openinverter forum

in 2019 Subaru released their second gen hybrid.

and it’s essentially a Gs450h trans with a center diff, and a front diff mounted in a Transaxial fashion. (Like all Subaru transmissions)

A variety of reports are saying it’s a camery hybrid gear box guts, and some Prius prime battery parts. Mg2=88kw
battery= 8.8 li-ion

I’m really hoping power is more battery limited than motor limited.


-centre diff

Subaru has a variety of awd versions. Their 5mt trains use a viscous lsd, autos use a ether a vtd(variable torque distribution) working similar vlsd with a added electrical control, or mpt (multi plate clutch pack)

Both vtd and mpt allow you to change the torque distribution between front and rear.

from the info I’ve gathered, it uses the same mpt system in the autos. all that is required for control is a PWM signal. At full duty cycle should provide a 50/50 power split.


on the hunt for one!

That's very interesting. Thanks.

Looks like the sort of thing you could turn backwards and mount in the rear of RWD car, ignoring the coupling that would usually drive the rear diff in the Subaru.

sfk wrote: ↑Fri May 14, 2021 9:00 pm That's very interesting. Thanks.

Looks like the sort of thing you could turn backwards and mount in the rear of RWD car, ignoring the coupling that would usually drive the rear diff in the Subaru.

http://www.subarugears.com/ do just that for old vw beetles and buses!

That is really cool exotically for use in a Subaru. I knew the old ones where a mish mash of Toyota parts but this version looks much more useful.

Bratitude wrote: ↑Fri May 14, 2021 10:34 pm
http://www.subarugears.com/ do just that for old vw beetles and buses!

Wow...I guess that's a bargain compared to a Mendeola or something, but that's pricey! And as they seem keen you point out, only for 6 speeds, so probably no help with a hybrid Crosstrek box. On older VW and Audi transaxles it was sometimes possible to "flip" the ring gear to the other side. For 2 grand (hopefully less!) worth of machining, maybe you could do the same here.

Glad to see these pop up here.

These transmissions are unfortunately not very common on the secondhand market yet, but I'm hoping to get my hands on one to poke around with and figure out how similar it is to the Toyota stuff that's pretty well documented here.

This might be a niche, but I can't imagine a more perfect solution for converting a Subaru and retaining the mechanical AWD system. Going back and forth between my i3 and my wife's Forester made me realize that a mid-2000's Subaru that happens to be electric is far more appealing to me than pretty much any new EV that's coming out.

Phate wrote: ↑Sun Aug 15, 2021 2:37 pm Glad to see these pop up here.

These transmissions are unfortunately not very common on the secondhand market yet, but I'm hoping to get my hands on one to poke around with and figure out how similar it is to the Toyota stuff that's pretty well documented here.

This might be a niche, but I can't imagine a more perfect solution for converting a Subaru and retaining the mechanical AWD system. Going back and forth between my i3 and my wife's Forester made me realize that a mid-2000's Subaru that happens to be electric is far more appealing to me than pretty much any new EV that's coming out.

yes, I’ve been watching some online wrecking sites to find one in BC. I’m sure within the next year (hopefully)

I’m hoping they end up able deliver 250 kw combined.

they are quite bulky compared to the 4eat or 5mt transmission, so shall be interesting fitting one in the older subies.

Bratitude wrote: ↑Wed Aug 25, 2021 8:16 pm
yes, I’ve been watching some online wrecking sites to find one in BC. I’m sure within the next year (hopefully)

I’m hoping they end up able deliver 250 kw combined.

they are quite bulky compared to the 4eat or 5mt transmission, so shall be interesting fitting one in the older subies.

I'm starting to see them popping up on ebay finally, there's one for $1500 USD in New Jersey. Unfortunately I'm not in a position to buy one at the moment, otherwise I'd grab it.

https://www.ebay.com/itm/165488625384?f ... SwpQpihVXN

Weberauto just did a teardown on one of these, currently watching to see just how similar it is to the Toyota stuff we like to abuse repurpose around here.



Cliffnotes based on my understanding of the video:
- MG1 and MG2 rotors/stators seem to be the same as the ones in the P710 Rav4 Hybrid transaxle.
- MG1 has 40lbft of torque and MG2 has 149lbft of torque? (not sure how these values were found)
- MG2 to output reduction of 3.4286:1, final drive of 3.7:1, total MG2 to wheels reduction of ~12.686:1 (~1890lbft to the wheels based on 149lbft rating)
- Power is always sent to the front wheels
- Front diff is open because of course it is
- Power split device has 3.6:1 reduction
- Engine to power split planet carrier has a ~1.057:1 reduction
- MG1 with power split device and MG2 with output reduction are on parallel shafts, connected with 0.781:1 gear ratio (effective MG1 to output ratio of 2.8116? aka MG1 to wheel reduction of ~10.403:1? ~416lbft to the wheels based on 40lbft rating)
- Does not appear to use both MG1 + MG2 for forward drive in stock form
- Uses an electromagnetic clutchpack to engage power to the rear axle, the bulk of the "locking" force in the center diff comes from a ball ramp actuator.
- Oil pump has two drive gears with a sprag clutch driven off both sides of the power split device (similar to the L210?) to ensure the oil pump spins when either MG1 or MG2 spin.


Other musings:
- I can't find the list right now, but there were definitely a few years of WRX (06/07?) that came with 3.70:1 final drives and some form of limited slip rear diff. Since Subaru likes to throw R160 rear diffs in everything that isn't "special", it should be easy to find a rear diff to match up with this transmission.
- AWD system seems to operate similarly to older 4 speed automatic Subaru's that engaged power to the rear axle through a clutchpack, although this setup may disengage more completely. This might be exactly how the current CVT cars operate, but I generally try to avoid thinking about them.
- I still want to put one in my 2nd gen Forester.
- Unless I misunderstood something somewhere, if MG1 can do 13500rpm like the other gen 3 setups that's 100mph with the 26.1in tires I have on the Forester, and 127mph at the 17000rpm I'm seeing listed for gen 4 hybrid stuff.
- Based on the gearing, the crosstrek's stock 27.8in tire size, and 109mph governed top speed, MG2 will do ~16700rpm in stock form, or 102mph with 26.1in tires.

Also found a link with some more info: https://www.marklines.com/en/report_all/rep1879_201906

If this transmission was used in Subaru conversion, how difficult would it be to work out when to activate the rear drive clutch pack ?

I suppose something would have to monitor wheel slip and determine when to activate it. Not trivial.

Does the electro-hydraulic clutch pack only engage when "switched on" or could it engage when there is differential rotation of the front and rear drives ? I am trying to figure out if it could just engage the ball-ramp without hydraulic pressure being applied ?


https://www.awdwiki.com/en/subaru

Scubascooby wrote: ↑Mon May 22, 2023 4:48 pm If this transmission was used in Subaru conversion, how difficult would it be to work out when to activate the rear drive clutch pack ?

I suppose something would have to monitor wheel slip and determine when to activate it. Not trivial.

Just a pwm signal. I think 50/50 or 100% duty results in full lock.

There’s aftermarket dcdc controllers available for Subarus, that use accelerometers and steering input to change torque delivery.