Fuso FG 6 speed conversion?

[yabanja]

After living with my FG for some time, I must say the only real weakness of the truck is the gear ratios in the manual transmission. Some of the 2 wheel drive models have a six speed transmission. Has anyone investigated whether the six speed will mate to the 5 speed transfer case?

Thank you!

Allan

 

[pugslyyy]

I have wondered about this as well, the power band is so narrow it would be nice to have the gears a little closer.

Sent from my SM-G975U using Tapatalk

 

[steve4wdaus]

Hi Alan
I have always thought if mine went i I would consider if a Rosa bus 6 speed box could be fitted as the Rosa uses the same FG649 engine. Anyway just an idea that. Good luck. https://www.trucksales.com.au/items/mitsubishi/rosa-6-speed-gearbox/ $1950

 

[Aussie Iron]

This I have looked into a fair bit before I had Transfer Gears cut. There is a lot for it and against it.
1st gear in the six speed is a higher ratio (this I didn't want at all if anything we need lower), the gear spacings are nearly the same as what we have now and they have a double overdrive. You would need to have a new rear output shaft made so that you could fit the transfer case drive gear.
I haven't checked whether the transfer case will actually bolt to the rear of the six speed case. I gave up after finding all the rest out.


Dan.

 

[yabanja]

This I have looked into a fair bit before I had Transfer Gears cut. There is a lot for it and against it.
1st gear in the six speed is a higher ratio (this I didn't want at all if anything we need lower), the gear spacings are nearly the same as what we have now and they have a double overdrive. You would need to have a new rear output shaft made so that you could fit the transfer case drive gear.
I haven't checked whether the transfer case will actually bolt to the rear of the six speed case. I gave up after finding all the rest out.


Dan.

Dan,

So the third/fourth gear spacing is the same? Bummer. It would be interesting to put one in and effectively make it into a close ratio box by significantly lowering the axle ratios. Really just speculating as this would be ungodly $$$$.

Allan

 

[Aussie Iron]

You Know :- While I was driving down the road today to get another load of sweet potatoes for the cows (yes we are still in the worst drought we have seen) if someone was to supply me with a six speed box, I would take a closer look and see if it is feasible to build a Hybrid out of the standard and the six speed. Mix and match gears. Essensually we need a six speed with a low 1st gear, 2nd and 3rd normal 4th/5th and 6th close ratio. 6th then being a single overdrive.

Dan.

 

[Spanna 53]

Dan if you could find a specialist gear shop that does race car gear boxes they may be able to do something but at what cost who knows one of the other mechanics in the neighborhood had one done a few years ago so there are people with the expertise could be a tub of grubs the trucks are pretty much bullet proof now might be better to leave it I asked about a six speed box when I ordered my NPS but it was not available as an option good luck Ross

 

[Curtis in Texas]

Have you guys considered a brownie box? if your transfer case is divorced you could easily install a Spicer 5831 3 speed aux transmission between the main and T case. They aren't that big, but will require the driveshaft lengths changed. IIRC they are rated for like 16K LBS or more.

I have one that has a 2.0 underdrive 1st gear; a 1 to 1 2nd gear; and a .74 OD 3rd gear.
Since you are using manual transmissions, shifting the Spicer would be simple. The shift pattern for the Spicer I have is the same as the old 3 speed on the floor manual transmissions of the 60's. You could just get an old Hurst 3 speed floor shifter and use cable linkage shifters to make it work with your tilt cabs.

I originally got mine and had it rebuilt, to use behind my Motorhomes automatic tranny, but then decided to just build an Allison 1000 5 speed with stand alone TCM. My original thinking was to just use the Overdrive on the highway with my old Allison 542 4 speed. But it didn't have a lock up torque converter in the 542, so very little mpg gains with that one. And I thought, if I ever needed to climb a steep hill from a standing start I'd down shift to the underdrive and run through the gears until it got to the top. I do a lot of rock crawling with my 4X4 rig we normally flat tow behind the Motorhome, so we sometimes take the Motorhome for a base camp way deeper than most would try to go with a big coach, to use it as a base camp for the rock crawlers we wheel with.
The AT1000 has the gearing I need now that I've regeared the rearend that's in it.

I can show you guys some pictures if anyone wants to see what I'm talking about. They are in my other computer.

I have kept it, thinking one of these days I would build a 4WD FSR Isuzu camper and just use it between the two gearboxes and have a heck of an off road rig. Talk about a crawling gear!

 

[Ambulando]

Have you guys considered a brownie box? if your transfer case is divorced you could easily install a Spicer 5831 3 speed aux transmission between the main and T case. They aren't that big, but will require the driveshaft lengths changed. IIRC they are rated for like 16K LBS or more.

