The semi-Comprehensive M60b40 into E30 swap Q&A

[Jean]

So you are saying 4.10 is not going to work eh? j/k

[The Dark Side of Will]

Lol... It'll *work* and make a quick car...

...that turns 3500 RPM at 60 and is RPM limited at 120 :p

I'm in touch with a guy who swapped out the stock 3.15 final in his E39 M5 for a 2.65. He said the S62 easily pulls the resulting 2.2 overall gear on the highway in a 4000 lbs E39.

[Jonsku]

Do M60B30's and M60B40's use the same cylinder heads?

Heads are different (valves are different size) but the camshafts are the same.

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

ETK says; 6-speeder 46kg / 101lbs and 5-speeder 36kg / 80lbs. Short-engine M60 154kg / 340lbs

source: www.bmwfans.info

[Jean]

Yeah, we've also seen the weights posted but that raises questions. So, instead I just weight the things myself, and another member put the 5speed on the scales as well! Our scales might be +/- a few lb's, but at least another valid source.

[Jonsku]

Yeah, we've also seen the weights posted but that raises questions. So, instead I just weight the things myself, and another member put the 5speed on the scales as well! Our scales might be +/- a few lb's, but at least another valid source.

Yap it's very good to get the weights verified!

[Garageaholic]

thank you, thank you!

so in laymans terms (if i'm understanding correctly):

5spd:
240mm flywheel only
any e36/e39 b28 clutch kit

6spd:
240mm or 265mm flywheel
respective V8 clutch kit only

So talking e34 6spd lightweight flywheel option only...

....does that mean that with with a choice between ltw jbr 240mm or 265mm flywheel (mounted to m60 e34), I HAVE to use the 265mm clutch kit to properly mate to the bigger input splines of the 6spd tranny? I think I understand this, but I think im still confused......

1. So that means that if I go with the smaller 240mm flywheel, I must still use the larger 265mm clutch disc. What happens to that extra 7.5mm "overhang" of the clutch disc on the flywheel on the edges???

2. If deciding to go 265mm all around to simulate a stock setup, then I see a problem with ride comfort by the lack of clutch springs in the stock e34 6spd clutch kit. Obviously, the dual mass setup accommodated for this originally, which is why it was not necessary to have springs in the clutch disc itself. Is this true?

[The Dark Side of Will]

The hub springs or corresponding function performed by the dual mass flywheel is only to quiet gear rattle in the transmission. It has nothing to do with being easy to drive.

[bmwmech1]

So talking e34 6spd lightweight flywheel option only...

....does that mean that with with a choice between ltw jbr 240mm or 265mm flywheel (mounted to m60 e34), I HAVE to use the 265mm clutch kit to properly mate to the bigger input splines of the 6spd tranny? I think I understand this, but I think im still confused......

1. So that means that if I go with the smaller 240mm flywheel, I must still use the larger 265mm clutch disc. What happens to that extra 7.5mm "overhang" of the clutch disc on the flywheel on the edges???

2. If deciding to go 265mm all around to simulate a stock setup, then I see a problem with ride comfort by the lack of clutch springs in the stock e34 6spd clutch kit. Obviously, the dual mass setup accommodated for this originally, which is why it was not necessary to have springs in the clutch disc itself. Is this true?

There are actually 3 clutch/flywheel options you have with the 6 speed.
1. E34 size flywheel and clutch, which is 265mm friction disc and flywheel, either OEM or lightweight
2 E39 size flywheel and clutch, which is 240mm friction disc and flywheel, either OEM or lightweight
3. E31 850CSI flywheel and clutch, which is 280mm friction disc and flywheel,
JB racing complete setup.

Obviously, the larger friction surface setups are better, in the sense of the larger area of the disc, but the 240mm setup is used in the E39 540, M5 and Z8, so it's not a "bad" choice. I have an E31 whole setup I pulled from a customers car, for sale. The friction disc needs replaced and the PP and flywheel surfaces need re-surfaced, but I'm selling the whole setup for $500. It's the aluminum flywheel, PP, disc, slave and throwout bearing. New, it goes for $2500 for the whole setup, so it's a pretty good price. I can't use it on my 5 speed setup, or I'd keep it. If it doesn't sell, I'll put it in my E34 540 6 speed.
Hope that helps out your "confusion" a little. If you're interested in the setup I have, or have any more questions, just PM me...

Garey

[The Dark Side of Will]

Obviously, the larger friction surface setups are better, in the sense of the larger area of the disc,

The larger diameter disk slows down shifting.
The synchronizers create the torque that accelerates or slows the input and counter shafts so that the transmission can go into gear. The clutch disk is obviously splined to the input shaft. Because of its diameter, the disk accounts for the vast majority of the moment of inertia of the transmission. A larger diameter disk is more difficult to accelerate or slow down by a factor of the radius squared relative to a smaller disk. This means it takes the synchros longer to match shaft speeds in the transmission and shift times are increased.

[bmwmech1]

The larger diameter disk slows down shifting.
The synchronizers create the torque that accelerates or slows the input and counter shafts so that the transmission can go into gear. The clutch disk is obviously splined to the input shaft. Because of its diameter, the disk accounts for the vast majority of the moment of inertia of the transmission. A larger diameter disk is more difficult to accelerate or slow down by a factor of the radius squared relative to a smaller disk. This means it takes the synchros longer to match shaft speeds in the transmission and shift times are increased.

