[ab987]

Hi all,

Documenting my swap from my factory 6MT (S6-53BZ) to an 8P70H because I don't see any good build threads around. It's internally similar to an 8HP70, with one difference covered later on in the thread that means you will have to open one up if you want it to work. No, 8P70H is not a typo, it's not an 8HP but is instead an 8P, because from the factory it does not come with a hydraulic torque converter and instead a clutch pack and electric motor (which we will be swapping out for a torque converter anyways). The first post will be a lot of the build plans, theory and information I have collected along the way through RealOEM, TIS, and comparing internal parts listings on eBay for part numbers, so if you want to get to practice, skip to the second post. If anything here is wrong, don't hesitate to speak up, I want this to be 100% correct for a point of reference.

This one won't quite be your regular 8XP70 swap, as I'm planning on keeping both the clutch and the H-pattern (I'll get to this later). I'm also using an N55 ActiveHybrid 5 8P70 rather than the usual N57 8HP70 + adapter plate solution. I'm not 100% sure that it will work, but so far everything I've seen indicates it should. The input shaft seems to be the same as an N57 box, the oil pump is the same PN, and the valve body also seems to be the same PN with a different revision between 2 other regular HP70s (-598 vs -426 and -666).

The N55 8P70 also seems to be the same length as the N55 8HP45, meaning I should be able to use a factory N54 flex plate with a factory N55 8HP45 torque converter (assuming input shafts between HP45 and 8P70 are the same diameter and spline layout) and spacing should be perfectly factory with no adapter plate nonsense. It is about 25mm longer than an S6-53 and a hair longer than a 6HP21, so we will be using a 335D driveshaft which is 6mm shorter than the auto driveshaft. It interestingly also has the 8HP45-sized 18mm cooling channels if RealOEM is to be believed, so I can grab an HP45-AN adapter from Domiworks and run some braided line to a 10-row oil cooler mounting where the 335is auxiliary cooler would go. We'll see how it goes with no thermostat.

Let's explore the ActiveHybrid 8P70 gearbox as well because there really is not much information around on these at all. There are 5105 total ActiveHybrid3+5+7s in the world, with 1592 in the US and 3513 elsewhere. This makes the gearboxes REALLY hard to find in the US. When I bought mine, there were 4 total gearboxes listed in the US (3 for $1900-2600 without the HCC, and mine for just over $700 with HCC and 83k miles, absolute steal!) and none anywhere else worldwide. The first generation AH7 (2009) is also completely different, it's actually an 8HP70H which has both a converter and motor, plus it's an N63 box, so that won't work for us.



Those of you that are keen-eyed will notice right off the bat that this looks... familiar but different. I know, it's dirty, I'll pressure wash it this weekend. For one, there are 2 connectors on the left rather than 1, and there is another on the right. Well, the bell-housing connector should be rather apparent - it's connected to an electric motor sharing a housing with something called a hydrodynamically-cooled clutch (HCC). It's not a torque converter, but instead a huge clutch pack that must be controlled similarly to a DCT. If you know anything about AMG MCT, those also use a similar design.



It has 2 sets of internal splines compared to the usual 3 we see on 8HPs, but otherwise has a normal-looking 8HP70 input shaft and bell housing.




Let's look again at that extra connector on the left.



This connector confused me at first, but BMW described it well in the "Drive ActiveHybrid" functional description. Regular 8HP-HIS (boxes suitable for start-stop) have a pressure accumulator so it can actuate solenoids and select gears while the engine is off. There's an additional challenge here with an HCC - without oil pressure, the clutch pack is unlocked and the input shaft doesn't spin. Because oil pressure that locks the clutch pack comes from the input shaft spinning the mechanical oil pump, it's a bit of a chicken-or-egg situation. Therefore ZF/BMW has chosen to replace the accumulator with an electric oil pump to both select gears while the HCC is unlocked, and provide the HCC with the pressure it needs to lock, and that's what that connector is for. Cool stuff!

Obviously because we are running a conventional torque converter that's always spinning with the engine, this is no issue for us.

Okay, it's time I explain how I'm doing this whole H-pattern+clutch thing. I'll be gutting the factory TCU and soldering it up for a TurboLamik TCU, which provides clutch-by-wire for 6HP and 8HP out of the box. They integrate well with our E90s and show up to 8 gears on the dash like factory, transbrake, support multiple programming modes, auto-learn, do everything over CANBUS including torque reduction (and blips coming very soon), basically a dream for those that want their gearbox to act exactly how they want it to, and still act like it came from the showroom floor. Really cool stuff!

