LSD stock vs 3.45 vs 3.62 for DCT

[M3 996]

Originally Posted by Sticky

If you just clicked the link 3 posts above you, you would have all the information you need.

My bad!

[doba_s]

Originally Posted by JMD0977

Just so you guys know, my 3.62 is running perfectly and shifts in D mode perfectly as well. Im in Cali right now testing my car.

This is very important though, BMW made 2 different diff covers for the M3. One for the Mt(bigger) and one for the DCT(smaller). Why? , I dont know. BMW has 2 different part numbers for the diff cover DCT and MT. I had a problem where the stock DCT diff cover did not work with the 3.62 and I needed a MT diff cover to go on my diff cuz the DCT cover was to small. I dont have enough time to explain but you guys get the idea. Nobody knows this since they had never tested the DCT 3.62.
I'll post the full details later. Worst case, you'll need to order a MT diff cover from BMW ($430).

Originally Posted by Sticky

If you could PM me the details I would appreciate it as my car is going under the knife as we speak.

I would also like to hear your impressions, the car should feel really "alive" now.

+1 ...

PM me details as well please, I would appreciate it

[bigjae1976]

Originally Posted by JMD0977

Just so you guys know, my 3.62 is running perfectly and shifts in D mode perfectly as well. Im in Cali right now testing my car.

This is very important though, BMW made 2 different diff covers for the M3. One for the Mt(bigger) and one for the DCT(smaller). Why? , I dont know. BMW has 2 different part numbers for the diff cover DCT and MT. I had a problem where the stock DCT diff cover did not work with the 3.62 and I needed a MT diff cover to go on my diff cuz the DCT cover was to small. I dont have enough time to explain but you guys get the idea. Nobody knows this since they had never tested the DCT 3.62.
I'll post the full details later. Worst case, you'll need to order a MT diff cover from BMW ($430).

Please post. I was thinking about getting a used MT diff and swapping it into the DCT car that I will be order soon.

Still, $430 isn't bad compared to $2.5k for the Dinan unit.

[doba_s]

Originally Posted by bigjae1976

Please post. I was thinking about getting a used MT diff and swapping it into the DCT car that I will be order soon.

Still, $430 isn't bad compared to $2.5k for the Dinan unit.

430 i think it is just the diff cover ...

[doba_s]

FYI - If anybody wants to get Dinan 3.45, or 3.62, or 4.10 you can pm me and I can try to help you to get a better price. Also they are offering 15% rebate right now so this way you will save even more.

[Driver72]

What's the expected gas mileage of an e9x M3 with the 3.62 gears?
In a poll I did seems most are getting 14-15 mpg on average driving, and with a bit of aggressive driving it drops to under 14 (some as low as 10-11)

So with 3.62 gears, is it expected to drop about 2 mpg overall?

[e46e92love]

Originally Posted by Sticky

Well, how would you put the gears in without the car first?

You just love being a dick, and an ignorant one at that. I am one of the original board members who would have been one of the first to own her but after my experiences being on of the first e92 335is on the road and my HPFP failure I decided not to be a first year model guinea pig again, and rather wait to see not only how the M3 worked out its kinks but how the M-DCT would play out as that was the transmission I wanted all along.

I live where snow and ice are, so mine is being delivered in the spring after my wedding, seeing how breaking in this car in freezing temperatures, ice and snow didn't seem like the best way to do it. Thus I want my mods bought before hand to be put on the car when it arrives. I don't criticize you, tell you what you do is no good. All I do is give my opinion of what I would want. Hence the NO THANKS. But you obviously are insecure and need everyone to agree with what you do and and what you want. I feel sorry for you.....

I apologize to the rest of the readers for my OT post.

Cheers,
e46e92

[Sticky]

Originally Posted by e46e92love

You just love being a dick, and an ignorant one at that. I am one of the original board members who would have been one of the first to own her but after my experiences being on of the first e92 335is on the road and my HPFP failure I decided not to be a first year model guinea pig again, and rather wait to see not only how the M3 worked out its kinks but how the M-DCT would play out as that was the transmission I wanted all along.

I live where snow and ice are, so mine is being delivered in the spring after my wedding, seeing how breaking in this car in freezing temperatures, ice and snow didn't seem like the best way to do it. Thus I want my mods bought before hand to be put on the car when it arrives. I don't criticize you, tell you what you do is no good. All I do is give my opinion of what I would want. Hence the NO THANKS. But you obviously are insecure and need everyone to agree with what you do and and what you want. I feel sorry for you.....

I apologize to the rest of the readers for my OT post.

Cheers,
e46e92

I asked you a question, why did you take it negatively?

So you wouldn't get them for what reason? How is this criticism? Am I not allowed to ask questions?

Seems to me you are insecure as you take a legitimate question as an attack.

[doba_s]

Originally Posted by M3 996

Anyone know what 80 mph "cruising" RPM would look like with the 3.62? Currently, a 80 mph clip happens ~3000 RPM.

With the stock diff the RPMs cruising at 80mph are around 3200-3300, not 3000. With 3.62 diff it is around ~3550rpm

[mixja]

Here's a comparison of the DCT with 3.62 vs C63...

