[DrGee]

New to the forum and really impressed with the knowledge level here.
I'm planning to convert a Range Rover HSE to an ev.
Questions:
Is it feasible to reduce weight by getting rid of the gearbox, prop shaft, rear axle & differential?
I would use two motors, one for the rear & one for the front & one for the rear.
Is there a lighter alternative to the heavy standard rear differential?
Love to hear from your expertise!
Greg.

 

[brian_]

Is it feasible to reduce weight by getting rid of the gearbox...?

You need some sort of gearing to match the speed of the motor (higher) to the speed of the axle/wheels (lower). Depending on your choice of motor, it may not need multiple ratios, so you may not need a transmission like the original, but you need something.

Is it feasible to reduce weight by getting rid of the ... prop shaft, rear axle & differential?

If you mount the motor at the axle, you don't have a prop shaft. The details from there depend on the vehicle - "Range Rover" covers four generations of vehicle with completely different designs for the early (classic and P38A) and later (L322 and L405) generations, and "HSE" is just a trim level, not a mechanical description. That's assuming it's not a Sport, Evoque, or Velar... which are different again.

I would use two motors, one for the rear & one for the front & one for the rear.
Is there a lighter alternative to the heavy standard rear differential?

If you use one motor to drive the rear axle, then you need a differential to split the power between left and right wheels, allowing them to turn at different speeds. If a lighter differential were practical, it would have been used.

 

[DrGee]

Is it feasible to reduce weight by getting rid of the gearbox...?

You need some sort of gearing to match the speed of the motor (higher) to the speed of the axle/wheels (lower). Depending on your choice of motor, it may not need multiple ratios, so you may not need a transmission like the original, but you need something.

Is it feasible to reduce weight by getting rid of the ... prop shaft, rear axle & differential?

If you mount the motor at the axle, you don't have a prop shaft. The details from there depend on the vehicle - "Range Rover" covers four generations of vehicle with completely different designs for the early (classic and P38A) and later (L322 and L405) generations, and "HSE" is just a trim level, not a mechanical description. That's assuming it's not a Sport, Evoque, or Velar... which are different again.

I would use two motors, one for the rear & one for the front & one for the rear.
Is there a lighter alternative to the heavy standard rear differential?

If you use one motor to drive the rear axle, then you need a differential to split the power between left and right wheels, allowing them to turn at different speeds. If a lighter differential were practical, it would have been used.

Thanks so much Brian,
This is all valuable information. I've struggled with the idea of using the Range Rover L322 from 2010 as a doner vehicle. This is because of the reliability issues and of course, cost. An alternative is a Jeep Grand Cherokee (WK2 from 2010) instead.

 

[brian_]

I've struggled with the idea of using the Range Rover L322 from 2010 as a doner vehicle.

Now we're in business
An L322 is built of BMW 7-Series components, so it has independent suspension at both ends. That means that in the rear the original final drive (differential, ring and pinion gearset, and housing) can be replaced by the corresponding parts of a complete EV drive unit - a "drive unit" is a motor with reduction gears and differential. The problem is fitting the drive unit in where there was just a much smaller final drive unit originally. In various projects in this forum, only simpler semi-trailing arm suspension has been found to readily accommodate the Tesla Model S/X drive unit in the rear.

An alternative is to mount the motors in the area of the original transmission and transfer case, running prop shafts to the original final drives at each axle... although the front final drive housing is integrated with the engines sump, and may not be practical to separate entirely from the engine.

An alternative is a Jeep Grand Cherokee (WK2 from 2010) instead.

If it's a WK2 from 2010, I think that makes it an early example of the 2011 model year. This is the current generation of the Grand Cherokee. While the Land Rover is really a BMW underneath, this Jeep shares a platform with the Mercedes-Benz W166 underneath. Since the configuration is essentially the same as the Range Rover L322, all of the same issues and options apply... except that the front final drive looks separate from the engine sump in this Jeep. The Allpar page for this model provides some good chassis illustrations.

 

[DrGee]

I've struggled with the idea of using the Range Rover L322 from 2010 as a doner vehicle.

Now we're in business

An L322 is built of BMW 7-Series components, so it has independent suspension at both ends. That means that in the rear the original final drive (differential, ring and pinion gearset, and housing) can be replaced by the corresponding parts of a complete EV drive unit - a "drive unit" is a motor with reduction gears and differential. The problem is fitting the drive unit in where there was just a much smaller final drive unit originally. In various projects in this forum, only simpler semi-trailing arm suspension has been found to readily accommodate the Tesla Model S/X drive unit in the rear.

An alternative is to mount the motors in the area of the original transmission and transfer case, running prop shafts to the original final drives at each axle... although the front final drive housing is integrated with the engines sump, and may not be practical to separate entirely from the engine.

An alternative is a Jeep Grand Cherokee (WK2 from 2010) instead.

If it's a WK2 from 2010, I think that makes it an early example of the 2011 model year. This is the current generation of the Grand Cherokee. While the Land Rover is really a BMW underneath, this Jeep shares a platform with the Mercedes-Benz W166 underneath.

Since the configuration is essentially the same as the Range Rover L322, all of the same issues and options apply... except that the front final drive looks separate from the engine sump in this Jeep. The Allpar page for this model provides some good chassis illustrations.

Brilliant! 👍🏾👍🏾
Based on what you have described, it would be better to use 2 motors mounted in the front.
The more powerful one would be connected to the existing rear axle /differential with a prop shaft. I'd like to achieve about a 40%/60% front to rear split in power. They'd both require gearing down as you described, so I might be creating an unnecessary complication in having two motors though. What do you think?

 

[brian_]

Brilliant! 👍🏾👍🏾
Based on what you have described, it would be better to use 2 motors mounted in the front.
The more powerful one would be connected to the existing rear axle /differential with a prop shaft. I'd like to achieve about a 40%/60% front to rear split in power. They'd both require gearing down as you described, so I might be creating an unnecessary complication in having two motors though. What do you think?

If you use one motor, you need a differential to split power between front and rear (and an unequal split requires a specific design of planetary differential), so there is no really simple solution. While one motor for both axles works (and there are examples in this forum), current production hybrids with AWD all seem to use a separate motor for the rear.

It would be good if you can squeeze at least one motor in the transmission tunnel, rather than under the hood. The battery needs to go somewhere, and most conversions which put the motor under the hood have difficulty finding a good place for enough battery.

 

[DrGee]

Brilliant! 👍🏾👍🏾
Based on what you have described, it would be better to use 2 motors mounted in the front.
The more powerful one would be connected to the existing rear axle /differential with a prop shaft. I'd like to achieve about a 40%/60% front to rear split in power. They'd both require gearing down as you described, so I might be creating an unnecessary complication in having two motors though. What do you think?

If you use one motor, you need a differential to split power between front and rear (and an unequal split requires a specific design of planetary differential), so there is no really simple solution. While one motor for both axles works (and there are examples in this forum), current production hybrids with AWD all seem to use a separate motor for the rear.

It would be good if you can squeeze at least one motor in the transmission tunnel, rather than under the hood. The battery needs to go somewhere, and most conversions which put the motor under the hood have difficulty finding a good place for enough battery.

Nice one.
One motor in the transmission tunnel looks like the way forward. The other motor can go under the hood.