fail-proofing full hydro steering

[m16ty]

I'm still a little skeptical of how well hydro will work at hwy speeds, but hey, if you figure out a way to make it work satisfactory I may be interested in doing this myself.

A full hydro system should be cheaper than the other power steering options for the deuce because the parts can be found cheap from old constuction and farm equipment.

 

[Wrench Wench]

For the longest time, I thought the Baby HEMMT project on here was just adding a second front steering axle to a traditional 6x6x2, to make it an 8x8x4, and I was excited to see how he would link the steering between the two front axles to keep from squealing tires or snapping linkages and was expecting to see a full hydraulic steering system on both axles with a simple proportioning valve between the two.

Imagine my dismay when the Baby HEMMT was just a teeny little 4x4.

 

[jesusgatos]

I'm still a little skeptical of how well hydro will work at hwy speeds, but hey, if you figure out a way to make it work satisfactory I may be interested in doing this myself.

A full hydro system should be cheaper than the other power steering options for the deuce because the parts can be found cheap from old constuction and farm equipment.

I think that's precisely why so many full-hydro rigs are NOT safe. They're just put together using whatever components the builder happens to find. Cheaper, sure, and fine for a trail rig. But I would budget at least $1500-2000 for a quality steering system like we're talking about.

 

[dozer1]

Sorry, I cannot get passed the the part that you think a drag link is a big limiting factor on your suspension travel of your RV. Look at most of these bobbers with big tires and other deuces and 5 tons with large tires and for that matter stock tires. They mud bog from time to time, trail ride, on and on. I just dont see them coming out and crying about that darn draglink messing up their day. Now here you are with a deuce rv conversion that is supposed to have so much suspension travel (only thing close is rock crawlers) that you need to eliminate the drag link.
This thread has been great as far as getting people to think and create and I have to give it credit for that. As far as being remotely practical for a deuce RV conversion, NOT!

 

[jesusgatos]

Forget the fact that I'm building a motorhome for a moment, and please, don't use the word 'practical'. It's not always going to be used a motorhome. I'm going to build a low-profile flatbed sandwiched between the frame and the box, so that I can drop the box (like an over-sized slide-in camper). I'm going to do the same thing with my enclosed trailer (remove the enclosure and use it as a shed on the ground). I'll do this occasionally, when I'm setting up camp somewhere for an extended period of time. It will be nice to have a house on the ground, and a regular truck to drive around. And even when it IS being used as a motorhome, the modifications I'm planning on making will only enhance the performance and comfort. If you click on the link in my signature line and take a look at some of the other vehicles I've built, that might give you some further insight into where I'm coming from.

Yes, the suspension is going to be reworked to resemble something more like what you'd expect to see on a competition-level rock crawler. I'm also going to be adding an anti-sway bar that uses hydraulic rams as end-links, so that I'll be able to turn the anti-sway bar on/off on the fly. But none of this has anything to do with the questions that I'm asking here/now. I understand why you might be curious, and I certainly don't mind talking about my plans, but I do take issue with the fact that it sounds like you're telling me that I don't know what I'm talking about. The fact is, I don't think many people have explored the REAL potential of these vehicles, when it comes to modifying them for off-road performance.

 

[m16ty]

I think that's precisely why so many full-hydro rigs are NOT safe. They're just put together using whatever components the builder happens to find. Cheaper, sure, and fine for a trail rig. But I would budget at least $1500-2000 for a quality steering system like we're talking about.

What does a hwy safe steering system consist of? I've worked with hydraulics for a long time and am very familiar with hyd steering as used on off road equipment.

The way I see it, you have 4 basic components. You have a hyd pump, a hand pump, a steering cylinder, and the hoses that tie it all together. There's not much to upgrade on the hyd pump, as long as it pumps enough volume and pressure you're good to go. There's not much to upgrade on a cylinder, it just goes in and out. There's not much to upgrade on the hoses, as long as they don't leak you're good. That leaves the hand pump. Do they make a hand pump that has road feel and return to center or do you add something else in the system to accomplish this?

I'm not trying to be confrontational, I'm just trying to learn.

 

[jesusgatos]

Take a look here to get an idea of how these components are priced. Yes, they make steering units that have return-to-center characteristics. They're called load-reactive (examples here). The budget I threw out there is generous, but it all adds up. Pumps, rams, steering unit, steering column, steering wheel, hoses, fittings, reservoir, cooler, filter/s, tie-rod/s & tie-rod ends, hardware, etc. But I guess you could probably get it done for under $1000 if you already have the 5-ton MF power-steering pump and saved money everywhere you could (do your own fabrication work & installation) without skimping on anything important.

 

[jesusgatos]

I'm not trying to be confrontational, I'm just trying to learn.

I'm really not trying to present myself as any type of expert on this subject. I'm posting about this project because I have questions, and I'm asking for help from those that might have more experience working with hydraulic components and systems.

 

[gimpyrobb]

I hate to muddy up the thread, but a drop side bed could work good for your removable box idea. The 109 box will not fit in a regular bed, but could slide onto a drop side bed with the sides removed.

 

[jesusgatos]

I hate to muddy up the thread, but a drop side bed could work good for your removable box idea. The 109 box will not fit in a regular bed, but could slide onto a drop side bed with the sides removed.

That's a GREAT idea. Can a moderator please clip this and move it to a new thread so we can continue this discussion?

 

[m16ty]

While searching I ran across this. LiftLaws.com - Is Full Hydro Steering Street Legal?

Looks like in TN hydro would be illegal.

