Alternative to Bobbing?

[eldgenb]

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.

Here is a pic of one I built, it had a 9' M105 bed on it that I deleted the wheel wells and a crane behind the cab. Your crew cab set up would be close to filling the gap that I had left. It was a great functioning truck and drag was never an issue. If you compare it to a singled out truck the proportions of the truck were much better, especially if you run 16 r 20's on it. The bobbed 5 ton in the pic belongs to John Capple and I photoshoped a front fender onto the bed, something I will do on the next one I build.

I also wanted to clarify that I think the crew cab was great, my comments were just in regards to over engineering a lift axle setup that in reality would cost you more than you would ever get back in reduced tire wear, possible failures and resulting maintenance to the assembly. I am a "keep it simple stupid" kind of guy and I don't try to reinvent the wheel unless the wheel is time tested. I really like your progress on the extended cab you do great work.

 

[Excuse Me]

Remove the rear of the tandem and put a front steering axle in its place. ??? With the proper caster shims and a spring shock on the tie rod, it will follow and track right. You can make a "lock/unlock" mechanism on the steering so you'd have a non steering axle when roading at speed or off roading, then a self steering axle when unlocked for sharp turning. If I'm not mistaken, you can make the front axle tack width gauge the same as the rear, so alignment should not be an issue.
???

 

[4x4e350]

Powerblock TV: Xtreme 4x4


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

I have used those "Ballistic Joints"(I believe that's what they are using on the ends of the links) on a 1 ton project, and I'm sure they are fine for that. I would be very skeptical using them on a deuce, let alone a 5 ton. But, then again, I tend to overdo everything.

Here is a pic of one I built, it had a 9' M105 bed on it that I deleted the wheel wells and a crane behind the cab. Your crew cab set up would be close to filling the gap that I had left. It was a great functioning truck and drag was never an issue. If you compare it to a singled out truck the proportions of the truck were much better, especially if you run 16 r 20's on it. The bobbed 5 ton in the pic belongs to John Capple and I photoshoped a front fender onto the bed, something I will do on the next one I build.

I also wanted to clarify that I think the crew cab was great, my comments were just in regards to over engineering a lift axle setup that in reality would cost you more than you would ever get back in reduced tire wear, possible failures and resulting maintenance to the assembly. I am a "keep it simple stupid" kind of guy and I don't try to reinvent the wheel unless the wheel is time tested. I really like your progress on the extended cab you do great work.

I appreciate all your comments, I didn't take any of them negatively, and thanks for posting that pic, it is very helpful. But in my own warped way, I think it looks good. If I wanted nothing but positive reinforcement, I would call Oprah, and ask what she thought about a 5 ton with a lifting axle for better maneuverability!
And thanks for the compliments.

Remove the rear of the tandem and put a front steering axle in its place. ??? With the proper caster shims and a spring shock on the tie rod, it will follow and track right. You can make a "lock/unlock" mechanism on the steering so you'd have a non steering axle when roading at speed or off roading, then a self steering axle when unlocked for sharp turning. If I'm not mistaken, you can make the front axle tack width gauge the same as the rear, so alignment should not be an issue.
???

I like this idea? Very interesting?????
Oh jeez, here I go again!!!!!

 

[Csm Davis]

Thinking of doing something along these same lines but will be going with the air bags, has anyone changed out the springs for bags and used the stock control arms?

 

[PackRatWrecker]

The steering axle idea isn't bad, until you consider that the carriers won't line up close enough, for proper driveline angle. The next consideration would be to use 3 steering axles, and lock the center axle, or configure the rear axles to countersteer, like the HET trailer. That, in itself, would work wonders toward handling, corner loading & tire scrub.

 

[CobraChris]

I may be simple minded, but couldn't you just add airbags to the center axle, leaving the stock springs in place, and air them up when turning? Think of them as helper springs. You could also keep low pressure in them all the time, as any pressure difference will allow the rear tires to have less pressure on them, and therefore, less traction. It would kind of lever the duals towards the center axle. Might even ride smoother, letting the air bag take up small bumps and what not... My thinking comes from something I did a while back....

I had a 24' enclosed trailer with linked leaf springs and dual axles. When turning tight, it used to tear up tires. So, I added some low buck air springs to the front axle, and keep some pressure in them (20-30psi), and it would turn on the front axle, and slide the rear. It also stopped tearing up the tires as much.

 

[4x4e350]

Air bags?

I am missing something here with the air bags.
If you don't air the bags up, they just go limp and have no lifting ability. So if you used air bags in the rear in place of the springs, what would lift the axle?

