6 speed box on a M20?

[knightmare]

is there one that could fit from a later model maybe?

[ross_jsy]

at a guess the 6 speed off an e36 m3 evo would work, but would sit 10 degree's out and need the rod bending. just a guess though.

[Simon13]

in a word no

[bss325i]

In a word why?

[e30topless]

something I looked into when building my current car,
I had a 2007 6 speed box from an e46 that mated up to the M20 block perfectly, the splines were different compared to the M20 clutch plate, but at a guess a bit of messing around it could be done ?

I couldn't be arsed to do the research and chances are the ratio's may have been wierd/ prop would need to suit, so I junked it !!

nothing wrong with 5 gears !

[knightmare]

something I looked into when building my current car,
I had a 2007 6 speed box from an e46 that mated up to the M20 block perfectly, the splines were different compared to the M20 clutch plate, but at a guess a bit of messing around it could be done ?

I couldn't be arsed to do the research and chances are the ratio's may have been wierd/ prop would need to suit, so I junked it !!

nothing wrong with 5 gears !

My car feels like it needs a 6th It feels like it pulls through 5th like it douse 3rd and 4th

[e30topless]

change the diff ratio ?

[knightmare]

change the diff ratio ?

lose the acceleration?

[Messenjah]

change the diff ratio ?

lose the acceleration?

no just move it.


f=ma a=f/m


you arent changing f or m so a remains the same it will change the way the car feels but the acceleration from standing fstart to terminal velocity will be the same

[harry_p]

but the motive force your car applies to the road via the wheels to get it's acceleration changes with gearing. a taller ratio, either by altering the gearbox gearing, or the diff gearing reduces the force at the wheels, which is why 6 speed gearboxes are pretty common these days, 1-5 for normal acceleration, an over tall 6th for cruising quiet and economy.

[jbh]

would be intresting to see if it could be done and at what cost..

also would the end results outweigh the final cost? im with the majority to change the diff for a better suited ratio but thats just me

[knightmare]

its got a 3.9 LSD on her at the moment whats the next LSD down?

[jbh]

3.64 as the tech1 sports have

[e30topless]

or a 3.73 ,but hard to find

[S38B38]

In a word why?

I agree .......

crazy cost

[knightmare]

£350 average for a LSD more to find the rare ones

£675 for gearbox clutch,flywheel and prop shaft deliverd
thats an E36 M3 6 speed manual and a few quid at a cheep engineering place i know

[pacerpete]

A 3.73 diff is the best plan. Spend the change on P40 and tiger seal !

[tomson]

S50 6 speed box will not mate with an M20 block without a custom bellhousing.
Then there is the issue of the S50 dual mass flywheel being so heavy it will make your M20 feel like its now got 100bhp, ok use the M20 fly...
Then there is the problem the E36 prop does not fit the E30, no problem you wont need it, custom prop all the way....

£675 is not such a good price now...

I'd look for a diff or a different 6 speed box !

[e21Jason]

S50 six speed box goes straight on the m20 with the m20 fly wheel and clutch it is the linkage and gearbox crossember that need modified

Jason

[town325i]

what happened to the m30 conversion you was planning?

[mrLEE30]

the fifth gear on a the 260 and 240 getrag is .81 which is an over drive

the sixth gear on a 6 sp M3 box is .83

thus fitting a six speed box would not improve cruising (in fact it would be worse by 1%)

all you would do is get a very low ratio 1st and a huge gap to second with a 6 speed box, which with the diff and power of a 325 would make 1st unusable, So the 6sp 2nd gear would effectively become a sluggish 1st on a G260 (2.5:1 vurses 3.7:1) then changing up to up to 5th gear which is a 1.1 ratio on 6sp, the same ratio as 4th on a G260

so fitting a six speed box is a complete and utter waste of time on a M20 as all it gives you is an ususable 1st, a sluggish 2nd and then a worse top end.

but by all means go ahead!

[325isporttech1]

I always think that the 325i needs a 6th gear, the revs seem far to high when cruising around at 80-90 would be nice to bang it down into 6th sometimes

[e301988325i]

My car feels like it needs a 6th It feels like it pulls through 5th like it douse 3rd and 4th[/quote]

If your car has sufficient power in 5th then changing the diff is your only answer, even the newest BMW's only have a 0.8ish:1 overdrive top gear.

By changing the Diff, the higher gears are affected more than the lower ones.

[Dave_M3]

Since my clutch was going as well as gearbox being on it's last legs, I put an E46 M3 box on my iS and it makes the car very entertaining on a backroad and quicker as well as more economical with a 3.91 diff than it would be if it just had the 3.91 or 4.1.
I wouldn't bother doing it in a 325 though considering you could just get a sport box and a 325i
at least on the iS all that's needed is to shorten the prop and gear-linkages rather than modifying them more for the 10 degree tilt of the M20

[325isporttech1]

much agreed on the sport 'box'

ive noticed huge difference since going from a sport to a normal 325i, a sport gearbox is much nicer but could still handle a 6th ger if there was a suitable of the shelf option

[Dave_M3]

There is no off the shelf box that will give you a good 6th gear though.

No matter what you do you'll also have to change your diff to a lower ratio to attain a cruising 6th as there isn't any BMW gearbox that has less than a .8:1 or similar top gear.

I have a 4.1 188 case LSD from a US M3 in my iS at the moment which makes the 6 speed box very entertaining on a back road or messy around with 2nd and 3rd gear in the wet however, I'm still looking forward to fitting a 3.91 diff which I'm gathering bits to do a total rebuild and to 40%

[bpowell555]

My front wheel drive french diesel turd is on 2.5k revs at 90mph. Nuff said

[Dave_M3]

Yea, but that's a diesel... Not to mention French!