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1972 Mini Cooper E.

28268 Views 44 Replies 13 Participants Last post by  onegreenev
First of all, I would like to let you all know that all of your hard work has inspired me to start my conversion a year earlier than I initially planned.

My car is a 1972 Mini. I have owned it since 2005. The engine has smoked since I got it and I've been dreaming for years now about ways to get away from this nasty old oil puffing raga-motor.

For those of you who've had any experience with this car, you know that space is the main issue with it. The car was very well designed and wasted no space at all.

The Transmission:

Most folks think the stock trany isn't of much use. I mostly agree with this. It sits in the oil pan of the ICE. Basically, it is the oil pan. It also sits in kind of an awkward position. It's right in the middle. there is a few inches in front of it, and there is a few behind it but not really enough space to put any batteries or the controller.

I'm using it anyway:
The thing is, I am converting this car in two stages. I want to get rid of my other car so I am converting this car now. That way, I can drive it while I work on the car's more permanent AC system. That means that quick and dirty (AKA, fast and cheap) DC system for now.

Slap Chop:
A very nice gentleman I met at the EVVCON sold me a Curtis DC Controller with a contractor, heat sink and two fans already assembled. On top of that, he offered it to me at a very good price. Thanks Einar!

Coils and armatures:
I picked a D&D 6.7" motor (that's right, just one). It puts out a bit more torque @ 1600 RPM's than the stock ICE peak torque of 52 lb-ft @ 2700. The D&D would put out 80 ft-lbs @ 1600 RPM if I could give it another 83 amps.

Connecting Bits:
I am going to use a chain drive and nix the clutch. The output shaft of the motor and the input shaft of the gearbox were at a one-to-one ration so I am going to gear up the motor a bit. I want to have some usable torque at 65 MPH and I figure most people don't really use 1st gear. I'll aim for a about a 2-1 chain drive (calculations pending).

I am currently working on the DC-DC Converter. I bought some 3.3V Vicor modules that I will wire the output in series for a max of around 20A @ 13.5VDC.

Some Pictures.


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chain-drive will be fairly noisy... and you need to be sure you have a way to adjust tension as it wears. You may want to consider the rubber belt drives found on some of the big touring motorcycles; much quieter and no lube required.
I am expecting the whole system to be pretty noisy. This motor and controller is kinda noisy. It makes this crazy tone at low RPM's before the PWM frequency changes. The transmission will probably be noisy. Maybe I'm wierd but I sorta like the odd sounds. Maybe because I've got no radio.

I drive motorbikes and I also have a Chinese electric scooter that I upgraded to LiFePO4. That thing is too quiet. I sometimes think that could get me in some trouble.

Thanks for the suggestions about chain tensioning. I am planning to use a Susuki GSXR Motorcycle chain. I am thinking to build in some tie rod style or pivot bolt style adjustments into the motor mount.

I am still working out how to switch the input gear with a sprocket. If I can manage to fit a small enough diameter gear, I will keep the stock end plate. That would be really nice. We'll see how it goes.

I've seen your car, It is amazing work. Your motor setup blows my mind every time I look at it and I do love the green.

My motor test from last month:
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aloha, looks like you got an original Cooper S. Why not repair it, sell it, and buy a regular Mini. In the US, Cooper S's in nice shape I see going for $25k+

Aloha Fransis!

I'm not sure it's a real Cooper S.

I was told it is but it only had the 998CC engine and it doesn't have disc brakes (yet).

I don't know that much about all of the different models.
Did they make a 1 liter Cooper S with drums in '72.

My theory, if it's worth $25K on gas, it's worth $50K to me on LiFe.

Aloha, It is a strange model then. As the 998 is the later Cooper engine, 997 was first. But I think the Cooper S came with 998, 1071 and 1275 engines. I never heard of a Cooper or Cooper S with drum brakes in front. And it has the right hand Cooper S gas tank (making twin tanks). So it is a real oddity to me. Someone in the UK would have to figure it out then. But it will make a nice EV!

The twin tanks do look original. I tried looking up the VIN (MXA251 717-850N) one day but it wasn't conclusive. I think it might be Australian made (Near Perth). Made by Morris BMC. This is kind of a hunch. When I got the car, it had what looked like old New Zealand plates and the VIN doesn't look like a UK VIN. It was original (besides being repainted) with no rust at all. They did make a Cooper S model but I read AU cars had some different features. Maybe they ran drum brakes in AU.

I don't really know.

Wow Duncan, Thanks for all the info.
Does that cover Aussie cars as well?

I read that they started installing roll up windows in Australia before they did on UK cars. Being that the environment is different, I imagine there are other inconsistencies as well.

I don't have hydrolastic suspension.

Whatever my car is, It's not a UK Cooper S so even if it was an Aussie Cooper S, It's still not worth what an original UK Cooper S is worth. By time I'm done with it, it will be very something completely different anyway. A custom Cooper E with adjustable suspension and all wheel disc brakes.

