# Retaining 4WD



## Greenbeast (Jun 23, 2009)

I realised i've been a member here for 11 years, so i really should build something at some point!

I'm playing around with the idea of converting my 4wd truck (Daihatsu Fourtrak/Rocky)
I'd like to retain the use of the 4wd, but i can't get my head around what needs to be kept, i've been looking at loads of youtube videos of conversion, mostly small petrol cars of course.
There seem to be plenty that retain use of the gear box.

Do i just need to make a bell housing adaptor plate and a motor shaft to transmission shaft coupler?
Or is it more complicated than that?
Would welcome being pointed in the direction of a video or picture description of the process, if different

Thanks


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## Greenbeast (Jun 23, 2009)

Found this video: 




So i now realise i need to hook my motor up to the flywheel, then the clutch goes on and i'm back to familiar ground


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## lj516 (Mar 11, 2020)

Gs450h trans and a transfer case would be less than 1k. Openinverter.org for more info


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## Greenbeast (Jun 23, 2009)

lj516 said:


> Gs450h trans and a transfer case would be less than 1k. Openinverter.org for more info


is that literally just a trans and t-case, no drive components? because i have a bomb proof trans and t-case in the vehicle already, i was just unsure how to retain full function. I think i've got it now


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## toper (Jul 12, 2018)

Greenbeast said:


> I'd like to retain the use of the 4wd, but i can't get my head around what needs to be kept, i've been looking at loads of youtube videos of conversion, mostly small petrol cars of course.
> There seem to be plenty that retain use of the gear box.
> Thanks


You're right, it's just a bell housing adaptor. My BMW conversion was actually a 325xi, which was AWD. The issue was, in my case, the front diff was a part of the oil pan and had to be removed with the motor. Still, using it as an example, it has a transfer case on the back of the transmission where your rear driveshaft starts. There is a second drive shaft that goes to the front differential. As long as the power goes in through the front input shaft of the transmission via a coupler, it will get split and sent to the diffs, no extra work required. Do be aware of drivetrain loss though, it's certainly not as efficient as 2WD.


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## Greenbeast (Jun 23, 2009)

So where some people make up an adaptor plate and then a shaft coupler for direct drive, i'll need a shaft-to-fly wheel adaptor, then the clutch goes back on as normal and everything gets married up as normal?


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## toper (Jul 12, 2018)

Greenbeast said:


> i'll need a shaft-to-fly wheel adaptor, then the clutch goes back on as normal and everything gets married up as normal?


You can do it that way, but it need perfect tolerances. My car is a manual and I just made a direct coupler from the motor to the transmission. No clutch or flywheel. I put it in gear and use the instant torque of the electric motor to get going. If you need to shift, let off and slowly engage the gear, the motor mass is minimal so your synchros will easily transition the speed.


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## Greenbeast (Jun 23, 2009)

toper said:


> You can do it that way, but it need perfect tolerances. My car is a manual and I just made a direct coupler from the motor to the transmission. No clutch or flywheel. I put it in gear and use the instant torque of the electric motor to get going. If you need to shift, let off and slowly engage the gear, the motor mass is minimal so your synchros will easily transition the speed.


Oh, ok, I see. And everything from the transmission driven shaft onwards will be behave the same. I'll retain low range (which I won't need with the low down torque) but also the ability to bring online the second axle


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## toper (Jul 12, 2018)

Greenbeast said:


> Oh, ok, I see. And everything from the transmission driven shaft onwards will be behave the same. I'll retain low range (which I won't need with the low down torque) but also the ability to bring online the second axle


That’s all! The conversion seems daunting at first but the steps are pretty straight forward. If you need tips on making the adapter plate between the motor and transmission, check out my most recent discussion, I talked about the process with some photos.


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## Greenbeast (Jun 23, 2009)

toper said:


> That’s all! The conversion seems daunting at first but the steps are pretty straight forward. If you need tips on making the adapter plate between the motor and transmission, check out my most recent discussion, I talked about the process with some photos.





toper said:


> That’s all! The conversion seems daunting at first but the steps are pretty straight forward. If you need tips on making the adapter plate between the motor and transmission, check out my most recent discussion, I talked about the process with some photos.


Yes, I watched the videos and caught it. I wasn't joining the dots with my application of bringing online a second axle..

I started stripping down my test bed vehicle this evening and measuring for battery boxes.
Not sure I'm going to be able to fit enough for the range I wanted though!
I'll do a build thread when I make some more definitive progress


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## Greenbeast (Jun 23, 2009)

I'm curious about ditching the gearbox but retaining the transfer case, it looks like I ca split the two and the T-case handles 4x4 and hi/lo gearing.
This would mean no gearing down from the motor shaft until I switched to Low range for creeping through mud. 

