openinverter forum

HI All,
I haven't posted much about my project because it is still in bits and pieces all across southwestern Germany but on the weekend I took my differential to a specialist to have it refurbished and put into an aluminum case (to save weight).

The car is a '72 Triumph Spitfire. Because of the low initial weight of the car (around 740 kg) and the overall size getting more than 20-25 KWh worth of batteries into is going to be challenge (I guy has already done it and lives only 10 km from me so I know it can be done!).

As such I am trying all I can to save weight (aluminum parts where allowed, lighter wight sound deadening etx) and power (LED where legal and redoing the wiring loom) use no matter how minuscule.

The specialist also does transmissions/gearboxes and has an overdrive for the Spitfire and suggested it might help.

On the dino-juice engine the overdrive is able to drop the RPMs be around 500 in 3rd and 4th gear (the car will be keeping its transmission gearbox for various reasons).

I am not sure the added weight (about 4-5 kilos) and the added complexity would really translate into higher overall range.

Does anyone have any thoughts on this?

Thank you in advance!

The overdrive will reduce range as it adds additional drag and electric EV motors are most efficient above 3000 or 4000 rpm.

Of course dropping the manual gearbox would help reduce weight but probably you want to keep it for vintage reasons?

Interesting and thank you!

Keeping the gearbox is mostly to make it easier to get through the TÜV. The less I change the less I have to explain.

I have an aluminum bell-housing and flywheel that bring down the weight by almost 20 KG. The gearbox itself only weighs about 15 KG (I know because I sent mine to England pre-Brexit to have it beefed up). I am not sure a reduction gear would weigh a lot less?

Also, you have to have functioning speedometer which on a Spitfire in the gearbox.

I know there is a Tesla swapped Spitfire in the Netherlands but a base Spitfire only had about 50-60 BHP and the differentials are already struggling (I am having mine modified with better parts to handle the low-end torque). If he stuffed it in the back I doubt he did it without modifying the chassis which is usually a no-go-

The Spitfire is very narrow. I can reach both window handles and open both windows at the same time! It has a chassis/frame construction which on the one hand makes it getting passed the TÜV easier (because cutting into the body is not so critical as cutting the the chassis) but there are very few spots you can mount things on and everything is very tight.

I highly doubt you could squeeze a reduction gear in the rear without going through some major re-engineering.

You could stuff it in where the engine and transmission are but that is where most of the batteries will likely live so I am not sure if that would work.

I know one of the rules is you have to have a mechanism that prevents the car from being switched easily from going forward to reverse. An old-style gearbox does that easily. If I have some other type of selector that might require more work.

I am not against the idea but I am not sure it would really make the whole thing better but maybe I am wrong...? (My kids usually say I am..!)