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Discussion Starter #1
Hi,

I'm new to this board and just had a question for the more knowledgeable amongst you. I have an M5 engine which I'm looking to mate to a 6-speed SMG manual from an E46 M3. Now, I know the manual transmission in the M5 is the same as the 540 and the M3. The SMG is in a way a bolt-on electronic/solenoid control to actuate the gearbox. So, theoretically one should be able to swap in an SMG into an M5 ... obvioulsy their will be issues, but the idea should be sound. Alternatively, I could use the standard 6-speed manual and attempt to move the parts from the SMG unit over and create another SMG gearbox.

My main question is, is their any hardware differences between the 6-speed manual in the M5 and M3, 540i etc.? Is the M5 gearbox stronger to handle more torque and more power? Or are the units in the M3 and 540i etc. just combined with an overly strong gearbox designed for the M5?

Getting the engine / gearbox configuration will be one problem, but would be simpler if I could just bolt in the full SMG gearbox rather than pulling the SMG specific parts off it and putting them onto the standard box that comes with the M5.

Any information / theories would be much appreciated. By the way, in case your wondering as too my reasons for doing this ... I have both gearboxes, I live in constant traffic and it sounds like an interesting hybrid. Anyone done this before? Thanks for your input.


Marc
 

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That's actually the first time I have ever heard that mentioned on this board.. quite interesting! Keep us posted if you end up doing the conversion!
 

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M5_SMG said:
Hi,

I'm new to this board and just had a question for the more knowledgeable amongst you. I have an M5 engine which I'm looking to mate to a 6-speed SMG manual from an E46 M3. Now, I know the manual transmission in the M5 is the same as the 540 and the M3. The SMG is in a way a bolt-on electronic/solenoid control to actuate the gearbox. So, theoretically one should be able to swap in an SMG into an M5 ... obvioulsy their will be issues, but the idea should be sound. Alternatively, I could use the standard 6-speed manual and attempt to move the parts from the SMG unit over and create another SMG gearbox.

My main question is, is their any hardware differences between the 6-speed manual in the M5 and M3, 540i etc.? Is the M5 gearbox stronger to handle more torque and more power? Or are the units in the M3 and 540i etc. just combined with an overly strong gearbox designed for the M5?

Getting the engine / gearbox configuration will be one problem, but would be simpler if I could just bolt in the full SMG gearbox rather than pulling the SMG specific parts off it and putting them onto the standard box that comes with the M5.

Any information / theories would be much appreciated. By the way, in case your wondering as too my reasons for doing this ... I have both gearboxes, I live in constant traffic and it sounds like an interesting hybrid. Anyone done this before? Thanks for your input.


Marc
that won't be an easy project, good luck.
 

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i'd think an electrical engineer might shy away from this. I would imagine the engine management system is very involved with the smg controls, blipping the throttles etc when you shift. I think you'd be money ahead to get on the list for an e60 m5 with smg...
 

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mottati said:
i'd think an electrical engineer might shy away from this. I would imagine the engine management system is very involved with the smg controls, blipping the throttles etc when you shift. I think you'd be money ahead to get on the list for an e60 m5 with smg...
I agree, I bet that it wouldnt be too much trouble to get the system fabbed up, but I bet the electronics and operation of it would require alot of work and know how in order to fully optimize the drivability of the unit, JMHO, Josh
 

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I would be very careful as everyone else stated. SMG isnt just involved with the tranny, and splicing electronics like that can lead to gremlins. But, given enough money anything is possible. I agree with mottati and I feel that getting downshifts to work would be very problematic. Someone would have to write code for all the combinations that would give you a blip. :crying:
Wait, heavy traffic in Thailand? I couldnt ever believe that there is bad traffic there, especially not on Sukhumvit... :1:
:cheers:
 

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I hadn't spotted the "Thailand" as an address. Having lived on Sukhumvit for 3 years, I can categorically state that I never noticed any kind of traffic problem ... :blink:

Jokes apart, it was awful; it's better now though, I was back there several years ago on business and they have the sky train thingy which is pretty neat.

