Alternative to Bobbing?

[4x4e350]

I've already decided I'm not going to eliminate a rear axle on my M818, I like the look and setup of the dual drive rear axles. But, I would like to eliminate as much of the turning resistance you get from the dual rear setup.
Being I've never driven a 6x6 around, like I plan on doing with my 5 ton, I really am not sure the resistance is really that much of a problem, or inconvenience.
I have turned my 5 ton into a crew cab, will have about a 8 ft long bed on the back, and have already removed the 5th wheel, so I really don't plan on carrying much weight.
My idea is to remove some of the rear spring pack, just to soften up the ride a little, I don't expect much. But then I was thinking, why couldn't I add a winch in the back bed, which would be attached on each side of the center axle, which could raise the center axle a small amount to get the tires off the ground, to allow better turning radius, and maneuverability, with less tire wear? Much the same rock crawlers do to their front axles for better approach angles.
Raising the center axle, would actually push the rear axle down with the rotating spring pack, so I would think only a few inches of lifting would get the center axle lifted enough. And I wouldn't think the drive shaft angles would be too excessive.
Does anyone see any issues with this, if it would even give an advantage?

 

[OutsideFamily]

I think that is a very clever idea. One thought, you might want to lift the REAR axle up so that the effective wheelbase is shorter. This will help with tight turns, but just remember you have a longer rear "overhang".

 

[4x4e350]

I think that is a very clever idea. One thought, you might want to lift the REAR axle up so that the effective wheelbase is shorter. This will help with tight turns, but just remember you have a longer rear "overhang".

Thanks for the response.
I was thinking raising the center axle may be more of an advantage, if towing a trailer, then backing it up. I plan on keeping the pintle hitch, and towing a camper with flat bed, nothing very heavy, but I could see the dual rear axles being a problem while backing with a trailer in somewhat tight spaces. Just a thought, the weight distribution might be better raising the center axle

 

[mudguppy]

my thoughts:

• it will take much more 'effort' with regard to winch pulling power to lift the rear axle than it will the center axle, especially if there is a trailer tongue load on the rear.
• however, lifting the center axle for tighter maneuvering may negate any effects. the reason is that, as already noted, you are essentially making the wheelbase longer by raising the center axle. in fact, it's possible that raising the center axle will create a larger turning radius than leaving both axles on the ground sharing the weight and amount of slip.

therefore, i think you'd be better off lifting the rear axle, thus shortening your effective wheelbase ~30". however design and construction of the winch / lifting device would be that much more critical due to the forces involved.

rather than the complexity of a winch, why not two hydraulic cylinders mounted horizontally inside of the frame channel; to lift, retract the cylinders which pull chains/cable over pulley blocks to lift the rear axle?

but if you used a winch system then you have a winch to use in extraction ops...

 

[4x4e350]

my thoughts:

• it will take much more 'effort' with regard to winch pulling power to lift the rear axle than it will the center axle, especially if there is a trailer tongue load on the rear.
• however, lifting the center axle for tighter maneuvering may negate any effects. the reason is that, as already noted, you are essentially making the wheelbase longer by raising the center axle. in fact, it's possible that raising the center axle will create a larger turning radius than leaving both axles on the ground sharing the weight and amount of slip.

therefore, i think you'd be better off lifting the rear axle, thus shortening your effective wheelbase ~30". however design and construction of the winch / lifting device would be that much more critical due to the forces involved.

rather than the complexity of a winch, why not two hydraulic cylinders mounted horizontally inside of the frame channel; to lift, retract the cylinders which pull chains/cable over pulley blocks to lift the rear axle?

but if you used a winch system then you have a winch to use in extraction ops...

All good points. I didn't think of that, with both axles on the ground, effectively the turning center line is between both axles, makes sense to me now. I guess I was more thinking of a plowing affect, but that would probably be non-existent with the load I plan on carrying.
I like the idea of a winch in the back bed, I could use as a dual purpose, but the safety factor and cost may be a problem.
Rather than having to add a hydraulic system, I wonder if air cylinders could be used like you said? I like the idea of everything being below the bed with that type of setup.

 

[donttreadonmebmg]

4x4e350 said "I have turned my 5 ton into a crew cab"

Do you have any pics of the process?

I would love to do the same thing to mine, crew cab w/8 foot bed.

 

[4x4e350]

4x4e350 said "I have turned my 5 ton into a crew cab"

Do you have any pics of the process?

I would love to do the same thing to mine, crew cab w/8 foot bed.

http://www.steelsoldiers.com/5-ton-mods-hot-rodding/61640-extended-cab-4-door.html

This is my truck, I haven't made the bed yet, but to have a 8 ft bed, and still retain the spare carrier/tool box, I had to shorten the rear doors 12".

 

[kennys@wi.rr.com]

If you are looking for more of a smooth ride that load capacity why not consider a dual 4 link set up that uses air bags? If you have already converted the truck to a crew cab you must have some metal working skill so figuring out the mechanics of a 4 link is all you need, then get to work and do it. Then you can set the system to inflate or deflate whatever axle you choose at the time. There are many benefits to doing this.

Just my thoughts.

 

[4x4e350]

If you are looking for more of a smooth ride that load capacity why not consider a dual 4 link set up that uses air bags? If you have already converted the truck to a crew cab you must have some metal working skill so figuring out the mechanics of a 4 link is all you need, then get to work and do it. Then you can set the system to inflate or deflate whatever axle you choose at the time. There are many benefits to doing this.

Just my thoughts.