 

[jesusgatos]

Thanks for sharing. That's really interesting, and I'm surprised (I've only looked at the federal vehicle codes and the state vehicle codes for state I've lived in). While I might not be able to register a vehicle with full-hydro in TN, but I don't think they can ticket me for driving my vehicle in/through their state, since it's NOT prohibited/illegal in the state where it's registered.

 

[jesusgatos]

In case anyone wants to look into it, the places where I've found the most helpful guidelines regarding steering requirements has been in the guidelines for special construction vehicles. They vary from state-to-state, but they usually spell out what kind of performance is expected of a steering system. There are similar requirements for things like braking performance, chassis dimensions (ground clearance, bumper heights, etc.), etc.

 

[Wrench Wench]

Been watching through the Xtreme 4x4 eps this season and at about 12:50 here Powerblock TV: Xtreme 4x4 your friend and mine, Ian, dropped a four wheel hydraulic steer into the Budget Buggy, but then, it's a rock crawler powered by a Honda Acura engine.

 

[Coldfusion21]

I think the engine driven pump IS your most likely single point of failure.

It's not because of mechanical failure of the pump, but the engine stoping while in motion. Engine failure, stalling or simply running out of fuel will kill the engine and you're toast!

A hydraulic accumulator with a low pressure warning system, a hydro version of the brake air reservoir system that would give you a few more turns before you're out of juice, could be a possibility but better yet an electrically driven hydo pump as a backup.

I've read on here about the hydraulic powered brake systems and i think one of those factory systems (hydroboost?) actually has a backup system powered by an electric hydraulic pump. Granted this doesnt get past the hoses bursting (in my mind the most likely failure point) but obviously the OEM thought this was a good idea.

Sounds like an awesome project and you have a great attitude towards it.

 

[jesusgatos]

That's a good thought, as far as taking a look into the hydraboost setups. Thanks for the suggestion. I'll see what I can dig-up.

 

[jesusgatos]

Got Mah Deuce pretty well stripped down. Took the old cab off today, and I'm getting ready to pull the engine. Removed the pitman arm so I can take the steering box out, and took a few measurements. I would have to take the leafsprings apart and cycle the suspension and steering to do this accurately, but I just wanted to get some rough numbers to support my position - that the stock drag-link is a major limitation when it comes to modifying the front suspension for better off-road performance.

The tierod-end at the knuckle is really the limiting factor, so that's what I focused on. First I made sure that the front wheels were pointed straight ahead. Then I removed the pitman arm from the steering box, and let the drag-link drop. Making sure that the drag-link was still aligned with the steering box when viewed from above, I made a note of the distance from the bottom of the framerail to the center of the tie-rod end (the one that's connected to the pitman arm). Then I lifted the drag-link up until the tierod-end at the knuckle made me stop, and making sure that the drag link was still aligned with the steering box, I made another measurement. The distance between those two measurements was only 9.5".

What this means is that in a best case scenario, the stock drag-link might allow for up to 9.5" of vertical suspension travel. But the tierod-end at the knuckle isn't anywhere close to binding when the suspension is at full compression, probably because it has to allow for articulation and steering. Depending on how much the front bumpstops actually compress, it looks like that eats up about 2.5" right there. And we can't actually let that tie-rod end bind when the suspension reaches full extension, because that could obviously cause that tierod-end to fail. So that leaves us with less than 7" of suspension travel. I'm talking about vertical wheel travel. Straight up and down. Not enough. Not for me.

The other problem with the stock steering arrangement is the relationship of the drag-link to the leafsprings. Specifically, I'm talking about the length of the drag-link, compared to the length of the front half of the front leafsprings, when looking at the vehicle from the driver's-side. Ideally, they should be close to the same length, and close to parallel. But the stock drag-link is only about 16.5" long, while the front half of the leafsprings is something like 24" long. This creates, and exaggerates, bump-steer.

So it's a matter of quantity AND quality. I could make some adjustments to the steering linkage, like tweaking the tie-rod to allow for more droop-travel. I'm sure I could get somewhere close to 8-8.5" by modifying the stock setup, but I think that's about the limit when it comes to what a person can do with the stock steering linkage. And I could push the steering box forward in order to lengthen the drag-link, which would help to reduce bump-steer. But we would quickly run into clearance issues, and the pitman arm and drag-link would be a lot more vulnerable. I'm guessing that's why the steering geometry is the way it is.

I'm sure that the engineers that designed these vehicles knew all about the compromises they were making, and I think they did a **** fine job. But I'm looking to go beyond their original intent, and improve on things a bit. Switching over to a fully hydraulic steering system means that the steering will never restrict the suspension in any way, and it will also virtually eliminate bump-steer, AND make Mah Deuce easier and more enjoyable to drive on/off-road. I hope this helps to clarify things for those of you that are questioning my intentions (and maybe my sanity).

 

[mikew]

Maybe I missed it, but what other suspension changes you're making?

I mean; I assume you're modifying the springs or something to allow more travel, or are you only changing the steering so that the drag link doesn't limit travel?

On another note: the "Hydraboost" brake master cylinder has a built in accumulator and the "Hydroboost" typically has a built in, electric-driven, backup hydro pump.

 

[jesusgatos]

I'd rather not share my plans for the suspension just yet, as I haven't put a whole lot of thought into that part of the project. I've just got too many more pressing concerns.

Thanks for adding to the info about the hydraboost setup. I read about someone converting to hydraboost on here, and have been meaning to go back and re-read it. Seemed like a great way to get dual-circuit brakes, and was something that I was interested in learning more about. Just reluctant to get too many projects going at once. But this is probably a good time to figure out whether hydraboost is something that I should incorporate into my plans as far as the hydraulic system goes.

 

[jesusgatos]

Took me a few minutes to find the thread I was thinking of, but here it is, in case anybody else is interested.