# Where would you mount a motor on an AWD car?



## Dlee (May 13, 2021)

I’m trying to think of what it would take to convert an existing AWD car to hybrid without disrupting the AWD system. Specifically a Subaru, where the center diff is locked between 60:40 to 50:50 range and isn’t open.


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## Electric Land Cruiser (Dec 30, 2020)

Going to be incredibly tough because modern cars are packaged tightly to maximize efficiency of design. On a Subaru you could possibly put a sprocket on the rear driveshaft and cut away body to try and fit a motor next to it.


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## reiderM (Dec 30, 2020)

Hook a motor up direct to transmission/differential


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## hallkbrdz (Jan 2, 2018)

Hybrid is near impossible. Full EV with the motor in place of the engine is much easier - other than finding space for cells.

I'd love to convert my Outback XT some day, but batteries are definitely the challenge. Maybe with solid state cells in the future.


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## reiderM (Dec 30, 2020)

hallkbrdz said:


> Hybrid is near impossible. Full EV with the motor in place of the engine is much easier - other than finding space for cells.
> 
> I'd love to convert my Outback XT some day, but batteries are definitely the challenge. Maybe with solid state cells in the future.


Ah yeah I missed the hybrid part.

One idea is to hook a motor up to the timing belt. Not sure if it would work, but it's a thought.


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## brian_ (Feb 7, 2017)

reiderM said:


> One idea is to hook a motor up to the timing belt. Not sure if it would work, but it's a thought.


That's a P0 or P1f parallel hybrid configuration, meaning that the motor is connected to the "front" (accessory end) of the engine. This is the least capable hybrid system, because it is limited in how much electric motor power can be handled and because it can't drive the vehicle without the engine running; it is only used for "mild" hybrid systems, and it does work for that purpose.

You don't actually use the timing belt , but a separate belt to its own crank pulley.


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## pengyou (Nov 21, 2012)

Is there some way to install 2 motors - connect one to the rear diff and one to the front? I am interested in doing something similar, so glad you asked this question, though I am looking for something a little bigger - maybe a Suzuki Samari? I have measured the newer cars (2005+) and also found that there is little empty space in them these days.


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## pengyou (Nov 21, 2012)

reiderM said:


> Hook a motor up direct to transmission/differential


Can you do this? or do you need at least a short driveshaft to help cushion the motor from some of the bumps?


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## Electric Land Cruiser (Dec 30, 2020)

pengyou said:


> Is there some way to install 2 motors - connect one to the rear diff and one to the front? I am interested in doing something similar, so glad you asked this question, though I am looking for something a little bigger - maybe a Suzuki Samari? I have measured the newer cars (2005+) and also found that there is little empty space in them these days.


There is always a way to do anything you want.

-Cheap
-Good
-Fast

Pick two.


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## brian_ (Feb 7, 2017)

pengyou said:


> Can you do this? or do you need at least a short driveshaft to help cushion the motor from some of the bumps?


The original proposal was for a car in which the rear has independent suspension, so the differential does not move with the suspension. If you were to connect a motor to the Samari's rear axle, you would need to either use a jointed shaft, or have the motor attached to the axle (which the motor can withstand, but isn't good for suspension performance).


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## brian_ (Feb 7, 2017)

pengyou said:


> Is there some way to install 2 motors - connect one to the rear diff and one to the front?


The original proposal was to leave the AWD system intact. As an alternative, it would be practical to eliminate the mechanical connection between axles of the stock AWD system and to drive each axle with a separate motor; Toyota does that in their transverse-engine hybrids (such as the RAV4 and Highlander) so the rear axle has only electric drive (with the power being generated by the engine and the generator of the hybrid transaxle) and the front axle is driven by the engine and hybrid transaxle.



pengyou said:


> I am interested in doing something similar, so glad you asked this question, though I am looking for something a little bigger - maybe a Suzuki Samari?


Any recent Subaru is much bigger than a Samauri.


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## CaptD (May 6, 2021)

Dlee said:


> I’m trying to think of what it would take to convert an existing AWD car to hybrid without disrupting the AWD system. Specifically a Subaru, where the center diff is locked between 60:40 to 50:50 range and isn’t open.


