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8x8 Deuce

offroadexpeditions

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8x8

Jeremy, the way I see it.......... The more opposition and nay saying you get from the group here, the more drive you should have to be able to accomplish this:) That's the kind of person I am. If I am met with opposition, I only push harder.

I have actually spent a great deal of time looking into what it would take to do this myself. Looking at how the steering linkage would work, and drive shaft angles and everything. I live for stuff that is different and makes people say "Why?". I never have understood people who say "Why would you need something like that?" Or "There is no need for something like that!". Comments like that only make me want it more:)

I think if you personally feel you might have the mechanical and engineering ability to make it happen, by all means, have at it! We all of course would love to own a HEMTT, but since it is out of our price range, maybe an extra axle or three under the Deuce or five ton just might hold us over for a couple months or so. ha ha.

I wanted to do two steer axles, and 4 drive axles, and leave the first two drive axles right where they are, and extend the bed, and put the other two drive axles behind them with the back of the bed just slightly overhanging the rearmost axle. So there would be 6 axles total. And since I know the deuce and a half engine and drivetrain would have a heck of a time turning all of that and would probably never get over 15 or 20 miles per hour and be more subject to breakage, I decided it would have to be built with a 5 ton truck. So I've spent quite a bit of time envisioning this beast, and just what it would take to build such a thing. I think it would be totally awesome. Of course then I realize, by time I put all the time into building it, I could probably afford to just buy a real HEMTT. Although, I keep my eyes open and search occasionally for one for sale, and have just not seen one listed anywhere for quite some time.
Hi, I have spent some time with this topic too. I had hummer off road tours before, and I have been looking for some ways to build the vehicle, which can handle the stress. Deuce is too heavy for real off road, but making it 8x8 would solve the problem. All 8x8 trucks are too heavy by themselves, except M656, which is too rare with no parts available. I think the best way would be to copy the steering system from this truck. BTW there was one Hemtt sold on govliquidation last week for $28 000.
 

robert c neth

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it seems pretty simple with hydraulic steering. use a rear suspension setup with 2 front axles,dont know why it wouldnt work.this thread has a lot of good info about cdl,s and weight classifications!!!!!!!!!!
 

offroadexpeditions

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Location
florida
8x8

it seems pretty simple with hydraulic steering. use a rear suspension setup with 2 front axles,dont know why it wouldnt work.this thread has a lot of good info about cdl,s and weight classifications!!!!!!!!!!
Is the hydraulic steering street legal? I am thinking about weight primarily because of off road capabilities. The extra axle would spread the weight of the vehicle over the larger area, so it wouldn't sink easily.
 

mudguppy

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it seems pretty simple with hydraulic steering. ... dont know why it wouldnt work. ...
the two front axles will need at least a mechanical linkage between them to keep them in sync. individual hydraulic circuits (one on each axle) will eventually, or quickly, become out of phase with each other, even with 'divider valves'.


Is the hydraulic steering street legal? ...
it can be. it's been discussed a lot on here; best anyone can produce are state DOT laws that give performance specifications. a well-designed hydraulic system can meet the test specifications that have been presented and, thus, be 'legal'. to my knowledge, no one has posted a state DOT code with verbiage indicating that a fully hydrualic steering system is not permitted.


i still think the easiest thing to do is to have a common steering box and steering box arm; use seperate drag links from the steering box arm (aka pitman arm) to the respective axle steering arms. add hydrualic assist cylinders on each axle to provide the lion's share of the steering force (alleviating strain from the steering box). adjusting for ackerman ratios can be performed at the pitman arm or steering knuckle, or both.

the steering box could be located out front of both axles. however, a simpler design would be to have the steering box located between the two front axles; drag link forward to the lead steer axle and rear to the trailing steer axle.


to add rear-steer (which i don't know why anyone would...?) is more involved. PLS trucks use a front steering box that has a thru-put of the steering input shaft. this shaft travels from the front box down the length of the frame, through a counter-rotate box, and into a rear steering box that controls the rear-most axle. you would almost always see the rear axle tires badly worn because aligning this rear axle was a serious PITA and never seemed to take for long. the PLS truck was/is being replaced with the HEMTT-based platform; i can only speculate that this overly complicated steering and suspension setup (as was everything else on the PLS) just really didn't have the practical advantages that the brochure claimed it would.
 

olly hondro

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To address the level of difficulty of this project.......its easier than understanding how women think.....so go for it !!
 

