emini

I strongly recommend filling your socket set completely before taking it somewhere. If there is one socket missing then inevitably some other socket will take it's place, leaving a gap in an unexpected place. I spent a good 20 minutes looking for the 10mm socket, I knew I'd used it and now it was missing. I eventually remembered that the 1/2" socket was at home and sure enough the 10mm had taken it's place. I wasn't watching the time and the unlike their other Pick-A-Part branches, the Takanini branch doesn't have a big siren to warn you they are closing. I had just found the socket and was about to leave when someone thought of coming over to tell me they had closed. By this time they had closed off their computer and I couldn't pay for the parts that I had extracted.

I didn't even have the iPod up very loud.

I've got a long driveshaft, another gearbox & a speedo cable waiting for me.

Checking driveshaft alignment

I'm reasonably happy with how I've fitted the gearbox to the motor. I'm going to weld a plate into the bottom of the bell housing, cut it square in a mill and attach the motor to that. Above you can see everything fitted to check the driveshaft lengths (fans of the Mini will note that the hubs are on backwards -- the Mirage gearbox is biased to the right while the Mini is biased to the left). I have another Mini undergoing a gearbox & subframe overhaul. Since it's already apart I'm using it to prototype the conversion while I drive the donor. The fancy brakes aren't part of the electric project. At some point I have to reassemble the other car and take the donor apart.

I'm not using a Mini gearbox, I'm using a gearbox from an early 80's Mirage. This is an interesting 8 speed box -- the input shaft drives the laygear through one of two ratios, doubling the available speeds. It has some good properties, it's small, the input shaft doesn't need to be supported by the motor & there is reasonable separation between the input & output (making it easier to fit into the Mini).

Unfortunately when I got driveshafts I didn't realise that the short Mirage driveshaft is too short by about 3cm. I will be going back to the wrecker to get another long driveshaft. While I'm there I'll get a new gearbox to replace casing I broke.

Mini (below) & Mirage driveshaft assemblies

14 people & 2 electric vehicles turned up for an NZEVA meeting at Galbraiths.

Ross brought his electric ute.

Keith brought a working model of his Segway project.

Steve's MRS isn't yet electric but still drew a crowd. His plan is to create a poor man's Tesla Roadster.

Cutting is tedious. I've got to move the motor about 10mm closer to the gearbox. I've been doing this with a mix of chain drilling, jigsaw & angle grinder.

In other news, you can't cut a block of nylon with a jigsaw -- the blade heats up and melts the plastic which makes for rapid progress until you realise the material is closing behind the blade as you move forward. A hacksaw is very slow and you can't get a straight cut (well, I can't). A circular saw with a medium wood blade works quite well but you still have to wrestle with melted plastic coating the teeth.

For your entertainment I present the crappiest aluminium welding I've ever seen (well, almost). I've put the centering ring on a couple of times and even mounted the motor and so far it hasn't fallen off.

While I don't claim to be the greatest welder, I feel I must point the finger at low argon flow for the very poor finish. I didn't want to attempt a continuous bead because the argon pressure is OK but the flow rate is very low, so you get a burst of gas when you pull the trigger and then very little. I'm not sure if I'm low on gas or the regulator is faulty (for argon I use very small disposable cylinders and my small regulator doesn't have pressure gauges).

The break profile allowed reasonably good relocation, so there is a chance I got the back into the right place. If the shaft runs smoothly after everything is assembled then I'll be very tempted to use this case instead of spending a few hours getting another one from the wrecker.

I'm using a 175A MIG welder, 1mm aluminium wire, argon shield gas, wire feed 5, power 6 and this is the second time I've tried to weld aluminium. I chose not to practice on scrap aluminium in case I ran out of gas completely -- I'm a little surprised that the weld is as good as it is.

Everything was going according to plan. I had the motor centering nicely, cutting the bellhousing to clear the motor was going well. Then disaster struck. While "tapping" the centering ring into place for the nth time, the clutch release bearing sleeve broke off. I was using a rubber hammer, honest. This is either the end of this gearbox casing or the end of my plan to center the motor. I think I'll get another gearbox.

I'm going to try welding the sleeve back into place. This will do for further test fitting but won't be sufficient for proper motor location. I haven't successfully welded aluminium before so this should be interesting.

Campbell very kindly cut my nylon stock into something that will hopefully hold the motor centred on the input shaft of the gearbox. You can see the outer diameter has been cut to match the motor and the inner diameter is being bored to match the sleeve around the input shaft. We aimed to cut the two diameters concentrically and produce a close fit to the motor and the gearbox.

To do this we faced the same problem that Precision Engineering complained about when cutting the input shaft -- the part must be taken out of the machine to check the fit. Unlike the professionals, we don't have much hope of accurately re-centering the part. Nylon is a little flexible so we aimed for an interference fit rather than a slip fit. This means that we are less likely to over machine and make the coupler loose.

In the end we made it much too tight and had to cut again. We managed to re-center it fairly well and make another cut deep enough that (hopefully) the part isn't too oval. The center hole is still a little too tight for easy assembly, I may have to use some sandpaper.

I have to slice a little off the outside diameter to clear a projection in the bell housing and then I'll be in a position to remount everything in the subframe.

Getting the motor to fit onto the spline is tricky since the motor lives inside the bell housing so you have to use a little mirror to see what's going on. Not only do you have to center the motor on the shaft and get it at the right angle, you also have to rotate the the shaft so that the splines line up. I can't turn the input shaft by turning the output shafts (there isn't much inside the gearbox right now) and the motor has no tailshaft so getting everything lined up is basically impossible.

I got some nylon stock from Ludowici Plastics and a friend of mine has offered to turn it on his lathe. We'll turn the outside to match the centering ring on the face of the motor and bore a hole through it to match the sleeve around the input shaft. With everything held true I only need to rotate things until the spline lines up.

My current plan for attaching the motor to the gearbox is to use this nylon centering ring to hold the motor centred while I tighten the bolts on the adapter plate. Because the motor is held centred by the nylon block, I don't have to worry machining the adapter plate to the required tolerance. If the nylon version has too much give in it then I'll have one cut from aluminium. The adapter plate will attach to the back side of the mounting ears on the motor, hopefully they're sufficiently perpendicular to the shaft. With the adapter attaching to the back side of the motor, I can use a fairly thin piece of aluminium. If I want to attach to the front surface then I would be watching an awful lot of expensive aluminium pile up under the mill.

The shaft is cut! My goal of rolling under electric power by the end of the month is now slightly less outrageous.

An observant reader will see a remnant of the old spline visible for 3/4 of the new spline. This is because the old spline was just a little bit too small to cleanly cut the new spline. I'm told this won't be a significant problem because the spline is so deep (3mm according to the drawings) and the torque isn't unreasonable. I'm likely to cut some of the shaft off to get the motor deep enough into the bell housing so this may make it even less of an issue.

The spark erosion machine left an interesting speckled finish to the spline. Less visible in the pictures are what look like marks from turning the outside in a lathe.

I'm hoping to have the car rolling under electric power by the end of the month. This was always going to be quite ambitious, and is looking increasingly unlikely. Basically there are 3 steps that require expert services: coupling the motor to the gearbox input shaft; attaching the motor to the gearbox; connecting the gearbox to the wheels. I've been stuck at step 1 for the last 10 days. To be fair they said I might get the shaft back this week, but now they can't promise early next week -- apparently the machine they need to use is busy on other jobs.

If anyone can recommend a machinist in Auckland who can cut a new spline onto a shaft then I'm open to taking my business elsewhere.