OEM-level 8HP swaps in E-series cars

MR-KRAKA

Specialist
May 23, 2020
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"unfortunately n63 flex plate has 9 bolt and n54 has an 8 bolt crank. There is not really an easy way to adapt this unless you make a special flywheel, doable but a lot more expensive" from DomiWorks

I guess I'll search for an N57 8hp70/75 from a seller across the pond
What if you were to grind the rivets off the torque converter and mate/weld the 6hp plate to it? Of course only if they line up correctly. I count 12 rivets on my old 6hp21x I have laying here. If you were to use an adapter I believe you will be needing to shorten your driveshaft as well. On my xi it is a tight fit…
 

TheFixer

Sergeant
Aug 16, 2020
493
352
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Tennessee
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2008 535i
if you do it I’ll go buy another 5 series and do it to.
If an 8hp falls into my lap I will. I know a few places I can get one cheap.

Crazy though. Three years ago I was wondering about swapping an 8hp in. Hardly anything about it then.

Only conundrum I have is I refreshed my 6hp almost two years ago. Rebuilt the valve body. New mechatronics. New seals. Running xhp on it. The difference was night and day afterwards.

But an 8hp in it..... man it will be even better.

Ugh!
 

taylorw2421

New Member
Oct 10, 2022
2
1
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2009 ST BMW 335i Xdrive
Im looking into doing this and want to make sure I have all the needed parts on the shelf ready to go.

2009 BMW 335i Xdrive

Acquired a 8HP45 from a 2011 BMW 535i Xrive
Shifter from the same vehicle

will be purchasing the cantcu
connectors
cooler fitting adapters
shifter adapter
connector kit

What else will I need to find or purchase to make this as seamless and easy as possible?
 
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MR-KRAKA

Specialist
May 23, 2020
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55
0
Im looking into doing this and want to make sure I have all the needed parts on the shelf ready to go.

2009 BMW 335i Xdrive

Acquired a 8HP45 from a 2011 BMW 550i Xrive
Shifter from the same vehicle

will be purchasing the cantcu
connectors
cooler fitting adapters
shifter adapter
connector kit

What else will I need to find or purchase to make this as seamless and easy as possible?
Ideally you would find an 8HP45 from a N55 powered xDrive vehicle so it bolts right up to the N54. You are going to have a tough time making that bolt patter/torque converter work for you. I don’t think there is any room to be adding adapter plates without going to a custom driveshaft for xDrive cars. I highly recommend selling the one you aquired and finding one of the many available from an N55. You will also need to get the EGS security reset on the donor trans so figure out the method you will be using on that front. Other than that you should be good with the rest.
 
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taylorw2421

New Member
Oct 10, 2022
2
1
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2009 ST BMW 335i Xdrive
Ideally you would find an 8HP45 from a N55 powered xDrive vehicle so it bolts right up to the N54. You are going to have a tough time making that bolt patter/torque converter work for you. I don’t think there is any room to be adding adapter plates without going to a custom driveshaft for xDrive cars. I highly recommend selling the one you aquired and finding one of the many available from an N55. You will also need to get the EGS security reset on the donor trans so figure out the method you will be using on that front. Other than that you should be good with the rest.
My apologies it is from a 2011 535xi, n55 powered. I will correct my original post
 
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Svmp

Specialist
Dec 23, 2019
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M50 DCT & M57 DCT
You will also need to get the EGS security reset on the donor trans so figure out the method you will be using on that front.
Nowadays this can actually be done through CANTCU without any extra hardware/software, just a remote flashing session after everything is installed and wired up. :cool:
 
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135boost

Corporal
Oct 28, 2017
243
1
136
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Finland
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135is
I'm just building a zf6hp28 swap to mine because after all issues regarding misfires and things got my car run properly and first tests, first full pull i broke my e clutch shaft. That was with only 27psi and shifts at only 7krpm.

Got on dragy some 4.6s 100-200kph, assume it will run 4.0-4.3s on full boost.

Some 8hp75 could be a choise too instead of this 6hp28
 

Svmp

Specialist
Dec 23, 2019
62
69
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M50 DCT & M57 DCT
I'm just building a zf6hp28 swap to mine because after all issues regarding misfires and things got my car run properly and first tests, first full pull i broke my e clutch shaft. That was with only 27psi and shifts at only 7krpm.

