Hi folks,
Since I recently aquired an E38 with the 5HP switchtronic tranny it becomes even more obvious to me that the 4HP24 is really outdated.
Mechanicaly the 5HP30 fits to the M70 engine but the electronics.....
I wonder if anyone has already tried to bring them together or do I have to do it all alone? I'm sure it is possible and shouldn't be rocket science.
But why eventually invent the wheel a 2nd time.
Don't know of anyone but very interest in your progress, Wolf. I really enjoyed the 5hp30 in my E39 with Dinan tune and these gearboxes are much easier (and cheaper) to come by in New Zealand than a manual V12 box.
Wolf, just get a manual
where is the challenge besides finding one
And why change gears myself with a more or less stubbern 6-speed if I can have it much more comfortable.
I now have the direct comparison between auto and manual tranny because we have two identical E38-735i (OK. almost identical, one is short and one is LWB).
The short one has 5-speed manual and the LWB has the 5-speed auto box. The 5-speed isn't any faster at all.
I can agree on one thing.
Automatics are amazing but in a fun car a manual is just perfect.
My Old E38 with a 5hp30 was the smoothest auto I've ever drive. In sport mode i would guess it was quicker than a manual. It's just the constant engine sound between gears I find off putting.
Even more interresting would be the 6HP26, rated at 600Nm vs the 5HP30s 560 Nm which is right on the limit for an E31.
I'd be very interrested in this if you make it work
Current Cars:
1994 BMW 850 CiA (2017 km). My black on black Wokke'd 5.4l V12 autobahnmuncher
1992 Donkervoort S8AT (105k km). The mad dutch "Super 7." 300hp/ton of turbo power!
2013 VW Caravelle 4Motion (57k km). A dark wine red 180PS/400Nm 2.0 BiTDI rocketvan
2007 SMC F-Kart 50. 88cc of street legal go-kart hilarity, and a 1968 Cadillac Coupé DeVille Convertible 472.
"The best way to go broke-by-german-car is to buy an 8 series bmw with a v12" - Perc
"Torque is like pron. You can't really define it, but you will recognize it." - ElToro
I was wondering about this the other day. I was planning on doing a little research into this when I got some free time, laughable.
The fact that you guys are choosing the auto over the 6 speed really makes me glad I'm swapping my own transmission in...
WTF?
so how are you measuring whether the auto is faster than the manual?
is this done with the Bum dyno
the only differences between the two can only be
1)fluid pumping losses(surprisingly considerable)
2)interval between gears
3)gear ratios
i would be very curious just what info the gearbox (egs) computer shares with the dme my guess is really only vehicle speed, rpm and trans is ok i think the egs is more or less a stand alone unit
Last edited by merlin840; 08-28-2014 at 09:59 PM.
Well, I measured it by driving my auto against a 6-speed owner, then swapping cars and trying it again. Both cases auto won.
I did the same thing with a 2000 Pontiac WS6 Ram-Air back in 2001. My friend bought a 6-speed manual, I had a 4 speed auto - same scenario.
'93 850Ci - Mineralweiß Metallic
2001 740iL - Titansilber
ALPINA B7 -Alpinweiß III
...the price of cool ain't cheap!
Please don't compare a TT Auto against a 6 speed TT, Embarassing for the 6 speed, Losses a lil more every shift.
Hummm, Apparently you have yet to drive an 850/840 with a 5-speed Steptronic coupled through a 3.23:1 LSD!!
I have driven several 6-speeds and IMHO the V12/2-valve head and throttle-by-wire is a little lazy for manual shifting (my preference is the S38's snappy throttle response) but the 5-speed Steptronic is a better match for the V12's narrow HP curve and wide Torque band.
No offence to the many with 6-speeds since that is at least a better sport performer than the 4-speed auto.
Unfortunately the E31's last model revision with the M73/5-speed auto had all too few examples enter the US!!
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You will want to experience the M73/5HP30 combination.
The V8's cable throttle can't touch it!!!
