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Discussion Starter #42
I've noticed whilst watching that some of the conversions are quite recent (they've been at this for some time. Met them first at Malvern in 2015) and wonder why they're not using a motor between the axles and leaving out the gearbox? That would leave more room for batteries and make the vehicle lighter.
Each one is different from what I've seen.
 

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Can you change gear??
In the ones that retain their original gearboxes often yes the ratio can be changed. They tend to be locked off to the user, of course, but indeed these adaptions still allow the ratio to be swapped, so you can have faster and slower off the line, or vice versa.

In general you want to run the lowest gear that makes sense, else the slack in the driveline causes a transmission shunt. Imagine in an ICE in top gear at 10mph and you floor it, the driveline will shake and the engine jerk back and forth on its mounts because too much torque is being fed back to the engine. Same sort of thing happens in EVs, but of course you can fit much harder 'engine' mounts to try to stop that sort of thing, because motors don't shake around and have vibrations that need to be filtered by soft mounts.
 

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In a lot of these, Yes. But there's still a considerable weight and packaging penalty.
 

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It is a very very special motor that can deliver enough torque at zero speed, and still spin fast enough for motorway speed.

These are essentially confined to the preserve of axial flux motors, like Yasa and EVO (now bought out by Avid).

You still need a gearbox to match any other electric motor to road wheels, and why would you make a new one when you're adapting a car with one already?

You can take a ride in my Zoe if you like, which has a noisy way of reminding its occupants there are still gears in EVs.

EVs have gears.
EVs have gears.
EVs have gears.
EVs have gears.
EVs have gears.
EVs have gears.
EVs have gears.
EVs have gears.
EVs have gears.

Not sure how many times we repeat this here.
I was thinking along the lines of what VW have come up with for conversions for the Beetle and the type 1/2 campers. It removes the engine altogether and puts a motor in-line with the rear axles. Creates so much space that they end up with a boot where the engine was.
 

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I was thinking along the lines of what VW have come up with for conversions for the Beetle and the type 1/2 campers. It removes the engine altogether and puts a motor in-line with the rear axles. Creates so much space that they end up with a boot where the engine was.
Sure, if that is available then it makes sense.

Making a high speed motor with a reduction box reduces the required mass of conductor/magnets in the motor considerably. A motor that spins twice as fast only needs to generate a half of the magnetic torque, thus using less windings/magnetic material to do it with.

Your example will be something with an integral gearbox. For sure, such an assembly makes a lot of sense, but also requires quite a lot of development of course.
 

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To do it in the most efficient way, you would use a custom reduction gear with a (slippy?) diff and then you can put it all together with equal length driveshafts and have no torque steer even on FWD cars. I bet the black box system that Swindon Powertrain are producing does something along those lines because it's supposed to be a one size fits all solution. Engineering that for a custom install each time would probably add 50% to the cost of the conversion, and would make thing especially difficult for stuff like the Range Rover that they converted. Far simpler to use the approach that engine swaps do in the ICE world and just fit an adapter plate to the end of the gearbox. It also means you don't have to do anything with reverse - it's there mechanically. Some EV conversions leave the clutch in there as well to make it as ICE like as possible - with these you can change gear on the move. Some of them have a fixed linkage, and so you select the gear at standstill .
 

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.... put it all together with equal length driveshafts and have no torque steer even on FWD cars.
FWIW, torque steer is due to an offset between hub axis and pivot. A "zero-centred hub axis" means you don't get torque steer.

Only cars I know of deliberately designed for zero centred hub was Citroen in the 80's, BX, CX etc ...

You might (if of a certain age) recall an advert of a BX driving between two trucks and one of its front tyres being deliberately blown out.
 

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Personally I thought the treatment of the Visa was more appropriate ;)


I suspect that @Problemchild will be after me now. :p

Dragging myself back to topic, the Swindon Powertrain HPD only comes with two very widely different final reductions - 11.508 or 6.332 - I bet that lots will be wrong.
 

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The latest episode with the motorbike seems quite impressive. I did wonder about the client, you chose the bike?

A few minutes research reveals the Eva ribelle with double the battery and 120 bhp. New price the same and grant to take off. I suspect that would be my choice
 

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One thing I wondered about the bike is throttle range - with the ICE, the speed range of the twist throttle is only that for a single gear, but with the electric drive, the twist of the throttle goes all the way from stopped to max speed - I wonder if this makes it any harder to control. Not a biker myself - any bikers here like to comment?
 

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One thing I wondered about the bike is throttle range - with the ICE, the speed range of the twist throttle is only that for a single gear, but with the electric drive, the twist of the throttle goes all the way from stopped to max speed - I wonder if this makes it any harder to control. Not a biker myself - any bikers here like to comment?
The throttle is just like a single gear ev car. It is not a speed control directly but a torque control, which eventually controls speed.
 
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