FG4x4 5.285 vs 5.714 ratios

Hello,
Does anyone have experience with the 5.285 gear ratio? It seems like most folks prefer the 5.714 on the current truck. I'm trying to balance cruising speed with off-road ability and it's hard to tell from reading about it what it would be like given the duonic gearbox.

Thanks!
 

Czechsix

Watching you from a ridge
I've got the tall gears in a 2012, problem is that without having the same rig, on the same trail, with the different gears - no real way to tell.

What I can say is that there's a good chance I get better fuel mileage.

As to the trail behavior, well, everything has idiosyncrasies. To make it worse, I have a different suspension too, plus a relatively heavy coach.

What the lower gearset might help with is the initial push out of soft surfaces, or on slopes. But without solid figures and comparisons, it might well be just having to adopt a different driving style.
 
Hey Czechsix, thanks for the reply. Couple questions: What is the max cruising speed you feel comfortable at on the highway? What's your preferred cruising speed?

Given the gearbox is an automated manual, do you feel like you can crawl adequately without smoking the clutch? I watch this video: https://www.youtube.com/watch?v=8KWZ9ID_SEc

and it makes me worried about crawl speed. I hope that isn't the minimum speed you can reasonably drive... What do you think?
 

dlh62c

Explorer
The Duonic has two clutchs, one for the odd gears, one for the even.

YouTube is your friend.
https://youtu.be/ZUH7L-KclaE
 
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Czechsix

Watching you from a ridge
Hey Czechsix, thanks for the reply. Couple questions: What is the max cruising speed you feel comfortable at on the highway? What's your preferred cruising speed?

Given the gearbox is an automated manual, do you feel like you can crawl adequately without smoking the clutch? I watch this video: https://www.youtube.com/watch?v=8KWZ9ID_SEc

and it makes me worried about crawl speed. I hope that isn't the minimum speed you can reasonably drive... What do you think?

Max cruising, if it's under 75 degrees or so, has been 75mph, up to 80mph or a bit more in spurts. Much depends on the tire temps, if it's a hot day I'll run slower. Preferred cruising speed is 65mph, truck is pretty happy there.

Forget about crawling with the Duonic, not going to happen. What will happen, in slow speed/high torque situations, is you'll get a nice transmission oil overheat indicator. At that point you have a couple of options: one, stop what you're doing. Which can be an issue if you're trying to get over something, or up a hill. Two, is floor it and if you can make it over/up and increase the revs in the next few seconds the transmission oil will cool down fine. As with all vehicles, getting in the proper gear is essential to making it over obstacles - and even more essential with these trucks.

When off road, the truck is always kept in the full manual option. Even with that, gear changes are slower than I'm able to do with a regular clutch. The Duonic system is definitely slower between gear changes. I don't care what they say about their fuzzy logic learning and optimizing the gear selections. It probably works fine for city driving (which, after all, is pretty much what these trucks are designed for), but for serious off road it's a big issue.

I still think that I'll wind up doing a few more things to it, one is working out a solution to the DPF system, two is possibly putting a two speed transfer into it ( I still have to check angles, space limitations, etc), and three is a total repower with a 12 valve Cummins and an Allison with a two speed transfer case. At that point it'll get a reworked suspension too.

What you saw in that video was Howard keeping his revs up over 2000, and he has the lower gearset too. "Idiosyncrasies of the vehicle design" etc etc.

If you foresee doing really slow speed crawling, opt for the older trucks, not the Duonic.

For my purposes, it works fine. I just want to be able to get into the back country, and if there's a snowfall, some mud in the way, sand - to be able to make my way in, and back out with minimal drama. Serious uphill/downhill ruts, ledges, rocks I have to avoid.
 

dlh62c

Explorer
^ When you referred to smoking "the clutch" in your post.

Have you driven a Duonic equipped truck?

http://forum.expeditionportal.com/threads/90471-Fuso-3-0-Duonic-transmission-SCR?highlight=Duonic+creep
 
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It's only using one clutch at a time, hence *the* clutch.

I have not driven one or I wouldn't need to come on here and ask a bunch of basic questions about it's drivability. :)

Thanks for the insight, Czechsix. To confirm, you moderate your cruising speed by the ambient temperature because you're worried about tire temps? The truck itself doesn't overheat, does it?

Thanks!
 

Czechsix

Watching you from a ridge
Correct W, tire temp is what I worry about, truck itself has never overheated.

The tires are at max load all the time, and the customer service drone/tech help knucklehead at Toyo was absolutely useless when I asked about safety margins, max temps and pressures, etc. So I probably obsess about tire temps more than I should, but then again losing a tire at speed would not be a good thing either. I try to err on the side of caution.
 

gait

Explorer
Correct W, tire temp is what I worry about, truck itself has never overheated.

The tires are at max load all the time, and the customer service drone/tech help knucklehead at Toyo was absolutely useless when I asked about safety margins, max temps and pressures, etc. So I probably obsess about tire temps more than I should, but then again losing a tire at speed would not be a good thing either. I try to err on the side of caution.

you probably have it already but I have load/pressure/speed table for Michelin 285/70 19.5 equivalent of Toyo. All the way from higher than max load at lower speed through higher than max speed at lower load to crawling with low pressure for traction. Like you, temperature is my check.
 

Czechsix

Watching you from a ridge
you probably have it already but I have load/pressure/speed table for Michelin 285/70 19.5 equivalent of Toyo. All the way from higher than max load at lower speed through higher than max speed at lower load to crawling with low pressure for traction. Like you, temperature is my check.

Believe it or not gait, according to the [sarcasm]customer service/very professional[/sarcasm] drone at Toyo - no such information exists for their tires.

I'd like to see that Michelin table, if you have it as a pdf or can direct me to it somewhere in the wilderness of the 'net....
 

yabanja

Explorer
Hello,
Does anyone have experience with the 5.285 gear ratio? It seems like most folks prefer the 5.714 on the current truck. I'm trying to balance cruising speed with off-road ability and it's hard to tell from reading about it what it would be like given the duonic gearbox.

Thanks!

We went for a multiple week hard core off road trip this spring with vehicles equipped with both ratios. You would think that the lower ratio would make a big difference, (and personally I would choose it due to the increased tire sizes), but the high ratio vehicles didn't seem to be too hindered by their handicap. (although to be honest the only vehicle that had to be winched on the entire trip was a high ratio one that couldn't make it up a steep slope with large rock steps.).

Hope that is helpful!

Take care,

Allan
 

gait

Explorer
Believe it or not gait, according to the [sarcasm]customer service/very professional[/sarcasm] drone at Toyo - no such information exists for their tires.

I'd like to see that Michelin table, if you have it as a pdf or can direct me to it somewhere in the wilderness of the 'net....

send me a pm with your email address and I'll send you a pdf. I tried the tyre and rim associations but I couldn't get their gatekeepers to understand the question. Michelin were very good/patient and found it on the third attempt.
 

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