 

[Excuse Me]

The steering axle idea isn't bad, until you consider that the carriers won't line up close enough, for proper driveline angle. The next consideration would be to use 3 steering axles, and lock the center axle, or configure the rear axles to countersteer, like the HET trailer. That, in itself, would work wonders toward handling, corner loading & tire scrub.

I was wondering about that a bit. The housing does not care whether the tie rod is in front of back, so you can, if the amount of fabrication needed is not excessive, put the tie rod on whichever side makes for better interaxle driveline lineup. Right?,...or.......? A lot of tie rods today have some pretty interesting bends done to clear various frame and engine protrusions. Perhaps a bend or two can get the tie rod around the link arms if needed. ??

The alternative, which is very possible and for some maybe even preferable, is to have the steer housing modified to accept either both short axle shafts, or both long shafts, then flip the hub accordingly. ? I have not measured this possibility for tire tracking as most of my rockwell axle applications require custom made wheel offsets anyway.

Boyce equipment just finished a front housing length mod for me. I recieved it monday morning and will be installing in my application this week. It is an 88" king pin center measurement. I dont want to bore you with the details and hijack this thread, but it can be done and done well. I will even be using it as a front steer axle and be hauling some seriously expensive and dangerous chems. Either I'm an idiot for considering this, (quite possible) or I have a lot of faith in the military spec pieces.

It depends how far out of original the OP wishes to go with the truck, but you can go ahead and install the bobber kit on the permanent axle and increase the interaxle spread. Then install the driven pusher axle on a lift. That would really be something to see, a 5 ton with a mega spread axle setup.

If the pins on the paralell link arms are not tapered, it would be a snap to fab up some new brackets, then use air springs to ride on. Even if they are tapered, brackets are not that difficult to make. Machine out some tapered inserts and weld them into the plate brackets where needed.

As long as the lift of the pusher is not too out of line, it could be driven down the road lifted as the spread would lengthen the driveline, increasing its angle differential tolerance.

Shoot, now that I think about this, I may have to cancell my civi truck purchase for the truck/rv conversion, and go back to the military M820. I can make that thing ride like a car now that I think about this suspension setup.......

 

[Excuse Me]

I am missing something here with the air bags.
If you don't air the bags up, they just go limp and have no lifting ability. So if you used air bags in the rear in place of the springs, what would lift the axle?

I certainly cant speak for CobraChris, but if I read his idea right, he is meaning that when pressurizing the air bags, the rear axle would then be near weightless. It may skid a small bit, but the leaf springs, when pushed down in the front, would tend to lift the rear axle some.?? However, that axle is very heavy and the slack in the spring bracketry may only remove down pressure from it, but not actually do any lifting. Again, CobraChris will have to explain further as I am only guessing at what he wishes to convey.

Basically, rather than lifting an axle, push one down further.

 

[4x4e350]

I certainly cant speak for CobraChris, but if I read his idea right, he is meaning that when pressurizing the air bags, the rear axle would then be near weightless. It may skid a small bit, but the leaf springs, when pushed down in the front, would tend to lift the rear axle some.?? However, that axle is very heavy and the slack in the spring bracketry may only remove down pressure from it, but not actually do any lifting. Again, CobraChris will have to explain further as I am only guessing at what he wishes to convey.

Basically, rather than lifting an axle, push one down further.

I think you are correct (let CobraChris answer), but you would have to lift the front axle an excessive amount, to get the rear to move at all, I would think?
But the air bag idea, did give me a idea.
I could make a cam linkage, attached to the rear axle with chains, and use air bags to lift the axle. This would be about the most cost effective and simple setup, that could still use the trucks air supply. Plus, if it didn't work out as I would expect, it could easily be removed with out affecting the trucks suspension at all.

 

[CobraChris]

I certainly cant speak for CobraChris, but if I read his idea right, he is meaning that when pressurizing the air bags, the rear axle would then be near weightless. It may skid a small bit, but the leaf springs, when pushed down in the front, would tend to lift the rear axle some.?? However, that axle is very heavy and the slack in the spring bracketry may only remove down pressure from it, but not actually do any lifting. Again, CobraChris will have to explain further as I am only guessing at what he wishes to convey.

Basically, rather than lifting an axle, push one down further.

I think you got what I meant. I wish I had pics of my trailer, but then again, there is alot of difference between a 24' enclosed trailer that may weigh 6500lbs at most, and a truck that triples that. It worked on the trailer, but I was just trying to make a pivot point. I was doing landscaping out of it, and when making tight turns, it would pull the tire down to the point the sidewall would drag the ground, and even broke the bead a couple of times. My new trailer has torsen axles and 16" tires, and does not have the same problem.


