of the finish line in 3rd before hitting the rev limiter. So I'd be surprised if the 3.45 would require yet another shift (into 5th). This is easily predicted (calculated) if someone with a 3.45 cares enough to run the numbers.

But the real question - that STILL remains unsubstantiated - is will the 3.45 gears actually improve 1/4 times? Many think that with the S62's torque curve, there would be no benefit. I just don't know.

MEnthusiast · 12th October 2004, 19:32

Doesnt the higher gearing create more power at the rear wheels? If so, why wouldn't it improve times (shifts excluded)?

SC'dKellenersM5 · 12th October 2004, 21:22

Thank you to all of those who saw that i had the dinan diff availible. I would like to say that currently it is spoken for. Thank you.

The diff creates a higher multiplication of torque to reach the ground...it really doesnt make any more power, it just forces the wheels to spin faster, as if there was more power.

Carbo · 12th October 2004, 23:53

What about going to a 3.64 ratio?

Has anyone done this? My shop says I might not be satisfied with the 3.45 and the 3.64 will give me even more (15% more revs. over the stock 3.15).

The Quaife sounds like the way to go with 40% LSD and fresh clutchs.

XrayMD · 13th October 2004, 04:13

I have a custom made 3.45 by Evosport with 30% static lockup and 2x dynamic lockup...I love it. Definitely woth the bucks.

Pete · 13th October 2004, 08:34

If I'm not mistaken hasnt the 3.64 pretty much been dismissed as a viable option for the M5. In the 3.45, first is pretty darn short , and with a 3.64 would be even worse? Kind of an unacceptable trade off in driveability? At least that's what I remember from the thread.