1972 Mini Cooper E.

28271 Views 44 Replies 13 Participants Last post by onegreenev, Aug 2, 2014

Jaesin

Discussion Starter · Oct 31, 2011

10

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).

12V+:
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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21 - 40 of 45 Posts

Duncan

· #21 · Nov 5, 2011

Hi Jaesin

You just need the front hubs and driveshafts off any post 1984 mini - they all have the disc brakes after 1984.
I think you will need 12 inch wheels - the Cooper S brakes that can be fitted in 10 inch rims are like hens teeth

The inboards CV's don't seem to wear out much - the outboard ones only fail when they get grit in them

The diff is dead easy - practice on the spare gearbox you have - just take off the side covers - undo the fore-aft bolts and it comes apart

You should check that your old diff has the same input gear - if it has just drop the new diff into your cooper box and bolt on the side covers - if it has a different gear swap the gear from your old diff first

Swap the diff over - swap the side covers and you have a cooper gearbox (I think they were also fitted to std minis for a few years - if you have close ratios it's a cooper unit) with inboard CV joints

Jaesin

Discussion Starter · #22 · Jan 21, 2012

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.

tc.

-Jaesin

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etischer

· #23 · Jan 22, 2012

Just use a sawsall =)

Jaesin

Discussion Starter · #24 · Apr 2, 2012 (Edited)

2

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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MalcolmB

· #25 · Apr 3, 2012 (Edited)

Hi Jaesin. Yes, the space in the rear subframe is just about right for 30 x 100 Ah cells. Those prismatic cells make packaging so much easier than any alternative, especially in a Mini. I've been struggling to find a way to fit a relatively small pack of cylindrical cells in the boot, and finally admitted defeat, so they're going in the rear seat space instead. The cells would have been so close to the boot lid that the slightest nudge would have meant disaster. The improved weight distribution has to be an advantage. I don't have any experience racing Minis, but would expect that it will reduce understeer without causing any unwanted tail happiness.

Jaesin

Discussion Starter · #26 · Jul 10, 2012

2

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. http://www.kleenspeed.com/ev-x11/ <- 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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MalcolmB

· #27 · Jul 11, 2012

Great to see this Jaesin! I was very close to trying this myself, so it's good to see someone else have a go. The aluminium mount looks nice and solid and the Union Jack pattern on the end plate is a nice touch.

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?

Did you have a new input shaft made or just modify the existing one?

Studebaker

· #28 · Jul 11, 2012

Beautiful work, mate.

Jaesin

Discussion Starter · #29 · Jul 11, 2012

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

MalcolmB said:
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.

MalcolmB said:
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

MalcolmB

· #30 · Jul 12, 2012

Thanks for the info Jaesin. I'll be interested to hear how the gearing works out. 2.2:1 does sound a bit high, but on the other hand most people seem to find that the stock first gear ratio is way too low to be useful.

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, as it leads to accelerated wear. I think a lot of the documentation is over-conservative though. If you look at most motorcycle drives they seem to be outside the recommended envelope for long life. You've also got the advantage of a sealed oil bath, which makes a big difference.

I went to the opposite extreme and used 3/8" duplex chain, which lets you use a higher tooth count but isn't as strong as 5/8". There's only one way to find out if it's strong enough...

That's useful feedback about chain versus belt from Kleenspeed. I've heard a couple of other people say that belt is noisy and runs hot, so I guess I'll stick with chain too.

Jaesin

Discussion Starter · #31 · Jul 12, 2012

MalcolmB said:
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

Jaesin

Discussion Starter · #32 · Jul 12, 2012

2

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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Studebaker

· #33 · Jul 13, 2012

Here:

69.5 mm

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Joey

· #34 · Jul 13, 2012

Jaesin said:
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!
- Jaesin

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

Woodsmith

· #35 · Jul 13, 2012

I personally prefer flush fitting with internal lock.
Prevents people being nosy about the fuel filler on and EV.

Otherwise I vote for the second one, no bolts.

Jaesin

Discussion Starter · #36 · Jul 13, 2012

Studebaker said:
Here:

69.5 mm

Awesome! Thanks for that.

Joey said:
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

Woodsmith

· #37 · Jul 13, 2012

Jaesin said:
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

In which case Monza cap for me too. I just wasn't keen on the ring of bolts.

Jaesin

Discussion Starter · #38 · Jul 22, 2012

2

Progress

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.

-Jaesin

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Jaesin

Discussion Starter · #39 · Jul 30, 2012

2

I got my new end mills from shars.com.

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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Jaesin

Discussion Starter · #40 · Aug 2, 2012

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.

-Jaesin

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