100 Series LX470 8HP swap

[Papa Wickey]

Starting this thread to have something to point people to while documenting my swap. Much of the info I have gathered has come from this thread as well as this thread in the 80 series section.
I will still post some updates in the original thread but I'm going to try to move the bulk of my traffic here. I will be doing my best to document all of this as the only other place I have found a real wealth of info has been from @OutlawMike many thanks to him for pioneering some of these pieces and working with Domiworks on adapters.

When I bought my Lexus I wasn’t really thinking anything about this. I just wanted to have a cool old 4x4 since my 3rd gen T4R died a rusty death. But here we are, I’m trying to swap my 4 speed for a ZF8HP. I’m not the first one to do this but I haven’t really seen much documentation on this so figured I might as well do it.

 

[Papa Wickey]

took a bit of a gamble and grabbed a spare HF2A out of a 91-92. Not sure if the output shaft from the A440 will match up to my current A343 but I am hoping to do a under drive, maybe a low range kit for my transfer case so I was hunting for a donor case.
The main thing though is I’m trying to get the input shaft with the underdrive kit so I can attempt to start a 8hp swap

 

[Papa Wickey]

I had been trying to figure out what 8hp I wanted to go with for this swap. I had seen some swaps done overseas but I found out most of them tend to use the N57/M57 diesel 8HP70 found in a plethora of BMWs overseas. Diesel BMWs in the US are much less common so options really narrow down to BMW and Dodge transmissions since Stellantis (overall Dodge/Fiat owner) licensed ZF's transmissions.

There are adapters out there for UZ to 8hp but what is important to note is the different bell housing sizes of all the 8HP models. The N57 is the same pattern as the B58/S58 motors in US spec M cars or M sport(lite) models but mostly those are 8hp45-50. The next BMW candidate is the N63 8HP, otherwise known as the "medium" bellhousing which is found in cars like the M550 etc 4.4L turbo V8s. Finally there is the Dodge adapter for the 8hp that uses the Hemi bolt pattern. which is the bigger bellhousing (mainly for the Hellcat's 8HP90). However since the dodge version has the starter low on the passenger side I was slightly adverse to that for trying to clearance my transmission tunnel.

So after frustrating myself trying to hunt around on marketplace for an 8hp I eventually landed on ebay. I found 2 local-ish wreckers, one had a lot of Dodge transmissions and a few BMW trans, and another that had strictly BMW parts.
I had read into the service life for these transmissions and found that while most car manufactures went away from trans dip sticks and maintenance intervals, with BMW calling the transmission fluid "lifetime" I found that ZF stated that their scheduled service interval for the 8HP family was 50-75k miles/8 years.

I then was able to find a low mile BMW M5 transmission and made my way over to pick it up.

 

[Papa Wickey]

This transmission is stated to have been pulled from a 2018 M5 with 43k miles but we will see what the condition of the fluid looks like. I am currently waiting on one of these domiworks adapters from drift HQ so I can replace the a440f input axle with one that will slide onto the AWD 8hp output shaft

After talking with another mudder on here, also doing the swap on his SAS'd 100, @TrailBornRunner the N63 trans should be a pretty close match for the a343f so hopefully with adding 37mm/1.45" for t case adapter and 20mm/0.78" bell housing adapter I will only need to make some slight adjustment to the driveshafts vice getting custom shafts. But that is still TBD.

Up next will be trying to get a rebuild kit for my 91 HF2A from @cruiseroutfit so I can install the new input axle with fresh bearings and seals since it came from a 224k mile 80 series cruiser.

 

[Papa Wickey]

Additionally I have started to post videos on my Youtube channel so expect some updates there as well.
First actual video (it's just me talking about the swap):

 

[cruisermatt]

Subscribed.

 

[Papa Wickey]

I had some comments about why 8HP over something like the the 5 speed offered in the 100s in other world markets (H151F). Initally it was about gaining more gears for me but then I learned about the much greater spread of gear ratios.
Gear Ratio Comparison Table

Transmission	1st Gear	Top Gear	Total Spread
A343F (Your Stock 4-Spd)	2.80	0.75 (4th)	3.73
A750F (03-07 5-Spd Auto)	3.52	0.71 (5th)	4.95
H151F (Land Cruiser 5-Spd Manual)	4.53	0.88 (5th)	5.14
CD009 (Nissan 6-Spd Manual)	3.79	0.79 (6th)	4.79
8HP75 Gen 1 (Ram 1500)	4.71	0.67 (8th)	7.03
8HP75 Gen 2 (Your BMW F90)	5.00	0.64 (8th)	7.81