I guess possibly the biggest cons here are loss of top speed and comfortable cruising.
But pros are a chunk of saved weight and being able to shift the motor further down the tunnel 

Thoughts? Is this crazy?


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## Greenbeast (Jun 23, 2009)

lj516 said:


> Gs450h trans and a transfer case would be less than 1k. Openinverter.org for more info


I now understand this more, wondering if i can use the GS450 to hook up to my T-case, so i can get 4wd still


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## lj516 (Mar 11, 2020)

Greenbeast said:


> I now understand this more, wondering if i can use the GS450 to hook up to my T-case, so i can get 4wd still


Is your transfer case chain driven? Then no, otherwise yes I wouldn't see why not!


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## MattsAwesomeStuff (Aug 10, 2017)

Greenbeast said:


> it looks like I ca split the two and the T-case handles 4x4 and hi/lo gearing.


That's generally what the transfer case does.



> This would mean no gearing down from the motor shaft until I switched to Low range for creeping through mud.


Indeed. And 4x4 disabled unless otherwise clicked in.



> I guess possibly the biggest cons here are loss of top speed and comfortable cruising.


Does your transmission have that significant of an overdrive?

Why are you thinking you'd lose comfortable cruising?

How badly do the OEM-tranny output RPMs mismatch with what the GS450H spins at?

Biggest obvious loss I'd see is the efficiency drop from using a transfer case, but that's included in the drawbacks of your project goals of maintaining 4wd so, no big deal.



> Thoughts? Is this crazy?


If the RPMs are in the same ballpark, this is what I expected you were after right from the start. Seems simple and achievable. All you've gotta do is line up the GS450h to the transfer case. Mechanics takes are of the rest of it.


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## Greenbeast (Jun 23, 2009)

lj516 said:


> Is your transfer case chain driven? Then no, otherwise yes I wouldn't see why not!


No, it's pretty standard, thank you



MattsAwesomeStuff said:


> That's generally what the transfer case does.


Yeah it's my first 4x4 (although i have had it 4 years now)and my first time delving around in the workings.



> Does your transmission have that significant of an overdrive?
> 
> Why are you thinking you'd lose comfortable cruising?


This was more specifically about using an ungeared oem motor like the leaf, when i started looking seriously at the GS450H, i started to switch tack



> How badly do the OEM-tranny output RPMs mismatch with what the GS450H spins at?


This i don't know, i will research



> Biggest obvious loss I'd see is the efficiency drop from using a transfer case, but that's included in the drawbacks of your project goals of maintaining 4wd so, no big deal.


Yes, quite



> If the RPMs are in the same ballpark, this is what I expected you were after right from the start. Seems simple and achievable. All you've gotta do is line up the GS450h to the transfer case. Mechanics takes are of the rest of it.


Yes although the input to my stock T-case is obviously not going to be 'plug and play', i have the flange on the gs450h side but one i've split my transmission down presumably i've then got a splined shaft protruding either the gearbox or T-case. The mating face then has to be taken care of, i know we generally have to do motor adaptors anyway, but this might involve transmission fluid? I really don't know until i break it open (although! i have just acquired a detailed service manual.....)


Thanks for helping me bounce this idea around


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## MattsAwesomeStuff (Aug 10, 2017)

Greenbeast said:


> This was more specifically about using an ungeared oem motor like the leaf, when i started looking seriously at the GS450H, i started to switch tack [...] This i don't know, i will research


In my very much novice understanding of automotive drivelines, just about 100% of a transmission is to gear down, to give you more power at lower speeds. One of the higher gears will generally be 1:1 with the engine, and for the fastest and light load highway speeds, sometimes an overdrive gear (overdrive being that it speeds up the output, rather than slows it down).

So, as you highlighted your top speed as the concern, I'd wondered just how significant of an overdrive your transmission had just to reach reasonable top speed.

Low-end acceleration you generally don't have to worry about, as electric motors have plenty of that. Back in the day of DC builds, it was normal to leave your car in 3rd gear indefinitely, except on the highway. Shifting down to 2nd was all but dangerous with the amount of torque, and gunning it in first would certainly shave teeth off the gears or snap shafts.



> i know we generally have to do motor adaptors anyway, but this might involve transmission fluid? I really don't know until i break it open


Depends how much you need from it, but, yeah, I imagine you'll be cutting into the housing or disassembling it. Either way, you'll have fluid. Don't do it before church, but, it's a low barrier. Work on cars, gonna get oily.