What it doesn't support out of the box is an H-pattern. That burden falls on me. For this I've chosen an ESP32 because of how insanely cheap and powerful they are. I know they aren't automotive rated and the 3.3V operating voltage may be interesting, but I should be able to map the Lamik to accept 0-3.3V for all necessary inputs and outputs, or worst case make a simple voltage divider. I'm writing a Lamik library in Rust and will be using it in a modular fashion to interface with the TCU. It'll read what it needs via analog inputs with an ADS1115 ADC as well as CANBUS with a transceiver, and have a nice little OLED screen that will output everything we want to know. That'll all be open-source and I'll publish the repo link here once it's ready for consumption along with a PCB that will make things easy!

Of course, you can't shift an H pattern into "automatic." That's why I also bought an LCI steering wheel with paddles for sub-$200 and of course I wanted the ergonomic shape.



The ESP32 will define the behavior, and I'm still working on defining the behavior. The H pattern will always override the paddles, but the paddles will handle shifting from Neutral to Reverse (left) to Drive/P1 (right) to Sport/P2 and finally to "M2"/P3. Holding right paddle will go back to drive, and holding both will activate our favorite feature, transbrake. Park will act like a DCT M3 where it will do it by itself when you shut off the car. At any moment you can start using the H-pattern which will probably select 2-7 because 1 will be utterly useless. The ESP will send upshift/downshift signals to the TCU which will hopefully handle skip-shifting without delay. Maybe I can convince the guys at TurboLamik to add proper support if it turns out well, so far they seem hesitant.

The H-pattern itself will be tough. I could 3d-print some retention mechanism and design some fancy potentiometers but I am thinking a really nice sim shifter might do better in the end, with some 3d-printed adapter for my factory shift knob. That's where you all come in - does anybody have a sim shift apparatus that has really nice effort and feel?

This all sounds great in theory, but let's get into practice!

[ab987]

Alright, first thing's first - mounting the gearbox in the car. Andrew from Zero to 60 explains well in his YouTube video that neither an F30 8HP45 or E9X 6HP19/21 mount will work. In my case nobody has documented (to my knowledge) going from S6-53 to HP70, so tonight I pulled off my S6-53's bracket to see.




Not a chance. This one seems even smaller than a 6HP bracket. I've ordered a 6HP28 335d bracket which should bolt right up on the 8HP70, and will have it either tomorrow or Monday to test out. The only question mark is whether or not the mount spacing and keys will fit up to the manual cross-member. Time will tell, and hopefully the front-to-back spacing is good too. Time will tell!

[ab987]

Onto electricals while I wait for the bracket. I'm looking to recreate whatever parts of the 6HP harness are used in the Lamik 6HP adapter (which I don't know yet).

Here's what I need to pin/re-pin so far:
- Pin paddles, pins 22 and 38 on the blue JBE connector/X14271. I found the terminal connectors here. Also ordered a set of JBE connectors off of eBay just in case I can't figure that out which works out to be ~$0.10 per terminal.
- Re-pin/tap PT-CAN! H and L are 1 and 2 on X14271 (blue JBE connector) respectively (red and red/blue), so I will likely be purchasing some male and female terminals so I don't need to modify any factory harnesses. Also messed with the ESP32 along the way and dumped some PT-CAN messages over wifi, these things are really neat.

> ~/rust/CAN/target/debug/CAN
BMW Frame: EngineData(EngineData { coolant_temp: 16, oil_temp: 27, alive_counter: 7, engine_state: Off, warm_up_state: WarmingUp, ambient_air_pres: 980, injection_amount: 0, shift_lock_control: NotRequired, rpm_idle_target: 775 })
BMW Frame: EngineData(EngineData { coolant_temp: 17, oil_temp: 27, alive_counter: 70, engine_state: Off, warm_up_state: WarmingUp, ambient_air_pres: 980, injection_amount: 0, shift_lock_control: NotRequired, rpm_idle_target: 775 })

Back on track.

- Power. Because I want the lamik to have its own fuse, why not use fuse 22 like the factory TCU? I pulled out the fuse box and it's not pinned in pin 2 of X11003 (black connector on the back of the fuse panel behind fuse 22). Normally it's a harness that goes through the E-Box in some purple connector that feeds power, terminal 15, and PT-CAN to the gearbox in a harness that goes under the cowl. Luckily BMW sells both standalone contacts and pre-crimped contacts.
- Terminal 15. I was originally going to grab it from CAS, but if I'm already tapping into JBE I may as well grab it there too. Connector X14271, pin 45.
- Ground, of course. Haven't decided where I'm getting this yet, might tap into something, might just bolt a nut to the chassis somewhere. I'll look around.

Here's what I probably need to pin/repin:
- Clutch safety should be de-pinned and moved to the lamik. For this build I may leave it because the clutch pedal will be functional. If you are getting rid of the clutch, de-pin pin 4 on X13635 (blue/black) and move it to the lamik.

