[Driving] MG F - Outlander Rear motor and inverter.

Tell us about the project you do with the open inverter
LRBen
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Engine has been sold. Subframe currently being cleaned up and repainted along with all the suspension components. It's all in pretty good condition given the age. No sign of anything more than just surface rust and road crude. Will wire brush everything down, treat hard to reach places with rust converter then Hammerite paint over everything.
Put a few of the smaller items in the Electrolysis tank, it's a bit overkill but it impresses people at the farm.

Took the fuel tank out after giving it a few weeks to shrink down a little bit(It's plastic). There is a good amount of space there, but I will have to wait on the batteries to arrive before I can figure out exactly how much I can fit there. It's a little narrower on the driver side so that might limit things.

Talking of batteries I have those secured. Got in on the Kokam cells and have 180 cells on the way. Planning to use them in a 72s2p config. Should give a 266v nominal pack with a 28kWh capacity. The cells are rated at way higher discharge than my inverter can handle, so I figure that is a neat safety feature. Then I have a few spare cells for another quadbike or motorbike project.

So next steps are to carry on cleaning up the subframe, test mount the motor and inverter, make up the new battery and throw it all in. Easy...
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

Great update, I loved my old F but it needed a pile of money spent on it and I wasn't using it enough to justify.
Going electric means loosing the bits that let it down like poor gear change and rubbish clutch.
I did like the engine but lack of torque let it down.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Batteries arrived!

Turns out they are bigger than I expected and they won't fit in the fuel tank area without some modifications. I did briefly consider keeping them as they are and just doing a roughly 84s1p battery so I don't need to reassemble them or find as much space in the car. But I think I will push ahead and reconfigure the 10s modules to 5s2p. Then aim for my original 72s2p battery.

I can fit 40 cells in the front where the spare tire usually goes without any cutting. So that just leaves 104 cells to be placed in the fuel tank area. I will have to remove the firewall which originally separated the engine bay and fuel tank. It's just a thin piece of metal so isn't structural.
My plan is to do this and then test fit the subframe with motor and inverter mounted. This will then allow me to see how far back I can go with the batteries. Then I can make up a casing and the structure to hold the pack.

So for now I'll leave the cells as they are and keep working on the subframe and getting the motor mounted. A couple of these 10s1p modules would make a great 72v motorbike/quad battery pack though.

Subframe is almost all back together now with some fancy new polybushes in places and looking nicely painted. Then it's fabrication time to make the mounts. Time is being split between this, the MPCNC router build, 72v quadbike upgrade and the Defender. Too much time, not enough projects!
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

Where did you get the batteries? I'm not far enough on to be searching yet but probably should keep an eye out for them.

Have you considered fitting a TF suspension? I'm not sure what would be involved and haven't looked at MG's in a few years but the Spheres were a big issue last time I checked.
My F had an issue with being tracked and I couldn't figure out why. I took it to several tyre places to set the tracking but every time I drove away the car was pulling to the left. I always ended up tweaking the tracking myself to dial out the pull but in the end I put the problem down to bent suspension at the rear. The paint was poor too so in the end I lost heart in it and sold it on.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Picked up the batteries from the Kokam batteries thread on the classified section. Worth keeping an eye on on the classified section here, there have been a few decent things come up.

Had a quick look at coilover kits for the MGF, too pricey to be worth it for me at this moment. It was handling fine before I took it all apart so I'll hope for the best and worry about it later on. Also I think I need to be careful about changing too much of the vehicle or the DVLA will want to get it retested as a radically modified vehicle.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

Cool thanks, I must keep a closer eye on it.

Good point about the changes. I was thinking more of swapping out the F sub-frame and suspension with same from a TF but if it was OK before then it should still be. Maybe the F suspension will be even better since it is so easy to adjust the ride height.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

So a bit of a slight change in design now.

Subframe is all restored, and I was looking at mounting the Outlander motor/Diff. I did initially decide that I would make up the new driveshafts myself, using the two original pairs. Getting custom drive shafts made was was going to be around £200-300+VAT each!
However I realised that in the Outlander the motor is sat to the rear of the differential. Which meant that in my setup the motor would be backwards as that is the only way it would fit.