Acceleration at the wheels vs Speed (km/h)...

Data is based upon dyno tests and weights published at www.rri.se - does not take into account aerodynamic drag...



As you can see the C63 only has a small advantage between 60-85km/h in 2nd gear and ~135-142km/h in 3rd gear, otherwise the DCT 3.62 is ahead. The DCT will pull well in front from a rolling start and the C63 won't be able to catch up....

Now look at the stock M3 DCT diff vs C63:



Here the C63 has a big advantage in 1st, 2nd and a lot of third gear - basically the C63 will get a large lead over the M3 DCT from 0-130km/h, after which the M3 DCT will claw back a little but not enough...

[doba_s]

Good info mixja ... Thank you for posting it !

As soon as I'll get my car back, i'll go and try to drive both c63 and mine to see what it feels like !

[Kev]

Originally Posted by mixja

Here's a comparison of the DCT with 3.62 vs C63...

Acceleration at the wheels vs Speed (km/h)...

Data is based upon dyno tests and weights published at www.rri.se - does not take into account aerodynamic drag...



As you can see the C63 only has a small advantage between 60-85km/h in 2nd gear and ~135-142km/h in 3rd gear, otherwise the DCT 3.62 is ahead. The DCT will pull well in front from a rolling start and the C63 won't be able to catch up....

Now look at the stock M3 DCT diff vs C63:



Here the C63 has a big advantage in 1st, 2nd and a lot of third gear - basically the C63 will get a large lead over the M3 DCT from 0-130km/h, after which the M3 DCT will claw back a little but not enough...

What happened to gear 6 and 7 on the C63?

[mixja]

Originally Posted by Kev

What happened to gear 6 and 7 on the C63?

Not much point in showing them on the graph, gear 5 finishes close to 300km/h....

[Kev]

Originally Posted by mixja

Not much point in showing them on the graph, gear 5 finishes close to 300km/h....

I see, so they still haven't fixed those two useless O/D gear on the 7G-Tronic. If they had a close gearing ratio instead of two useless O/D 6th and 7th gear, the C63 would be more beasty.

[mixja]

See later post...

[mixja]

Based upon Pencilgeek's data from this post (http://www.m3post.com/forums/showthread.php?t=180765), here's a comparison of MT stock vs MT 4.10 vs DCT stock vs DCT 3.45 vs DCT 3.62.

I think this shows that the higher diffs get most advantage at low speeds, at higher speeds the differences are not significant. This is illustrated if you compare 20km/h-250km/h vs 50km/h-250km/h.

Note that the start gear is based upon whatever the best gear available is for each different diff - e.g. for a start at 100km/h, the MT 3.85 will start in 2nd gear whereas the DCT 3.62 will start in 3rd gear...

Examples (using stock MT as baseline):

20-100km/h (rolling start in 1st gear)
MT 4.100: +3.9%
DCT 3.154: -1.1%
DCT 3.450: +4.5%
DCT 3.620: +6.6%

20-160km/h (rolling start in 1st gear)
MT 4.100: +2.6%
DCT 3.154: =0.0%
DCT 3.450: +3.9%
DCT 3.620: +6.0%

20-200km/h (rolling start in 1st gear)
MT 4.100: +2.5%
DCT 3.154: +0.6%
DCT 3.450: +4.1%
DCT 3.620: +5.9%

20-250km/h (rolling start in 1st gear)
MT 4.100: +2.2%
DCT 3.154: +0.6%
DCT 3.450: +3.6%
DCT 3.620: +5.2%

50-250km/h (rolling start in 1st gear)
MT 4.100: +0.5%
DCT 3.154: +2.0%
DCT 3.450: +2.7%
DCT 3.620: +2.9%

100-250km/h
MT 4.100: -0.1%
DCT 3.154: +2.7%
DCT 3.450: +2.5%
DCT 3.620: +3.3%

150-250km/h
MT 4.100: -0.1%
DCT 3.154: +0.8%
DCT 3.450: +2.1%
DCT 3.620: +2.0%

I'm interested as to what effect drag has on the numbers - I'm guessing they'll favour the higher diffs as the gains at higher speeds that the lower diffs seem to get will be reduced...

[Sticky]

If someone is interested in 3.62 gears and a diff CHEAP: http://www.m3post.com/forums/showthr...50#post4376050

[Adonislike]

Originally Posted by Sticky

Well, how would you put the gears in without the car first?

Look whos back!! Welcome back Sticky

[Sticky]

Originally Posted by Adonislike

Look whos back!! Welcome back Sticky

Thanks.

[nfreyre]

Hi Sticky

Do you still recomends 3.62 now that you test it or gi whit something different

[Sticky]

Originally Posted by nfreyre

Hi Sticky

Do you still recomends 3.62 now that you test it or gi whit something different

It just depends on application and what the person wants.

For people who want torque down low, 3.62's give that sensation.

[doba_s]

Originally Posted by Sticky

It just depends on application and what the person wants.

For people who want torque down low, 3.62's give that sensation.

so, what are you planing to put in your car ?