6 speed boxes

[HairyScreech]

this is probably more one for the bmw techs but anyone is free to pitch in.

need a little guidance on the newer 6 speed boxes and the specific fitment differences.

i assume the guts of all of the GS6-xxx transmissions are the same with only the ratios and the bell housings differing between each fitment in a similar manner to the getrag 240 series boxes being internally similar across the 6 and 4 pot versions.

now getting a bit more specific, which of the versions of the box can be interchanged, ie have the same bell housing?

any idea what the torque limit is on these? i assume as they are fitted to the later 3.2 evo engine and the 3l diesel engine that they can cope with quite a lot.

[Simon13]

i believe they are a 420 series? which is 420Nm is their rating. The 6 pot from an S50 belhousing means at a guess it would bolt on the back of an M20 but they are big

but weren't they used on the e34 m5? which would mean that would bolt onto an M30

Then the v8 e34 540i used it too? and the v12 850CSI so those 2 will have different bellhousing maybe aswell?

[DanThe]

S50 bell housing is pretty much the same as the iS and m40, different mounting angle to the M20. What is the box you are looking at from and what do you want to fit it to? I dont pay much attention to the codes TBH

[Andyboy]

i believe they are a 420 series? which is 420Nm is their rating. The 6 pot from an S50 belhousing means at a guess it would bolt on the back of an M20 but they are big

but weren't they used on the e34 m5?

Yep, Getrag 420G. Think he's on about later E46 or e90 shizzle, the GS6 on the 330i which I think is a ZF.

[HairyScreech]

posted this as i started looking really, its for mating up to a v8 via an adapter plate/flywheel for pauls v8 project, so pretty much the world is my oyster in terms of transmission selection but the best bet would be to stay with a bmw transmission for ease of application.

seems there are 2 types of 6 speed boxes used recently, the getrag 420G and the ZF SG6.

getrag 420G as you say si is used as follows.
http://en.wikipedia.org/wiki/Getrag_420G_transmission

pretty much m/s50, m60/62 v8s and 850 v12s. So as said 3 types of bell housing.

some time after this there is a zf version, looks to be fitted to the newer diesels and v8s and looks to be about the same size as the 260G boxes.
these are a hell of a lot more common and even the 320d version has to deal with 240lb/ft day to day.
they also seem to be cheep enough to go smashing up on a day to day basis. :winkeye:
http://www.ebay.co.uk/itm/Bmw-E46-320-D ... 500wt_1287

they have a further advantage as the overdrive 6th produces ratios similar to the 260G and prevents a diff change for anything with over a 3.5:1 diff.

[e301988325i]

they have a further advantage as the overdrive 6th produces ratios similar to the 260G and prevents a diff change for anything with over a 3.5:1 diff.

I posted up in another thread that the 6 speed boxes have a super wide range and are not that clever in terms of ratios. However blanking off first gives a very close (closer than the next best 5sp that fits) ratio 5 sp gearbox using gears 2-6, which as you state with the overdrive suits stock E30 diff ratios.

[HairyScreech]

aye, and by just ignoring 1st you get a psudo dog leg pattern, as you would be using 2nd as 1st it would be like having 1st as left and back with 2nd and 3rd on the middle and 4th and 5th on the right.
at least that would be the way it would work out for us with the jag/scimitar axle ratios, for an e30 it would be possible to down gear it and have the full benefit of the 6 speed by having the long overdrive gear for cruising.
from what i can see the 6 speeds are really a transmission aimed at higher powered engines where the larger spread of gears is required to be civil on the road.

[HairyScreech]

http://tis.spaghetticoder.org/s/view.pl?1/06/17/95

just found this, sheds a lot of light on the transmissions, the sg6 is not a zf designation after all.

