The electric motor delivers full torque from zero rpm so you certainly don’t need to use 1st gear.

I have a book from USA on DIY electric conversions for pickup trucks, in that the author suggested leaving gearbox in place and running it in 2nd gear all the time after replacing engine with motor.  That arrangement apparently gave adequate acceleration and top speed.

Max rpm of the original engine should give a rough guide to input speed capability for the gearbox.

Hi ,this might give you some ideas .   https://www.imdb.com/title/tt12421846/     It’s an episode of Vintage Voltage.

Maurice

An EV series 3 is an interesting concept but the gearbox is not intended to take a high input speed and low output continuously. Top gear the one used most is a locked first motion and main shaft set up = straight through, the box was not really being used ! Almost continuous use of second gear would soon overheat the box. The torque characteristics of an electric motor make the normal gearbox almost redundant. Why do you need to use such high input speed ? As has been said, a 2:1 from the motor then use the gear box as normal. I have  a 50 year old S3 with a perkins 203 diesel, I had the opposit problem, max rpm 3000, so used an overdrive box, it would cruise at 50ish all day ! Good luck. Noel.

Are you removing the clutch so can’t change gear? Seems daft to not use the gearbox when it is still there.
Keep us informed on your progress. I have a 110 that might need conversion. Big lead acids in the Sankey may be an option.

Just to add to Noels comment, the ‘calculated’ lives of the bearings in 1st gear configuration are typically less than 10 hours. (In fact I have seen some as low as 3!). This is sufficient in relation to how much this gear is used in normal manual gearbox duty.  If used 100% of the time they unlikely to be reliable. There is lots of shaft bending in 1st gear too which could also be a limiting factor, depending on the quality of the design.

Gerry

You would need about 2:1 reduction between the motor and gearbox. You also need to remove the overdrive too. A polyvee belt drive would probaly be the easiest and quietest.
However there are other rhings to consider. For example regenerative braking. There is a LOT of backlash in a old landrover transmission so it may not be smooth and I don’t know how well it will handle being back driven. Personally I’d ditch the main gearbox and go into the transfer box directly. You can drive the PTO “output” the same as the gearbox input. Possibly dual motors or dual belt drives to divide the power. Still need some reduction on that 7000 RPM though. Going to the transfer box saves weight and the losses of a multispeed gearbox.

Robert.

This will give you an idea what Vintage volt do https://www.youtube.com/watch?v=HoqoL1EyAHk

And an idea of prices from a breakers https://www.evbreakers.com/

Or https://www.electrogenic.co.uk/kits/conversion-kits/series-land-rover-kits/ but for some reason not for DIY and the cheapest kit is off road only.

No doubt the Thai’s have a looser H&S system around high voltage DC than we do as well. Nanny doesn’t insist you have training to jack a car up, but does for electric conversions.

On 15 November 2023 at 18:29 Robert Atkinson 2 Said:

Dave H, can you point me to the legislation that says this? Other than general H&S competence etc that apply to all work. They of course mean that if someone jacks a car in a workplace without training and has an accident the employer could be found liable.
There are lots of things you can do in your own home quite legally that you can’t do in the workplace easily.

Indeed, and in the workplace, the primary onus on the employer is to make a safety assessment as to whether the action presents a hazard, and if so to devise (and follow) a plan to mitigate the hazard. This may involve training, but it isn’t generally prescribed* – the assumption is that those involved in a particular business are probably best able to make such an assessment.

*Though certification may be required for things like installing gas boilers or wiring in bathrooms