Hi Guys
You seem to have a rod change gearbox - that came out in 1973 and has a completely different exhaust tunnel and much better driveshafts - much better my old 1430 used to bend the old rubber hardysplicers - I got used to changing them fast, the inboard CV joints are much better
Man.. 1430cc sounds like a monster, hahaha.

The gearbox is a spare. I have the rest of the engine if anyone is interested in it (998cc "99H791P"). I need to get rid of it.

I will probably go by the local Mini supply shop to pick up the suspension parts on Thursday. Is there anything I will need to match the gearbox to my '72? I guess I will have to check the gearbox in the car before I go. What should I look for to tell which gearbox is in the car.

The Coil Conversion:

- Jaesin
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First of all, I just want to say thanks for helping me keep my focus on this project.

I would be very wary of that coil spring set-up
The mini doughnuts are very progressive - they have to be because of the
I was originally thinking about adjustablilty. I've had the car for about 6 years now and I think the cones are a bit harsh for daily driving so I kinda wanted to try something different. I think these are even cheaper than the doughnuts: so I still might try them. I've read some post from a few guys that have put them on:,

The cooper gearbox had a nice aluminium extension going to a shorter gearlever,
This is what I have. A long rectangular aluminum tunnel attached to the gearbox. Complete with floor hump by the driver's seat (RHD). I am not sure if the tunnel will attach to the rod change gearbox. It doesn't look like it.

Inner CV Joint:

Anyone know what's invovled with converting to inner CV joints?

As for brakes, the front drums are actually pretty good if well maintained. The 8.4" discs are a significant improvement. It's not worth doing much at the back, as the performance of the existing drums if well maintained is more than you can use – it's limited by the proportioning valve, as Duncan said.
I mainly wanted the rear discs for cosmetic and weight saving but I am going to hold off on all not essential upgrades for now. It's a good point to think about the cost of all this stuff. I was getting a little too excited about wasting money. hahaha.

The last couple of years have been hard on "Champ". I am going to need to do a fair bit of body panel work. I should definitely take care of that and get some new paint before wasting money on stuff I don't need.

- Jaesin
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Thanks Duncan!

A simple steel spring has a constant rate (lbs/inch) so if it is going to stop the movement in a short distance it must have a very high rate,
Sracer advertises that the springs are progressive. Maybe not as progressive as the cones. Who knows, it's hard to get specs for these things. I had new doughnuts on it when I got the car but maybe they were not late model replacements. It could be that the seller wasn't perfectly honest.

I do appreciate you keeping me informed.

Later drive shafts on an older gearbox
I did this on my 1430
You have all of the bits you will need on the other gearbox, take the diff side covers off - I think you will need the diff output shafts

If you get a later disc brake setup you will need the CV's and drive shafts as well
Its all pretty clear when you get the bits together
So I guess I will need to rebuild the diff to use the older output shafts because I don't really want to buy new CV joints and axles at the moment.
Maybe it's possible to get standard axles but the ones I have sourced so far are beefed up $500 units. Ouch!

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I just wanted to leave a quick note about my project for anyone that is interested. I started my build a couple of months before I was scheduled to leave town for the winter.

Before I left the US, I picked up 30x 100AH Calbs. The 10KW pack will sit in the boot below the level of the hinges. I still have to make the battery box but everything measures up just fine.

I tried to cut the motor bracket at the shop but the FlowJet was having issues with the abrasive so I still have to finish some parts on the mill and the band saw then weld it up. If I were to do it again, I don't think I would bother with the FlowJet. There is a Tormach CNC mill I can use. I still have to pay per minute to use the FlowJet because of the abrasive and the crap-load of energy it uses but I can use the Tormach all I want with my own endmills.

I am in Thailand at the moment. I will be leaving for Peru next week then I will spend 3 months in Brazil, Argentina and Chile. If any of you are in South America and you are working on a project, I would love to come check it out so send me PM and I'll try to meet you if I am coming through your area.


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I picked up 30 CALB 100AH Cells back in November. That is just about a 10 kW-h pack which will give me a maximum range of 50 miles. That's fine for me for now.

I did some measurements and discovered that all 30 cells will fit in the trunk (mostly below the floorboard). The sub-frame in the rear of the car has a relatively large unobstructed rectangular opening that will allow me to drop the battery box down into it. I can create a new floor in the trunk just above the battery box and it will still be below the hatch opening which means that I will still be able to haul lots of groceries in the boot.

It looks like the stock mini is a bit front heavy (front/rear = 64/36) or about 828 lbs in the front and 446lbs in the rear. I am estimating that I will loose 100 lbs in the front by replacing the stock motor with the air cooled electric powertrain which should give me 728 lbs in the front. I will also add 135 lbs to the rear ( Li batteries +220, gas tanks and stock battery -85) giving me around 581 in the rear. Total estimated weight will be 1309 lbs giving me a front/rear ratio of 56/44.