I'm not looking for a smoother ride, I just will remove some of the spring pack, to maybe benefit a little, if not, that is OK.
I am really looking for the benefits of a single rear axle, as far as maneuverability and handling tighter turns. I would also like to eliminate any added tire wear, due to the skidding of the rear tires during sharp turns on hard surfaces.

 

[drgreg]

I would agree with Kenny. If you make a system that just lifts one of the existing axles, you are looking at a massive amount of force. I think your first bump would see twisted metal and parts flying.
Tag axles, used on dump trucks, have many of the answers you are looking for.

 

[m38mike]

I would recommend using an electric hoist instead of a winch to lift the axle. Hoists usually have a brake/catch/cog that allows them to hold the weight. Winches usually don't. And you may want to have a safety chain set up to hold the axle up so the winch/hoist/hydrolic cylinder don't carry the weight all the time, especially when your travelling.

 

[4x4e350]

Thanks for the replies everyone.
I think I need to clarify what I would be using this for. I would always have both axles on the ground, except when turning sharply on hard surfaces, and probably backing up. So when the axle is lifted, I would never be moving very fast. For safety purposes, I would even have a warning light come on, when the axle would be lifted, so I wouldn't be moving very quickly.
I really just want to gain the slow moving maneuvering ability, that a bobbed truck would have over a 6x6. If there even is an advantage.

 

[kennys@wi.rr.com]

Again I think the best way to acheive this is to use a tag axle type set up. You choose the axle to lift depending on the situation and you do it all from in the cab. Use lighted switches so when the axle is up the light is on. Real tight turns lift the back axle and watch for swing, not so tight lift the middle and have more control. Have heavy stuff to load, lift them both and drop the height of the deck. Use that option with low obstacles as well.

I like the idea of using the airbags, so I'm sure there is a major draw back I am unaware of.

 

[kennys@wi.rr.com]

I would agree with Kenny.QUOTE]


I think this is a sign of the comming apocalypse!!!

 

[4x4e350]

Again I think the best way to acheive this is to use a tag axle type set up. You choose the axle to lift depending on the situation and you do it all from in the cab. Use lighted switches so when the axle is up the light is on. Real tight turns lift the back axle and watch for swing, not so tight lift the middle and have more control. Have heavy stuff to load, lift them both and drop the height of the deck. Use that option with low obstacles as well.

I like the idea of using the airbags, so I'm sure there is a major draw back I am unaware of.

Besides complexity, I'm sure the airbags would be the best option.
But, I really don't want to get into a complete custom rear suspension on this size of a truck, I would like to keep everything as stock as possible, for parts replacement availability if need be. If I keep the suspension mostly stock, which is a proven bullet proof design, then the winch, lifting, pulling, prying, etc. device fails, I just can't lift one axle, and I drive home to fix it, no big deal.
I've done 4 link suspensions on smaller buggies, and I just don't want to get into that type of suspension on a 5 ton truck, so my goal would be simplicity also.

 

[Stalwart]

I assume than that the 5 ton doesn't have an inter-axle differential . . . if it does, then you're sunk unless you lock it. BTW, as noted before, you must lift the rear axle or your turning radius will be worse.

 

[drgreg]

I would agree with Kenny.QUOTE]


I think this is a sign of the comming apocalypse!!!

Even a blind squirl finds a nut sometime.

 

[eldgenb]

it sounds like to want to have one's cake and eat it too, either you bob it to save tire sear, better ride, better turning radius or you don't and deal with the repercussions either way, With surplus tires selling anywhere from 200 to 350 a piece I don't think tire wear (unless its a daily driver) would be worth the extra engineering and steps needed to complete a basic maneuver. With an 8 ft bed it would think it would look goofy with the tandems, believe me I built one and did not like the looks at all, not to mention you will make your passengers piss blood. If you truly want the best of both worlds bob it and use airbags with a suspension setup like justin wehring is using out of a freightliner. Otherwise leave it alone. just my .02

 

[4x4e350]

it sounds like to want to have one's cake and eat it too, either you bob it to save tire sear, better ride, better turning radius or you don't and deal with the repercussions either way, With surplus tires selling anywhere from 200 to 350 a piece I don't think tire wear (unless its a daily driver) would be worth the extra engineering and steps needed to complete a basic maneuver. With an 8 ft bed it would think it would look goofy with the tandems, believe me I built one and did not like the looks at all, not to mention you will make your passengers piss blood. If you truly want the best of both worlds bob it and use airbags with a suspension setup like justin wehring is using out of a freightliner. Otherwise leave it alone. just my .02

Well yeah, I want my cake and eat it too, don't we all.
It's too late as far as the 8 ft bed, I already did the crew cab, and can't turn back now, I'm not convinced yet that it will look goofy, but it has crossed my mind. I will have to see how it looks with tires running the entire length of the bed. I don't know, I keep convincing my self it may actually look cool?????
I will have to see how it drives and looks I guess, and make the necessary changes from there. I just don't want to bob the truck, because I've always wanted two rear axles, ever since seeing the old Mercedes cars from WW II.

 

[Gunnar1071]

Besides complexity, I'm sure the airbags would be the best option.
But, I really don't want to get into a complete custom rear suspension on this size of a truck, I would like to keep everything as stock as possible, for parts replacement availability if need be. If I keep the suspension mostly stock, which is a proven bullet proof design, then the winch, lifting, pulling, prying, etc. device fails, I just can't lift one axle, and I drive home to fix it, no big deal.
I've done 4 link suspensions on smaller buggies, and I just don't want to get into that type of suspension on a 5 ton truck, so my goal would be simplicity also.

Powerblock TV: Xtreme 4x4


They cover doing a 4 link with airbags, looks like a 1 day project.