I have a PICKUP truck AWD. It has two motors front and head with separate gearboxd's. Rear motor drives a short 10" driveshaft. I believe they work to equalized load and current draw through the regenerative brake guns. ? Hope that is helpful.. 
D


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## brian_ (Feb 7, 2017)

CaptD said:


> I have a PICKUP truck AWD. It has two motors front and head with separate gearboxd's. Rear motor drives a short 10" driveshaft. I believe they work to equalized load and current draw through the regenerative brake guns. ? Hope that is helpful..
> D


This is the Phoenix SUT. It is based on the SsangYong Actyon so in the rear it has a beam axle, and so the short shaft to a motor mounted to the frame makes sense; this would correspond to a suitable design for a Samurai (but not for a Subaru, which could use but wouldn't need the shaft).

I think the "autocorrect" feature messed things up here... "gearboxd's" was obviously supposed to be "gearboxes" and I assume that "front and head" was supposed to be "front and rear", but I don't know that "guns" was supposed to be.

Running with equal load (torque output) is pretty good, but ideally the torque would be distributed more to the more heavily loaded axle (including the load shift due to acceleration), if a tire slips the torque to that motor would be reduced (traction control), and if the control system detects excessive understeer or oversteer the drive torque would be adjusted to suit (stability control).


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## CaptD (May 6, 2021)

Brake drums. Darn auto correct...


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## CaptD (May 6, 2021)

Yes they are traction motors. Correct. Sounds like you know some stuff buddy. About Phoenix Actyon endeavours. Kinda left out of the history book. Is love to talk to you sometime. As far as AwD. ... Phoenix m.c. integrated the TCM transmission module for control of solenoids for brakes ,self parking, suspension modes, not sure all but left the brains and Removed the actual transmission. Just a lonely shift lever. May be a good thought to do the same . Or that could complicate things so much you go bankrupt. Like Phoenix. 
Might be better modern solutions.


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## CaptD (May 6, 2021)

Hey Brian. Did you see my pics of the battery mods after I dropped it from under the SUT?


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## brian_ (Feb 7, 2017)

CaptD said:


> I have a PICKUP truck AWD. It has two motors front and [rear] with separate gearboxd's
> ...
> I believe they work to equalized load and current draw through the regenerative brake guns. ? Hope that is helpful..
> D





brian_ said:


> ... I don't know that "guns" was supposed to be.





CaptD said:


> Brake drums. Darn auto correct...


Okay... but "regenerative brake drums" doesn't quite make sense, either. The control system would appropriately balance both drive torque from the motors as well as regenerative braking torque from the motors; it also needs to reduce the hydraulic brake system pressure to reduce braking by the friction brakes (disks, and drums if it has rear drum brakes) to compensate for the regenerative braking.

AWD is a good thing to have with regenerative braking, because balanced front and rear braking can be achieved without having to use the friction brakes.


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## brian_ (Feb 7, 2017)

CaptD said:


> Hey Brian. Did you see my pics of the battery mods after I dropped it from under the SUT?


Yes... see that separate thread.


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## CaptD (May 6, 2021)

Makes sense so good that its on there. Why are not alll highway , normal use vehicles all wheel drive? For various reasons.


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## CaptD (May 6, 2021)

Photos- Phoenix SUT undercarriage minus the battery bank.


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## CaptD (May 6, 2021)

Actually is an enormous shorter driveshaft up forward also. U- joints on each end of an 8" long shaft. Wow. Guess it can be done


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## brian_ (Feb 7, 2017)

CaptD said:


> Photos- Phoenix SUT undercarriage minus the battery bank.


The second one, in which the blue motors are clearly apparent (the rear is the one closer to the camera), explains the shape of the battery, which has sections notched out to accommodate the motors. This (with the battery case as shown in the other thread about the Phoenix battery) is a nice illustration of how a typical pickup truck could be converted to an EV.



CaptD said:


> Actually is an enormous shorter driveshaft up forward also. U- joints on each end of an 8" long shaft. Wow. Guess it can be done


The front uses a shaft instead of directly mounting to the front differential because the motor would interfere with other components if attached directly. The rear needs the shaft to allow the axle to move.

