Electric cars and the 240 future avlues.

[Othen]

Originally Posted by Othen

I think they do that because it is easier than doing the job properly, indeed they sometimes leave the clutch in as well (probably without the master cylinder) because it is easier than taking it out.

You will notice in modern EVs that there is no gearbox - because there is no need for one (electric motors produce much the same torque from 0-maximum RPM). EV conversions often leave the gearbox in place but this is pretty sloppy engineering and means the car has to lug around 50kg extra and has pretty considerable friction losses that don't need to be there.

I don't know if you looked at the link I posted above about my thought experiment for the RB, but I'd envisaged putting a 70kW motor where the BW55 gearbox sits now (they are about the same size).

... and the dimensions are:

Diameter 255mm (approx)
Depth 260mm (approx)
Height 280mm (approx)
Spine Diameter 20.02mm
Cooling Hose Connector Diameter 17.06mm
Mass 42Kg

... so very much the same size and weight as a BW55 auto gearbox.

There probably be a need for a 3:2 (or thereabouts) gear reduction (but no clutch or reverse gear of course) - so maybe a gear or chain drive inside an enclosure (and probably oil bath). This bit would need some engineering but it would hardly be complex (and probably exists already on a boat, plant machine or some other machine).

Another alternative would be to find a rear axle with about double the reduction - I think the RB has a 3.72:1 axle, so something around 6:1 - I don't know where that would come from, I think Volvo used a 4.1:1 axle in the 740, so it might be worth trying that as the RB is pretty low geared anyway. Maybe find a more powerful electric motor that would turn slower and so pull a 4.1:1 gear with a straight connection (just a sleeve with some splines each end, probably mounted in a bearing holder like it is now).

I'm always irritated when I see these conversions (like on 'Vintage Voltage' TV programme) when they leave the gearbox (and clutch) and then just drive the car in third gear all the time rather than bothering to solve a pretty simple engineering job. I think if I ever do this conversion (I suggested in my last piece I might in 10 years or so time, when the RB is 50) then I'd want to engineer the power train properly (particularly as the RB is an auto).

Interesting discussion.

Alan

Continued: I have done some research and found the Meiden 60kW engine I referred to above normally fits on the rear transaxle of a Mitsubishi Outlander PHEV. I suppose a really neat solution would be to fit the whole transaxle from an Outlander PHEV to the back of a 244 (there would be loads of room once the fuel tank was removed) - but the suspension would then be problematic in that the Outlander seems to have IRS, whereas the 244 has a live axle. This would not be insurmountable (if you excuse the pun) of course, but there would have to be some sort of subframe to hold the transaxle assembly - I suspect it would not be worth the effort.

This being a motor that normally powers a large and heavy SUV (albeit only for about 10 miles before the gas motor kicks in) is a good indication that it might be suitable for a 244 though. Thinking through this the Outlander PHEV's battery pack would be useless for this application (unless one was happy with a 10 mile range) so an EV conversion would still be prohibitively expensive for the batteries.

:-)