Hey All!
Some of you may have heard of my long progressed 6 speed swap I've been contemplating on over the past year with my E31 M70.
After extensive research and spending hours on end sifting through threads and blog posts, speaking to mechanics and confirming fitment using parts, I can now confirm the following:
- You can use the Getrag 420G Transmission with the M70 - The bellhousing will NOT line up, you will need to purchase a custom adapter plate.
- As the early model M60, alike the M70, didn't have the crankshaft sensor on the flywheel - the car will start fine as if stock.. if using the 420g from a M60, not M62!
- It is important to use the transmission from an E34 540i, or SOME from an E39 540i - some later model 540i's have the updated M62 with the crankshaft sensor at the flywheel, I cannot confirm or not if these will work, as I will be using an E34 540i 420g as I wont be taking the risk. I am sure there would be some way to make it work, but why the extra work?
- As the 840 came out with the Getrag 420g, you can infact use the shift linkage E31 specific, 840 parts... driveshaft and diff alike.
- So far, I have still yet to 100% confirm this - you cannot use the M5 E34/E39 transmission (bell housing)
- The clutch from the V12 will fit the 420g, and the V8 clutch will of course fit - with the 420g having more clutch options aftermarket this is most likely more desirable.
- The Getrag 420g is rated up to 499nm of torque, the M70 - in good working order, has 450nm of torque - as such, it can easily handle the big 12.
- The cruise control will not work, you will need to cut and connect a few wires together to enable this - I have a write up on this.
- The dash will display an "S" indicator, to clear this off you will need a Manual gearbox computer, once installed... the display will display nothing, please note though, this is not necessary to run and drive the car - it is merely cosmetics.
- To avoid changing the Diff, you COULD leave the 850i Automatic diff in the vehicle and split the driveshaft's, using the front half of the 840iM driveshaft connected to the rear of the 850iA driveshaft. Though, in turn you are better to use the 840iM driveshaft with an LSD... if your swapping out most of the drivetrain you might as well do the rest, and replace the CV's while you are there too.
- The V12 and V8 share the same bolt pattern at the crank... 9 bolts, fortunately.
- You can use the pedal box from a wrecked 540i E34 and clutch hydraulics, I have yet to confirm E39... I'll personally use an E34 pedal box and clutch hydraulics as I can confirm these will fit.
- the V12 clutch and flywheel fit right into the 420g in stock form, and vise versa. You will WANT to use the V12 clutch as the V8 clutches are known for sheading themselves, expecially considering you'll most likely become pedal happy every now and then?
- From what I have researched, this has very similar "guts" to an E46 M3 transmission - in other words, its robust asf.
- There are many of people who have used this transmission instead of the 560g (Mostly due to cost) and if you have a look online, like I did, before contradicting me.. you'll soon agree.
If theres any questions, concerns or queries I am open to them below, though hate for using a different gearbox and etc.. please, go somewhere else.. at the end of the day, this is my car not yours.
And for people who will still contradict me, why would an adapter plate exist if it wont work? Please post your criticism along with an answer to that question, as I have confirmed it will work using parts I infact have at home, and that my mechanic has.
Thanks, I'll slowly add to this thread - the tranny comes out next month, so I will post many of photos and updates along the way for the enthusiasts and anyone else interested in this swap.
http://www.ebay.com.au/itm/BMW-V12-M...-/181808475657
Bellhousing Adapter link below
Last edited by FRIENDLYMONKEY; 06-01-2016 at 06:19 PM.
Overall what do you believe it will cost you in parts ? Will you do the labor or a shop ? How much would a shop ask if you've asked ?
Hey mate, No I will be doing the labour myself. I expect to be spending upwards of 5,000$NZ, downwards of 10,000$NZ - I am keeping a wide ballpark figure, I would likely expect it to be closer to the bottom end, though I will be going with an upgraded clutch, and all new shifter and linkage parts, as well as parts of the hydraulic clutch system. I will keep an update on pricing, and will post all part numbers - including the part number of the 420g, that I do use.
It does not matter. I am using an S6S 420G from a 2000 E39 540i in an M60 840Ci.
What extra work would that be?
Minus the provision for the crankshaft sensor, the bell housing is identical. You can use a late transmission on an early car, but you just have the sensor stub in the bottom.
As for the pedals, they are the same for every manual E31, E32, or E34. 525i, 535i, 530i, 540i, 735i, 850i, it does not matter. You cannot use any others.