I'll check back in tomorrow with bracket findings.

[ab987]

Quick little update - dealer did not have the bracket in time, and I'm headed out of town. Have a Ryutech PCB and Domiworks oil cooler AN adapter on the way. Looking into a small core and braided lines to button it all up - and might replace rod bearings because of the car's history and nuggets I've found in the filter recently.

In terms of electricals, I'm considering fitting the TCU in the e-box and routing a harness through the firewall because I need paddle inputs anyways and want the E-box to look clean. Found some TE MQS bushing terminals that are the same 1.8x1.8 dimensions as the JBE's, so I am also looking at male spades and making proper harnesses with a 2x2 connector. I'll post the specs if they fit up.

Next post will be in a few weeks when I'm back. Happy late Thanksgiving and can't wait to get the car back on the road!

[Hoody007]

This is a super interesting build!
What was the main reason for going from 6MT -> 8AT?

[Dave92N54]

I don't think i'd ever want anything but a GS6-53bz in my E92 but man, i'm subbing. This is awesome.

[ab987]

Originally Posted by Hoody007

This is a super interesting build!
What was the main reason for going from 6MT -> 8AT?

There's a couple big ones. There's one that you are probably familiar with, Atlanta traffic. Feel like I'm always going just slow enough where I can't be in 1st and slipping the clutch into oblivion. Another reason is the input shaft bearing making noise on this gearbox and the price of used boxes/inability to source a new input shaft bearing. Final reason is why not? Super stout gearbox (some folks are pushing 1100ftlb+ on stock hardware), it was cheap, and the duality of an auto with 3 pedals and h-pattern seems like a really cool idea that nobody (bar somebody named Christian) has tried.

[bantam]

This looks like a cool project! Glad to see some real projects still taking place on this forum.

I did not entirely understand, what is the function of the clutch pedal going to be in this application?

[ab987]

Originally Posted by tharptroy

This looks like a cool project! Glad to see some real projects still taking place on this forum.

I did not entirely understand, what is the function of the clutch pedal going to be in this application?

The clutch will disengage whichever clutches are engaged in the gearbox to functionally decouple the gearbox and motor. Could use it for clutch kicks or simply trying to replicate a manual gearbox. Why? Because why not?

As an update, pretty much have everything I need at this point to get the car driving besides the ZF8 service kit and cooler. Got a set of used JBE connectors for all of the spades, and ended up finding the genuine part numbers for not only spades, but also crimped spades, crimped terminals, and a male/female 6-pin MQS connector so we will end up having a 100% factory component harness for the lamik! How cool.

Also got the ryutech TCU PCB and billet cover, Domiworks HP45/N63 HP70 to 10AN adapter (note the N57 box is different), all new guibo nuts/bell housing bolts, and the 6HP28 bracket from Germany.

Also decided I am going to try and fit the lamik into the E-box so everything is out of sight. Out of town until Sunday and then it's go time. Ill try and fit the gearbox first and see how well it fits.

[iqraceworks]

Really cool idea...looking forward to seeing how this all works.

But like others have said.....it seems way too complicated than it needs to be, but I guess that's half the fun.

[feuer]

Drifter guy name Dan in Australia has build e46 with single turbo n54 stand alone, no DI, ZF8HP 90 from diesel, with clutch pedal and shifter. He used some hydraulic throw out bearing and valve spring to replicate the true clutch feel. Lamik TCU transmission control from Poland. I have heard that some company from Michigan, Seems Legal or Seems Legit ???, does the same, minus the standalone for the n54, for lot more money. I’m going for trans 8 speed as well for my single turbo n54. Probably will go for zf8hp45/50 as is direct for from n55 engine. If that transmission doesn’t hold then next choice will be from b58, 340i/440i or Supra. Would not go for ActiveHybrid trans as is unnecessary more involved.

[ab987]

Had my first day back, still waiting on the electronics I ordered last week as well as picking up the 335D trans bracket, but I bring awesome news.

HP45 converter fit right up perfectly to the HP70. Looks like the flexplate is probably roughly in the correct position too, meaning everything is more than likely going to bolt right up like factory!



DomiWorks HP45 cooling adapter also fit right up just as I expected, use that instead of the usual N57 HP70 cooling adapter if you go the ActiveHybrid HP70 route.

[ab987]

Originally Posted by feuer

Drifter guy name Dan in Australia has build e46 with single turbo n54 stand alone, no DI, ZF8HP 90 from diesel, with clutch pedal and shifter. He used some hydraulic throw out bearing and valve spring to replicate the true clutch feel. Lamik TCU transmission control from Poland. I have heard that some company from Michigan, Seems Legal or Seems Legit ???, does the same, minus the standalone for the n54, for lot more money. I’m going for trans 8 speed as well for my single turbo n54. Probably will go for zf8hp45/50 as is direct for from n55 engine. If that transmission doesn’t hold then next choice will be from b58, 340i/440i or Supra. Would not go for ActiveHybrid trans as is unnecessary more involved.

