Dez racing with full hydro steering?

scottm

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I know you're not supposed to. The mechanical connection of a steering gear keeps the wheels tracking straight at high speed, plus allows some amount of steering in case you lose the power assist. But they are also heavy, especially with a big swingset and a ram assist, and wear out quickly from the high loads. I have considered a tt power rack, but it would be very difficult to connect the steering column without a chain and sprockets to the input, since it would be blocked by the oil pan.

So I am starting to wonder about full hydraulic. On the plus side, my truck has 9 degrees of caster for stable tracking. The ram mount would add a lot of stiffness to the chassis by connecting between the frame rails. And with the rate ultra 4 has developed, does anyone know if the down sides of full hydro have been overcome or minimized?
 

*TRD*

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The really fast U4 guys are running IFS almost entirely for the improved steering at speed. Being able to run a rack and pinion is a big chunk of that. They say full hydro doesn't give you enough feedback. Maybe one of them will chime in with more info.
 

Chris_Wilson

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I ran full hydro on a boat and liked the feedback but the steering wheel would not stay centered. I think you would have the same issue on a truck, the toe setting would drift and get to a point where the truck is not driveable. So I think you have to have a mechanical link between the front tires for any type of full hydro steering. And if you are running I beams then that means swing sets so may as well just go full mechanical to the steering box. Has anyone ever ran full hydro steering without a mechanical steering link between the two front wheels?
 

ghostwhite

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I ran full hydro on a boat and liked the feedback but the steering wheel would not stay centered. I think you would have the same issue on a truck, the toe setting would drift and get to a point where the truck is not driveable. So I think you have to have a mechanical link between the front tires for any type of full hydro steering. And if you are running I beams then that means swing sets so may as well just go full mechanical to the steering box. Has anyone ever ran full hydro steering without a mechanical steering link between the two front wheels?
I believe he means without a mechanical link from the steering wheel to the tires. Most full hydro steering setups use a single double-ended cylinder to connect the knuckles together.

 

Chris Tobin

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I personally would not want to rely on hydro ONLY for anything high speed at all!!!

I was prerunning with a group once and the driver was not downshifting to keep the RPMs up heading into the turns and he partially blew a couple tight low speed turns because the power steering was not assisting enough. If you have full hydro and the engine dies you are left without steering completely. That could be scary!!!
 

JEFFRPM

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At speed such as a lake bed or even 55mph on pavement you can't drive it because the Charlyn control valve is constantly "adjusting" flow to the ram, even if you hold the wheel dead still it's sending fluid to one side or the other of the Ram in very slight amounts and it's hard to drive straight, everything else thier a breeze to drive and very comfortable oh yea they don't return to center you have to do it like a forklift.
 

lllux

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I know this is an old thread but it comes up in Google so I'd like to correct some of the bad information.

You can still steer if you lose power or your pump fails with full hydro steering. A decent amount of orbital valves use check valves that turn it into a manual pump. It will be very difficult to steer but you can still steer.


There are also load reactive valves that return to center if your steering geometry is setup correctly. These are the way to go if you must run full hydro and do go fast stuff.
 

michael.gonzalez

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This is a good thread about a 4500 build


"I know there is both a go fast steering thread and a recent thread inquiring about our steering. We have been hounded about our secret steering all this year so I am about to drop the secret, but first. In previous years racing we were breaking 1 to 2 steering boxes and pumps per race with a traditional ram assist steering setup. After racing a season with both Ultra4/DirtRiot and getting on the podium 6 times in 8 races. This year we did all that on the same parts we started the year with at KOH. "
 

isdtbower

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Two Miller Motorsports Rigs found their way into overall and 3rd at KOH 2020. Straight axle and hydro steering. Eric has worked hard with the info on that thread and pump efficiency. The quickness of the steering in the rocks was easy to pick-up. Another SA didn't make the list for several positions so it is not a slam dunk deal apparently. But the tech is out there.
 

J Burleson

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My Bunderson class 1 is full hydro. With the car off, I can turn the wheels as easily(hard) as any box or rack setup. The "return to center" in regards to tracking straight is a product of geometry, not steering system type. But the steering wheel is not always in the same place, so if you had a wheel with a center line on it, it will wander around. Kevin and Jeff Howe have both said they designed the system in 2000 because big racks werent as available at that point. I dont have a lot of time in the car yet, but it feels pretty good, and Jeff Howe said the system was designed to actually provide some feedback at high speeds. I do believe that Pat Dean's Bunderson that was originally built full hydro has been converted to a rack.
 

lllux

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My Bunderson class 1 is full hydro. With the car off, I can turn the wheels as easily(hard) as any box or rack setup. The "return to center" in regards to tracking straight is a product of geometry, not steering system type. But the steering wheel is not always in the same place, so if you had a wheel with a center line on it, it will wander around. Kevin and Jeff Howe have both said they designed the system in 2000 because big racks werent as available at that point. I dont have a lot of time in the car yet, but it feels pretty good, and Jeff Howe said the system was designed to actually provide some feedback at high speeds. I do believe that Pat Dean's Bunderson that was originally built full hydro has been converted to a rack.
Are you running a single our double ended ram? Load reactive or non reactive valve?
 

Fifty

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The drive by wiring systems in road cars will at the very least have a clutch system that locks during electronic failure (so it fails into a mechanical state).
Many have a constant mechanical but use an electronic motor to boost the rack.
I don’t think there are any dot approved full drive by wire with out mechanical back up.
 

lllux

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The drive by wiring systems in road cars will at the very least have a clutch system that locks during electronic failure (so it fails into a mechanical state).
Many have a constant mechanical but use an electronic motor to boost the rack.
I don’t think there are any dot approved full drive by wire with out mechanical back up.
Yeah I've never seen a 100% electro with no mech linkage. It's usually electric assist.

I would love to see one of these full electric systems and what kind of safety fall back system is in place.
 
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