'07 e65|N62 - Alpina B7 - Black Sapphire|Black|Loaded|GONE
'02 e46|M54 - Orient Blue|Beige|'Vert|GONE
'00 e39|M52 - Anthrazit Metallic|Grey|GONE
'01 e38|M73 - Anthrazit Metallic|Schwarz|Shadow-Line|GONE
'91 e31|M70 - Schwarz|Schwarz|M70|FOR SALE
'13 328i Auto - Black Sapphire|Coral Red|Sport Line|GONE
'05 545i SMG - Jet Black|Black|Bamboo Anthracite|GONE
'07 335i Auto - Montego Blue|Grey|GONE
'05 545i SMG - (Euro Delivery 7/22/05)|Black Sapphire|Auburn|GONE
'97 528i Auto - GONE
The M70/73 have a bellhousing bolt pattern that is UNIQUE to them-PERIOD!!!
The crankbolt pattern is shared w/ the V8 and V10.
The question-
What is the input shaft length on the 420 versus the 560...as it looks like the adapter will space the trans back an inch plus. So then will the input shaft seat in the pilot bearing AND will the hydraulic throw-out have enough throw or movement?
I simply used a auto bellhousing -cut down and put a ½" plate on it with a very common Tremec (Chevy) bolt pattern. Used a the V12 flywheel and drilled and pinned it for a standard very inexpensive Chevy clutch. The Tremec/Chevy share the same input nose size- as you can use the BMW Pilot bearing w/ no mods on the Chevy input shaft. Also used a very inexpensive Chevy hydraulic constant contact type throwout bearing
P1010447.jpg~original by Richard Hayes, on Flickr
DSCN4073 by Richard Hayes, on Flickr
My build-http://stingrayv12.com/home.html
Thanks for clarifying this, I never said it wouldn't work though... What I said was that the early model ones didn't have the drilled hole for the crankshaft sensor, As the later ones do.. I think personally its better to get one that doesn't have the crankshaft hole, as its not required... sure, its not critical to the car running but I would rather not have it, myself.
Again, I never said there would be any work to make it work... but what I mean by "why the extra work" is, surely you would have to block up/fill in the hole, as I certainly wouldn't want a hole there.. you may feel different about this though.
Exactly
Really? I was dead sure, and so was HELLBM in NZ who also confirmed, the pedal box must be from a 540i. I will confirm this as the swap progresses.
- - - Updated - - -
I agreed, that's the point of the adapter plate.
Yes.
Wish I could confirm that at the moment, I still have some investigating to do on that exactly.. maybe you could help shed some light?
Sounds like you did some heavy work... Interesting, will be in contact.
- - - Updated - - -
540i is the key here, yes, though bear in mind later model ones coming from an M62 versus M60 will have a drilled hole for where the crankshaft position sensor would have been.
yes
- - - Updated - - -
Confirm what??
I already did it....and I'm not sure what you mean by "pedal box." There is just a bracket (which is the same for all the cars) and you swap the brake pedal for the smaller one, and add the clutch pedal to the end of it. I did not remove anything except the auto brake pedal. If you order a blank pedal bracket from BMW, the same part arrives whether you have a manual or auto, with any engine.
If you don't believe me, look at the part number for the pedal bracket:
35111159647
Supporting bracket, foot controls
Supersedes:35111157759 (04/03/1987 — 05/25/1993), Exchangeable retrospectively35111155657 (06/01/1986 — 03/22/1991), Exchangeable retrospectively35111155658 (06/01/1986 — 11/10/1986)
Part 35111159647 was found on the following vehicles:
5' E34 (03/1987 — 06/1996)
7' E32 (10/1985 — 04/1994)
8' E31 (07/1989 — 05/1999)
And the brake pedal...
35211155686
BRAKE LEVER
Supersedes:35211158950 (07/07/1988 — 03/07/1990), Exchangeable retrospectively35211155685 (06/01/1986 — 11/09/1990)
Part 35211155686 was found on the following vehicles:
5' E34 (03/1987 — 06/1996)
7' E32 (10/1985 — 03/1994)
8' E31 (07/1989 — 10/1996)
And the clutch pedal...
35311155691
Clutch lever
Supersedes:35311155690 (06/01/1986 — 10/27/1994)
Part 35311155691 was found on the following vehicles:
5' E34 (03/1987 — 06/1996)
7' E32 (10/1985 — 04/1994)
8' E31 (07/1989 — 05/1999)
How's that for "confirmed"
I feel as if you think im arguing with you? Look, I'm not arguing with you, what im saying is as the swap progresses I will confirm this 100%... I'm not going to lie and agree to something I am not sure on, Im buying a wrecked 540i E34 manual and using that as a parts car for my swap - so when I begin disassembling it and the E31, I'll let you know. How does that sound? I think that is fair.