Yes, the two-motor approach can certainly be done, completely replacing the stock AWD power distribution components, even with a vehicle not designed for electric drive. But that isn't what the original question in this thread was about...


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## popobowa (May 4, 2021)

i am not so sure what a subaru looks like underneath..... I recently looked at 2 converted HZ Toyota LandCruisers in South Africa. One had a motor bolted to the transfer case , this was a hunting car, the other was fitted with one motor driving each diff, front and rear.. was meant for roaduse. The latter claimed a 250mls range. These cars were in use since over a year then. Cant remember the company name.. something weird.


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## brian_ (Feb 7, 2017)

Dlee said:


> Specifically a Subaru, where the center diff is locked between 60:40 to 50:50 range and isn’t open.


I should have mentioned this earlier... but this description doesn't make sense. "Locked" means that the front and rear axles speeds are the same, but ratios (such as " 60:40" and "50:50") describe front to rear torque distribution which requires that the axles be able to turn at different speeds.

There are no Subaru AWD systems which are locked all of the time.

Some AWD systems use a differential between the front and rear axles, which means that the torque split between the two axles is a constant ratio, unless a friction device (limited-slip differential) is used. If there is no limiting device, it's called an "open" differential. Some Subaru models use a differential, with a 50:50 normal distribution and usually with limiting devices.

Most AWD systems in cars now drive one axle all of the time, and use a controlled clutch to engage drive to the other axle as required. The torque distribution can be anything and varies moment-to-moment, because it depends on the traction available to the tires. Most Subaru models use this system, with the front wheels always driven (so 100:0 normally) and a clutch for the rear.


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## brian_ (Feb 7, 2017)

popobowa said:


> ... I recently looked at 2 converted HZ Toyota LandCruisers in South Africa.


In a Land Cruiser, "HZ" is an indication of the engine (1HZ diesel), not the model. I assume that these are J70-series trucks (originally equipped with 1HZ engines), a very traditional style of 4WD vehicle.



popobowa said:


> One had a motor bolted to the transfer case , this was a hunting car, the other was fitted with one motor driving each diff, front and rear.. was meant for roaduse. The latter claimed a 250mls range.
> ...
> Cant remember the company name.. something weird.


Both Electric Safari Vehicles (ESV) and Tembo appear to be converting J70-series Land Cruisers with a motor driving the transfer case. ESV is converting for safari use; Tembo targets mining companies. I haven't found the other type of conversion, with two motors, which would be the more interesting one to me.

The ESV conversion appears to place the entire battery pack - consisting of ten Tesla Model S/X modules on edge - under the hood over the motor. This is ridiculously high and front-heavy, but in a vehicle that came with a 1HZ diesel that might not be so bad; this engine weighs over 300 kg.

Tembo apparently offers 28 kWh or 56 kWh, which are likely 5 or 10 of the same Tesla modules, likely placed like the ESV.

_Edit note (2021-12-02): replaced original ESV link target with link to new site, since electricsafarivehicles site is gone. There is a __Wayback Machine archived version__, but it the "How it Works" content is not functional. _


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## Thang Nguyen (Aug 9, 2021)

Dlee said:


> I’m trying to think of what it would take to convert an existing AWD car to hybrid without disrupting the AWD system. Specifically a Subaru, where the center diff is locked between 60:40 to 50:50 range and isn’t open.


Connect the motor directly to the transmission the way the engine was .


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## brian_ (Feb 7, 2017)

brian_ said:


> ...
> The ESV conversion appears to place the entire battery pack - consisting of ten Tesla Model S/X modules on edge - under the hood over the motor. This is ridiculously high and front-heavy, but in a vehicle that came with a 1HZ diesel that might not be so bad; this engine weighs over 300 kg.
> 
> Tembo apparently offers 28 kWh or 56 kWh, which are likely 5 or 10 of the same Tesla modules, likely placed like the ESV.


Apparently Tembo uses two battery boxes, one in the front like ESV and the other in the rear:









They apparently also have their own 3.041:1 reduction gearbox - that would be handy for anyone doing their own conversion of this type, especially with a matching Toyota transfer case, but I don't see any indication that it's available to anyone else.


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## remy_martian (Feb 4, 2019)

Worthy of note - the Tesla modules are not designed to be mounted on edge.


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