Toyota MGR Transaxle - Alternative Orientations?

[Matthew Dresser]

@kevin
Granted a bit of driveshaft angle would be ok- but in this case I think the unit would be about 20cm behind where it should be . Also driveshafts are quite diddy and short, which would worsen the problem.

[sfk]

Well you could mount it facing forward and with correct axle angle then chop out the rear floor to make it fit...

[konstantin8818]

Well you could mount it facing forward and with correct axle angle then chop out the rear floor to make it fit...

As far as I can see the floor isn't an issue, but mounts for trailing arms are. As an option, it might be feasible to widen the track, but it is cutting/welding and I believe it is not an option in this case, or is it?

[sfk]

You can do whatever is legal in your country! There is no steering geometry in the rear so widening the track width will not effect that.

Lengthening the arms won't have any real effect on the suspension spring rates. But shifting the pickup points could do, depending if you move them inboard or outboard. It's to do with the pivot points.

But then, I can't imagine the Fiat 124 has particularly sophisticated suspension tuned for handling?

[SciroccoEV]

The 126 is in the UK, so cutting into the structure would take you down the IVA (Individual Vehicle Approval) route. You've have to have a qualified automotive engineer sign off on the modifications and the basic IVA test itself is about £400.

Worse, unless you kept the voltage below 75v, you would likely have to pass the hybrid and electric vehicle part of the IVA. That part of the test is in the thousands.

In all likelihood, given the speeds that a 126 is likely to be driven at (not sustained high speeds along the motorway), the MGR lubrication is probably adequate in reverse without modification. Many transmissions are lubricated by nothing but dip, cling and splash.

[konstantin8818]

the MGR lubrication is probably adequate in reverse without modification. Many transmissions are lubricated by nothing but dip, cling and splash.

I think it will not be adequate in reverse for the motor. Motor is in separate section, and oil goes there from upper catch by the means of gravity and partially some oil slings from final drive. Even keeping in mind that 126 is light and will not be used for long distances, making lubrication and oil cooling even worse as it was isn't a good idea.
However there is a thing called real life tests, as long as Matthew agree to be a lab rat

[Matthew Dresser]

Thanks for all the input guys.

Quite a bit of work would be needed to move the suspension mounts in order to allow the MGR to sit far enough forward to fit. That would more or less be a complete suspension redesign... One of my wild ideas was to rip out all the suspension and fabricate a double-wishbone setup in a subframe + battery cradle which could bolt onto all the existing suspension mounting points. Could actually make the rear of the car much stiffer.

Also, good spot re the outer driveshaft connectors - not CV joints, but those rubber things. My plan is to test with MGR until those joints fall apart and then upgrade to proper CVs - they cost more than my MGR though, so will only buy them if/when they fall apart

[konstantin8818]

Keep in mind that that rubber bushing lives only because axis of trailing arm is close to point where axle goes into gearbox. If you replace gearbox with wider one, or install double wisbone suspension, that bushing will die instantly. Any change must be done with CV joint instalation.

[ZooKeeper]

post deleted

[mike77cos]

I'm looking forward to seeing the progress of the blue yacht

[konstantin8818]

I wonder if anyone have got access to infrared camera, to watch MGR running under load. I would like to see what spots are the most heated, to glue there a liquid heat exchanger of brass pipes

[UStas]

I wonder if anyone have got access to infrared camera, to watch MGR running under load. I would like to see what spots are the most heated, to glue there a liquid heat exchanger of brass pipes

I think Toyota engineers are done it for us . As you can see o the MGR exist cooling ribs. On the top, where oil capture chamber, bottom where oil flows down by gravity and motor cap where we have heat from stator and oil comes from rotor shaft bearing lubrication.

I think about additional cooling MGR and make heat absorber for a liquid cooling in bottom from fiberglass and epoxy. See a photos.
Material for a forming:

Inlet/outlet tubes:

Walls forming:

Epoxying:

After removing a forming and sanding, close by aluminum plate with a screws:

[ZooKeeper]

Nice!

[Ctwidle]

Hi, I’m new here and not quite ready to start my own thread. I have a 72 super beetle in pieces and I’m considering replacing the original traction system with an MGR. In the photo the gearbox is as close to its original position as the cardboard box will allow.

I’m wondering if one of you kind souls could run a tape measure over an MGR and tell me if it will fit running in it’s original direction? The axle centres are approx 250mm below the floor and 125mm in front of the firewall leaving around 355mm clearance to the front.
If it doesn’t fit (maybe with a slight tilt to the front?) I will look at the Outlander rear motor unless someone has cracked the addition of a cooling system and/or oil cooler/pump system to run the MGR in reverse.

