Connecting a GS450H to an existing Transfer Case?

[Greenbeast]

Looking to retain 4WD capability on my truck, if i could hook the gs450h up to my transfer case i will retain the ability to go Hi/Lo and also engage the front wheels, i might also save a bit of engine bay space for batteries and ancillaries.

Any thoughts?

[celeron55]

There exists a 4wd variant of the LS600H transmission with a transfer case (altough it's quite heavily integrated, I don't think it's removable at all), one being sold on Ebay right now. It doesn't have hi/lo but given these things can nevertheless put out about 1000Nm at the propeller shaft do you need hi/lo?

[Greenbeast]

There exists a 4wd variant of the LS600H transmission with a transfer case (altough it's quite heavily integrated, I don't think it's removable at all), one being sold on Ebay right now. It doesn't have hi/lo but given these things can nevertheless put out about 1000Nm at the propeller shaft do you need hi/lo?

Aha, i saw mention elsewhere but typed GS600H instead of LS600H into ebay.

The only complete one i see is in the States? At about £2k inc shipping, quite pricey

[sfk]

Yes the LS600H has a variant of the transmission with the type code L110F

[nkiernan]

My understanding was that the transfer case off the back of a LS600H transmission would bolt onto the back end of a GS450H transmission to convert it to a LS600H. I picked up a LS600H transfer case, but its not that simple. There is a short adapter section that is required between the back end of the GS450H gearbox and the LS600H transfer case. Haven't been able to source one yet, but not a straight swap.

One thought was to make a simple coupler and adapter between the output of the GS gearbox and the input of the LS transfer case as it is a tidy transfer case compared to some 4x4 types.

Not needed anymore though, so if its of interest shout.

[Greenbeast]

My understanding was that the transfer case off the back of a LS600H transmission would bolt onto the back end of a GS450H transmission to convert it to a LS600H. I picked up a LS600H transfer case, but its not that simple. There is a short adapter section that is required between the back end of the GS450H gearbox and the LS600H transfer case. Haven't been able to source one yet, but not a straight swap.

Ah, good to know, i've been searching around to see if that was possible

Not needed anymore though, so if its of interest shout.

you mean the ls600h transfer case is available?

Initially that sounds inviting, but i will have to adapt the gs450h to my existing transfer case anyway, plus the front shafts/hubs can't handle permanent 4x4, so if i keep the stock T-case then i keep the switching ability. So although the two lexus parts might adapt relatively easily i would presumably lose the ability to disengage the front shaft

[New Electric Ireland]

There is a short adapter section that is required between the back end of the GS450H gearbox and the LS600H transfer case. Haven't been able to source one yet, but not a straight swap.

Is it worth buying another front end and then selling what you don't need? Lots eastern European breakers split the CVT at the transfer case leaving the adapter in place;

https://www.ebay.co.uk/itm/LEXUS-LS-F4- ... 3956781508

[nkiernan]

Is it worth buying another front end and then selling what you don't need? Lots eastern European breakers split the CVT at the transfer case leaving the adapter in place;

I've been contacting ebay sellers as I've seen LS600H drivelines come up to try get that adapter section to test it out but no joy yet. So far they wouldn't sell that section alone, and the gearboxes have been pretty expensive if it turned out I couldn't sell on the front end of the gearbox alone afterwards. I'm just not sure if there is some gear sections inside that adapter!

During the EV course last August, there was a discussion about a late 90's Toyota Landcruiser transfer case bolting/connecting directly onto the GS450H gearbox, same pattern. Did some looking but never confirmed that in the end.

[Greenbeast]

I'm trying to figure out compatibility here but i'm a little out of my depth, i don't really know how to approach or understand these numbers in the context of a power plant and/or transmission swap-out

These are the gear ratios for the truck in stock setup

1 2 3 4 5 Hi LO Axle
Gear rations 3.477 2.037 1.317 1 0.82 1.295 2.367 3.363

An here is ratio info for the GS450H provided by @sfk
viewtopic.php?f=11&t=222#p2617


So presumably if i ditch the stock gearbox and retain the stock T-case i'm looking at GS450H ratio of 3.9:1 or 1.9:1 then my T-Case ratio of 1.295 or 2.367 then axel ratio of 3.636 (GS450H was paired with rear diff of 3.266:1 according tp above link)

I don't technically need the stock Lo range with this transmission swap but i do want the ability to engage the front axle.

So am i right that effectively i want the GS450H to stay in Lo speed (1.9:1 is closest to 2nd/3rd gear as stock) and the stock T-case in Hi range (1.295: is closest to 1:1)? Or have i completely misunderstood?

