FG buildup

[Scott Brady]

I just spent a few days with Doug and Stephanie and their UBER cool FG. The truck performs excellent on rough secondary roads, with the FG exhibiting good traction (strong limited slip), and articulation. The torque in the diesel combined with the 60:1 low range, first gear is awesome.

 

[dhackney]

Some thoughts and conclusions from the tests:
1. The truck is extremely easy to drive. Scott termed it "The Camry of Trucks." Clutch effort is easy and engagement smooth. The throttle throw is a little short but manageable. Throttle tip in is fine and well matched to the driveline. It is tough to foot-roll throttle, but manageable. Extremely, eerily quiet in the cab, especially on the highway. Smooth transmission. Very tight turning radius.
2. The rig meets our design goals for access. We didn't set out to build a Unimog, we set out to build a truck to take us as far as we felt comfortable and then we'd get on the dirt bikes. Scott rated the rig as capable of trails "a solid 2, a 2.5 if required." In real 3rd world terms, that means we'll be able to go down any "paved" road, any primary unpaved road and most "secondary" roads - given adequate bridge capacities. We'll also be able to do some two tracks if thoroughly scouted on the dirt bikes.
3. I was very surprised by what the truck could traverse. We never once made ground contact during the tests, including over some whoops that I thought for sure would drag the departure angle. It will always be limited by its short tires and low inherent ground clearance of the transfer case & diffs. Aside from that, we'll be limited by weight & height characteristics and pucker factor related to roll center.
4. This was the first opportunity for me to watch the truck in action. The camper is very "active" off road. The three point pivot frame performed exactly as designed in protecting the camper from torsional forces. However, we need to add some dampening to quiet some of its transverse motion. This should help a lot on paved roads as well. We'll probably use motorcycle shock absorbers attached to the rear of the pivot frame for this purpose.
5. We plan to replace the stock components with Deaver springs & Bilstein shocks. We believe this will significantly improve ride quality on paved surfaces and off road performance.
6. Weight for this test was 10k lbs. on the rear axle and 5,180 lbs. on the front axle. For this test all suspension components were stock. Air bags were installed on the rear axle and portions of the test were run with the bags inflated to ~90 lbs. No significant differences in handling or off road performance were noted when using the bags inflated. No measured or instrumented tests were performed.
7. The camper is extremely comfortable, roomy and well appointed. The camper remains water tight and free of rattles, squeaks, etc. There is a lot of storage space available, more than enough for our needs. Construction quality is probably as good as it gets in the RV world and most materials have a quality feel to them.


Photos from Beta Test One are in Album Fourteen at:
http://www.hackneys.com/mitsu/index-buildup-photos.htm

 

[flyingwil]

Looks great Doug!

It will always be limited by its short tires and low inherent ground clearance of the transfer case & diffs.

Do you have any options for this or are you "stuck" with what you got?

 

[Scott Brady]

2. The rig meets our design goals for access. We didn't set out to build a Unimog, we set out to build a truck to take us as far as we felt comfortable and then we'd get on the dirt bikes. Scott rated the rig as capable of trails "a solid 2, a 2.5 if required." In real 3rd world terms, that means we'll be able to go down any "paved" road, any primary unpaved road and most "secondary" roads - given adequate bridge capacities. We'll also be able to do some two tracks if thoroughly scouted on the dirt bikes.
[/QUOTE]

Here is the trail rating definition for Doug's comment above.

2
Formed Track: Not passable by standard passenger vehicles.High clearance preferred, AWD preferred. Steep grades present, larger rocks embedded in trail (less than 7”). Some loose trail surfaces and shallow water crossings possible. A spotter may be required on the most challenging portions to prevent body damage on vehicles with less clearance. Sand and dry washes may challenge available traction requiring lower air pressure on some vehicles. Trail may be narrow and require backing to allow other vehicles to pass. (Example Trails: Temporal Gulch, AZ / Red Canyon, CA)

2.5
Rugged Track: Not suitable for 2wd vehicles, or low clearance cross over vehicles. AWD required, Low Range preferred. Rutted, crossed axle terrain possible, with loose, steep climbs required. Deep sand possible. Some rock crawling possible on loose rocks up to 8” in diameter. Some larger rocks may be present, possibly requiring a spotter to negotiate. Small ledges possible, with larger embedded rocks present. Water crossing to 12” possible. Loose surfaces will be present, with tight clearance, smaller margin for error, and the possibility of body damage. Within the capability of any high clearance stock SUV or truck. AWD cross-over vehicles will struggle and may suffer damage due to lack of low range gearing. (Example Trails: Chloride, AZ / Chiricahua's, AZ)

 

[BajaTaco]

:lurk: I love this thread. It's an epic build-thread if I ever saw one.