Between the available options, I had seen some also talking about swapping a CD009 manual 6 speed from a 350Z/G35, the 8HP gives a much greater spread with a very deep 4.71/5.00 1st gear over the 2.80 in my factory transmission. From my reading it's not very possible to swap one of the 03-07 100 series 5 speed transmissions due to the differences in engine/ECU. ex the 03+ got a drive by wire throttle and the 06/07 are also VVTi. The 1st gear in the Toyota 5 speed manual is deeper still than the auto options across all years but the top gear suffers a bit which would result in higher RPM at speed on the highway.

It was also at this point that I found out that the 8HP offered in the RAM transmissions also use the gen 1 gear ratio vice the F90 transmission I picked up has the gen 2 gear ratios resulting in a deeper first gear and an even taller 8th gear so hopefully I can expect a decent increase in range/drivability while also potentially not needing to regear my differentials from the stock 4.30 ratio in the 98-02 (4.10 in the 03-07).

I am still thinking I will probably add 4.88 gears down the line but that will be more to deal with added weight from bumpers/ and ideally an LRA aux tank and maybe trying to run 37s.

An additional possible data point is when I was looking through @OutlawMike swap he also has a 1" body lift on his 80 series using his ram 8hp and I wanted to avoid doing any body lifts if possible though I may need to later down the line if I end up trying to do 37s.

 

[excessive]

honestly i think it would make more sense to sell yours and buy a 2004+ that already has the 5 speed

 

[Papa Wickey]

honestly i think it would make more sense to sell yours and buy a 2004+ that already has the 5 speed

But that's not the fun way that involves me spending a bunch of money. Plus I like my early LX interior

 

[hoser]

I am still thinking I will probably add 4.88 gears down the line but that will be more to deal with added weight from bumpers/ and ideally an LRA aux tank and maybe trying to run 37s.

The '16+ AE60F 8sp Transmission has very similar gearing to the 1st Gen 8HP75. I'd say the 4.1/4.3 gearing would be best for 35-37" tires. 4.88's would make 1st gear nearly unusable in road use. Do you know if the controller can force 2nd gear starts with the ZF transmissions?

 

[Papa Wickey]

The '16+ AE60F 8sp Transmission has very similar gearing to the 1st Gen 8HP75. I'd say the 4.1/4.3 gearing would be best for 35-37" tires. 4.88's would make 1st gear nearly unusable in road use. Do you know if the controller can force 2nd gear starts with the ZF transmissions?

The turbolamik can do 2nd gear starts and you can still have the 1st gear in manual mode. I’m thinking the ideal path for this will be the transmission on stock gearing first and see how it behaves with my current mud tires before I swap to a/t or r/t tires, the mud tires came on the truck when I bought it so I’m gonna try to run them down before I swap on another set.

As far as gears themselves stock gearing should do well enough given my current setup I just think with going up in weight it may necessitate shorter gears. 4.56/4.88 are on the table right now but I think post trans I’m going to try for a bumper.

 

[hoser]

These 8sp transmissions typically run a final drive ratio of 3.2:1 or 3.3:1. Going to 4.88's is a ~50% increase. That's like going from a 31" tire to a 45" tire.

 

[Papa Wickey]

These 8sp transmissions typically run a final drive ratio of 3.2:1 or 3.3:1. Going to 4.88's is a ~50% increase. That's like going from a 31" tire to a 45" tire.

That is a very good data point and also letting me know that ideally best case scenario I keep my current 4.30 diff gears and I won’t need to spend any extra money on a re-gear, just lockers install down the line. I did look into what people with the 2016+200s are running and at most, I’m seeing a 3.9 gear ratio so I think I should be pretty safe not touching my differentials.

 

[AnthraxVX]

im stoked on ur build, how are you going to control the transmission? i was under the impression that the transmission computer is tied to the engine ECU, im in california and cant swap that because of CARB. how are you planning on the transmission control and also what are you going to do about the gear shift lever.

Just noticed ur in san diego, im up in murrieta now, lmk if you need any help or want to plan anything out, i have like every tool i have a lift but my garage doesnt accommodate the lx on the lift because of height, just the s2000 and wifes car etc. was going through this and we totally have to keep stock ecu for carb.