So I have decided that I will have the motor attach to the original gearbox via an adaptor plate. The pros of this setup:
  • No making up drive shafts.
  • Making up an adaptor plate is simpler.
  • Makes mounting the motor in the subframe easier, as the gearbox already mounts on the one side.
  • 2nd gear is almost exactly the same ratio as the Outlander Differential. 1st gear is a relatively big jump down in the ratio, so that will be the tyre spinning mode.
  • Speedo will work again with no extra work
  • Reverse light will work with no extra work.
The PG1 gearbox variant in the MG is good for 216nm of torque, so there is a little bit of headroom. If that breaks there are pretty cheap options to upgrade the gearbox with steel caged bearings and an LSD etc. It was used on everything from Rover 25s and Freelanders to the Lotus Elise in various gearsets.

The main con is the loss of efficiency by going through the gearbox, and now I have to put the gearstick back in the car.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

Just a thought and maybe not simple but if you have access to a lathe it might be possible to cut the Outlander and F drive shafts then turn down a steel rod to put inside the two halves. That way you'd be guaranteed to have them straight and it would be possible to weld them.
Maybe hard to keep them balanced though.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

That was pretty similar to what I had planned to do with the driveshafts.
But then I was wooed by the ease of using the gearbox and 2400nm to the wheels in first gear.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by jap »

Efficiency difference should be just 1-2% at most with a FWD style gearbox vs. EV single reduction.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

How do you plan to make the coupler?
Hopefully if it goes to plan mine will be made as shown below with two clutch disc centres on the motor side.
Coupler2.jpeg
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

I haven't thought too far ahead to the coupler bar its going to be a tube with some internal splines in it.

Last time I was trying to get internal splines cut it was some obscure Japanese standard from the 1980s, didn't have much luck with that. I am hoping the more prevalent and modern nature of these two splines should mean they are easier to get machined.
If that doesn't work I'll use a similar approach to you. Clutch centre on the gearbox and the first gear centre from the Outlander diff.

Currently working on some photogrammetry in order to design the adaptor plate. It's looking rather promising so far. Should have something to show off tomorrow. Time for a computer upgrade I think...
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

Lol, I just upgraded my pc with a new motherboard, processor and RAM but I would still be rubbish at creating a design for my adapter plate. I'll just stick to cardboard aided design and tracing with crayons.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by rob bell »

Thanks Ali for alerting me to this thread - going to follow this with great interest Ben!

I am a bit of an MGF nerd - I have two, one is converted to go sprint and hillclimbing, the other has been modified continuously for the 25 years I've owned it lol

For corner weighting, I use 500kg postal scales from an auction site of your choice. Pretty cheap, and the MGF will not weigh more than this at each corner (standard weight approx 1100kg, depending on specification - typically 300-ish Kg each rear wheel, 200-ish kg each front with a weight distribution that is approx 40:60 F:R as standard. If increasing the weight up front, you may need to consider fitting alternative front hydragas spheres to alter the spring rate of the unit. Conceivably, you could use either MGF rear Hydragas at the front as well as the rear, or Metro front units. Your choice will be dictated by the front end weight. Standard ride height is 368mm +/- 10mm front, 358mm +/- 10mm rear at 17 Celsius, measured from wheel centre to wheel arch lip vertically above. Unit fluid line pressure should not exceed 400psi at rest. Ali is thinking of individualising each of the spheres - the Hydragas system is interconnected front to rear as standard - as per Dr Alex Moulton's original.

Be wary of cutting that rear bulkhead (fuel tank/engine bay fire wall). It may be made of only 1.6mm of Birmingham's finest steel, but it is a structural part of the car (torsional stiffness) - and even the boot firewall is structural in this regard. If cutting out, add cross-braces to get the torsional strength back.

The electronic systems on the MGF are a doddle. All pre-CAN-bus. All units work independently of each other. You'll likely have EPAS. But you will need a vacuum pump and a reservoir (Ali has been looking at this already).

PG1 is a pretty solid gearbox. Retro-fitting steel caged bearings can be done fairly easily - I had this done to my race-box, along with a Torsen type-A diff.

As you probably know, quite easy to make the MGF 4WD - the front hubs are Metro and are CV-joint ready! Take a look at the MGTF200HPD - petrol rear and electric front drive train for all-wheel skids. 8-)

I should probably stop giving you bad ideas... LOL
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

That's very useful information!