This is a new area for me

[sfk]

I'm trying to figure out compatibility here but i'm a little out of my depth, i don't really know how to approach or understand these numbers in the context of a power plant and/or transmission swap-out

These are the gear ratios for the truck in stock setup

1 2 3 4 5 Hi LO Axle
Gear rations 3.477 2.037 1.317 1 0.82 1.295 2.367 3.363

An here is ratio info for the GS450H provided by @sfk
viewtopic.php?f=11&t=222#p2617


So presumably if i ditch the stock gearbox and retain the stock T-case i'm looking at GS450H ratio of 3.9:1 or 1.9:1 then my T-Case ratio of 1.295 or 2.367 then axel ratio of 3.636 (GS450H was paired with rear diff of 3.266:1 according tp above link)

I don't technically need the stock Lo range with this transmission swap but i do want the ability to engage the front axle.

So am i right that effectively i want the GS450H to stay in Lo speed (1.9:1 is closest to 2nd/3rd gear as stock) and the stock T-case in Hi range (1.295: is closest to 1:1)? Or have i completely misunderstood?

This is a new area for me

The 2 stage (High / Low) output of the L110 is a reduction ratio. High mode takes 1900rpm from the motors and outputs 1000rpm to the driveshaft. Low converts 3900 in to 1000rpm out.

Your transfer case ratios above will also be reduction ratios (since the LO ratio is larger than the HI ratio) and your rear axle differential too.

What you need to do is figure out how fast your tyres need to be spinning to achieve the speed you want and work backwards from there. Firstly by calculating the circumference of your tyre.

[Greenbeast]

Thank you, i had an inkling but didn't know what to do with that information.

Ok, that's great, something to work with

[Greenbeast]

Found this, thought it might be useful for others:

https://www.blocklayer.com/rpm-gear.aspx

So keeping my rear diff and transfer case and using the Hi speed of the GS450H i would need an motor rpm of 7200 @ 75mph and 5310 @ 55mph (more my speed)

[sfk]

Worth pointing out that MG1 and MG2 could be operating at different RPM depending if you use the Lock Input Shaft method or Lock Planetary Gearset method.

Locking the planetary gearset will cause them to spin at same speed and direction with a max RPM around 11,000ish due to the limits of the bearings. In High gear 1.9 reduction this will result in about 5,250rpm coming out the back of the transmission.

Locking the input shaft will cause MG1 to spin 2.2x in the opposite direction to MG2. Thereby MG1 will reach the bearing speed limits much earlier than MG2 and limit the total output RPM. This will result in a max RPM of about 2,600.

Divide that by your 3.36 axle ratio and you have your rear wheel RPM and it's just a final step to factor in your tyre circumference to find your max road speed.

[Greenbeast]

Worth pointing out that MG1 and MG2 could be operating at different RPM depending if you use the Lock Input Shaft method or Lock Planetary Gearset method.

Locking the planetary gearset will cause them to spin at same speed and direction with a max RPM around 11,000ish due to the limits of the bearings. In High gear 1.9 reduction this will result in about 5,250rpm coming out the back of the transmission.

Locking the input shaft will cause MG1 to spin 2.2x in the opposite direction to MG2. Thereby MG1 will reach the bearing speed limits much earlier than MG2 and limit the total output RPM. This will result in a max RPM of about 2,600.

Divide that by your 3.36 axle ratio and you have your rear wheel RPM and it's just a final step to factor in your tyre circumference to find your max road speed.

Presumably i also have to factor in 1.295 reduction in keeping my transfer case?
So for locked input shaft it's 2600/1.295=2007, 2007/3.36=597rpm at the wheel, which i think makes 40mph top speed given my wheels
Or am i wrong again?

[sfk]

Would help to know the specs of your tyres.

Yes, you need to factor in the ratio of your transfer case.

[Greenbeast]

235 /75/R15 MT tyres

[sfk]

About 83kph or 50mph.
The max speed of the motor bearings isn't exactly 11,000. I've seen the limit stated as high as 14,000. But the aim would be to keep those speeds low.

Your options are :
- Use larger wheels
- Change rear diff to lower ratio (would have to swap front diff also)
- Use the Welded Planetary Gear option instead of Fixed Input Shaft
- Or just find the real RPM limits of the bearings

What's the vehicle anyway?

[Greenbeast]

Daihatsu Fourtrak.
Wheels are already pretty big.
I will look at the welded gears method, don't particularly fancy changing ratios in both diffs, that said I'm not particularly excited about mating the transmission to the transfer case!

[sfk]

Honestly, I'd be looking far more closely as using the Nissan Leaf motor mated to the existing gearbox and transfer case. That motor has superior statistics to the origin petrol/diesel engines and would make a far simpler conversion.

[Greenbeast]

Yes, I think you may be right.

