Got my donor car! MR2 mk2 G Limited

[Night Train]

Thanks Greg.

So for the efficiency and weight saving I will be looking at 3-4 times the cost invested in the motor, £1200-£1600 for the pair of Agni motors. Ok, not impossible.

From the Agni and Lynch websites I need a suitable controller, will this be essentially the same as I would expect to use for a forklift motor anyway or is it something extra special or specific?

Are the Agni motors going to have any long term problems with servicing, performance and reliability or is it too early to tell?
I know that forklift motors are well proven designs that will run for decades if looked after. I know nothing about Agni motors at the moment.

From the Lynch site I see that their motors can be Siamesed end to end with one output as if a single motor. Chris' are facing with what appears to be the output in the centre. Any benefits with either?

I will need to consider the mounting location and coupling to the gearbox via a clutch, or not. Given the even smaller amount of spinning mass I would assume that makes the clutch even less necessary for smooth gear changes.

[ChrisB]

Also from Chris' photo the motors are coaxial to the gearbox. How have you connected it and have you got a clutch or a direct connection?

The two output shafts where joined together using a large toothed pully (like a cam belt pully, just bigger) then the clutch was removed and butchered to get the spline bit from the center and this was then mounted onto another toothed pully (cant remember the ratio's off hand) and then this was slid onto the input shaft of the gearbox and the end of the input shaft was supported by a bearing. Of course a toothed Gates belt was used to join the two together. The two motors where then wired in series and thus the pack voltage was nominally 120v although just off charge it would sit upwards of 140-145volts.

One thing I would say is becareful when doing range calcs compared to batterys, its never seems to work out like it in real life and generally a lot lower, mainly I suspect due to wind, tyres, gearbox losses, road and traffic conditions etc etc
My fiesta was calculated to be able to do just over 50miles at 30mph, in practice I never managed anything closer than 35miles at best and the norm was 30miles, that was with Lead acid's mind you, but then if I could have just done 30mph in a striaght line for 50miles then the discharge would have been correct, but normally you cant, you have to stop, start, pull out of junctions etc and this all takes it toll.

Sorry for all the questions but this has thrown a whole load of other factors into the equation that I need to take into account now. I only want to do this once and I can't really afford to make a test bed and then improve later. I also can't afford to make a very expensive car either with too much costly new technology so it is all a balance.

Thank you.

Far better to ask questions at this stage than make an expensive mistake later

ChrisB

[Night Train]

Thanks Chris.

That looks like a good way to couple up the motors. I used to have abelt drive Harley Davidson so I know the belts are stronger then they seem.

I assume gear changing hasn't been a probmel without the clutch?

I'm aware of the limitations of the calcs but it was a ball park to get an idea of whether I needed 10 cells or 100 cells to get to work. I am working on return range to work but also expecting to convince work to allow me to recharge while I am there. Also it is mostly up hill there and down hill back so 100% over estimate should allow me to get there no matter what.

I managed to get the engine ready to pull out today. A few cheats allowed me to remove the drive shafts without completely dismantelling the suspension and brakes. The engine will come out the top, I am determined of that, I'm not into breaking half the car apart to pull an engine out from underneath.

[ChrisB]

Thanks Chris.

That looks like a good way to couple up the motors. I used to have abelt drive Harley Davidson so I know the belts are stronger then they seem.

Yeah tell me about it, my main issue was trying to stop the dam belt from slipping due to the huge amount of torque those motors produce, I had to use a hydralic ram to tighten the belt, although Alan who bought it off me changed the design somewhat and made the adjustment via a threaded bit of bar I think, which apparently works much better

I assume gear changing hasn't been a probmel without the clutch?

It takes a bit of getting use too TBH, gear changing is slower than with a clutch as going up the box its foot off throttle, shift to neutral , shift to next gear, re-apply throttle, which all take a lot longer than your normal wanging it through the gate to the next gear, going back down the box is even more fun or impossible if your not use to and goes something like this. Remove throttle, shift to neutral, re-apply throttle to match motor speed with gearbox speed (which can be the tricky bit) and shift down to the next gear, its like double de-clutching but without the clutch

All in all its not too bad, and given time you do come quite quick at it.

I'm aware of the limitations of the calcs but it was a ball park to get an idea of whether I needed 10 cells or 100 cells to get to work. I am working on return range to work but also expecting to convince work to allow me to recharge while I am there. Also it is mostly up hill there and down hill back so 100% over estimate should allow me to get there no matter what.