One thing I will say about Thailand though, the labour will (in comparison to US and UK) cost nothing switching components in and out so the price of the venture will be down to sourcing the parts. :)

Notwithstanding everyone's comments on the electronics though - I tend to agree, it will be a significant challenge. You'd need the BMW workshop manuals for both E46 SMG and E39 M5; first to work out what the I/O's are for the SMG control unit (I presume there's one) and second, to work out how to link this control unit to the ECU of the M5.

While writing this, I wonder if it may be possible to take out most of the electronics from the equation. It would be a huge risk (no electronic safety barrier) but if you only connected the steering paddles to the clutch actuator and the actual gear changing mechanism, you could do the blipping manually (treat the throttle as if you were driving a manual). No ECU links, no "blipping", no checking revs before changing etc. etc. Of course, one wrong press on the paddle and you do serious damage to a very expensive engine.
Perhaps not such a good idea after all ...:rolleyes:

Tough job - good luck :)

Regards,

Gary.

BmwNut said:
I would be very careful as everyone else stated. SMG isnt just involved with the tranny, and splicing electronics like that can lead to gremlins. But, given enough money anything is possible. I agree with mottati and I feel that getting downshifts to work would be very problematic. Someone would have to write code for all the combinations that would give you a blip. :crying:
Wait, heavy traffic in Thailand? I couldnt ever believe that there is bad traffic there, especially not on Sukhumvit... :1:
:cheers:
 

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Discussion Starter #8
The traffic did get better for awhile, but at the moment its probably the worst it has ever been. If you were here pre-1997, then you'll understand...its a parking lot....everywhere. We've even got a subway now, still not helping. Economy is booming and so is car sales. Everyone who lost their car from the economic crisis, now has it back again.

As you all said, the electronics and getting it sorted just right will be the biggest problem. Getting the technical data should be possible, then its just sorting through it all or go the low road and drive simply as a clutch-less manual. A fine alternative to me really.

Any ideas about the hardware side of things? Differences between a 6-speed SMG and 6-speed manual? You guys reckon its identical, besides the SMG specific components? The gears themselves, clutch, synchros etc. the same? If thats the case, I'll swap complete gearboxes and work my way from there. Much preferred over trying to get all the SMG specific equipment off and put onto another gearbox.

Thanks for your comments!
 

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Wont import duties kill if you need to get something out of country? If I remember correctly they used to be pretty bad.
I am not 100%, but to the best of my memory the gearboxes are the same, but I am not sure sure about some of the internals. Now, I dont know if SMG just has a controlling unit for the shift forks, or if it has it's own way of doing things. If it just controls the stock forks, then a normal tranny will work. If not...
Doing the blipping yourself will be really hard, as you dont know exactly when the clutch releases and engages. One or two blown shifts and you could fry some synchros. I would invest in the electronics side of it.
Good to hear the economy has rebounded out there. My father worked as a consultant for Telecom Asia before the market died, and I got to visit numerous times. Wonderful country, some of the best food in the world (my step mother who my dad met out there is a wonderful cook, so trips home are great). I cant believe the traffic got worse, as I remember it as being terrible last time I was out there (1999). I really need to make a trip back out there one of these days.
:cheers:
 

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Discussion Starter #10
Thats true, the duty is very very high over here. However, so is the corruption ... their are ways to get around the issue :haha: .

Not really too worried about blipping the throttle, as it isn't really vital or absolutely necessary ... especially with synchros. Just shift the old rude way, back off the throttle hit the shifter and re-engage the throttle. I don't believe the SMG waits for any particular throttle input from the driver wether your shifting up or down; so it should go ahead and perform the gearshift while your off throttle. Or have I forgotten something? As long as I don't give full throttle upshifts or over-rev on the downshifts, everything should hopefully hold together...a burnt clutch is the least of my worries.

Of course, getting some if not all the electronics working would be a big added bonus. Just keeping my worst case scenario options open.

1999 ... that was great traffic! Compared to now or pre-1997, I wouldn't consider that traffic. Its really that bad now ... and of course, the worse the traffic gets the worse peoples driving habits become.
 