robert c neth

Banned
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Location
girard pa
i built one of these 30 year ago for a logging company.the steering was similar to a thread posted on here .the steering gear was from and old ford cabover semi.it lasted ten years until the logging co sold it .so im saying it can be done and wish you luck on your build.i welded all the steering gear and it wont pass pa state inspection.you may want to check with your dmv on do,s and dont,s.or go antique that requires no inspection.again good luck and keep us posted.
 

offroadexpeditions

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florida
8x8 deuce

the two front axles will need at least a mechanical linkage between them to keep them in sync. individual hydraulic circuits (one on each axle) will eventually, or quickly, become out of phase with each other, even with 'divider valves'.




it can be. it's been discussed a lot on here; best anyone can produce are state DOT laws that give performance specifications. a well-designed hydraulic system can meet the test specifications that have been presented and, thus, be 'legal'. to my knowledge, no one has posted a state DOT code with verbiage indicating that a fully hydrualic steering system is not permitted.


i still think the easiest thing to do is to have a common steering box and steering box arm; use seperate drag links from the steering box arm (aka pitman arm) to the respective axle steering arms. add hydrualic assist cylinders on each axle to provide the lion's share of the steering force (alleviating strain from the steering box). adjusting for ackerman ratios can be performed at the pitman arm or steering knuckle, or both.

the steering box could be located out front of both axles. however, a simpler design would be to have the steering box located between the two front axles; drag link forward to the lead steer axle and rear to the trailing steer axle.


to add rear-steer (which i don't know why anyone would...?) is more involved. PLS trucks use a front steering box that has a thru-put of the steering input shaft. this shaft travels from the front box down the length of the frame, through a counter-rotate box, and into a rear steering box that controls the rear-most axle. you would almost always see the rear axle tires badly worn because aligning this rear axle was a serious PITA and never seemed to take for long. the PLS truck was/is being replaced with the HEMTT-based platform; i can only speculate that this overly complicated steering and suspension setup (as was everything else on the PLS) just really didn't have the practical advantages that the brochure claimed it would.
Hi Travis, thanks for your post, very helpful. That is what I was thinking- the box between the axles with two drag links. Would you be able to put it together? Peter
 

offroadexpeditions

New member
65
1
0
Location
florida
8x8 deuce

i built one of these 30 year ago for a logging company.the steering was similar to a thread posted on here .the steering gear was from and old ford cabover semi.it lasted ten years until the logging co sold it .so im saying it can be done and wish you luck on your build.i welded all the steering gear and it wont pass pa state inspection.you may want to check with your dmv on do,s and dont,s.or go antique that requires no inspection.again good luck and keep us posted.
Hi Robert, would you be able to build it? Peter
 

Flat Black

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Georgia state
Are you talking about adding a second steering axle behind the deuce cab and leaving everything else as is? If so, I think that will look strange. Most 8x8s are cabover (HEMTT, MAN KAT, TATRA, etc) for several reasons.

If you are going to start with two straight box/channel frame rails, I would build a ladder frame from 9" x 3" x 1/4" channel and set all four axles where you want them. Set the engine, transmission and transfer case wherever you want and rotate the transfer case down into the driveline tunnel.

Use full hydro steering for both axles (insert comment here about hydro being dangerous or illegal on the road, its neither, go educate yourself) along with some Ouverson goodies and ARB lockers in all four axles with link suspension and you would have a one of kind truck that would go almost anywhere.

I would ditch the OEM engine, trans and case and use a Duramax or Cummins with built 1 ton driveline parts. They are stronger than the 40-50 year old stuff in you truck now and infinitely better engineering, efficiency, serviceability, etc. Unless you drive like a complete idiot, you will not break these parts.

You could do it on a budget for probably 15-20k if you get good deals and do all the fabwork yourself. To do it top notch with new or reman high quality parts will be 4-5 times that amount easily. You could spend 35-40k on axles alone, another 25-30k on engine, transmission and transfer case and only have a roller with 60-70k invested. The killer setup would be to use 2.5 ton chunks in a central cradle and make the entire rig independent suspension.

Get out your credit card and start building.
 
