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My PCB arrived earlier than I thought, so I quickly started to put it together. The Arduino is to manage the coolant temperature into the battery pack. Precharge delay timer is for the master contactor - it will look after the DC/DC converter and aircon compressor capacitance. Also, the DPDT relay and OR gate locks out the inverter and drive contactor so you can't drive off.

So my lump of aluminium arrived at work the week I was off, so I managed to find a bit of time over lunch to cut the plate out on the band saw. It's 40 mm thick, but will eventually be machined down to 37 mm at the edges around the flange, and a recess of about 20 mm where the motor and flywheel sit. My plan is as follows:

(Critically) flip the plate so I am looking at the inside (from the gearbox).

Centrepunch the centre of the plate where the shaft is. With a set of dividers, draw a 222 mm PCD and mark the 4 x M10 bolt holes for the motor, centrepunch these. Draw a 100 mm diameter circle inside this which will eventually be removed completely.

Machine up several transfer pins and insert these into the dowel holes and the threaded holes so they protrude by about 1 mm.

Drill the centre hole to 18.85 mm so the gearbox shaft can clear the plate.

Line the plate up with the other holes, clamp somewhat, and tap the plate from behind so the centring pins mark the inside of the plate. Remove, drill to their respective sizes and depths.

Machine out the 100 mm hole so it fits snugly over the motor flange.

Then machine the inside of the plate to a depth of 10 mm or whatever it is.

Bolt it all up, attach flywheel, clutch and pressure plate.

Line up gearbox and all going to plan, bolt it on.

...spin drive shafts in gear freely and effortlessly

I should add I have enough plate ally left for two more of these should someone need a bit.

Steps 1 and 2 sorted...
Thankfully Rod still had a dimensioned drawing of the Greatland motor - the PCD was 221.5 mm (close enough) and the keyway is 8 mm (not 6, like I thought it would be).


Why they chose bright green on white I have no idea...

The 19 mm hole made for a slightly sloppy fit (0.1 mm radius too large) but unfortunately 18.8 mm drills are not common. So the gearbox input shaft had a little bit of tape put around it until it was nice and uniform, and the plate didn't budge in any direction.
Time to get the transfer pins sorted and ready for the big 'mallet tap'.

jonescg wrote: ↑

Tue, 30 Apr 2019, 21:38

The 19 mm hole made for a slightly sloppy fit (0.1 mm radius too large) but unfortunately 18.8 mm drills are not common.

Why wouldn't you get it profile (laser or water-jet) cut?

blwnhr wrote: ↑

Wed, 01 May 2019, 08:21

jonescg wrote: ↑

Tue, 30 Apr 2019, 21:38

The 19 mm hole made for a slightly sloppy fit (0.1 mm radius too large) but unfortunately 18.8 mm drills are not common.

Why wouldn't you get it profile (laser or water-jet) cut?

The centre-punched point is my only datum, so all points are relative to this. I could possibly take it to a machinist who could bore it out on a rotary table, but it's just as easy to do it this way. Once I have all the holes drilled to the right clearances I can machine out the 100 mm circle in the middle to full depth and then the surrounding flywheel clearance to about 20 mm depth. I can band-saw the remaining tabs then.

Mark Winstanley kindly turned up some transfer pins which fit neatly inside the blind holes of the gearbox. Critically the dowel pins were nice and accurate, while the central 19 mm shaft seemed as central as I could get it.
I put lots of marker pen on the recieving face to ensure a clear shot was visible. The aim is to have these prodtrude enough that they punch the back of the plate right where we need to drill a hole.
After double-checking the marks with the points on the gearbox I gave them a solid hit with the punch. I removed all of the pins and lined up the plate once more for the three M12 through-bolts which are clearance only - I used a 12.7 mm transfer punch for these to good effect.

It's ready to mill!

G'day Chris, did you get those links I sent you about machinists? Sent to your gmail address.

Also, you might want to invest in an adjustable reamer if you want accurate holes.

Cheers, Geoff

Geoffozz wrote: ↑

Tue, 07 May 2019, 13:07

G'day Chris, did you get those links I sent you about machinists? Sent to your gmail address.

Also, you might want to invest in an adjustable reamer if you want accurate holes.

Cheers, Geoff

Thanks Geoff, yes I did get them. Ended up going back to Mike McCarthy since he had time to get onto it. He's already made the hub blank using EDM wirecutting.
An adjustable reamer eh? Sounds like a great idea. Wished I'd thought of that earlier...

We're almost ready to bolt her up!

Hub is finished too. Hope I sent the right dimensions

Frustratingly, the flywheel sits 10 mm too proud of the plate face! How on Earth did I manage this? I had the flywheel thickness correct but must have forgotten to subtract the offset at the hub mounts or something...
In any case the motor can be mounted 10 mm back with a spacer plate, provided the 100 mm diameter hole and 221.5 mm PCD can be reliably mounted together.
Sigh.

Spacer plate made, flywheel sits in exactly the right spot
Just need to source some bolts, bolt it all up and fit the clutch, then mate it up for the big hand-spin test...

Clutch went on like a dream.
The whole lot bolted up like they were supposed to - no tapping or coercion, just tighten the bolts and we're rolling. Next job is to fabricate the mid-shaft support and the engine mounts, and do some test-fitment.

Looks great! Crazy how tiny those motors are compared to the gearbox!

They sure make up for their size with weight though!

The weight of the motor for the bus project was the same as the weight for the trick 4 speed gearbox, a real eye opener to the amount copper etc inside these motors.

T1 Terry

Well now at least the passenger side motor mount and mid shaft support plate are done. It needs about 5 mm of plate aluminium to space it out, or alternatively, a piece of 15 mm plate (preferred). Once this is together and the shaft is supported, we can drop it in the engine bay and mount the last two engine mounts!

If the plan to weld this piece of plate to the piece attached to the motor, then the holes for the driveshaft mounting drilled and helicoiled for thread strength? Will there be enough support positions for bolts available on the back of the motor? I'm guessing you would need to add dowel pins to ensure location as there is no provision for out of line movement of that shaft in the diff assembly.

T1 Terry

Hi Terry,
The plan is to bolt this plate to the end of the motor, and then bolt the bearing support plate to the face plate. The exact position will be in the centre of movement of the mid shaft, with the spacing set accordingly. At this end it has about 5 mm of free play in all directions. Fortunately the shaft will see very little force outside of the rotational, but I sure don't want to mash up the spline inside the diff with a misalignment.
The engine bay mount will then bolt to the upper half of the face plate.

Mmmm....... Personally, I'd get it welded by someone who was really good at the job to make sure it was square to the base plate. Just too many bolted together pieces to ensure good alignment every time and it remain aligned. Just from experience as an industrial fitter for many yrs

T1 Terry

I machined the edge nice and flat so the two parts bolted up square.

Next step is to add the spacer plate and mount the bearing to it. Going to have to use countersunk bolts with the nuts on the outside I think.

Seems 4 mm is exactly the right amount of spacing required to get the shaft to sit at the right fore/aft neutral spot. I've found the same sweet spot for up and down too.

Haha, whoops. I got too excited, put my spacer plate in there, transfer-punched the centres and drilled them out. Went to bolt it all up and realised I don't actually have enough bolt poking out the other side, let alone room for a nut!

So I will have to re-make this backing plate out of 10 mm steel and tap the threads directly into it. Unless 10 mm thick ally is up to the task?