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If you dont have the electronics for the engine, it *should* do an up or downshift regardless of your manual throttle setting. Wont be the smoothest, so beware of locking up tires on a downshift to high rpm. I think it will all depend on how fast the SMG has the clutch engage, as if it dumps it then downshifts will be violent, but if it takes its time then they should be ok. Heck, I think most owners of M5's dont blip downshifts and they get away with it.
I was there in 1995 a couple of times, 1997 and 1999. I guess 1999 stands out as the worst as I had a drivers license then, and it was the rainy season so some of the streets were flooded. What a crazy place to drive, but the worst I saw were trips up country... talk about scary.
:cheers:
 

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the 1st generation SMG shifted exactly like that... lol... :7:
 

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I would imagine there is a big difference. I mean one if a I6 and one a V8. It might be possible to exchange the bellhousings on both transmissions to make it work but I wouldnt start to assume they are the same.
 

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Discussion Starter #15
Just went through the BMW ETK again, the M3 6-speed manual, M3 6-speed SMG and M5 all have the same transmission number...S6S420G. Therefore, you would assume they all use the same manual transmission to start off with. I've put together a picture of the transmissions straight from the ETK. As you can see, the M3 and M5 6-Speed are identical, but the SMG is quite a bit different. This makes me think I the 6-speed manuals and SMG must be pretty much identical internally since they are swapablem; though they appear different. With that reasoning intact, the SMG should bolt into the M5 assuming dimensions and space are there. What do you guys think?

Also had a look at the replacement units for an SMG transmission. Their all interchangeable with the 6-Speed manually apparently, BMW doesn't list the internals as being different. The only additional thing you get with the SMG is the SMG control unit. Could it really be this easy to swap in?

Have a look at the pictures and see what you think...thanks for the feedback so far fellas!
 

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I think they might have an error there... The M3 manual and SMG are the exact same trans, but the pictures are totally different. Even the bolt pattern on the bell housing is different.

I would also imagine that the gear ratios between the M5 and M3 are much different.

EDIT: Ok, confirmed the gear ratios are the same.
 

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Discussion Starter #17
Yeah, thats exactly where I'm getting confused. The main body of the transmission for manual and SMG is the same, except for that little bolt on piece at the back. That doesn't worry me much, but as you said the bell housing and bolts are different...seems very strange, why would you bother changing the bellhousing ?!

So, I'm basically at the point that I believe the SMG and manual transmissions are the same; except for the SMG control of course. So, I should be able to swap the SMG into an M5 and it should be able to handle the torque and power. If the clutch requires a stronger pressure plate or what not, thats not a big problem ... can go aftermarket, UUC or something. Getting the electronics to work will take a bit more fudging around.

Another question, with these supercharger kits for the M5 ... as far as I understand the standard manual transmission is used. No internal changes, perhaps a stronger twin-plate or so clutch. So, therefore the transmission can hold a fair bit more torque & power than standard. Correct?

This little project is sounding more & more interesting by the minute :haha:
 

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Well, I am not surprised that a SMG bell housing could look different than a standard one, since something has to actuate the clutch. What concerns me with this picture is the bolt pattern. Hopefully one of the M3 owners can clear it up? In fact, might be worth posting something in the M3 section, asking for information on the SMG trans, pictures, etc.

Could be some issues with finding SMG compatible clutch to work on the M5, but I am sure someone can figure something out in that area.

Electronics... that is a much bigger issue.
 

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That box is stronger than all get out. I believe some of the very high HP DA cars are running the stock box. 1000hp Supras usually run a derivative of that box, and they usually run stock IIRC. It does sound entertaining, even though I hate SMG... :D
:cheers:
 

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Discussion Starter #20
Ok, so power & torque is not an issue.

Let's recap, were basically all agreed that an SMG transmission can be bolted into an M5. Electronics and such, are an unknown quantity as to their operation.

Now, just to complicate the issue further I've gone through the TIS and gotten some pictures from the repair guide on how to remove & install an M3 6-speed manual, M3 SMG and M5 6-speed manual. This time, however, the pictures of the bolts on the bellhousing between the M3 6-speed manual and SMG are identical ... unlike the other pictures I posted earlier from the ETK.

But, the M5 6-speed manual has a different bellhousing according the TIS. Completely different bolt configuration and an extra bolt. So, I'm think use the entire SMG transmission but swap the bellhousing of the M5 onto it. According to the images from the TIS, this might not work ... but according to the earlier pictures from the ETK it should work fine.

Hmmm...I guess I'll just have to wait and see once I have both transmissions sitting next to each other.
 

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