Thanks in advance,

Chris

PS if I click on the image it turns the right way up! What am I doing wrong?

[ZooKeeper]

Welcome! That photo actually helps me too, as my car is planned to be a '71 Squareback!

The axle c/l to top of MGR = 7" (180mm) and to the front edge of the mount casting 14" (355mm). Looks like it will fit just fine

If I find cooling is needed, I will just install a low pressure BOSCH (or similar) fuel pump to circulate the oil thru an external cooler. But, these motors will tolerate temps well over 150*C, so am hopeful that added measure will not be needed.

The one measurement I do not have is the flange-to-flange width of the stock VW transmission.

[Ctwidle]

Thanks for the prompt reply Zookeeper. I’m following your progress with interest as we look to be approaching a similar project from opposite ends! My gearbox is in a million pieces so I am not sure that I can work out exactly how big the flange to flange distance is but I will see if I can assemble enough of it to get a measurement.
I have downloaded a working drawing and images of an adaptor plate that someone created to join a diff to VW axles but I failed to record the source and details of the diff involved. I will have a search this evening after trying to find a suitable MGR downunder.

Chris

I managed to put together enough pieces from my diff jigsaw to get a pretty good idea of the distance between the flanges. It’s a 72 super beetle 112 2890 748 if that is the same as the square backs.
Looks like it’s about 258 overall but I can’t guarantee the accuracy as there may be spacers missing from the assembly.

[ZooKeeper]

Thanks Chris, that measurement is really helpful! The MGR is about 280, so shortening will be required

My current plan to join Toyota & VW is to mount the flanges in a lathe face-to-face, true them up and start melting metal!

[Ctwidle]

My MGR just arrived so, what do I do now?

I’m months away from dong anything practical with the electrical side of things but wondered if there is any way of checking this thing out with just the power that can be provided by a couple of 12v batteries?

Although I wasn’t really ready for this I figured that if the Blue yacht sets sail anytime soon the availability of MGRs could be rapidly diminished so I grabbed one of the two that were on offer DownUnder. Haven’t made any decision on the rest of the package but you have to start somewhere!

Chris

[ZooKeeper]

If you have an inverter and VCU, they will run on 12v, but something closer to 60v would be a lot better. First is to check out the FOC Tuning video w/o skipping ahead, TRUST ME! LOL

[Ctwidle]

Anyone know if there is anything holding the differential side gear shafts into the diff casing on the MGR other than the bearings and seals? I don’t particularly want to split the case open just to find out.
To reuse my original VW CV joints/axles I need to loose 8mm per side and I’m thinking that cutting back the flange with the 4 studs and welding a flat plate to the stub with threaded holes to match the VW would be better than trying to shorten the shaft.
Chris

[ZooKeeper]

Anyone know if there is anything holding the differential side gear shafts into the diff casing on the MGR other than the bearings and seals? I don’t particularly want to split the case open just to find out.

They typically have keepers, no case-splitting needed, just "Excessive Force".

To reuse my original VW CV joints/axles I need to loose 8mm per side and I’m thinking that cutting back the flange with the 4 studs and welding a flat plate to the stub with threaded holes to match the VW would be better than trying to shorten the shaft.
Chris

Ha! That is similar to what the VW guy told me to do! His suggestion was to remove the studs, chuck both the Toyota and VW parts up in a lathe, get them dialed in and just weld them. I suppose, material permitting, one could take off the needed material from the flange and VW axle cup.

There is also the potential to use shorter aircooled shafts, I think there are like 4 common lengths.

[Ctwidle]

Thanks for that, My neighbour just suggested that as I was not using the VW diff I could cut the stubs off the back and weld them straight to the Lexus stubs and not have to bother with drilling and tapping the steel plate. I had a look at a table of VW axle lengths but saw that many of them had the 100mm flange instead of the 6 hole 90mm. So many options!

Before I do any cutting I need the MGR in position on the floor plan to see if it fit in between the fork or if it will be offset in which case I will need uneven shafts....

Chris

[bexander]

Thanks for that, My neighbour just suggested that as I was not using the VW diff I could cut the stubs off the back and weld them straight to the Lexus stubs and not have to bother with drilling and tapping the steel plate. I had a look at a table of VW axle lengths but saw that many of them had the 100mm flange instead of the 6 hole 90mm. So many options!

Before I do any cutting I need the MGR in position on the floor plan to see if it fit in between the fork or if it will be offset in which case I will need uneven shafts....

Chris

I THINK the shaft splines are the same so 100mm and 90mm CV joints are interchangeable on the driveshafts.