Gearbox question. Getting the best out of the M44B19

[WSP_Dave]

I have just put in a lightened fly wheel with an M20B25 clutch and plate, which has made a huge difference. When removing the gearbox I couldn't help thinking that it all looked very similar (if not identical from a bell housing perspective) to the E8X and E9X gearboxes. If this is the case, and this is my question, could a six speed out of an E87 not be fitted? (the prop would need to be changed too) This would mean that the 4.44 diff could replace the 3.45 and the 0.8 final drive of 6th would combat the short fall. Has anyone done this?

 

[IainP]

Ooh there’s an Alex Salmond answer to that!
Yes, but No!

There are a few 6 speed conversions, I plan to do one to my own M44, needs a new crossmember and the prop shortened 100mm (or so I’m told, I’ve not measured myself yet). I think the linkage needs some work depending on which gearbox is used.

I’m not aware of anyone fitting the 4.4 diff to a 6 speed conversion. That’s quite a clever idea to drop the gearing, but 1st without an lsd might be ‘eventful’ in the wet.

 

[WSP_Dave]

I put a 4.1 diff, and an E87 120 prop and gearbox in a 116i, just cut and welded the linkage and rod. Worked great. I am right in thinking that the e87 bell housing is identical? And the gearbox spline?

 

[IainP]

Afik the 4and 6 cyl’s share the bellhousing pattern, there are 3 spline counts. Unfortunately neither of the 6 speed spline counts match the Z3. The Getrag I have is 22, not sure what the ZF count is, 26 I think, and a larger diameter.

 

[WSP_Dave]

Different clutch plate then? On realOEM this week. I’ll get it sorted.

 

[IainP]

Yes, it’ll depend on which ‘box you go for.
The Getrag are a lot cheaper than the ZF. Can’t remember what mine cost, but it was really cheap.
I think there’s a 228mm with the 22 spline fit, I was told there’s a 215 but I never found it. A quote to have one made was over £200
I didn’t search for a ZF fitment disc.
The flywheel I have is for a 6 cylinder, I couldn’t find an M20 ‘ wheel I was happy to use. It requires an e36 M3 clutch cover, same as 5/7 series, I have the part number somewhere.
The disc for that flywheel is 240mm, spring center for an smf, not available on its own unless you have one made. Borg and Beck 3 part kit is £116 though. I don’t have that yet, doing too many other things, if I buy it, I’ll start it and it’s one thing far too many at the moment.

 

[WSP_Dave]

Okay, Parts to do it. M20 Flywheel and Clutch ( 11221706573 and 21211223101 ), GS6 - 17BG Gearbox, E8x Clutch plate ( 21207567842 ) and a Z4 Prop ( 26117514471 ) - and of course a 4.44 diff. Have the diff other parts are ordered I'll keep you posted how it goes.

 

[Duncodin]

Okay, Parts to do it. M20 Flywheel and Clutch ( 11221706573 and 21211223101 ), GS6 - 17BG Gearbox, E8x Clutch plate ( 21207567842 ) and a Z4 Prop ( 26117514471 ) - and of course a 4.44 diff. Have the diff other parts are ordered I'll keep you posted how it goes.

What would happen if the original m44 diff was kept?

 

[WSP_Dave]

Better fuel economy in sixth, quieter cruising. Putting the 6 speed on with the 4.44 diff effectively provides a close ratio gearbox with a final drive that’s not to far of the original set up.

 

[IainP]

Okay, Parts to do it. M20 Flywheel and Clutch ( 11221706573 and 21211223101 ), GS6 - 17BG Gearbox, E8x Clutch plate ( 21207567842 ) and a Z4 Prop ( 26117514471 ) - and of course a 4.44 diff. Have the diff other parts are ordered I'll keep you posted how it goes.

Correct me if I’m wrong, I frequently am, but isn’t the M20 flywheel a single mass wheel?
All the E8x clutch discs are for dmf, dual mass flywheels, no center springs, unless it’s for a smf conversion, so no BMW part number.

I didn’t know the Z4 prop is shorter, that’s a good shout since I know where there’s one for £20.

 

[WSP_Dave]

Yes, Iain, you are right. The M20 is a single mass flywheel but we use non-sprung clutch plates with single mass flywheels all the time. The prop shaft has to be out of the 2.5 auto Z4.

 

[IainP]

Yes, Iain, you are right. The M20 is a single mass flywheel but we use non-sprung clutch plates with single mass flywheels all the time. The prop shaft has to be out of the 2.5 auto Z4.

Drifting, Javelin or MUK events
As usual, the local Z4 prop is a manual, I’ll search the bay.
Did the Z3 come with a 4.4 diff? I was considering the 6 speed just for the lower revs, I hadn’t thought of diff gearing.

 

[WSP_Dave]

MUK, The Z is for track days and driving. Got the 4.4 diff off eBay there are always some on there. Collected an e87 120i off my mate as it has the right gearbox and clutch plate.

Prop I think is BMW E85 Z4 2.5i – Automatic part number 7514471, one due today cost £50

Pardon our interruption...

 

[Duncodin]

Better fuel economy in sixth, quieter cruising. Putting the 6 speed on with the 4.44 diff effectively provides a close ratio gearbox with a final drive that’s not to far of the original set up.

So you're saying that the 6 speed box with 4.44 diff gives a 6th gear with the same 'legs' as the old 5th. The idea being you have closer ratios lower down but similar top gear.

I'd be more interested in longer legs. When driving my z3 on the mway I find myself reaching for another gear.

 

[WSP_Dave]

Then that’d be the same conversion without the diff.

 

[Duncodin]

Then that’d be the same conversion without the diff.

Where does the speedo get it's signal. Will it need recalibrating?

 

[WSP_Dave]

Not sure, I guess it’s the diff. Iain might know.

 

[Delk]

Where does the speedo get it's signal. Will it need recalibrating?

It gets its signal off a toothed wheel in the diff. Measures alxe rotational speed so changing the ratio doesnt change the speedo.