Yep, in contact with Dan, great guy. IIRC he's also using an N57 HP70 box. Single turbo N55s burn up HP45s pretty quickly so the general recommendation for these is the HP70. HP45s usually get dodgy around 700Nm and HP70s are known to hold 1300+ when in good condition.

ActiveHybrid trans may be negligible added work compared to the HP45 and of course is a lot more beefy being an HP70, for a ST car like yours I would personally go with it. Same HP45 cooling adapter, just buy an N55 HP45 torque converter and 335D bracket and I think you're good to go. I'll test fitment with the factory cross member and N54 flexplate this weekend. Cheers!

[mistawall]

CMON I NEED UPDATES, im actually considering the same. ive been reaching out to dismantlers in germany trying to find one that will ship n57 8hp

[mistawall]

Originally Posted by Hoody007

This is a super interesting build!
What was the main reason for going from 6MT -> 8AT?

so n54 can actually be fast. guy in poland did 9.9 with 8hp70

[ab987]

Originally Posted by mistawall

CMON I NEED UPDATES, im actually considering the same. ive been reaching out to dismantlers in germany trying to find one that will ship n57 8hp

Haha it's been a busy week but I'll try and fit the cross member to see if it'll fit tonight. Looks to me like it should. Also receiving the very last of what I need for the basic swap today, so next weekend I'll probably start and finish it. I am doing struts right now too so I might get it aligned Monday so I don't cause confusion with an 8HP and a floppy shifter and clutch.

[ab987]

Guys, the factory crossmember fits right up. No surprise though because I used an E90 N57 6HP28 bracket. Today I'll do the TCU modifications with the ryutech board and I'll power it up from the car for the first time. Will be getting the car aligned if it feels like it needs it, otherwise I'll go ahead and start pulling the S6-53!

[mistawall]

im finding a few GA8P70HZ from the active hybrids. i assume this is a variation and not the same as the 8hp70 from active hybrids? did you come across this?

edit: OK it appears they moved the H to the end to define HYBRID

[ab987]

Originally Posted by mistawall

im finding a few GA8P70HZ from the active hybrids. i assume this is a variation and not the same as the 8hp70 from active hybrids? did you come across this?

edit: OK it appears they moved the H to the end to define HYBRID

Yep, you got it! You may want to pick one up if you can find em cheap - I can never find them sub-$1700.

Quick update, investigated some extra vane that the HP70H has, and turns out it's probably identical to other 8HPs albeit this shifted hole with a vane. Will it affect anything? Unlikely.




After making that discovery, did the usual TCU modification.




Gearbox is ready. Put on the special HP70H oil pan and booted up the gearbox with the lamik - no errors! Time to get this thing in the car.

[ab987]

Well, pulled out the S6-53 and it's not looking good. The 8HP is definitely about 20mm longer so the factory 6MT cross member definitely won't work. Luckily I found an auto one half an hour away for $15. Should close the gap.

Speaking of closing the gap, the driveshaft is probably too long as well. I will try it just to see but I don't have high hopes. Good thing I have a 335D driveshaft sitting around, ordered a 50mm crowfoot just in case I need to swap them over.

There's gotta be a bright side right? Well yeah. Wiring is all done and I booted up the TCU with the gearbox - no errors! CANBUS is setup properly, it detects paddles with the signal wire plugged into A6 out of the box, everything's working beautifully. Just need to sort out the mechanical side 😒

[ab987]

Good news - everything is bolted up and it all fits perfectly, just like factory. Converter has 2-3mm of clearance which I'm told is normal for 8HPs. Only one problem - I tried using 6MT bell housing bolts. These are 90mm compared to the 75mm 6HP/8HP bolts, so I'm bottoming out on all 5, even with a few washers on some. Gonna cut the bolts down tomorrow and put them back in - then work on cooling and hopefully do our first start!

[mistawall]

Originally Posted by ab987

Good news - everything is bolted up and it all fits perfectly, just like factory. Converter has 2-3mm of clearance which I'm told is normal for 8HPs. Only one problem - I tried using 6MT bell housing bolts. These are 90mm compared to the 75mm 6HP/8HP bolts, so I'm bottoming out on all 5, even with a few washers on some. Gonna cut the bolts down tomorrow and put them back in - then work on cooling and hopefully do our first start!

Love to hear it, was there any reason u went with lamik over htg? I’ve been researching and I’m finding a lot of unhappy htg campers