Last edited:

tcody

Member
560
5
18
Location
Illinois
Don't want to rock the boat, but instead of trying to fabricate a second steering axle which would be both costly and time intensive, why not buy a twin steer 8x8 or 8x10 from the local junk yard. They made Mack and Oshkosh chassis for concrete mixer trucks that are already set up in this configuration and they are cheap. It is easier to graft a cab onto a chassis than to engineer a whole new chassis. Just a thought.
 

offroadexpeditions

New member
65
1
0
Location
florida
Don't want to rock the boat, but instead of trying to fabricate a second steering axle which would be both costly and time intensive, why not buy a twin steer 8x8 or 8x10 from the local junk yard. They made Mack and Oshkosh chassis for concrete mixer trucks that are already set up in this configuration and they are cheap. It is easier to graft a cab onto a chassis than to engineer a whole new chassis. Just a thought.
Hi Cody,

I am trying to make it the lightest possible. Those trucks are heavy, they would sink into soft soil. This would be the vehicle application.[media]http://www.youtube.com/watch?v=eLx-ko9WjMg[/media]
 

offroadexpeditions

New member
65
1
0
Location
florida
Are you talking about adding a second steering axle behind the deuce cab and leaving everything else as is? If so, I think that will look strange. Most 8x8s are cabover (HEMTT, MAN KAT, TATRA, etc) for several reasons.

If you are going to start with two straight box/channel frame rails, I would build a ladder frame from 9" x 3" x 1/4" channel and set all four axles where you want them. Set the engine, transmission and transfer case wherever you want and rotate the transfer case down into the driveline tunnel.

Use full hydro steering for both axles (insert comment here about hydro being dangerous or illegal on the road, its neither, go educate yourself) along with some Ouverson goodies and ARB lockers in all four axles with link suspension and you would have a one of kind truck that would go almost anywhere.

I would ditch the OEM engine, trans and case and use a Duramax or Cummins with built 1 ton driveline parts. They are stronger than the 40-50 year old stuff in you truck now and infinitely better engineering, efficiency, serviceability, etc. Unless you drive like a complete idiot, you will not break these parts.

You could do it on a budget for probably 15-20k if you get good deals and do all the fabwork yourself. To do it top notch with new or reman high quality parts will be 4-5 times that amount easily. You could spend 35-40k on axles alone, another 25-30k on engine, transmission and transfer case and only have a roller with 60-70k invested. The killer setup would be to use 2.5 ton chunks in a central cradle and make the entire rig independent suspension.

Get out your credit card and start building.
Hi Flat Black, there will not be any cab, just a cage similar to those I had on my humvees. [media]http://www.youtube.com/watch?v=eLx-ko9WjMg[/media]
 

quickfarms

Well-known member
3,495
25
48
Location
Orange Junction, CA
If you are not going to put a cab on it and just use a cage why not just build a 4x4? But an 8x8 would be unique.

The idea of picking up an existing 8x8 chassis would same a lot of work and dollars even if you just striped it for parts.
 
Last edited:

offroadexpeditions

New member
65
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Location
florida
If you are not going to put a cab on it and just use a cage why not just build a 4x4? But an 8x8 would be unique.

The idea of picking up an existing 8x8 chassis would same a lot of work and dollars even if you just striped it for parts.
The weight is the reason, those trucks would sink. I had 4x4, they sunk too, they were fully loaded. I try to spread the weight over a larger surface. [media]http://www.youtube.com/watch?v=eLx-ko9WjMg[/media]
 

Flat Black

New member
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9
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Location
Georgia state
sorry if missed that before, I thought you were looking to build something like a Tatra 815 or a MAN KAT.

If you plan to use it for off road touring like the video above, that changes a few things. This is what I would do if I were going to build something like that, so take it for what it's worth.

Buy two pairs of re-conditioned axles, done by a reputable shop with good parts, but I would not get into upgrades on the axles at all. Drum brakes are heavy and trap mud and water so they will need lots of service from the off road use, but you are going at slow speed so you should have no problems stopping with eight drums. I would throw on a couple of driveline brakes for emergency use or parking brakes. A disc brake conversion can be done on a budget and that would be my choice if you have the cash for it. There are tons of shops and vendors for the 2.5 ton axles. Anything you "could" want to do has been done by the mud guys or the rock crawling crowd, so you can go crazy if you want, but I see no need for that in this application.

I prefer a fully boxed frame over C-Channel, you want your suspension to flex, not your frame. Leaf springs are dead simple and reliable. Use a stock or similar to stock setup with a good number of leaves removed since you will not be carrying a huge amount of weight. (Thirty people at 200 pounds each is only 6000 pounds.) You can add a track bar to control axle wrap if required (from reduced leaves) and an anti sway bar to control body roll and make it a bit more comfortable for your passengers. You should not need huge articulation, but the anti sway bar may limit it some depending on how its setup.