 

[Papa Wickey]

im stoked on ur build, how are you going to control the transmission? i was under the impression that the transmission computer is tied to the engine ECU, im in california and cant swap that because of CARB. how are you planning on the transmission control and also what are you going to do about the gear shift lever.

Just noticed ur in san diego, im up in murrieta now, lmk if you need any help or want to plan anything out, i have like every tool i have a lift but my garage doesnt accommodate the lx on the lift because of height, just the s2000 and wifes car etc. was going through this and we totally have to keep stock ecu for carb.

View attachment 4084569

My plan is to use a turbolamik TCU on this build, @TrailBornRunner is doing the MaxxECU for his N63 8HP70. The turbolamik is acting as an external TCU whereas the Maxx is using the factory TCU to communicate to the maxx and push data back and forth from the engine and stock TCU.

I believe I will lose VSC/ATRAC once I do this swap but I'm not that worried about it and I should be able to fool any CELs with either the ATEMU or power resistors. On how it will affect smog I'm not totally sure, I have to do my next smog check in August so I may wait and see, I can check "emmissions status" with my scanner so I might try to unplug the transmssion connector and see what pops up. I believe I shouldn't have any limp mode issues but that still remains to be seen.

For the gear selector, I have a bambu printer with some PETG and ASA filament so I wil likely try to figure out out to make a plate with a cutout for ideally an A90 shifter or possibly a DCT style sequential shifter with another spot for the mode select switch. Maybe a CAN touchpad if I go the DCT route.

 

[GTV]

Cheers to you for taking this on, my kinda project!
You won't need to touch the gearing, that's the beauty of having 8 speeds. Unless you wanted a wicked low crawl ratio in the t/c.
It will accelerate like it has a supercharger while netting better mileage. At least in my dreams

 

[AnthraxVX]

My plan is to use a turbolamik TCU on this build, @TrailBornRunner is doing the MaxxECU for his N63 8HP70. The turbolamik is acting as an external TCU whereas the Maxx is using the factory TCU to communicate to the maxx and push data back and forth from the engine and stock TCU.

I believe I will lose VSC/ATRAC once I do this swap but I'm not that worried about it and I should be able to fool any CELs with either the ATEMU or power resistors. On how it will affect smog I'm not totally sure, I have to do my next smog check in August so I may wait and see, I can check "emmissions status" with my scanner so I might try to unplug the transmssion connector and see what pops up. I believe I shouldn't have any limp mode issues but that still remains to be seen.

For the gear selector, I have a bambu printer with some PETG and ASA filament so I wil likely try to figure out out to make a plate with a cutout for ideally an A90 shifter or possibly a DCT style sequential shifter with another spot for the mode select switch. Maybe a CAN touchpad if I go the DCT route.

sounds like u got a good plan, let me know if u need anything , got 3d scanners, vorons, just ordered a fiberseeker 3 and a DMC2 mini that should be here soon. I do conceptual design/engineering for my drone company so this stuff is relatively easy to make inserts/mounts etc, you have a resource local if u need it

 

[Papa Wickey]

Finished the partial teardown/inspection of the transmission. Everything seems pretty good, trans fluid doesn't smell burnt. Didn't break anything that I can't get a replacement for ($20 TCU connector sleeve).
For the future if you're trying to do this You need some picks, 8mm/10mm hex, T40 and T30? (I used a T27) to get the pan off and valve body out. The oil pan/drain plug is plastic and the transmission filter is integrated to the pan, or it seems that way when I pulled it.
Don't do what I did and pull all the big T40s before you remove the TCU connector sleeve, pull the start stop tube, then the sleeve before you move onto unbolting the valve body.
Once you get the valve body off need to get a solenoid at the end of the valve body off (just the connector) and another plug on the mechatronics side of the TCU, you can use a 90 degree pick to get the connectors off and then unclip the connectors for the start stop and aforementioned connections.
From there the valve body separates from the TCU with 5/6 long T30s and then you can work it off.

I ordered the turbolamik PCB/cover so waiting on those. Might try to finish up some other corrective/preventative stuff in the mean time while I'm waiting on that. Still need a T case refresh kit but trying to avoid pulling that apart until I get the adapter from domiworks via driftHQ.

Video is rendering and will be linked here shortly I hope

 

[Papa Wickey]

Video is live:

 

[benznotmercedes]

Definitely following this. Great stuff so far.