Congrats to the Hackney's on a well laid out plan and great documentation so we can all enjoy the outcome. Sounds like you still have some things to finish, but my guess is not much. I can't wait to see the reports from the trip!

 

[dhackney]

Do you have any options for this or are you "stuck" with what you got?

We will add 1.5 to 2" of sprung weight ground clearance when we put the Deaver springs on, but that won't change the Lilliputian tire height or the low hanging diffs and transfer case. The Michelins would add 2-3" of circumference and give us about 300 lbs. more front axle capacity.

I agree with Scott on the fundamental character of this chassis: "It's a delivery truck capable of working in unpaved environments." If we carved off the lower level of storage boxes and moved the spares to the back or genset space we'd have more rough terrain off-road capability, but that wouldn't help us in deep mud, silt or sand, where the dragging diffs will always be the limiting factor.

From what I've seen so far, it will function very well as a delivery platform for the camper and the dirt bikes, which was our fundamental design requirement.

I'd like to close our knowledge gap on roll angle, which is a pretty easy test on a sailboat but very "expensive" with a truck of this size unless we can find a tilt table that can accomodate its dimensions & weight. Untill then we'll be operating with only our "pucker factor" as gauges, and my wife's kicks in at about 2.327 degrees.

 

[BajaTaco]

Untill then we'll be operating with only our "pucker factor" as gauges, and my wife's kicks in at about 2.327 degrees.

:xxrotflma

question: It looks like the over-cab tubing/rack has been removed. What is the status of that? (sorry if I missed it earlier in the thread).

 

[dhackney]

to make this HUGE project come together so quickly!

When it's in the shop HUGE is definately my operative perception. Strangely, when we got it out on the trail and I had the opportunity to stand and watch Scott or my wife drive it around, it just didn't seem all that large.

In open savanna or Baja / Sonorran desert terrain it will fit fine. In tight, twisty forest roads and Byzantine alleys of Old Cities, not so well.

fair seas

And thanks for the support! Greatly appreciated. I think we're all ready for this development, fabrication & assembly chapter to conclude so we can begin the final testing, provisioning and departure portion of the adventure.

 

[dhackney]

:question: It looks like the over-cab tubing/rack has been removed. What is the status of that? (sorry if I missed it earlier in the thread).

Mark pulled the rack off to finish the fabrication. We may delete the rack portion and just run a light/antenna bar across the front. We can't put any more weight on the front anyway, so we wouldn't be able to carry anything up there but toilet paper.

I'm also reaching the limit of what I can lift with the cab. Even with the torsion bar cranked up to max pre-load, those air seats really make it a grunt to tilt.

 

[dhackney]

An update on weight:

Mitsubishi Fuso FG 140 4x4
GCWR......17,045 lbs.
GVWR......14,050 lbs.

Stock chassis weight....................5,842
Stock max body-payload capacity...8,208

GAWR..............Front..5,730
......................Rear.. 9,480
Combined axle rating..15,210

Front axle tire capacity...6,084
Rear axle tire capacity...11,112
Total tire capacity........17,196


Our Beta Test One meausured weight was 15,180 lbs. The spread was 10k on the rear and 5,180 on the front.

Based on our measured weight in Beta One configuration I estimate our finished weight at around 16,164, probably more like 16,300. That’s with only one bike. If we take both bikes we’d be at 16,402 (estimated) / 16,550 (probable).

That would keep us within 110% over combined axle rating and below tire capacity front and rear (assuming we maintain our current front/rear weight distribution) and below GCWR.

Our challenge remains front tire capacity, as most of the remaining weight is located directly behind the cab (2 batteries, gen set, 2nd bike, etc.).

 

[sleeoffroad]

Excellent reply. I was looking at the pics of the water distribution panel. Have you ever considered the "push to connect" type fittings. Less clutter than a gazilion hose clamps and easy to fix. Search www.mcmaster.com for "push to connect" fittings.

 

[FusoFG]

I'd like to close our knowledge gap on roll angle, which is a pretty easy test on a sailboat but very "expensive" with a truck of this size unless we can find a tilt table that can accomodate its dimensions & weight. Untill then we'll be operating with only our "pucker factor" as gauges, and my wife's kicks in at about 2.327 degrees.

Turns out that you can measure the height of the center of gravity pretty much the same way you can on a sailboat. Weigh it level and then tilt it and weigh it again.

All you need is a truck scale and a couple ramps like people use for oil changes to create the tilt. But in this case all you have to do is raise the front wheels a little bit.

