The semi-Comprehensive M60b40 into E30 swap Q&A

[mkcman17]

i hate all of you. i searched for a 6spd forever just to be slowly turned against it. fu guys!

[Jean]

lol...but having 6th gear is still pretty pimp on it's own accord.

[Mr Two]

The lowest gear ratio possible (2.73) puts you at 164mph@6500rpm in 5th. If you were interested in a higher top speed you'd need to go with the 6

http://www.fatboyraceworks.com/gears/index.php?MaxRPM=6500&TireDiameter=23.07&GearRatio1=4.32&GearRatio2=2.54&GearRatio3=1.62&GearRatio4=1.23&GearRatio5=1&GearRatio6=.83&FinalDrive=3.25&TireWidth=205&TireAspect=50&RimDiameter=15&MaxRPM_2=6500&TireDiameter_2=23.07&GearRatio1_2=4.32&GearRatio2_2=2.54&GearRatio3_2=1.62&GearRatio4_2=1.23&GearRatio5_2=1&GearRatio6_2=&FinalDrive_2=3.25&TireWidth_2=205&TireAspect_2=50&RimDiameter_2=15&Calculate=Calculate%2FGraph&Compare=1

You can run a 3.25 with the 6 speed trans and still retain the same top speed you'd get with the 5 speed with a 2.73.

The difference in acceleration between a 3.25 rear and a 2.73 would be fairly large, I'd imagine.

Look at this video - the yellow cars are both stock, the red car has intake, exhaust, and 4.30 gears. Stock is 4.10. It has an intake and exhaust as well, but these mods don't really do anything power wise for an s2k. Check out the difference in acceleration. http://youtu.be/NtdOU-yyZ_w?t=2m42s

e: though granted, the S2000 has a much more narrow powerband

[The Dark Side of Will]

There are lower ratios... down to 2.35, but you have to go to Europe for them.

The V8 can pull a very tall top gear. With the 6 speed and a 2.73, you can have extremely relaxed cruising, while maintaining the same acceleration as the 5 speed. IOW, in order to have the same relaxed cruise, a 5 speed would have to have 2.21 rear, which would cost acceleration significantly.

Even with a 2.73 rear, the 4.23 first gear of the 6 speed will give you an 11.5 overall first. That's a pretty aggressive gear for that much power in a package as light in the rear as an E30.

[mkcman17]

i really have no intentions of hitting anything resembling 164mph anytime in the near or distant future.

[Mr Two]

I don't think first gear would be useful with this swap, no matter what ratio diff you plop in there. ;)


First gear never really comes into play on a track anyway

e: destroying tires counts as awesome, not useful

[Jean]

Well, look at what diff is used on e34 540i cars for example...something like 3.15? is very popular upgrade. I don't think there is any reason to go with some stupid rare/tall gear.... guys with turbo m50/s50 cars still use 3.25 and shorter unless you are trying to go for something with super low cruising rpm?

I plan on giving something like 3.25 a shot...I tried that diff before and it was too long for m30b35 with g260/6, but it may just work with m60 with 5speed.

Will just have to try it and see how it works out.

[Wh33lhop]

Well, look at what diff is used on e34 540i cars for example...something like 3.15? is very popular upgrade. I don't think there is any reason to go with some stupid rare/tall gear.... guys with turbo m50/s50 cars still use 3.25 and shorter unless you are trying to go for something with super low cruising rpm?

I plan on giving something like 3.25 a shot...I tried that diff before and it was too long for m30b35 with g260/6, but it may just work with m60 with 5speed.

Will just have to try it and see how it works out.

3.25 with the direct drive 5 speed will be quite a bit shorter than 3.46 with the OD 260/6. I probably wouldn't go that short.

IIRC the stock 540i6 rear end is like a 2.82. They sit at ~2200rpm at 80.

[bmwmech1]

Anybody with the 5speed on hand that can weight it? The 6speed is 110lbs dry.

Just weighed the 5 speed... 82 lbs wet. Almost 30lbs lighter than the 6 speed. I would have guessed a little lighter, but the scale don't lie, lol!

Garey

[JGood]

Just weighed the 5 speed... 82 lbs wet. Almost 30lbs lighter than the 6 speed. I would have guessed a little lighter, but the scale don't lie, lol!

Garey

Wonder what the gas mileage difference would be with the extra overdrive gear, given that all other things remain unchanged. It would have to be 3-4 mpg to be worth the extra associated cost / labor, IMO. And I don't see that happening...

[Jean]

Just weighed the 5 speed... 82 lbs wet. Almost 30lbs lighter than the 6 speed. I would have guessed a little lighter, but the scale don't lie, lol!

Garey

Thank you! Mine was 110lbs dry, yeah I'll stick with 5speed plus it's smaller in terms of fitting it in the e30.

[Mr Two]

Where are you guys sourcing your 5 speeds?

[bmwmech1]

Where are you guys sourcing your 5 speeds?

I bought a 94 530i, running, but no title car from Virginia to get mine. Cheap and I was able to verify the transmission's condition before I parted out the rest of the car that I didn't need. Made 3 times what I paid for the car, selling off the parts and got the stuff I needed for free... this is a good way to get stuff, if you have the time and space to make it work. Since I own a shop, it's doable... I realize that it doesn't work for everyone though...

Garey

[The Dark Side of Will]

I looked on www.car-parts.com and found one with 78K miles for $250 within driving distance... Application is '94-'95 530i

[Jean]

You suck