Possible to fit a manual 6-speed transmission to an M42..?

[Frederic318is]

I was just thinking about this and asked myself if there are 6-speed transmissions who fit right onto the M42..?
I am aware that the ratio's would be different, but maybe in combination with the wright differential it is possible to remain the character off the M42.

I'm really curious if anyone has done this or taught it over..

I think it would be a great upgrade, especially if the character could remain in low gears and for the highway you could use 6th gear..

[wazzu70]

Yes, any 6spd mounted to an M5x/S5x will work as the bolt pattern is the same. The ratios are usually close to E36 ratios plus an additional overdrive 6th.

[benz-tech]

If only I had that in the budget.

[Beeker1972]

looked up real OEM it looks like a

Getrag S6S 420G out of an E46 M3, and a ZF GS6-37BZ from a 2004 and newer 3 liter BMW inline six equipped BMWs should fit  I think you'll need front half of the drive-shaft, and shift linkage from the cars where the transmissions came from.  I have seen the 6 speed manual transmissions for BMW M5x, S5x, and N5x on EBAY for under a grand ... The drive-shaft will most likely need to be rebuilt, and re-balanced.  While under the car I would try to find the larger 6 cylinder LSD to put in the back.  If it's done right you should have no issues putting a well built M42/M44 based engine in the car.  I wonder what's the HP/Torque limits of a M42/M44 based build?  325hp?  That's what Metric Mechanic has advertised on their website. 

[romkasponka]

As I know the easiest way is to fit E36 M3 6spd gearbox (expensive). For this you will need to shorten driveshaft.

E46 and newer 2,0tdi 6spd gearbox (cheap and easy to find in Europe) have different splines and pilot bearing is fixed in flywheel instead of crankshaft. In this case you will need adapater for pilot bearing relocation closer to gearbox and custom clutch disc and probably shorter driveshaft.

[wazzu70]

Its always fun to figure out what you could do if you actually had the money I know I do this daily!!

If the 6spd is going in an E30 you will probably need a custom length driveshaft as the front section will be a unique length. If this is going in an E36 the 6spd driveshaft will fit right up.

The E30 has the 4cyl moved forward in the engine bay unfortunately. The E36 has the M42 and M50 aligned at the rear plane of the engine making trans back parts a direct swap.

[Beeker1972]

You can always use a M20 based Getrag 260 it has the same overdrive ratio as the six speeds.

[wazzu70]

But its lacking the other gear....

[Beeker1972]

Other than the oo aah factor of having a 6 six speed manual in an E30 what would an extra gear do.  Are you tracking, or auto crossing the car?

[Beeker1972]

If you have an E30 318i/is it has an wide ratio 5 speed made by Getrag if it an manual.  If you have a E36 318i/is made before 1995 it's a close ratio 5 speed made by Getrag. I have uploaded a pdf on 6 speeds ...  I also cut and pasted manual transmission ratios

getrag 260
1st 3.83:1
2nd 2.20:1
3rd 1.40:1
4th 1.00:1
5th 0.81:1
R 3.71:1

Getrag 250
1st 4.23:1
2nd 2.52:1
3rd 1.66:1
4th 1.22:1
5th 1.0:1

getrag 240
1st 3.72:1
2nd 2.02:1
3rd 1.32:1
4th 1.00:1
5th 0.81:1
R 4.10:1

ZF 320/310
1st 4.2:1
2nd 2.49:1
3rd 1.67:1
4th 1.24:1
5th 1.0:1
R 3.9:1

[benz-tech]

I'm hoping my g250 and a 2.93 rear end will make mine more lively in between shifts. I know it's tall but I love around 2600rpm @60mph on the freeway. Overall taller first gear might be interesting with a LTW flywheel. We'll see how it goes.

[wazzu70]

Other than the oo aah factor of having a 6 six speed manual in an E30 what would an extra gear do.  Are you tracking, or auto crossing the car?

5 normal gears and a heavier overdrive for cruising...

The E30 and E36 have significantly different rear end ratios. I have an E36 ZF trans in my E30 with a steep rear gear ratio (3.73) which is equivalent to between a 4.27-4.44 with an E30 trans. Of course, I wasnt concerned with freeway cruise efficiency!!

[Beeker1972]

Putting a 2.93 to 1 rear end with a Getrag 250 would give you better highway speeds, and better MPG ...

I'm hoping my g250 and a 2.93 rear end will make mine more lively in between shifts. I know it's tall but I love around 2600rpm @60mph on the freeway. Overall taller first gear might be interesting with a LTW flywheel. We'll see how it goes.

[Beeker1972]

So you track the car?

Other than the oo aah factor of having a 6 six speed manual in an E30 what would an extra gear do.  Are you tracking, or auto crossing the car?

5 normal gears and a heavier overdrive for cruising...

The E30 and E36 have significantly different rear end ratios. I have an E36 ZF trans in my E30 with a steep rear gear ratio (3.73) which is equivalent to between a 4.27-4.44 with an E30 trans. Of course, I wasnt concerned with freeway cruise efficiency!!

[Beeker1972]

If you want a really stout manual transmission go find a 1982 e28 528e they had Getrag 265 manual transmissions with the removable bell housings made for the early ETA M20B27 engines.  They would fit any M20 based engines like M4x, and M5x.  You could also find a Getrag Dogleg 5 speed manual that had removable bell housings in the early E24 635csi, or first couple of years of the E30 M20B23 sport models.  I think they also came in the E12/E28 M535i cars, and E21 323i sport models.