The V12's throttle-by-wire does a "let off - shift - WOT" all while the throttle is held to the floor, that has all the sounds but more pleasing than manual shifting!!
Seriously, something to be experienced.
The neat thing about the 5HP30 is, that you won't have any mechanical problems in terms of mounting the tranny to the engine or space in the chassis etc.
And used units are plenty and cheap.
Whenever I think about such things one important factor is to make it halfway affordable plus make the conversion rather easy.
Same as with the M70B54 conversion. A good used M73 plus some parts from the M70. a bit of wrenching and that's it. No machining, no programming or anything specific.
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With the 4HP24 in S- mode I'm still in 1st gear while the poor 6-speed driver already had his first fight with the Getrag box.
IMO even these older auto trannies at the end are shifting faster than the average driver in a 6-speed.
But I have to admit, when I was younger any automatic car was something for old people
Maybe I am old by now. For sure have entered the 2nd half of my life.
from external sources the tranny needs
1. engine rpm
2. kick down info
3. shift lock input
4. gear selector info
6. ASC signal
7. EKM connection (various)
8. brake light switch
That's all I can think of right now.
In addition to the above there is of course some data transfer between the EGS and engine electronics ( DME and EML).
IMO the electrical part is the challenge but should be rather simple. All what needs to be done is probably create the proper wiring loom so that the M70 engine management can communicate with the EGS.
Everything else is off the shelf mechanics.
wokke: The main problem is that the 4HP24 EGS has individual inputs for all these signals whereas the 5HP30 EGS has no individual inputs but a single digital CAN-bus for all. Since the M70 DMEs and EML don't "talk" CAN-bus you're in for a serious challenge.
That was of course what was meant by No 2
i could also add the saving of approx 75 kg in weight by having the manual box
and if the auto was that much faster then why is there such a disparity in the published acceleration times?
Performance
(Euro-spec, source: BMW)850CSi 850Ci 850i 840Ci M62 840Ci M60 B12 Coupé 5.7 B12 Coupé 5.0 Top speed 250 km/h (limited) 250 km/h (limited) 300 km/h 281 km/h 0-100 kph / 0-62 mph
...with automatic6.0 s
--
6.3 s6.8 s
7.4 s6.6 s
7.0 s6.9 s
7.4 s5.8 s
--
6.880-120 kph / 50-75 mph
in 4th gear (standard gearbox)5.9 s - 6.0 s 6.3 s 6.9 s ? ? Standing start kilometre
...with automatic25.5 s
--
26.1 s26.3 s
27.0 s26.2 s
27.1 s26.9 s
27.4 s24.9 s
--
26.6 s
Figures care of e31.net
Current Cars:
1994 BMW 850 CiA (2017 km). My black on black Wokke'd 5.4l V12 autobahnmuncher
1992 Donkervoort S8AT (105k km). The mad dutch "Super 7." 300hp/ton of turbo power!
2013 VW Caravelle 4Motion (57k km). A dark wine red 180PS/400Nm 2.0 BiTDI rocketvan
2007 SMC F-Kart 50. 88cc of street legal go-kart hilarity, and a 1968 Cadillac Coupé DeVille Convertible 472.
"The best way to go broke-by-german-car is to buy an 8 series bmw with a v12" - Perc
"Torque is like pron. You can't really define it, but you will recognize it." - ElToro
Brilliant plan - and I'll help as much as I can.
Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i
My BMW Repair YouTube Channel
My Current 840ci Sport Individual
My Current 650ci Sport Individual
My E31 Repair and Information Website
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No one said the auto tranny is that much faster and above values are like fuel consumption values. All measured under top conditions with professional drivers I guess.
And BTW, compare the standing start kilometre: 0.7sec between auto tranny and 6-speed with the M70 engine - WOW
And the 80HP more powerful CSi in the same discipline outperformes the 850i by just 0.8 sec.
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something I'm absolutely non familiar with - yet
If you can offer a relatively easy way of adapting the 5HP tranny to the OBD I M70, you'll have a customer on this end.
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