Once you have the height of the center of gravity and the track you can quickly calculate the the theoretical maximum side angle.

here's the web site detailing the procedure and calculations:

http://www.jeepaholics.com/tech/cog/

All his explanations aren't text book perfect but the science is right.

Fuso used to sell a nice dash mounted tilt gauge that helps prevent arguments between driver and navigator.

The Fuso body builder manual states you should keep the cog height under 59 -60 inches above the ground. I thought it was 60 for the FE and 59 for the FG, but I can't find the 59" reference anymore.

The chassis only cog is 28 inches, just below the frame rails which is theoretically good enough for driving across a 100% percent grade ( a 45 degree slope). About the same as a Hummer H1.

Then there's traction, bumps, holes and dynamic movement and the weight of whatever structure you add that detracts from that ability.

It sounds like you added about 10,000 punds to the bare chassis. Some of that weight is at or below 28" so that's good. Some of it's above 28". The question is how much weight and how far above 28".

I think that worst case, if the cog of the 10,000 pounds of payload you added was less than 78 inches above the ground you would be within in fuso's 60 inch guideline.

I think that would be a theoretical maximum side angle of 28 degrees. That's static - the dynamics of a vehicle going over bumps and down into holes and springs compressing would make it risky to approach that angle.

It's unlikely that your cog is that high, but if it is, the worst offenders are the roof rack and anything you stow there (very high), the generator (high and heavy, the motorcycles (high and heavy), the roof mounted air conditioners and the 3rd and 4th house battery.

It's obvious that you should load your heaviest gear in the lowest tool boxes, but it's not obvious that you shoul load the vehicle evenly side to side. If you don't the cog will shift closer to the heavy side and your side angle capability will be less on the heavy side.

That's why I dob't like inter connected fuel tanks. The weight will slosh to the low side.

It would make sense to determine the cog from a safety point of view as well as peace of mind and to answer those naysayers you will meet along the way who will tell it must be top heavy because it "looks" top heavy.

good luck on the journey.

Tom

 

[dhackney]

Have you ever considered the "push to connect" type fittings.

Christo,

I hadn't looked at that type of connection. I need to re-engineer the entire water system around a new valve so I'll take a look at that option. Thanks for the info.

And thanks again for your help when we were starting out on this expedition vehicle path. This thing is a long ways from an LC100!

Doug

 

[dhackney]

Weigh it level and then tilt it and weigh it again.

Tom,

This is super info. Thanks for the link.

Agreed on vehicle dynamics affecting any theoretical limit. All it takes is one rock or hole.

But having said that, I'd take great comfort in knowing the lateral, longitudinal and vertical location of the CG and resulting roll angles.

On the measurements that this guy is using for Jeeps, do you think a 24" front tire patch lift is valid for the FG? He is adament about >24", which I'm assuming is related to the wheelbase of the Jeeps he is including in his sample set. If the FG has a longer wheelbase would we need to elevate the tire patches to 36", 48", etc.? I don't know enough math to calculate this out for myself.

Our camper weighed 3,700 lbs. out of the factory. There have been some things taken away and some added since then, so there's no current way to know exactly how much it weighs sitting in the assembly shop, but 3,800 is a reasonable estimate. Fully loaded and wet I'd estimate the camper at around 4,500 lbs.

We've had a number of conversations walking around it talking about where the CG of the camper itself is. The longitudinal CG is marked on the camper, but what we don't know is lateral and vertical CG.

If we can, we'll get a bare chassis and a chassis with camper weight and then we'll know how much that element itself weighs.

Until then we'll have to be content with an estimated loaded wet chassis weight of 10,680 (half tank of fuel). I think the majority of that weight is at or below 38 inches. We did everything we could to centralize the mass between the axles and the frame rails.

Based on the weights we took this week we know that 66% of the loaded wet weight is on the back axle, so using the Jeep guy's calculations the longitudinal CG is 33% ahead of the rear axle.

Vertical and lateral is unknown, but I'd guess the longitudinal is just forward of the AC/DC distribution panel located in the step up into the berth. Vertical could be anywhere, but I'd love to find out it's below the floor level of the camper. (one can always dream...) After working through this exercise I would be surprised if it is 60" or higher, which I wouldn't have said just looking at the rig.

Doug

 

[Scott Brady]

I think that would be a theoretical maximum side angle of 28 degrees. That's static - the dynamics of a vehicle going over bumps and down into holes and springs compressing would make it risky to approach that angle.

Tom,

Based on my time with Doug's FG, this is a good number in my book too as a maximum. I would avoid anything over 20% on the trail, and that would be with very slow and smooth progress.

That's why I dob't like inter connected fuel tanks. The weight will slosh to the low side.

Good point. Cross-linked airbags fall into the same category IMO.