However, my idea was to bascially make a pivot point. If you put more weight on the center axle than on the rear, the rear axle will slide, and the center will be the pivot point. It certainly would take a bunch of pressure to completely lift the rear axle off the ground, and I'm not sure if that would be do-able.

Just throwing out ideas! I eventualy want to build a 818 with 16's and a bed, so, it would be nice to know what works

Chris

 

[CobraChris]

But the air bag idea, did give me a idea.
I could make a cam linkage, attached to the rear axle with chains, and use air bags to lift the axle. This would be about the most cost effective and simple setup, that could still use the trucks air supply. Plus, if it didn't work out as I would expect, it could easily be removed with out affecting the trucks suspension at all.

Seems like it would take the same amount of pressure to lift one, as it would to push the other down. And the addition of a cam linkage and chains seems like it would add parts to fail.

Technically, lifting the rear axle 3" will take the same amount of force, no matter if you do it by pushing one axle down, or picking the other up. Because the axles are connected to one another with a relatively ridgid spring, equally spaced from the fulcrum, it should require the same amount of lift.


Don't get me wrong, I am not saying my idea will work, I have very little experince with these trucks. Just writing out the thoughts in my head

 

[obee1kubota]

sorry complete noob here. I have been perusing this site for 5-hrs a day for the last 3 days so please don't tell me just do a search. I am wondering if a simple bob could be done by removing the rear axle and custom building a shorter bed. If so could the ride be improved by removing a leaf or two. Many thanx

 

[kennys@wi.rr.com]

Part of what you want to do the answer is yes and the other is no. The rear axles share a leaf spring so you can't just remove an axle and have it work. You can remove the suspension and replace it with the same style they do for a normal bob job but keep the frame the original length. The bed can be shortened by removing whatever amount you need to and then weld it back together. Personally I prefer that look. It all comes down to time, money and ability.

 

[madmanvillain]

i think that the air bag on the front axle is probably the simplest and best solution. it wouldnt take much pushing the front axle down to get the rear axle up. (assuming that the suspension is symmetrical front to back) push the front down one inch the rear goes up one inch, two inch total difference.

 

[davesgmc]

ELMO is an extra long wheel base truck, I never altered the wheelbase and I dont have any problems turning it aound any where. Especailyinthe woods, I just make my own trail if i ant make the turn! lol. actually in the woods wherei HAD to manuver it around, i was going aroud the corners and around obsticles just as well as a regualr 2.5 truck.nI have not noticed any excess tire wear from driving o hard pavement at all. I wouldnt change it at all, just leave it the way it is.

 

[NSCoyote]

it actully wouldnt require that much work but heres a crude diagram on a simple system to perform what you would need to do.


create a new link set up axle to bogie so that the front and rear axles pivot on the bogie independently via the new links, on the top of that install a main bracket that will hold the suspension air bag between the link and a fixed point on the bogie hanger, and on top of the fixed point bracket would be the lift bag with the bottom of the lift bag being bolted to the fixed point and the to being bolted to a bracket going down to the link system. during main oeration the suspension bag(s) would be inflated while the lift deflated. if you want to lift the forward axle then flip switch suspension bag deflates and lift bag inflates on forward axle, flip switch back and suspension bag inflates while lift bag deflates same process for rear axle. while the plumbing for air system could be a bit challenging to get it right the actual set up would be easy to do, down side is that it would likely limit free articulation if your doing any serious off road

 

[Blind Driver]

Maybe I'm not understanding something here....

you want to lift a drive axle to save on tire wear? Air bags don't inflate quickly. When one drive comes off the ground, those tires will start to spin losing forward motion. Do the drives stay locked or is there a power divider on these trucks?

If you really want to bag it, you'll need to mount leaf springs upside down which will raise the axle, then use bags to apply weight. Use can you the control valve to rgulae how much air pressure is applied to the bags.

I think the time and money spent wont come close to helping anything. But when I buy my first truck, is getting air bagged on all corners

 

[4x4e350]

Since starting this thread a year ago, I have since had some time on the road with the truck. Plus I singled it out with 14 x 20's.
I really haven't seen a need to increase the turning ease or radius of the truck, so far it has been able to do all I need it too, in the area required.
My initial reasoning to lift one of the axles, was to eliminate the rear tire scrubbing while low speed manuevering. But as stated, that really doesn't seem to be a problem.

 

[jesusgatos]

...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?

Planning on doing something sort of like this on mah deuce.

I have used those "Ballistic Joints"...

Wouldn't use a Ballistic ANYTHING. These are what you'd want to use.