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What size orbital valve

RobC

RobC

Well-known member
Joined
May 20, 2020
Member Number
444
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109
Loc
St. Louis Mo
Never had hydro steering before so I have no experience in what I may like or not like for the size of it. I have a 2x8 single ended ram. Looking for opinions on fast steering or slow or whatever else. Looking to buy from Rockwell off-road. They offer a lot of different ones, I’m looking at the 12.2, 15.26 and 19.22 ci ones. I think I’m doing the math right that the 12.2 would be 4.11 lock to lock, the 15.26 would be 3.3 and 19.22 would be 2.6.

Thanks
 
What are you using the rig for?

I think mine was around 3 turns lock to lock and it was decent for all around, including street.

Occasional street driving: get the 12.2ci that will be closest to a box.

Pure trail rig: get the 19.22, you will enjoy the quickness for dodging rocks.
 
Just trail rig. No street time in this piece of shit. I’d like it to be quicker on the steering but also wondered if anyone ever thought they went too quick.
 
RobC said:
Just trail rig. No street time in this piece of shit. I’d like it to be quicker on the steering but also wondered if anyone ever thought they went too quick.
Click to expand...

I remember a conversation with Jason Shererererer soon after he took his first KOH win. He said that rig had 1.5 turns lock to lock with 50* of steering :eek: apparently hauling through the desert was 2 hands death gripped on the wheel.

I think one of my combinations was under 3 turns and it was pretty nice on the trail.
 
YotaAtieToo said:
I remember a conversation with Jason Shererererer soon after he took his first KOH win. He said that rig had 1.5 turns lock to lock with 50* of steering :eek: apparently hauling through the desert was 2 hands death gripped on the wheel.

I think one of my combinations was under 3 turns and it was pretty nice on the trail.
Click to expand...

Wooo I bet that was interesting lol
 
It's a lot personal preference, but I'd also ask what you have for a pump. If you can't supply fluid to it fast enough to get it to turn, a 19 won't turn any faster than a 12, you'll be limited out on how fast you can turn the wheel. The net there is if you have pump enough for a 3 second lock to lock cycle, but a valve that can get there in one turn, you'll feel like it's glacial, where a valve that can takes three turns to get there will feel more normal.

Also, with a 2x8 single ended cylinder, I think you've got something scrambled a bit, using a 19.22 CI valve, I get 1.3 turns extend direction and 0.9 turns retract direction. That's pretty fast, I'd be looking at more like a 6-9 CI valve to use with a 2x8 depending on what you want behavior-wise.
 
ScottRS said:
It's a lot personal preference, but I'd also ask what you have for a pump. If you can't supply fluid to it fast enough to get it to turn, a 19 won't turn any faster than a 12, you'll be limited out on how fast you can turn the wheel. The net there is if you have pump enough for a 3 second lock to lock cycle, but a valve that can get there in one turn, you'll feel like it's glacial, where a valve that can takes three turns to get there will feel more normal.

Also, with a 2x8 single ended cylinder, I think you've got something scrambled a bit, using a 19.22 CI valve, I get 1.3 turns extend direction and 0.9 turns retract direction. That's pretty fast, I'd be looking at more like a 6-9 CI valve to use with a 2x8 depending on what you want behavior-wise.
Click to expand...

Yeah I wasn’t sure if I did the math right lol. I did (2x3.14)x8/19.22. Basically just tried figuring out the volume and valve output. I hadn’t thought about the flow of the pump, which btw, I’m using a 350 out of a 1980 3/4 Ton suburban, so whatever came on that.
 
Cylinder size also comes into play here too. The setup I put on my rig has a bigger diameter cylinder than the one I put on my sons rig. Same pump. Mine turns with one finger. His turns more like thick sludge.
 
rockdog57 said:
Cylinder size also comes into play here too. The setup I put on my rig has a bigger diameter cylinder than the one I put on my sons rig. Same pump. Mine turns with one finger. His turns more like thick sludge.
Click to expand...

Interesting. What size cylinders do you guys have?
 
Cylinder piston area is pi x r^2, that x h is volume. R on a 2" cylinder is 1". But retract side you subtract out the crosssectional area of the rod, which is probably 1.125 or so diameter.
Anyway, the 19ci orbital will be huge for that. I have a 2.75 DE cylinder with a 1.5 rod and a 9.7ci valve for about 3.5 turns lock to lock.
The burb pump is probably a Saginaw P pump, good in stock form for about 3.5-5gpm. A gallon is 231ci, a decent steering speed is about 1 revolution per second, you'll probably have a hard time getting faster than 2 rev/second in anything, if you can get lock to lock in under 2 seconds I'm impressed...
So at that, pi r squared h on a 2" cylinder is about 25ci, your pump moves about 13.5ci/second, so if you look at it as pump limited, bigger than 13.5ci in the valve is of little benefit. If you look at it in terms of "normal-ish" lock to lock count, most small performance cars run in the 2-2.5 turns range, full-size trucks in the 3.5-4 range, for 3ish turns you'd want 25/3 or about 8.3something on the extend side. Retract side drops about a third of your volume, so increases steering speed, and reduces power, by about that ratio.
How big a tire, how much scrub, and how heavy a rig? That all plays into sizing this right.
 
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