I'm currently only looking to put 40 cells in the front, I can fit this in the spare wheel area without cutting anything. I think I might look at putting 100 cells in the front and make some changes. That would be around 70KG of extra weight, minus spare wheel.
I didn't realise the rear bulkhead was structural. So I'll be sure to add in cross braces if I do have to start cutting things out. I think I might be able to squeeze the batteries in above the motor, but that will be weight quite high off the ground. Once I get the motor and gearbox together and back in the subframe I will have a better idea of what space I have to use. I'm very keen to keep the boot area if I can. I don't like losing utility in a conversion.

Individual spheres could be quite useful actually. Thinking about it, it wouldn't be very hard to separate the rear spheres at least. That would just need me to add a Schrader valve to the end of the pipes correct? Would make refilling easier.

I'm a big fan of the PG1, it's in my Freelander and Rover 25. For the moment I am going to keep it stock, on paper it can handle the motor torque with a tiny bit of headroom. If it does fail then I will go for the steel caged bearings. I have been looking for an LSD for it, but can only find the Quaife ATB which is a bit more than what I would like to spend on one. Those Torsen diffs seem pretty rare now.

I did not know about a 4WD MGF... That looks like a very good stretch goal though.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

LRBen wrote: Mon Nov 23, 2020 5:37 pm That's very useful information!

I'm currently only looking to put 40 cells in the front, I can fit this in the spare wheel area without cutting anything. I think I might look at putting 100 cells in the front and make some changes. That would be around 70KG of extra weight, minus spare wheel.
I didn't realise the rear bulkhead was structural. So I'll be sure to add in cross braces if I do have to start cutting things out. I think I might be able to squeeze the batteries in above the motor, but that will be weight quite high off the ground. Once I get the motor and gearbox together and back in the subframe I will have a better idea of what space I have to use. I'm very keen to keep the boot area if I can. I don't like losing utility in a conversion.

Individual spheres could be quite useful actually. Thinking about it, it wouldn't be very hard to separate the rear spheres at least. That would just need me to add a Schrader valve to the end of the pipes correct? Would make refilling easier.

I'm a big fan of the PG1, it's in my Freelander and Rover 25. For the moment I am going to keep it stock, on paper it can handle the motor torque with a tiny bit of headroom. If it does fail then I will go for the steel caged bearings. I have been looking for an LSD for it, but can only find the Quaife ATB which is a bit more than what I would like to spend on one. Those Torsen diffs seem pretty rare now.

I did not know about a 4WD MGF... That looks like a very good stretch goal though.
What type of cells are you using?
Have you seen this thread in Landyzone? https://www.landyzone.co.uk/land-rover/ ... ev.360880/
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Using the Kokam pouch cells.
I've been following that thread for a while, my name is Wonk on Landy Zone.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Haven't made much progress in the last week. Just been trying to get useable data from my photogrammetry setup. Going to have another go at getting a dataset of photos tomorrow with some tweaks and improvements to the setup. I am almost at the point of getting a useable CAD file which will pay dividends for anything in the future.

I have made some changes to the plan of the car. I am now going down the route of having everything in the engine bay. This means only one string of cells, probably 76s unless it turns out the prius inverter can also boost up 240ac as well as rectify it. In which case I will try to aim for around 90s if there is space, keeping battery voltage under 400v so I can keep the prius dc-dc operational.

This means not having to split a battery string between the front and back, reducing lots of work. It also means I don't have to cut anything up at all. It turns into a bolt on setup in the subframe that then slots back in the car. There will be some battery weight up above the motor which isn't ideal, total weight will probably be about the same as the ICE with a full tank of fuel. It will limit the range to around 50-60 miles.

However MG Fs are starting to get to that age where they will go up in value soon so I would rather not cut one up. This also means in the future I can drop the subframe and potentially upgrade the battery pack, or place batteries in the fuel tank compartment when I get them in a suitable form factor. It also reduces the amount of work that needs to be done, for me an operational EV with even 30 miles of range is worth it if I get it running a few months sooner.

Then I can also leave the front subframe free for a 2nd motor one day...
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Managed to get my photogrammetry setup to a useable standard. When you add textures it actually looks pretty impressive, doesn't make it anymore accurate though.

I have now designed the adaptor plates to mate the motor and gearbox. Planning to get some mockups made in either plywood or just thin sheet steel to make sure the holes all line up. Then I can make up a shaft connector with a couple clutch hubs.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Alibro »

Looking good mate.
Better than my CAD template.