If you are not going to drive the truck on the road, I would do a 12 valve B series Cummins that has been mildly modified, no need for crazy high HP in this application. You want good torque and good area under curve for all around performance, smooth throttle response, etc. If you want an auto, get one from Suncoast or Goerend Brothers built for your application and you will never kill it. An NV271 (manual) or NV273 (electric shift) transfer case will be fine in this application and an NV241DHD would probably be fine too honestly.

Build the cage however you want it to look and feel and weld it or bolt it right to the frame rails. This will give the frame an increase in rigidity and reduce flex. A 2" DOM tube in .120 wall should be fine for the main cage structure and you can use 1.75" or even 1.5" in non stressed areas.

An off road suspension seat from PRP or Mastercraft will go a long way to making the ride comfortable, even with just a lap belt, though I might suggest a four point harness.

With full hydraulic steering you can easily tie the two front steering axles together and could even counter steer the rears but that can be quite difficult for the operator, so I would probably stick with two front steering and two solid rear axles. If you feel like you want to tackle more aggressive terrain, I would throw in at least two ARB lockers or a Detroit/OEM style. With open diffs all around your eight wheel drive is really only four and that may or may not be enough depending on what you are doing on the trail.

I would finish the rig with things like heavy powder coat, spray on bed liner, POR-15, etc.. With the harsh environment cleaning the rig and preventative maintenance will make it last a long time. For the cab design I like the cabover style with the engine under you or behind you. Especially for off roading this gives the driver a great view and they need not worry about having a front end/nose to clear or hang up on obstacles.

I would take design ideas from other similar rigs like MAN KAT, HEMTT, TATRA 815, KAMAZ, Unimog, Actros (Actros 8x8 and a 6x6 Very Nice! Looks very capable for a large truck! - Benzworld.org - Mercedes-Benz Discussion Forum) and the like. The driver could sit lower, kind of over the front axle to see the trail better, where the passengers could be raised up like in the HMMWV. For wheels and tires, the rockwell pattern is very common and a 20" wheel with some 38 -42" off road tires will be fine. No need for huge heavy tires for the terrain that you are going on. Continental makes a great MPT in a 38" version and a 41" version IIRC. They are true off road tires that can be aired down for off roading. A bottom diff mohawk with any number of kits on the market will give your axles the ground clearance of a Dana 60 if you are concerned with ground clearance.

EDIT: http://www.pirate4x4.com/forum/showthread.php?t=569157&highlight=

EDIT2: you could start with a chassis like this:


which would give you frame rails and a driver's cab. Cut the back of the cab out like a van cutaway, sell off the box, engine, trans, axles, etc to someone like Doug Busbee and build your cage on the existing frame. It could save you some time and money, as this one is listed for $7,000 in Arizona. Doug may sell you a wrecked one even cheaper.

Two pairs of axles should be about $3,000, wrecked Dodge Cummins truck for a few grand (take the driveline, sell or scrap the rest), wheels and tires (??), add your tube chassis and seats and you have all the majour components that you need.

What is your budget and timeline on this? Is it something that you are serious about constructing for your tour business?
 
Last edited:

offroadexpeditions

New member
65
1
0
Location
florida
sorry if missed that before, I thought you were looking to build something like a Tatra 815 or a MAN KAT.

If you plan to use it for off road touring like the video above, that changes a few things. This is what I would do if I were going to build something like that, so take it for what it's worth.

Buy two pairs of re-conditioned axles, done by a reputable shop with good parts, but I would not get into upgrades on the axles at all. Drum brakes are heavy and trap mud and water so they will need lots of service from the off road use, but you are going at slow speed so you should have no problems stopping with eight drums. I would throw on a couple of driveline brakes for emergency use or parking brakes. A disc brake conversion can be done on a budget and that would be my choice if you have the cash for it. There are tons of shops and vendors for the 2.5 ton axles. Anything you "could" want to do has been done by the mud guys or the rock crawling crowd, so you can go crazy if you want, but I see no need for that in this application.

I prefer a fully boxed frame over C-Channel, you want your suspension to flex, not your frame. Leaf springs are dead simple and reliable. Use a stock or similar to stock setup with a good number of leaves removed since you will not be carrying a huge amount of weight. (Thirty people at 200 pounds each is only 6000 pounds.) You can add a track bar to control axle wrap if required (from reduced leaves) and an anti sway bar to control body roll and make it a bit more comfortable for your passengers. You should not need huge articulation, but the anti sway bar may limit it some depending on how its setup.