[HairyScreech]

ok some more info, seems the designation is:
SG5/6 = 5 or 6 speed
37 = 37kg*m force/torque
B/D = petrol/diesel
G/Z = getrag/ZF origin.

so it sounds like the 320d box is good up to ~280lb/ft, although the suggestion is that due to the safty factor of the boxes there is room to go up to 1.7x the rating, which would make 426lb/ft possible on the 320d box.
the 330d box is a 53 box so thats 383lb/ft rating and 651lb/ft before it starts blowing, which explains why its behind some of the more potent bmw engines.

now bell housing patterns, are the 4 and 6 pot diesel bell housings the same as there petrol counterparts?

[bss325i]

ok some more info, seems the designation is:
SG5/6 = 5 or 6 speed
37 = 37kg*m force/torque
B/D = petrol/diesel
G/Z = getrag/ZF origin.

so it sounds like the 320d box is good up to ~280lb/ft, although the suggestion is that due to the safty factor of the boxes there is room to go up to 1.7x the rating, which would make 426lb/ft possible on the 320d box.
the 330d box is a 53 box so thats 383lb/ft rating and 651lb/ft before it starts blowing, which explains why its behind some of the more potent bmw engines.

now bell housing patterns, are the 4 and 6 pot diesel bell housings the same as there petrol counterparts?

AFAIK, The gearbox bell housing on gearbox's behind M47/57 diesels is the same as M4x/M5x petrol engines.

[DanThe]

The 6 speed on my chromie started out in a 320d, same bolt pattern but the angle it sits is the same as an M20. So on the back of my M52 block its tilted clockwise about 10 degrees, see pic \/



Note the spline on that gearbox in the ebay ad, 22 teeth and only comes in dual mass fit, input shaft is also shorter than the usual gearboxes

[HairyScreech]

i assume you are still on the dual mass flywheel then dan?
do you know the diameter of the input shaft? perhaps there is a 240mm disc from something else that happens to share the spline pattern.

short input shaft dosent sound to clever, could really do with all the length i can get my hands on (couldnt we all :winkeye: )

any idea how big the inside of the bell housing is?
in order to get the ring gear in we need minimum 340mm and even then it would be pretty much touching.
i gather none of the 6 pot bell housings are significantly larger than any of the others.

[DanThe]

Bell housings are all about the same, I am using a dual mass yeah, lucky enough to get hold of one that had only done a few hundred miles from new. The spline is unique to BMW, believe me ive been there. You can buy a custom sprung job from the states but ive only seen clutch plate/cover/flywheel kits and your looking at £800+

[HairyScreech]

sounds like it might be a no go for the v8 then, shame really.

might still have a look for the touring as a 6 speed would be nice, it always feels like it needs another gear and im sure the eventual 2.8 will make things even worse.

for reference what is the shaft size, there may not be anything cheap single mass off the shelf but there is no reason a nice solution couldnt be invented.

is the 22 spline shaft across all models? as the etks show 10 splines for some of the earlier cars and for the 530d, i assume its an oversight on the etk rather than anything significant.

edit - im guessing that its the uuc conversion kits your talking about then.

[HairyScreech]

actually dan, there's no reason other than driveline vibration for needing a sprung center clutch with a single mass.
i can think of a handful of applications that are unsprung.

i guess only giving it a try will say if the engagement is to harsh or if the noise/vibration is unacceptable but there is no real reason you couldn't bolt that clutch onto an m50 or m20 flywheel and give it a go.
only thing with going down this route would be the clutch finesse required to get a smooth start.

edit - guess this proves the point.
http://www.r3vlimited.com/board/showthread.php?t=174815

[e21Jason]

Euro carparts diesel single mass flywheel conversion?

http://www.eurocarparts.com/ecp/c/BMW_3 ... c8f&000299

[HairyScreech]

valeo are doing more and more of these, might be worth asking about a version with a 22 spline plate.
its one of the things on my hit list as the worst they can do is say no.

the hub that sits on the input shaft is just riveted to each clutch after all, don't see a reason why the rivets couldn't be drilled out and the hubs swapped.

