550isport

Jet Black,
Do you know why it is that the Dinan diff can only be used with a manual trans? My 740i sport had an OEM higher stall speed torque converter and a higher rear ratio than a standard 7 and it was an automatic? Just curious since you have a connection at Dinan...

Thanks,
DRP

alpineweiss

Did you notice a change in the way each gear engages after a downshift? For example when off throttle, the blips for the downshift seem about 200 rpm short of perfect for my regular SMG (and I heard so too for M5)...I'm wondering if the lower diff ratio affects this.

wolverine

No changes whatsoever in the shifting. Except when you nail it, the shift points come up a lot quicker .

In normal driving, the diff is exactly the same as stock. Even the rpm increase is difficult to notice. For example, cruising at 70 mph in 7th gear, you're at 2900 rpm instead of 2700 - really impossible to tell the difference by ear. The only other significant difference is it won't automatically upshift at full throttle in D mode. That will be corrected with Dinan's upcoming chip, which should raise the rev limit, remove the speed limit, and supply some extra HP!

xexyus

I heard that with that differential plus the rest of the mods there was no significant increase in HP. I was reading a real good writeup on m5board of a guy with an M6 who had that differential and he had no significant gains. In the end I believe he said that his gearing was the problem but im not sure..

wolverine

The differential doesn't add any engine hp, but the performance increase is like adding an extra 40 HP. What the diff does is add 8% more torque to the rear wheels, in any gear, at any speed, so you're accellerating harder at all speeds. It's definitely the best bang for the buck modification you can do to this car (other than removing the charcoal filters). The guy you're talking about is having issues related to multiple modifications, and not getting the HP increase he expected. In no way is the differential hurting his hp measurements.

The top 2 M6 times on dragtimes.com are using the Dinan differential, 12.1 @ 120mph, and 12.3 @ 121 mph. Pretty good ET's for 2 second 60' times.

http://www.dragtimes.com/results.php?carmo...earch+DragTimes

Alex.br

Wolverine,

Will loss Vmax a delimited M5 with this diff comparing to OEM delimited one?

Thanks,

Alex

wolverine

Sorry Alex - I don't understand your question.

Mike

Alex.br

I was asking about the top speed in delimited cars (with Dinan and oem).

wolverine

OK, if you figure the stock M5 is geared for maximum top speed, that puts it at 204 mph at 7960 rpm, very close to the HP peak of 7750 rpm. With the Dinan, you would need to run almost 8600 rpm to hit 204. More likely you would be able to hit redline of 8250, which would give you a top speed of 196 mph. But, the Dinan 3.91 will get to 196 mph a lot quicker than the stock car!

Alex.br

Thnaks Mike. Now it is clear to me.