I managed to get the engine ready to pull out today. A few cheats allowed me to remove the drive shafts without completely dismantelling the suspension and brakes. The engine will come out the top, I am determined of that, I'm not into breaking half the car apart to pull an engine out from underneath.

Yep I'd allow a good 100% over estimate, although with LiFePO4's it could be totally different?? I know I'm on a learnng curve with my little baby pack of them and they do seem to be very good at what they do.

ChrisB

[Night Train]

Doesn't applying a bit of throttle in neutral risk over speeding the motor?

I have almost got the engine out of the car now. Everything is disconnected and the engine gearbox unit is only held in by two of the four engine mounts.

It is an awkward lump to get around. To remove the unbolted exhaust manifold I needed to remove the oil filter. To remove the oil filter the exhaust manifold needed to be removed!

I managed to get everything disconnected without completely removing the rear brakes, suspension and subframe. This way I can keep it on its wheels and mobile.

Just need to set up a gantry crane now.

[granada203028]

All those big fork lift motors must be capable of much higher peak powers, and higher continuous ones with suitable forced cooling. The modern pan cake motors are the best but at a price. The fork lift ones must still do 80% efficiency, so not that much worse than the 90% for the pancakes.

The aircraft dynamo used in my electric bike manages 80% efficiency - I have measured it with two back to back. That is at 6KW, 3000 rpm through a 25Kg machine. A 40 year old design.

I have a similar sized aircraft starter motor which is rated at 45HP for 1 min, 112V 455A.

[Night Train]

The aircraft dynamo sounds like an interesting idea. Not so sure about the strter though, they are not meant for continuous running though I think that may be to do with whether or not it has plain or ball bearings.

So anyway, if I save up for an Agni motor in the longer run I would still want to have a cheap cheap motor to get me running initially.
So should I really pass on those motors and keep looking or would anyof them be passible?

I think I am looking for:
9"-11" diameter depending on clearance
About 17" long as I have 20" from bell housing to chassis member
Male shaft to take a taper lock
Series wound
Long commutator bars about 2 1/2" - 3" long
Lots of narrow bars
4 pairs of brushes

I would need to get about 4002rpm to get 70mph and at least 14.6kW at the wheels.

[Night Train]

Wayhay! The engine is out and on the ground!

I was going to set up a tall tripod with scaffolding poles but my Dad, who was supposed to be helping, had this strange concept in his mind that tripods were top heavy and would fall over easily even without a load on it. we had a bit of a heated debate about this and Dad went off in a strop. In the end I resorted to a bit of scaffold tower and an A frame linked by a long pole over the back of the car. It wasn't very stable as it kept trying to lean one way or the other. I would have prefered the tripod, 5000 years of human engineering can't be wrong!

Although the MR2 Owners Club say it can't be done the engine does come out top ways but not if you have a lovely paint job in the engine bay.
The trick is to lift and lower a couple of times to get the mountings to seperate.
Then lower the engine onto a block of wood or a trolley jack so that the lift position can be moved towards the cam belt end of the engine.
Then lift again but push the gearbox forwards so that the mounting and the end of the gearbox clears the mounting on the chassis.
Then lift the engine upwards at a slight angle.
Watch for the front of the engine catching the rain gutter and the back of the engine catching the engine lid latch. A sheet of 6mm ply front and back would help slip the lump past these catch points.
Once the engine is out the car can be pushed out from underneath, Dad did come back to help at this point.
As the scaffold frame wasn't as tall as the tripod I wanted to build I had to remove the boot lid to allow for clearance.
With the engine on the ground it could be dragged out of the way and the car pushed back.
I am leaving the scaffold in place for putting the motor and gearbox back.











As you can see it was getting dark as I was finishing up. Most of the day was spent in and out as the rain came and went.
I also managed to get a load of my furniture into an exhibition today and print out a load of leaflets for it. It has been pretty nonstop.

[ChrisB]

Doesn't applying a bit of throttle in neutral risk over speeding the motor?

No as their rpm is directly related to voltage, thus as long as you are within their voltage you can run the motors totally unloaded without any risk of it going pop.

I could sit in neutral with my foot down to the floor on the throttle in my fiesta and both motors would be flat out but would never exceed their rated rpm due to my nominal voltage being 120v and thus 60v across each motor.

ChrisB

[Night Train]

Ahhh, I see.

I guess that is more of a problem for the 48 volt fork truck motors run at 144 volts.