[HairyScreech]

ok with a bit of google-foo in the zf catalog system it seems dans 100% right, the 22 spline is a bmw only thing, its 26,5x29-22N, which i assume is a 26.5mm spline toe, 29mm shaft and 22 splines.
the old profile is 23x29-10N, which im thinking is 23mm spline toe, 29mm shaft and 10 splines.

Absolutely nothing else comes close in spline size.

[DanThe]

As I said, ive been there! Spent months and months looking for a sprung alternative. I even stripped a sprung clutch and asked a gear manufacturer if they could reproduce the centre with the different spline (the centre sections are very different) the answer was yes, but it would cost £200+ due to the process involved, it would also need hardening afterwards of course.

I think I have some pics somewhere I will dig out later

If you wanted to risk it you could weld the 22 tooth hub into the sprung centre, but how long will it last? Taking the box out of mine is a serious chore, days work in reality for a clutch change and not something I want to be doing very often.

I tried the solid plate with M20 flywheel and cover, brand new sachs cover, on my 3 litre M52 and it slipped like it was greased at high revs, pretty much burned it out after one annoying track day. Changed to a sprung plate and its been fine for the last 3 track days but its now just starting to slip very slightly at high revs after lots of use when hot.
So my experience is the springs stop vibration which leads to slip, if you used a solid paddle clutch that would be very different in terms of grip and comfort, its finding a reasonable middle ground which is the hard bit

[mick_318is]

Screech, I have one of these boxes sat in my garage at the moment, waiting for me to do something with it!
If you need any measurements I can get them for you.

[DanThe]

Easy way out -

http://www.ebay.co.uk/itm/BMW-e34-540i- ... 500wt_1363

[e301988325i]

aye, and by just ignoring 1st you get a psudo dog leg pattern, as you would be using 2nd as 1st it would be like having 1st as left and back with 2nd and 3rd on the middle and 4th and 5th on the right.
at least that would be the way it would work out for us with the jag/scimitar axle ratios,

Yes that's exactly how it would work.

for an e30 it would be possible to down gear it and have the full benefit of the 6 speed by having the long overdrive gear for cruising.

I had the same idea, but 1-5 of a 6 speed box is unfortunately quite a normal set of ratios, similar to a 325 sport box which is a simple worthwhile upgrade from a stock 325 box, however, I would guess that someone wanting the performance from a close ratio gearbox would not bother with the trouble to fit a 6sp to then use ratio's 1-5 as the performance set.

from what i can see the 6 speeds are really a transmission aimed at higher powered engines where the larger spread of gears is required to be civil on the road.

Hmm, I'd say a powerful car would make first and second redundant in the 6sp boxes, more likely clutch wear, towing and economy duties.

325i box
1st 3.83 divided by 5th 0.81 = 4.73

320i g240 gearbox
1st 3.72 divided by 5th 0.81 = 4.59

325i sport box
1st 3.35 divided by 5th 0.81 = 4.14

262 from M535
1st 3.72 divided by 5th 1.00 = 3.7

G217 6sp
1st 4.23 divided by 6th 0.81 = 5.2
1st 4.23 divided by 5th 1.00 = 4.2
2nd 2.53 divided by 6th 0.81 = 3.1 this is really close

[HairyScreech]

Easy way out -

http://www.ebay.co.uk/itm/BMW-e34-540i- ... 500wt_1363

yes, seems the going rate is £500 for a 5 speed and £600 for a 6 speed.
which considering we are likely to break it at some point and they cant be rebuilt means it would quickly be a spendy solution.

the idea of mating a different gearbox up to the v8 is not so much to save money in the short term as the conversion, box and clutch will probably come to about the same price, its more in the long term, i expect we will have to uprate the clutch at some point and probably ruin a box or two, by using a box that is only £150 it means a dead box is not the end of the world.