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## brian_ (Feb 7, 2017)

Greenbeast said:


> I now understand this more, wondering if i can use the GS450 to hook up to my T-case, so i can get 4wd still


The L110 hybrid transmission from a GS 450h could be hooked to a divorced transfer case; the chances of readily connecting it directly to a married (directly attached) random transfer case seem small, but from a later post it appears that you understand the issues. Transfer case oil is normally separate from transmission fluid.

The same hybrid transmission comes in an LS 600h with a transfer case attached (and it looks closely integrated); it might be possible to use that instead of the original transfer case.


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## brian_ (Feb 7, 2017)

lj516 said:


> Is your transfer case chain driven? Then no, otherwise yes I wouldn't see why not!


I don't see how the internal construction of the transfer case (chain or gear) is relevant.


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## brian_ (Feb 7, 2017)

Greenbeast said:


> I'm curious about ditching the gearbox but retaining the transfer case, it looks like I ca split the two and the T-case handles 4x4 and hi/lo gearing.
> This would mean no gearing down from the motor shaft until I switched to Low range for creeping through mud.
> 
> I guess possibly the biggest cons here are loss of top speed and comfortable cruising.


The highest gears in a transmission are used to allow relaxed and efficient low engine speed at high road speed, not for top speed. Most cars with more than four gear ratios (in a manual) hit their highest speed in something lower than the highest gear. Continued high speed within the normal operating range are not a concern with an electric motor, so I don't see an issue with losing the upper gears.

With an OEM EV motor such as the one from a Leaf, if you used the stock transmission you would never get past second gear, because the motor should be run so much faster than the original engine. With a motor like this, omitting the transmission is an issue with losing the lower gears, not the upper gears.


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## Greenbeast (Jun 23, 2009)

MattsAwesomeStuff said:


> In my very much novice understanding of automotive drivelines, just about 100% of a transmission is to gear down, to give you more power at lower speeds. One of the higher gears will generally be 1:1 with the engine, and for the fastest and light load highway speeds, sometimes an overdrive gear (overdrive being that it speeds up the output, rather than slows it down).
> 
> So, as you highlighted your top speed as the concern, I'd wondered just how significant of an overdrive your transmission had just to reach reasonable top speed.
> 
> ...


Gear ratios of stock truck:




12345HiLoAxle3.4772.0371.31710.821.2952.3673.363

I'm not looking for some speed machine, perhaps i miscommunicated, i'm actually quite a sedate driver, but in recent bouts of EV conversion interest i gathered that gearbox retention from stock vehicle was to aid with easier cruising speed.

Getting oily is not my main concern (i have spent some time fixing my tractor, digger, etc, as well as blacksmithing) but my concern is containing oil if i use the transfer case in a non-standard manner, i.e. it's designed as married but it looks like i'll be using it divorced


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## Greenbeast (Jun 23, 2009)

brian_ said:


> The highest gears in a transmission are used to allow relaxed and efficient low engine speed at high road speed, not for top speed. Most cars with more than four gear ratios (in a manual) hit their highest speed in something lower than the highest gear. Continued high speed within the normal operating range are not a concern with an electric motor, so I don't see an issue with losing the upper gears.
> 
> With an OEM EV motor such as the one from a Leaf, if you used the stock transmission you would never get past second gear, because the motor should be run so much faster than the original engine. With a motor like this, omitting the transmission is an issue with losing the lower gears, not the upper gears.


Thank you, i have never had anything to do with gearing (or engine swaps, etc) and i'm trying to get my head round it


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## brian_ (Feb 7, 2017)

Greenbeast said:


> Gear ratios of stock truck:
> 
> 
> 
> 12345HiLoAxle3.4772.0371.31710.821.2952.3673.363


For comparison, a Leaf has reduction ratio from motor to wheels of about 8:1. If you used a Leaf motor with the stock transmission and axles, given the ratios reported above, you would need to be in second gear to get close to the same ratio (2.037 x 3.363 = 6.85) with the transfer case in high range, although the wheel diameter needs to be considered as well (larger tires need more gear reduction). The Leaf can go to about 150 km/h (90 MPH) with that gearing, and I assume you wouldn't want to try to go faster than that in the Fourtrax, so you would never need to shift to even third gear.


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## Greenbeast (Jun 23, 2009)

brian_ said:


> For comparison, a Leaf has reduction ratio from motor to wheels of about 8:1. If you used a Leaf motor with the stock transmission and axles, given the ratios reported above, you would need to be in second gear to get close to the same ratio (2.037 x 3.363 = 6.85) with the transfer case in high range, although the wheel diameter needs to be considered as well (larger tires need more gear reduction). The Leaf can go to about 150 km/h (90 MPH) with that gearing, and I assume you wouldn't want to try to go faster than that in the Fourtrax, so you would never need to shift to even third gear.