I have one that has a 2.0 underdrive 1st gear; a 1 to 1 2nd gear; and a .74 OD 3rd gear.
Since you are using manual transmissions, shifting the Spicer would be simple. The shift pattern for the Spicer I have is the same as the old 3 speed on the floor manual transmissions of the 60's. You could just get an old Hurst 3 speed floor shifter and use cable linkage shifters to make it work with your tilt cabs.

I originally got mine and had it rebuilt, to use behind my Motorhomes automatic tranny, but then decided to just build an Allison 1000 5 speed with stand alone TCM. My original thinking was to just use the Overdrive on the highway with my old Allison 542 4 spped. But it didn't have a lock up torque converter in the 542, so very little mpg gains with that one. And I thought, if I ever needed to climb a steep hill from a standing start I'd down shift to the underdrive and run through the gears until it got to the top. I do a lot of rock crawling with my 4X4 rig we nirmally flat tow behind the Motorhome, so we sometimes take the Motorhome for a base camp way deeper than most would try to go with a big coach, to use it as a base camp for the rock crawlers we wheel with.
The AT1000 has the gearing I need now that I've regeared the rearend that's in it.

I can show you guys some pictures if anyone wants to see what I'm talking about. They are in my other computer.

I have kept it thinking one of these days I would build a 4WD FSR Isuzu camper and just use it between the two gearboxes and have a heck of an off road rig. Talk about a crawling gear!

I for one would be interested in those pics, Curtis. I don't have the truck we're discussing here but one that is very similar in size and weight, and have just figured out there's a 6 speed overdrive box that will fit in place of my old 5 speed with some parts swapping. The trade off is I will lose my super low 1st gear, and I am looking into options to keep a low gear but I'm completely unfamiliar with Brownie boxes and the like.

 

[Curtis in Texas]

Here you go. It's a simple gear box that is built very robust.
1st picture is the left side, 2nd; a front view showing the push pull shifter rods on top. Followed 3rd; by the data plate.
A cardian joint joins the transmission to the Spicer. Then the drive shaft bolts to the flanges (not on in the 2nd picture) on the back of it.

 

[DzlToy]

IMO, budget is the limiting factour here. As we do not get the plethora of Isuzu and Fuso trucks and buses found in Australia, there aren't many parts from which to chose. Yes, you could get a manual transmission in a 2WD truck, but good luck finding someone who knows the various bolt patterns, tail shaft dimension and degree of interchangeability between makes, models, years and packages.

Contrast this with an NV4500, for example, where a company like High Impact, can make that transmission fit nearly any application. Companies like Quick Time will make custom bell housings and companies like TWF and Advance Adapters can mate their transfer cases to dang near anything.

Could this same goal be accomplished using all Mitsubishi parts from various years and models of trucks? Probably, but I would not have a clue where to tell you to start looking for that detailed information. No dealer in the US is going to be able to talk to you about bell housing bolt patterns or tail shaft conversions on a 2WD six speed manual transmission.

I will be interested to see what you come up with. Good luck.

 

[Curtis in Texas]

I had all that info dug up some years ago as I was going to build a FSR with a Hot Rodded 6BG1T and a 7 speed manual transmission, and the Spicer 3 speed Ov/ Un box then a divorced transfer case, I had it figured the T case would have been in about the center of my proposed truck. The plan was to have both driveshafts the same length, for interchangeable. (my 93 Rodeo does have interchangeable driveshafts. Long Story)

Ended up just buying a 37' Class A Motorcoach instead and Hot Rodding it. (Even Longer Story)
(Wife wanted a bigger Camper with more luxury!!!) (We flat tow the rock crawlers.)

Then I was planning on putting in a Dana 70 front drive axle under the FSR. More for sand and snow than rock crawling. All that research is in my old computer and will tke some digging, but I'll be happy to post up the swapability parts lists and charts I had for it, if I can find them.

My best friend was the Isuzu FactoryTraining Director for Isuzu in America (Atlanta) and specialized in NPR's and FSR's. It's his fault I have this Isuzu addiction. Current collection is 1 89 TD I Mark, 1 highly modified 93 Rodeo, and 5 86-89 Troopers in Turbo Diesel and Turbo Gas.
I still have a big stack of Factory Shop Manuals for the NPR"s. And the Above vehicles!

I always take it as a challenge when people tell me it can't be done. Once built a race car with a VW transmission, turned 180 degrees and a Honda Civic engine turned sideways. It was a fast mid engine car! Another long story!!!!!!

Anyway, I'll do some digging after the weekend if you guys are interested in my research. Happy to pass it along.

My apologies about the Isuzu Hijack since this is actually for an Fuso FG.