After all mate, im just trying to provide the information online so it is readily available.
Last edited by FRIENDLYMONKEY; 06-02-2016 at 12:50 AM.
Just wondering if anything ever came of this?
No kiddin.
Looks like they also offer these flywheel spacers to mate up (maybe??) for the M70 adapter plates that the OP posted.
http://www.ebay.ca/itm/BMW-M60-M62-V8-M70-M73-V12-FLYWHEEL-SPACER-for-M60-M70-to-M50-M57-240mm-CLUTCH-/182402175292?hash=item2a7804513c:g:nTEAAOSwcUBYEcA i
They've sold a few of each of these products according to the feedback given, sure would be nice to find a successful documented 420G->M70 conversion and what exactly was required. Would open up a lot of doors for us auto M70 guys who would love a 6 speed behind their V12.
I can attest to what Olin says. You don't need to swap the pedal box, you only need the clutch pedal and a brake pedal. The manual brake pedal is smaller than the automatic brake pedal. The longer bolt is what is needed to now go through two pedals. You may need a small adapter bracket to accept a cruise control kill switch for the clutch pedal if you have cruise control. If you don't have cruise control, then you won't need the bracket either. The clutch pedal bracket is very inexpensive.
As Olin says, forget the pedal box, just take the pedals and the bolt and you will save a lot of time and effort.
Op hasn't been on in a couple months, oh well.
Honestly the potential flip would probably pay for the entire endeavour, 6 speed E31s might end up being the norm some day.
Last edited by XAlt; 08-20-2017 at 10:46 PM.
I concur with RJ and Olin, just go for the longer bolt! And this pleases me that this is now an option for the 12-guys. Manual shifting makes the 8 a lot more fun!
just a few notes from my experience from the V8 manual conversion
1) i can confirm there is no need for a new pedal box just a longer bolt and i think it is the same pedal box as the E34 the only difference being a rib on the back wall of the box for the silly spring thingy which doesnt seem to do anything in fact when i removed it from my e34 m5 it seemed to improve the initial feel of the clutch when you engaged it my manual 840 has not got it fitted
2)it does not matter if you get a s6s420g from an E39 the sensor hole is still there on the E34 gearbox it is just not used/drilled and you just have a hole if you don't use the sensor if it worries you a rubber bung would do and look just like bmw had done it
3) if my 850CSI is anything to go by the 420 shifts better not quite so truck like,but still not great though
4) a short shift kit really improves them although it is worth keeping in mind not to get too enthusiastic shifting with these as it can be hard on the syncros you can still shift slowly with the quick shift but it does feel a lot better than the standard stick
5) the boot surround for the gearstick is one of the more expensive bits knob and boot are integrated into 1 part unlike other BMW's
6) the wing/support under the gearbox is different to the e34 but no panic as long as they are still available they are surprisingly cheap about $40 from memory
I was under the impression that the M73 bell housing bolt pattern was the same as the V8, probably to save money and use the 5hp30 trans that the V8 used, interestingly enough the M73 uses a smaller torque converter than the V8, which i am not sure whether this is connected but i have seen a few M73's fry there converters and thus auto
Last edited by merlin840; 01-21-2017 at 12:20 AM.
OP, any updates?
They also have an M5x adapter, hmm. Would anything be different?
Last edited by XAlt; 04-24-2017 at 07:07 PM.
Sorry I haven't been online much.
I've been busy with a top end recondition, I haven't even started removing the gearbox yet though do intend to before the end of this year,
With end of financial year at work, I've been flat tack busy and basically had to put my life on hold.
Glad this threads got so much interest, I'll post photos and updates as I go shortly.
Sorry for bumping an old thread,
Working on this swap in my own car. Just had a question for the conversion plate/ throw out bearing / input shaft. Was there anything needed to change the length of these to line everything up properly?
Anxious to hear what you discover. I'm making the same swap on my e31 (just waiting for my SPEC clutch kit to arrive!), and contacted the European seller who I recently purchased the adapter ring from on eBay to inquire. Their indication was that a spacer is necessary, but they couldn't provide details (lame). As you can see from the attached image, the ring is almost exactly 1in thick (.990 according to my caliper), so my current plan is to machine a flywheel spacer out of 1in 5052 plate (bonus question, at what thickness does plate become billet?)
20180526_134050.jpg
Does anyone have any updates in regards to the M70/M73 6-speed 420G conversion? Is a flywheel/pilot bearing adapter available to make up for the thickness of the PMC transmission adapter? Thanks,
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