That's it sitting beside the gearbox. :lol:
IMG_20201205_173859319 (1).jpg
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

I have been making slow but steady progress on this over winter. Finished my MPCNC over christmas and used that to sketch the cad design outlines onto paper, made a few adjustments and then tried it on plywood.
Still need to figure out correct spindle speeds and feed rates, as well as find some router bits that are not made of chinesium. However I managed to cut enough of a template out of plywood to confirm that the holes are in the right place. I have sent the designs off for laser cutting now.
IMG_20201226_231005_631.jpg
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Having heard nothing back from enquiries I made about getting a coupler made up I think I might have to do this myself. Current plan in my head is to use the hub from the gearbox clutch for that side, then the input gear from the Outlander differential for the motor side. Smoosh them together with a lathe/press/hammer/welder and it should be good. There was an old Ben Nelson video on couplers for electric cars which actually explained it much better. I'll go into more detail if I do it myself, otherwise I might get an engineering friend to do the complicated machining for me.

I have also put the motor back on the test bench and I'm attempting the FOC tuning finally. This time with a 72v battery made up from some of the spare Kokam cells and my old quad BMS. I realised that I need to go back to the resolver wiring and ensure the sin/cos polarities are correct, so cycling those those and then doing the FOC tune is my current plan for the weekend. It is slowly coming together in my head and making sense.
PXL_20210130_161828526.jpg
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Got my adaptor plates this week. Only done a very quick test but it looks like they fit good enough. Standoffs are now also on order.
Just need to get my lathe working so I can complete the coupler then I can do a real test fit.
PXL_20210225_110622222.jpg
Also played around with some other parts that need doing on the car. Got some heat pads from Ebay and installed those under the covers, the end results look pretty good.
Played with some arduino code and got the oil temperature gauge to move with pwm.
Ordered the last few parts for the electric brake vacuum assist. I will write more about that when I install it, but its basically just the Volvo XC90 pump and switch with some Audi vacuum reservoir.
Did some welding of the rear sills, no going to be showing off my welding skills until after it's covered in body filler and painted though. There was plenty of welding to do there though, had to rebuild a fairly large chunk.
PXL_20210221_123458265.MP.jpg
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Finally got my lathe in a semi functional state this last week so I was able to get started on the coupler to connect the motor and gearbox.
I did keep pretty closely to my original plan, I used the hub from the PG1 clutch plate and the input gear from the Outlander motor differential.

First I welded on a 10mm plate to the differential gear then put this on the lathe and machined it down, then machined the other side to accept the clutch hub. I then froze the clutch hub overnight and in the morning put a little bit of heat on the other side and pressed them together. Stuck some weld around the sides for good measure. The weld looks a bit messy but I was spot welding on four opposite spots each time before letting it cool down completely, so no fancy weld beads for me. I also cut the corners of the plate off before putting it in the lathe, this was a mistake as I cut off a bit too much.
PXL_20210318_174542957.jpg
PXL_20210318_163534016.jpg
I forgot to actually take a photo of the coupler when it was done. I was too excited to attach the motor to the gearbox. It spins up nice and smoothly so its a good first sign. I have some different spacers on order and some more bolts, as Mitsubushi like their fine pitch threaded bolts. So next week I plan to drill out out the rest of the holes on the adaptor plate and fully mount the motor to the gearbox. Then I can do some test fits to the subframe and get a better idea for how much battery space I actually have.



If I were to do this again, I would start with some round stock big enough to act as a collar for both gears, then machine it down and shrink fit on both ends.

I have also been looking into the details of the 12v wiring. It is looking quite simple actually. The new electric vacuum pump can be powered from the fuel pump fuse, which helpfully goes live with ignition.
I am going to put in an arduino/teensy board to take some info from the inverter and OpenBMS canbus, then turn this into PWM signals for the dashboard gauges. Luckily all the signal wires for the dash come out in the engine bay area, so I can connect to the wires there without having to take the dashboard apart. I also need to send some engine RPM data to the Electric power steering ECU, otherwise it won't play. Again this is solved by using the existing wiring loom as the signals are sent to both the tachometer and the EPAS ECU.
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by Mouse »

Would you be able to share a DXF or similar of the Outlander flange details?
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Re: MG F - Outlander Rear differential with Prius Gen 2 Inverter.

Post by LRBen »

Mouse wrote: Sat Mar 27, 2021 1:39 pm Would you be able to share a DXF or similar of the Outlander flange details?
The Outlander flange was taken from the differential. I just took out the first gear that the motor connects to and chopped off the bit I didn't want.
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