The semi-Comprehensive M60b40 into E30 swap Q&A

[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]

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]

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.

[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?

[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!

[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]

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

[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.

[Jean]

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

[The Dark Side of Will]

A 4.0-and even more a 4.4-when used with the non-overdrive ZF 5 speed could easily pull 2.56 or taller rear gear in a body as light as the E30. BMW makes them down to 2.35 for European diesel cars.
2.79 is the tallest that's easy to put in an E30 in the US, so we'll roll with that for an example. With the 4.20 first in the ZF and 2.79 rear, the overall ratio in first would be 11.7, which is quite aggressive. A V8 would be able to break tires loose at will in a RWD E30 with that first gear... especially if used with a lightweight flywheel and clutch.

[mkcman17]

i think by 'really tall' he's still referring to longer than 2.79 still.

[sticksdaman]

what's the point? i think most of us e30 guys have grown accustomed to cruising 4k at 80mph.

Speak for yourself!

I had a 3.73 mated to a zf320 in my e30 and I HATED it on the highway. My work commute is a 50/50 mix of highway and city driving so it gets old REALLY fast. I can definitely appreciate a lower revving more "refined" highway commute.

[mkcman17]

With the 5 speed, you'll need a very tall rear end ratio to keep the RPM down on the highway.

what's the point? i think most of us e30 guys have grown accustomed to cruising 4k at 80mph.

[jevijavi]

nope not really..i was thinking of using 3.15 from an e36 m3. what could be my topspeed if i used a 5 speed with this diff using the v8 setup?

[The Dark Side of Will]

Ahh... Ok, you got a complete pullout.

I was thinking "kit" meant mounts, wiring, right selection of hoses, etc.

Top gear in the 5 speed is 1:1, while top gear in the 6 speed is 0.83:1. They both have approximately the same 4.20:1 first gear.

With the 5 speed, you'll need a very tall rear end ratio to keep the RPM down on the highway.

Of course I expect you wouldn't log a lot of highway miles in DomRep.