That may be true in a very purist sense of crunching numbers, but we are talking about an increase of friction surface area vs. a 15mm increase in diameter. Some may feel that an imperceptible, nano-second slower shift is far less important than having the largest friction surface area available, especially in higher horsepower applications. This is debatable and subjective to the individual...;)

Garey

[Garageaholic]

thanks for the explanation! but I thought you can't use the e39 clutch which is 240mm because the 6spd input splines don't match up, hence you are pigeon -held into HAVING to use the 265mm clutch kit from e34 6spd. if I can use the 240mm clutch kit, then I might opt to do that.

[The Dark Side of Will]

That may be true in a very purist sense of crunching numbers, but we are talking about an increase of friction surface area vs. a 15mm increase in diameter. Some may feel that an imperceptible, nano-second slower shift is far less important than having the largest friction surface area available, especially in higher horsepower applications. This is debatable and subjective to the individual...;)

Garey

Both the torque capacity and the moment of inertia are proportional to the square of the outside radius/diameter.
Guys who went from 9 1/8 to 9 11/16 clutches (similar diameters to the BMW 240mm) in Fieros, for example, notice significant increase in shift times.

My recommendation is always to use the smallest diameter disk that results in pedal load and chatter that is acceptable for the application, understanding that smaller disk diameter, higher clamp loads and more aggressive friction materials all go together...

[bmwmech1]

thanks for the explanation! but I thought you can't use the e39 clutch which is 240mm because the 6spd input splines don't match up, hence you are pigeon -held into HAVING to use the 265mm clutch kit from e34 6spd. if I can use the 240mm clutch kit, then I might opt to do that.

The six speed transmissions in the E34 and E39 are the same input spline count and diameter, it's the 5 speed trans from the E34 530i that uses a different spline count and diameter. The 6 speed in the E39 uses the same friction surface diameter flywheel as the E34 5 speed, but the disc/PP setup is different to match the 6 speed's different input spline count/diameter. The diameter of the friction surface doesn't necessarily dictate just 1 clutch setup. There are several, across different body designations that are the same diameter, but use different stack heights and input splines, so you have to match the clutch setup with the transmission. That's why I said there are 3 different setups you can choose from for the 6 speed. The 5 speed is the one that can only use the 1 size because of the input spline differences. There are no other size friction surface diameter clutch kits with the correct spline size for the 5 speed, only 240mm...

I actually just put clutches in an 01 540i 6 speed and an 06 650i 6 speed and although the transmissions/engines are different, the clutches are the same size, 240mm. They both use the same Self Adjusting Clutch setup, even though the motors are different and the transmissions are different. That's why there's been so much effort in finding alternative clutch/trans options for the earlier V8's... different models and even engines can yield the same clutch setups, so you have to be diligent in your research. The clutch I'll be using is not even originally offered as a V8 clutch, but the spline/diameter/stack height is correct for my application. Does it all make more sense now?

Garey

[BruceBe]

Hey man, I thought I'd jump in and clear up some of your confusion... THE main difference between the 2 transmissions, besides the extra gear is the input shaft diameter and number of splines. The 6 speed was used in the E34 and E39 so either flywheel will work for the 6 speed, you just need the proper 6 speed clutch kit diameter for the flywheel you are using. The 5 speed proper clutch kit, with the correct shaft diameter and spline count only comes in a 240mm diameter friction disc, which negates being able to use the E34 6 speed flywheel which uses a 265mm diameter friction disc. You can use an E34 5 speed flywheel from an M60B30 or an E39 540i flywheel from an M62B44, which both utilize the 240mm friction disc diameter. Clutch kit for the 5 speed should be sourced as a E36 328i or E39 528i clutch setup, in whatever stage of performance you choose. Plenty of options out there. As far as lightweight flywheels go, either size can be used for the 6 speed, only the 240mm diameter unit for the 5 speed. The E34, 265mm clutch/flywheel setup will only work for the 6 speed. Bruce has a pretty comprehensive breakdown on what fits and what doesn't, we'll see if he chimes in.

Hope this helps...

Garey

So on the 5-speed, from another thread on the subject, here is what we came up with, and it *works*:

"Basically, there are three models of BMW that used this clutch kit - e36 328i (all body styles), E39 528i Sedan, and Z3 2.8 Roadster. The OEM clutch kit is part #21211223602, but again, we used the Clutchmasters upgrade for the application. Given the torque differences between the 2.8L six, and 4.0L V8, I would be very hesitant to use a stock clutch kit. We chose a lightweight flywheel, but it is dimensionally identical to a stock flywheel, so the stocker should work (just don't drop it on your foot)."

Flywheel is e39 540i. We used a JB Racing unit.

So now, when you do a search on "5-speed clutch", there will be yet another hit :-)

-Bruce

[bmwmech1]

So on the 5-speed, from another thread on the subject, here is what we came up with, and it *works*:
So now, when you do a search on "5-speed clutch", there will be yet another hit :-)

-Bruce

I will give all of the technical R&D credit to Bruce on this topic. He and I conversed about this around this time last year, as he was also searching for a 5 speed clutch/flywheel alternative. He did all of the legwork in finding what pieces did and didn't work together and from this, I gleaned all of my knowledge on the subject... Thanks Bruce:D

Garey