the other issue is the rear axle ratio. the scimitar uses a salisbury based axle, and the plan wasto fit it with a jaguar power lok diff from an xjs, which leaves us stuck with a 3.07:1 ratio.
for where paul intends to go only a 6 speed will gave a long enough top gear to get there with the smaller wheel size forced on us by the smaller arches.
its just convenient that aiming for something that works around the 3.5:1/3.07:1 ratio the scimitar and jag diffs provide means that it will be suitable for the e30 as well.

i wonder if your slipping was more due to the m50 solid disc being too thin for the correct pressure to be applied by the m20 flywheel and pressure plate.
in theory the only thing a solid plate should have caused was the gear box to chatter like a pig when it was out of gear, the guibo to take more of a hammering and possible the gear box to wear faster.

think the 1st motion shaft could be substituted for a 5 speed one? the shaft is the same nominal diameter so they havent re-invented anything just gone for a finer spline to keep the shaft core/cross sectional area larger and prevent the shaft twisting up with the higher torque. perhaps there
not really a viable solution for us as the whole point is higher torque capacity but for the m50 or m20 boys it might be a plan.



mick, that would be awesome, is there any chance you could measure across the narrowest part of the bell housing, ie maximum diameter that a flywheel could be, only needs to protrude about 15mm deep into the bell housing as its just the ring gear that concerns me.
also the depth from the face of the bell housing to the beginning of the splines on the shaft, as this will dictate the height that the flywheel and clutch need to protrude into the bell housing to meet the splines.

hows that project of yours going anyway?

[HairyScreech]

aye, and by just ignoring 1st you get a psudo dog leg pattern, as you would be using 2nd as 1st it would be like having 1st as left and back with 2nd and 3rd on the middle and 4th and 5th on the right.
at least that would be the way it would work out for us with the jag/scimitar axle ratios,

Yes that's exactly how it would work.

for an e30 it would be possible to down gear it and have the full benefit of the 6 speed by having the long overdrive gear for cruising.

I had the same idea, but 1-5 of a 6 speed box is unfortunately quite a normal set of ratios, similar to a 325 sport box which is a simple worthwhile upgrade from a stock 325 box, however, I would guess that someone wanting the performance from a close ratio gearbox would not bother with the trouble to fit a 6sp to then use ratio's 1-5 as the performance set.

from what i can see the 6 speeds are really a transmission aimed at higher powered engines where the larger spread of gears is required to be civil on the road.

Hmm, I'd say a powerful car would make first and second redundant in the 6sp boxes, more likely clutch wear, towing and economy duties.

325i box
1st 3.83 divided by 5th 0.81 = 4.73

320i g240 gearbox
1st 3.72 divided by 5th 0.81 = 4.59

325i sport box
1st 3.35 divided by 5th 0.81 = 4.14

262 from M535
1st 3.72 divided by 5th 1.00 = 3.7

G217 6sp
1st 4.23 divided by 6th 0.81 = 5.2
1st 4.23 divided by 5th 1.00 = 4.2
2nd 2.53 divided by 6th 0.81 = 3.1 this is really close

when i say civil i mean provide a ratio set that prevents it from drinking like a fish or spinning its tits off at the speeds dictated by the law, the more ratios you have the more choice you have to get the engine down to a more civilised rpm.
its why zf are pushing a new 9 speed manual transmission for emissions improvement.

i do plan on going 6 speed at some point, but more for the reasons above than getting a higher performance gear set, im forced to do quite a bit of sitting on the motorway and a 6th would really help, so in that case i would be best going for a longer diff to use 1-5 as normal with 6 as an over drive.
although as you say keeping the shorter diff would make for a really good low cost track transmission.

