Can you mate a 5hp30 with an M70?

[jeffbebe 1559]

So the 850i from 1989-1994 came with the 5L M70 V12 and a 4 speed ZF 4hp24 gearbox apart from a few rare 6 speed manuals. BMW produced only a very few 850ci's (in fact there were less of these than the coveted 850CSi) from 1994-1997 with the 5.4L M73 engine and a 5 speed tiptronic ZF 5hp30 (and even rarer six speed manual).

While a manual conversion is very appealing it's also bloody expensive and I think a GT car really should be an auto. My 4 speed with 3.64 LSD and Wokke chips is great but I can't help thinking how much better (and faster) it would be with the 5 speed tiptronic box which are far easier and cheaper to find than a manual six speed for a V12.

Fitment would be no problem but the issue - I anticipate - is going to be communication with the rest of the car since the M70 DMEs and 4hp24 EGS are non-CANBUS but the 5hp30 EGS is CANBUS. Can't find any examples of this being done online so I'm guessing it's not that easy.

So my questions are:

• Any ideas how you could translate DME data to the EGS from an analogue signal (or whatever it is) to CANBUS, and vice versa?
• Could you run a parallel but independent controller for the transmission? (or would that mean you lose things like cruise control, etc)
• Would it ultimately be easier (albeit time consuming and expensive) to swap a complete M73 and gearbox?

[francoisv 466]

Might be possible. Ray@HellBM is going to take my 540s 5HP30 gear box and mutate it with an M3 SMG box as the gear box apparently has 2 to 3 sections that could break apart for mounting to other gear boxes. So perhaps taking the front housing off your current gear box and mounting it to the rear of the 5HP30 gear box would work?

[jeffbebe 1559]

It's not the fitting as it will be straight swap, it's the transmission control module. M70 communicates with 4hp24 EGS via analogue, I think, whereas 5hp30 is CANBUS, so somehow the CANBUS signal needs to be translated to analogue and vice versa.

[_ethrty-Andy_ 2132]

i would say its more hassle than its worth, especially when the 4HP24 is a pretty strong box. I have done several track days, skids etc with it and its still fresh. if you put it in S mode and use the 123D on the gearlever its effectively tiptronic anyways. Im not really seeing the advantage, especially when (and I am assuming) your current 4HP24 is still fine.

[jeffbebe 1559]

haha, Andy! I don't think 123D manual mode is effectively tiptronic at all but maybe that's personal preference. I think the 5 speed is a much better box and the additional gear would make a helluva difference to the acceleration. Also, there are some good s/w upgrades for the 5 speed which can make them a lot more fun.

[francoisv 466]

You mean something like this?

http://www.alibaba.com/product-detail/CANBus-to-Analog-Converter_125351282.html

Im sure there is a way to do the conversion, just might need some deeper research.

[jeffbebe 1559]

Interesting... Not 100% sure the signal is analogue, so I need to find that out first! I guess the converter needs to be two way, i.e. convert CANBUS to analogue and analogue to CANBUS. Also would help to know what info the EGS and DME need from each other, I suppose as it might be different for the M73 DME vs M70.

[westy 614]

Was the 30 trans ever used in anything that didn't also use CANBUS? E34 or similar?

[Allanw 1071]

haha, Andy! I don't think 123D manual mode is effectively tiptronic at all but maybe that's personal preference.

They're both just autos

[jeffbebe 1559]

Was the 30 trans ever used in anything that didn't also use CANBUS? E34 or similar?

Don't think so.

[Michael. 2313]

Could be an idea to use a common 5 speed gearbox from Japanese model car, a few getrag options around.

I'm sure there would be some previsions to CNC up some adapter plates & modify the original automatic bell-housing.

[francoisv 466]

I see you are already on the bimmerforums on the same topic, so you know the box bolts straight up positive note. Just the electrics being sorted haha

[Ahmedsinc 414]

Quick look through Wiki shows the 5hp-30 was used on E31, E32, E34, E38, E39; M60, M62 & the M73. Apparently they were used from 1992-2001. Also in Rolls Royce & the DB7 Aston Martin.

Should hopefully broaden your scope a bit. Top gear on the 5hp is 0.79 vs 0.72 on the 4hp so your final gearing should remain basically identical to what you have now, saves effing around finding another diff

[jeffbebe 1559]

I see you are already on the bimmerforums on the same topic, so you know the box bolts straight up positive note. Just the electrics being sorted haha

Yeah! Only thing I could find online about it!

Quick look through Wiki shows the 5hp-30 was used on E31, E32, E34, E38, E39; M60, M62 & the M73. Apparently they were used from 1992-2001. Also in Rolls Royce & the DB7 Aston Martin.

Should hopefully broaden your scope a bit. Top gear on the 5hp is 0.79 vs 0.72 on the 4hp so your final gearing should remain basically identical to what you have now, saves effing around finding another diff

Only from 94 on the E31 with M73. Pretty certain any 92-94 bimmer with a 5hp were all DME 3.3 with M60... so CANBUS.

Not sure about Aston and Rolls though!

My 3.64 LSD might be a bit short for the 5 speed (but not harm in trying).

[polley 916]

What about an aftermarket trans controller?

[jeffbebe 1559]

I know even less about aftermarket controllers than I do about OE ones. What are the pros and cons?

[Ahmedsinc 414]

Probably a dumb question, but do the 4HP / 5HP use a bolt on bellhousing? Or are they a one piece casting? I only ask because the rotten old Jatco on my E36 had a removable bellhousing.

Would make life very simple - use the M70 bellhousing, 5hp trans & E34 TCU. IF it works out to be that easy, which I doubt

Edited December 23, 2014 by Ahmedsinc

[Michael. 2313]

Aftermarket trans controllers are pretty fiddly.

You need to custom tune all the shift points from 0-100% throttle in all the gears, as well as set the line & accumulator pressure to the clutch packs & brake bands which took quite a lot of test drives to achieve in my E36 setup.

Even then it was somewhat jerky due to the lack of previsions to fine tune the shift sequence like a factory ECU can offer.

A very niche market thing too in NZ so find it unlikely any service person would help.

Summary = manual gearbox ftw.

[antil33t 90]

convert it to dme 3.3, and add canbus

[jeffbebe 1559]

convert it to dme 3.3, and add canbus

That sounds easy... I'll just do that

[westy 614]

Think all ya need is a cheap m73 750 tbh.

[jeffbebe 1559]

You're probably right, Tony. You can help plonk it in when Alice is done

[westy 614]

Piece o' piss mate. Alls we need is beer and a stick.

Ps, does the V8 box bolt to the V12?

[jeffbebe 1559]

V8 manual box? Not 100% sure.

PS I've got a stick.

[BM WORLD 1283]

what tony said, just fit the m73 and trans etc from a early e38 750i .

5hp30 where also used in 92-95 e34 540i e32 740i , but different bellhousing etc