[Moltenmetal]

First of all, welcome- and congrats on your great choice of conversion target! Spitfires are a lot of fun!

My AC50 converted Spitfire is a riot- but it doesn't do 0-60 in under 8 seconds. It'll do 100 miles an hour, but not 0-60 in under 8. A big DC motor like Baratong's, or a dual AC35 setup might get you there.

As to re-purposing OEM parts- it's the only way to fly these days. Batteries for sure- Chevy Volt, Nissan Leaf etc. are the only ones worth considering. Forget the LiFePO4 bricks that Baratong and I used- they're too low in energy density and too expensive. OEM batteries are the only way to fly!

As to conversion strategy: the AC50 is far too gutless to use without a transmission- and the existing Triumph transmission is far too wimpy to use with any electric motor. It might survive but won't survive long term.

Mine has chewed up universal joints, but they should have all been replaced when I did the resto anyway. I've been through one differential and the 2nd one is making noise so I have it in to be rebuilt. The existing diff is up to what an AC50 can put out because the same basic diff, half shafts etc. were used in the 6 cyl 120 ft-lbs GT6.

If you can fit a Tesla "small" drive unit in there, that would be ideal- but I caution you that the car is narrow and its existing rear suspension design relies on using the half shafts as one of the control arms found in a modern independent suspension. Loadings on the rear wheels when cornering are transmitted THROUGH the half shafts and their u joints into the bearings in the differential, which perhaps explains somewhat why the car seems to chew up u joints and diffs (not just mine- if you go to the Triumph Experience, next to rear spring buttons and "bachelor's lean" (the tendency of the car to sag to the driver's side over time), you'll find more issues about UJs and the diff than about anything other than the (horrible!) original 1493 cc 4 banger in the car. Differentials usually are a bomb-proof component in cars in my experience, but not so with this one!

Oh, and before someone convinces you otherwise: safe use of Li ion batteries requires the use of a BMS. It's an essential part of your project- don't leave it out. Fortunately others here have built devices which can read various OEM BMSs so you can re-use them, so you don't have to go the home-made or low volume route the rest of us went. Just don't skip the BMS, OK? You might be lucky like some here, who seem to act as their own BMS- but you only have to be unlucky once and your whole project- and maybe your garage and house- will pay the price. Not a gamble I'm willing to take- others are free to make their own choices.

Find the E-Fire in the Garage and click on the link- you will see my suffering in detail- but I don't regret a minute of it- if I knew how well this would turn out, I would have thrown away my car and bought a New Mexico/Arizona/California car in better shape- fighting car cancer is not fun! 15,000 fossl-free miles so far, and my face is still sore from the EV grin! Can't wait until spring to drive it again!

Baratong's build is a lot prettier and better laid out, and he built his own kit DC controller which is the way to go if you decide on DC- it still gives you the most performance per dollar invested, short of a Tesla drivetrain I guess. CurtK's Bumblebee Spitfire is also a nice project to look through. Most of the older ones are "lead sleds"- lead-acid batteries are ancient history now.

 

[Moltenmetal]

I'm not jumping to the conclusion that the rear ends are no good- not yet, anyway. They are Leyland pieces of garbage, built at the lowest ebb of carmaking in history in my opinion, and the rear suspension design is problematic (trying to put thrusts on shafts containing U joints is just plain stupid in my opinion)- I don't deny any of that. But the same rear end, all except for ratio, was used in the 6cyl GT6 version of the Spitfire and didn't blow up routinely.

I'm chalking my experience up to bad luck and old parts so far. My first differential was the original one I had in the car- it never had the oil changed in it, ever, and it did sit unused for about 18 years before I did the conversion. I figured it was very likely to come to a bad end- and it did, tearing a tooth out of the crown pinion.

The 2nd was just one I had laying around, which I popped in when the 1st one failed. Again, with no drain plug in the bottom of the casting, there was no way to change the oil in it- the idea was that you just topped it up whenever it got low, which they did a lot because the oil seals usually leaked pretty badly. The diff design with no ability to change the oil in it was probably fine for the low torque of the original engine, but likely not a good strategy for long term survival with electric drive and all the extra torque.

My second unit was most likely just an original used diff, not one that had been re-built.

The noise I was experiencing was likely NOT my diff, but rather the diff end of the propshaft, which had a very bad U joint that is next to impossible to detect while the propshaft is still in the car...I was lucky I didn't blow the thing up and lose my propshaft on the way to work one day. The bad joint plus the poor balance of my home-made Toyota-Triumph driveshaft may have killed the differential input shaft bearing, and the gearing in the diff is likely worn and noisy too- but I don't have a report back from the shop yet as to the condition of the thing and what needs doing to it.

I know a guy who has a 400+hp Nissan drift car engine in a Spitfire, and as far as I know, he didn't change out the diff. He did reinforce its mounts though,as it does have a tendency for the pinion end to tip downward when the torque gets high, given the squishy rubber mounts holding the front of the unit to the frame.

It's a bear of a thing to replace. There's apparently a Subaru diff conversion that you can do, but I think that's limited to the earlier marks. And it's not a pleasant conversion either.

I'll keep you guys updated with my progress. But I"m not panicking, yet. And if I had gone direct drive, I wouldn't be as worried about torque- remember I still have a tranny, and always "launch" in 2nd gear...that, plus the heavy regen settings I have, are likely to blame for whatever longevity problems I'm having with the diff, and fair enough- it's worth it for the fun factor!