[e301988325i]

when i say civil i mean provide a ratio set that prevents it from drinking like a fish or spinning its tits off at the speeds dictated by the law, the more ratios you have the more choice you have to get the engine down to a more civilised rpm.
its why zf are pushing a new 9 speed manual transmission for emissions improvement.

i do plan on going 6 speed at some point, but more for the reasons above than getting a higher performance gear set, im forced to do quite a bit of sitting on the motorway and a 6th would really help, so in that case i would be best going for a longer diff to use 1-5 as normal with 6 as an over drive.
although as you say keeping the shorter diff would make for a really good low cost track transmission.

I looked into it for the same motorway revs option as you describe, but it was going to start getting really expensive to get a 2.93 (41/14 or 38/13 crown/pinion) E30 diff built. A 2.93 diff would provide these mph's @ 6,900rpm, giving a rough 30mph/1000revs in top which a 2.8 would pull ok for sure, whilst still leaving first as usable, a shorter diff than 2.93 starts to make first useless.

G217? diff ratio 2.93
1st 4.23 39.8 mph
2nd 2.53 66.6 mph
3rd 1.67 100.8 mph
4th 1.23 136.9 mph
5th 1 168.4 mph
6th 0.81 207.9 mph

[HairyScreech]

how much is really expensive? i might be able to get a diff built fairly cheep back in westbury provided the parts were all there ready to go.

that or i will just teach myself to build them, iv built lorry diffs before and there's nothing really that different about a car diff.
iv got a couple of bad ones here i can play with, could always build one up for you later on.

[DanThe]

There is a nice 3.15 diff in the for sale section

I have a 3.15 fitted to mine and its about right, although with the torque I could get away with a 2.93

[e301988325i]

how much is really expensive? i might be able to get a diff built fairly cheep back in westbury provided the parts were all there ready to go.

that or i will just teach myself to build them, iv built lorry diffs before and there's nothing really that different about a car diff.
iv got a couple of bad ones here i can play with, could always build one up for you later on.

I bought a cr 325 sport box, posted and had it fitted for under £300. At the time a 6sp box + two diffs merged into 1 + fitting of both was heading a considerable way into 4 figures. Albeit the box would have been considerably newer and the diff as new.

Thanks for the offer, they're not that complex but it's the labour time to build them that makes the rebuild costly. I think for the mileage I do in mine I'll probably keep the sport box and change to a 3.25 / 3.15 once the 2.8 is done (albeit finding an engine builder is proving to be more difficult than expected, they're all used to ford turds and want to bore the block and fit new pistons despite being told mine's fine and not using oil).

My E46 330i could definitely do with the 6sp o/drive box as it feels like it revs too highly on the motorway @ 30mph/1000revs, at the same time doesn't hit the power in 5th until over 90mph, who said more than two valves/cyl was a good idea.

[DanThe]

Pic of the M20 clutch hub I stripped,



And the 22 tooth jobie,



The 22 tooth hub is a separately made part to the plate and is pressed in (splined) and heat welded

[HairyScreech]

Ok correction then, the aftermarket valeo clutches seem to have a standardized riveted centre hub. Ill see if i can find a pic later but the ones i was looking at the other day had silver hubs riveted to a black centre, looked like they did the hubs on a lathe and fitted them to a standardzed centre plate.
If that is the way the aftermarket ones are done it would make sense as they would only have to make one pressure plate for several different cars.

Actually you know what, a quick spin on a lathe for the m47 plate and it could be made into a centre for riveting on.
It would just then be a case of knocking the old centre out of the m20 and providing through clearance for the m47 centre.
There's even a nice machined flat for the centre to mount to on the m20 centre.
With a sensible rivet pattern and neat work it should stay well within allowable balance as well.
Have you got an old dead clutch that won't matter if it dosent work? i should be quiet for most of Feb as the f4 engine important building can't go in the car until the end of Feb. i could have a fiddle and see what i can do.

[e21Jason]

Tried asking these guys

http://www.clutch-specialists.co.uk/

Rebuild a m3 clutch with ceramic pads for these than an new one

Jason