If you are not going to drive the truck on the road, I would do a 12 valve B series Cummins that has been mildly modified, no need for crazy high HP in this application. You want good torque and good area under curve for all around performance, smooth throttle response, etc. If you want an auto, get one from Suncoast or Goerend Brothers built for your application and you will never kill it. An NV271 (manual) or NV273 (electric shift) transfer case will be fine in this application and an NV241DHD would probably be fine too honestly.

Build the cage however you want it to look and feel and weld it or bolt it right to the frame rails. This will give the frame an increase in rigidity and reduce flex. A 2" DOM tube in .120 wall should be fine for the main cage structure and you can use 1.75" or even 1.5" in non stressed areas.

An off road suspension seat from PRP or Mastercraft will go a long way to making the ride comfortable, even with just a lap belt, though I might suggest a four point harness.

With full hydraulic steering you can easily tie the two front steering axles together and could even counter steer the rears but that can be quite difficult for the operator, so I would probably stick with two front steering and two solid rear axles. If you feel like you want to tackle more aggressive terrain, I would throw in at least two ARB lockers or a Detroit/OEM style. With open diffs all around your eight wheel drive is really only four and that may or may not be enough depending on what you are doing on the trail.

I would finish the rig with things like heavy powder coat, spray on bed liner, POR-15, etc.. With the harsh environment cleaning the rig and preventative maintenance will make it last a long time. For the cab design I like the cabover style with the engine under you or behind you. Especially for off roading this gives the driver a great view and they need not worry about having a front end/nose to clear or hang up on obstacles.

I would take design ideas from other similar rigs like MAN KAT, HEMTT, TATRA 815, KAMAZ, Unimog, Actros (Actros 8x8 and a 6x6 Very Nice! Looks very capable for a large truck! - Benzworld.org - Mercedes-Benz Discussion Forum) and the like. The driver could sit lower, kind of over the front axle to see the trail better, where the passengers could be raised up like in the HMMWV. For wheels and tires, the rockwell pattern is very common and a 20" wheel with some 38 -42" off road tires will be fine. No need for huge heavy tires for the terrain that you are going on. Continental makes a great MPT in a 38" version and a 41" version IIRC. They are true off road tires that can be aired down for off roading. A bottom diff mohawk with any number of kits on the market will give your axles the ground clearance of a Dana 60 if you are concerned with ground clearance.

EDIT: my new all purpose modular 8x8 rig - Pirate4x4.Com

EDIT2: you could start with a chassis like this:


which would give you frame rails and a driver's cab. Cut the back of the cab out like a van cutaway, sell off the box, engine, trans, axles, etc to someone like Doug Busbee and build your cage on the existing frame. It could save you some time and money, as this one is listed for $7,000 in Arizona. Doug may sell you a wrecked one even cheaper.

Two pairs of axles should be about $3,000, wrecked Dodge Cummins truck for a few grand (take the driveline, sell or scrap the rest), wheels and tires (??), add your tube chassis and seats and you have all the majour components that you need.

What is your budget and timeline on this? Is it something that you are serious about constructing for your tour business?
I will start with 2 M35A3s, use the second tandem for front suspension, and probably copy the steering from XM757. It will not cost that much. I am serious with this project, there is simply too much money and fun in this kind of business. If I find a partner with cash, I would like to start this season, if not, I will put money together, and start next year just by myself.
 

charlietango

Member
Steel Soldiers Supporter
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18
Location
Winnipeg
I know the Tundra Buggies company up here uses a MAN 8x8 and I believe they used the chassis of old airport firetrucks in the past. something to explore for ideas anyways but those things go through **** and back...but they do get stuck from time to time ;)

the tundra buggies are modified/built by a company called 'Anything Custom' here in Winnipeg, Manitoba. Couldn't hurt to call them and get advice because Im sure they have done it
 

offroadexpeditions

New member
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Location
florida
8x8 deuce

Hi guys, I need some education here. If I add the second M35A3 steering axle with air assist and the steering system pictured below to M35A3, will I be able to use the original steering box and pump, or will I have to upgrade it, perhaps from 5 ton truck? (I will have extra steering box and pump available as well).

 
Last edited:

spicergear

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Millerstown, PA
I wouldn't want to add that extra stress of the second axle on the original box. I'd look to something like a push-pull system or at minimum 5 ton stuff...
 
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