The car already corners like a champ but what differences should I expect with the new front to rear weight ratio as far as handling is concerned?

- Jaesin


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My drive end motor bracket is all welded up.

Last November, I tried to cut out my motor bracket parts on a malfunctioning flowjet cnc. After that failed to dice up my 1/2 inch 6061 stock, I decided to finish it up on the Tormach PCNC1100.

I am now back from a very long trip to SE Asia and South America and actively working on the mini.

So I have been spending my spare time using the Tormach and practicing my TIG welding skills. I tacked my motor bracket together and laid a couple of beads before deciding to let a pro finish it up. I wanted to be sure it was solid and my welds are lacking consistency at this point.

I am using a ANSI #50 roller chain rated a 1620 lbs working load. I was recently at a RE-Fuel races at Laguna Seca and I noticed that the Kleen Speed team switched from the belt drive they were using the year before to an ANSI #50 chain. I asked David Kichar (COO) about the switch and he said that chain ended up having less resistance and is quieter than the belt drive. Needless to say, I found some relief in that. <- For a look at the Kleen Speed car.

All in all the bracket is looking pretty good but I still have to do a bit of touching up work but it is functional as it sits.

I still have to fabricate a rear bracket for the motor and seal up the transmission so the oil doesn't go flying all over the place. I have a piece of aluminum plate that covers the top of the transmission and I have the stock end plate that will cover the bottom half of the chain drive. I just have to fabricate the oil cover for the top half of the chain drive.

You can see the chain adjustment mechanism in the second picture. I will have to lift the motor and re-tighten the bolts for now but I will probably add a tensioning bolt to be sure there is no slippage.

Everything squares up quite nicely.

- Jaesin


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Thanks allot guys. I figured, why not add a couple of nice touches while I am on the mill.

Did you end up going with the 2:1 sprocket ratio? I can see the top sprocket's a 22t, so 11t on the bottom?
The bottom has a 10 tooth sprocket on it making it a 2.2:1. There is very limited space inside the stock end plate and the 11 tooth probably would have rubbed.

I also have an 18 tooth sprocket to try on top if this it feels like it is geared too high for the hills here in San Francisco I'll take the highest ratio I can get. I would like to be able to make use of 1st gear and get the highest possible speed in 4th. I am planning to add an additional fan for cooling the armature.

Did you have a new input shaft made or just modify the existing one?
The 1 inch input shaft has splines about the same size as the keyway on the sprocket so I am making a custom key that will seat into one of the splines. We'll see if it holds. I'll make it a very tight fit. I may also pull the shaft and mill out one of the splines for a proper keyway which would probably be the better way to do it.

- Jaesin
I did a bit of reading about chain drives for my own conversion and one of the recommendations is to avoid using low tooth counts...
You are definitely right about that from all I have read as well. If I have a failure, I know for sure it is going to be because of that damn sprocket. Not only is it too small, the mounting for it is less than ideal but it is the biggest one that would fit inside the stock end plate. We will see what happens.

- Jaesin
I am designing a J1772 port for the mini that I plan to mill out of billet and I'm trying to decide on the cap style.

I wanted to see what you guys think between the Monza style and the typical rounded style flip caps.

I also have a design for a twist cap that has hidden hinges. It's a twist and flip design that looks like a regular round cap.

Opinions please!

Does anyone know the diameter of the port opening in the sheet metal?
I won't have access to measure mine for the next week or so.

- Jaesin


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69.5 mm
Awesome! Thanks for that.

I like the exposed ring of mounting bolts on the first option, but both look great.
Thanks for the feedback guys.

The mounting bolts are there in the first pic because that cap is on a motorbike. I think it looks great on the bike but it would start to take over on the rear of a mini. I'm was just trying to show the Monza style cap.

- Jaesin

I decided to take the first motion shaft out and mill a proper keyway.

It's killed two solid carbide ALTIN coated end mills so far. Now I wait for new ones to get here from shars.

I cut the transmission end plate and bell housing in half because the chain and sprocket didn't fit in the top half of the end plate. I still need the lower half because it has the transmission mount attached to it. I will have to weld in some reinforcements for it.



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I got my new end mills from

The 1/8th solid carbide ALTIN Stub length didn't have any problems cutting the shaft.

I have some clearance issues in the end plate I will work on tonight.

- Jaesin


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The chain is attached but things are a bit tight. I will do a bit of milling on the case around the idler gear bearing to allow a bit more space for the chain to move around on the sprocket. Everything is looking good though. I have another spacer for the lower sprocket I can try that will allow the chain to back off the transmission end plate a bit.


My buddy sent me this link for inspiration:

Besides that, We got the dirty old ICE out.

More interesting changes to this project coming soon.

- Jaesin


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