Thank you

Found this, very handy, might be useful to others
Gearing Calculator | RPM and Tire Diameter to km/h - mph with Shift Tracer

So keeping my rear diff and transfer case and using the Hi speed of the GS450H i would need an motor rpm of 7200 @ 75mph and 5310 @ 55mph (more my speed)


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## MattsAwesomeStuff (Aug 10, 2017)

brian_ said:


> The Leaf can go to about 150 km/h (90 MPH) with that gearing, and I assume you wouldn't want to try to go faster than that in the Fourtrax, so you would never need to shift to even third gear.


I'd say that's advantageous because he can get away with fewer batteries if that's the case. Depending on whether the Leaf gets grouchy or not about being fed the wrong voltage. The motor is fine, depends on the inverter.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> I'd say that's advantageous because he can get away with fewer batteries if that's the case. Depending on whether the Leaf gets grouchy or not about being fed the wrong voltage. The motor is fine, depends on the inverter.


It's true that if you don't need a wide speed range, you can use less voltage with the same motor and only lose high-speed performance that you wouldn't be using anyway. With a multi-speed transmission, high road speed can still be handled by shifting to a higher gear, so the motor turns more slowly and doesn't need as much voltage.

And I agree - controllers and inverters are designed to work with a specific range of voltage input, so going too low won't work at all - not because the battery can't supply enough power or the motor wouldn't work with the lower voltage (it gets lower voltage most of the time anyway), but because the internal circuit design isn't appropriate.


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## remy_martian (Feb 4, 2019)

You should be fine eliminating the transmission altogether, since the Leaf will spin close to 10,000RPM, so no issues revving the F out of it all the time (get ICE RPMs out of your head and the stuff Matt wrote on transmissions, after stating he was not expert, was mostly nonsense, especially the part about an electric motor having plenty of torque....it does, if you GEAR IT DOWN).

You can get manual locking hubs for that vehicle, so you should be able to run around in low _all the time_, since it's got a geared t-case, and the ratios will still be such that you'll exceed your tires' speed rating...in low, lol. You go mudding, you lock the hubs by hand - meh....worth it given how simple the drivetrain has become, how much weight you've ditched with your original trans or with that hybrid's _expensive_ boat anchor slushbox a lot of people are all starry-eyes about.

All info on RPM & your gearbox are according to five minutes of talking with Mr. Google about Leaf motor RPMs and Fourtrak xfer cases.


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## brian_ (Feb 7, 2017)

remy_martian said:


> You should be fine eliminating the transmission altogether, since the Leaf will spin close to 10,000RPM, so no issues revving the F out of it all the time...
> 
> All info on RPM & your gearbox are according to five minutes of talking with Mr. Google about Leaf motor RPMs and Fourtrak xfer cases.


Did Mr. Google tell you what input speed the Fourtrax transfer case can handle while in low range?


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## MattsAwesomeStuff (Aug 10, 2017)

remy_martian said:


> especially the part about an electric motor having plenty of torque....it does, if you GEAR IT DOWN).


That's a nonsensical statement. A hamster wheel has enough torque if you gear it down.

Motors have plenty of low-end torque compared to the ICE they're replacing.


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## brian_ (Feb 7, 2017)

It makes no sense to me to make general statements about the amount of torque produced by electric motors or engines, given that there is an effectively infinite variety of both. The relevant point is that any source of torque needs to be considered in the context of any multiplication of torque by gearing (or chain drives or belt drives or whatever) between the source and the wheel.


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## Westcott (Feb 9, 2021)

I'm so glad others are trying this out. How did it go? I'm looking to convert a Datsun 720 4x4 and want to survey examples of how others did it. This is a solid thread and I'll be combing through it carefully.


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## Greenbeast (Jun 23, 2009)

Westcott said:


> I'm so glad others are trying this out. How did it go? I'm looking to convert a Datsun 720 4x4 and want to survey examples of how others did it. This is a solid thread and I'll be combing through it carefully.


Sorry to disappoint but i bought a 2013 Renault Zoe and enjoy it so much i'm giving up on converting the truck!


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## Westcott (Feb 9, 2021)

Greenbeast said:


> Sorry to disappoint but i bought a 2013 Renault Zoe and enjoy it so much i'm giving up on converting the truck!


Ha! I've got my Fiat 500e in the driveway, so I can get my comfort needs met in the meantime.


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## Greenbeast (Jun 23, 2009)

Westcott said:


> Ha! I've got my Fiat 500e in the driveway, so I can get my comfort needs met in the meantime.


hehe lovely jubly
I've also taken on a new job with a paycut and less free time, so i need to free up the cash held in the vehicle, not spend more on it


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