Although i'm curious about locking the planetary gears, does that then not give me a higher max rpm? Does it not then give a max speed of 91mph?

[sfk]

Locking the gears will give you a higher top speed. I'm just imagining the amount of work required to connect the L110 to your transfer case. Mating the Leaf motor to your gearbox will be much easier.

[Bratitude]

you could just get a divorced transfer case.
450h->drive shaft->tcase->drive shafts->front/rear diffs

your truck doesn’t sound very big if your running 235/75/15s so a Suzuki samurai or nissan t-case would work great. And plenty of aftermarket gearsets for them.

or replace the trany and tcase altogether a put a ev gearbox between the front and rear diffs. I know zero ev sells a taller(?) gear set for the Tesla gearbox’s, for this exact purpose.

it would be awd at this point, but with a lsd in the centre diff you would be good to go.

[Greenbeast]

you could just get a divorced transfer case.
450h->drive shaft->tcase->drive shafts->front/rear diffs

your truck doesn’t sound very big if your running 235/75/15s so a Suzuki samurai or nissan t-case would work great. And plenty of aftermarket gearsets for them.

or replace the trany and tcase altogether a put a ev gearbox between the front and rear diffs. I know zero ev sells a taller(?) gear set for the Tesla gearbox’s, for this exact purpose.

it would be awd at this point, but with a lsd in the centre diff you would be good to go.

Yeah you're into the ball park size wise.
I saw the term divorced transfer case over on diyelectriccar, I started looking but it was looking like a pain in the arse. I'll have another little look around referencing those other vehicles.
You mention awd being fine with an lsd in the centre diff, you don't specifically mention a centre diff in the drive train, does the divorced transfer case act as such in this application? I ask because obviously have a transfer case now and it is not limited slip

[Bratitude]

you could just get a divorced transfer case.
450h->drive shaft->tcase->drive shafts->front/rear diffs

your truck doesn’t sound very big if your running 235/75/15s so a Suzuki samurai or nissan t-case would work great. And plenty of aftermarket gearsets for them.

or replace the trany and tcase altogether a put a ev gearbox between the front and rear diffs. I know zero ev sells a taller(?) gear set for the Tesla gearbox’s, for this exact purpose.

it would be awd at this point, but with a lsd in the centre diff you would be good to go.

Yeah you're into the ball park size wise.
I saw the term divorced transfer case over on diyelectriccar, I started looking but it was looking like a pain in the arse. I'll have another little look around referencing those other vehicles.
You mention awd being fine with an lsd in the centre diff, you don't specifically mention a centre diff in the drive train, does the divorced transfer case act as such in this application? I ask because obviously have a transfer case now and it is not limited slip

if you took a Tesla motor/gearbox and rotated it 90degrees, connect the front and rear diff to ethere side of the motor. This would be awd. The Tesla motor would become a “centre “ diff. there’s a variety of options to go from there.
1. leave the Tesla motor as a open diff. this would result in awd, but power would bias to the front or rear with the least traction.
2. Put a lsd in the Tesla motor. This would be awd, but would maintain a power split between the front and rear. Regardless of traction between the two.
3. weld the Tesla diff. the system is no longer awd and is now 4x4. 50/50 power splits between the front and rear. there would be torque bind between the front and rear if going threw a turn on high traction surfaces. Like pavement.
locking hubs would be used to disconnect a set of wheels for high traction surface driving.



or you put in a devoced transfer case.
the t-case has separate shifter sticks to engage/disengage 4wd, and low range.

The tcase has one input shaft (drive from the transmission, in this case the 450h) and 2 output: front and rear diff.



4wd≠awd there’s a big difference and people often conflate them.

4wd= 50/50 power split between front and rear.
Awd= active torque biasing between front and rear. (There’s a diff between the front and rear)

there’s a variety of awd methods.

Only one 4x4 method

[sfk]

You mention awd being fine with an lsd in the centre diff, you don't specifically mention a centre diff in the drive train, does the divorced transfer case act as such in this application? I ask because obviously have a transfer case now and it is not limited slip

Your transfer case is highly unlikely to have a center diff in it although it is possible. More likely to be 2wd (rear) for on-road use and 4wd for off-road use.

If you put a Nissan Leaf motor and gearbox sideways in the center of the car it would act as a center diff as it has an open differential inside it. But because it is an open diff the power would always go to the axle with least traction. And your front and rear axles probably have open diffs in them too so the power would then go to the tyre with the least traction.

But worth pointing out that the reduction gearbox attached to the Leaf motor is about 8:1 and your front and rear diffs reduce that ratio even further severely limiting top speed.

I believe your car has live axles (solid beam between the wheels). I would look at getting 2 Leaf motors and connecting 1 directly to each axle's diff input. That would be cool.