Got on dragy some 4.6s 100-200kph, assume it will run 4.0-4.3s on full boost.

Some 8hp75 could be a choise too instead of this 6hp28
Yea, surely a lot of power there, very nice! :sunglasses:

A 8HP70/75/90 would be a good alternative for the 6HP. The 70 takes around 1100Nm (800ft) of torque in stock form, and the others some more. With enough abuse, anything will break though. :grinning:
 

135boost

Corporal
Oct 28, 2017
243
1
136
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Finland
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135is
Some weldings and machining works
16657576305726872750442800784749.jpg
 

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MR-KRAKA

Specialist
May 23, 2020
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Nowadays this can actually be done through CANTCU without any extra hardware/software, just a remote flashing session after everything is installed and wired up. :cool:
You’ve been busy I see. Looking forward to the next update 👍
Some weldings and machining works
View attachment 74819
Wow if you weren’t so invested in the 28 I would say go 8HP70 but I can understand why you wouldn’t want to now seeing those pictures. So you converted the 6HP28 to xDrive by welding the tail/output shaft of the 6HP19/21 housing if I’m looking at that right? Your dedication to this project is impressive and so are those times on “low boost” I’m sure it will be all worth it once it’s all bulletproofed. And all in a xDrive converted 135 no less 👏
 
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135boost

Corporal
Oct 28, 2017
243
1
136
0
Finland
Ride
135is
You’ve been busy I see. Looking forward to the next update 👍

Wow if you weren’t so invested in the 28 I would say go 8HP70 but I can understand why you wouldn’t want to now seeing those pictures. So you converted the 6HP28 to xDrive by welding the tail/output shaft of the 6HP19/21 housing if I’m looking at that right? Your dedication to this project is impressive and so are those times on “low boost” I’m sure it will be all worth it once it’s all bulletproofed. And all in a xDrive converted 135 no less 👏
I had to swap front end too because diesels different bellhousing but now it's done
There is only few things to mod to get 6hp28 fit even as xdrive.
This test is so cheap, 28 trans for free, 21xdrive few hundred euros, maybe 20h labour by me and wear parts to trans. If this blow up, then it's 8hp time. Those 19-21 are native 400nm trans with added clutchplates to raise torque rating to 600, 28 is native 700nm trans with much beefier internals, maybe 30%, only consern at the moment is that e clutch shaft what is maybe only 15-20% more torque rated.
 

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doublespaces

Administrator
Oct 18, 2016
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2009 E93 335i
Maybe this was answered already, but how do the extra two gears come into the picture?

Continuing to hit the paddles, does what?
 

MR-KRAKA

Specialist
May 23, 2020
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Maybe this was answered already, but how do the extra two gears come into the picture?

Continuing to hit the paddles, does what?
I’m not sure specifically what you’re asking. As far as Kombi goes it works as if oem in D,S,M1-8. For the DME side it’s requesting or repeating the shift from 5-6 for the additional two gears IIRC. On the TCU side as far as it knows it’s still humming along with the F series it came from. There’s some coding involved in initial setup to make everything play nice then the Cantcu handles the communication between the 8HP TCU and the Car. Ken will be able to to get you a cleaner answer for sure.
 
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zyj98yj

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Oct 27, 2022
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E9X does not have ECO Pro/Comfort/Sport/Sport+button,how to selection Drive Mode ?
 

MR-KRAKA

Specialist
May 23, 2020
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E9X does not have ECO Pro/Comfort/Sport/Sport+button,how to selection Drive Mode ?
In the software you setup your default setting and one other to use with the DTC button single or long press. I assume most would be set up as mine is default Comfort and Sport+
 
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zyj98yj

New Member
Oct 27, 2022
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In the software you setup your default setting and one other to use with the DTC button single or long press. I assume most would be set up as mine is default Comfort and Sport+


thanks,When using the DTC button to select the driving mode, does the DTC function turn on and off at the same time?
 

MR-KRAKA

Specialist
May 23, 2020
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thanks,When using the DTC button to select the driving mode, does the DTC function turn on and off at the same time?
Yes, so if you want DTC fully on for whatever reason you will need to set your default mode to the aggressiveness you want there. I’m sure many people just run Sport+ all the time too.
 
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