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Old 03-20-2007, 07:36 PM   #1 (permalink)
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Fairly well researched hydro steering question

Problem: It takes too many turns to go from lock to lock.

System details:
Steeting control unit:
Charlynn 2415027-002
Open center non reactive 4.5 cu in/rev Series 4 with Power Beyond
rated 4 gpm flow, and 1800psi maximum system pressure
Hydraulic Cylinder:
Cheif ram/cylinder 2" bore 8" stroke
Pump:
Stock jeep PS pump capable of 2.4 - 2.8 gpm and 1350-1450 psi.
Other notes:
In addition to the integrated reservoir there is another reservoir and a cooler in the PS system. I'd guess it hold about 5 quarts in the system.
37" krawlers
Question: According to the math it takes 5.6/4 turns lock-to-lock. If I move to a 6.0 CI control unit like this one it should take 4.2/3 turns lock to lock. If I go with a 7.5 CI control unit like this one it will take 3.12/2.4 turns lock to lock.

Aside from the change in turns, what will the impact be? Will turning the steering wheel be too hard? If so, what fixes that, a new pump? Which would you choose?
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Old 03-20-2007, 07:55 PM   #2 (permalink)
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should just be the maximum speed that you can turn the wheel effected
limited by pump volume
try it and let me know
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Old 03-20-2007, 08:17 PM   #3 (permalink)
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When you say "it takes too many turns" do you mean on paper, or in practice?

First - your pump is undersized - whether you change your steering unit or not the pump needs to be upgraded.

If you go to a steering unit with greater cu in/rev you will certainly need a pump capable of greater flow. If not, you will steer and then lose all power until the pump can catch up.
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Old 03-20-2007, 08:46 PM   #4 (permalink)
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Quote:
Originally Posted by BillaVista View Post
When you say "it takes too many turns" do you mean on paper, or in practice?
I mean in practice. For slow stuff it's just an inconvenience but sometimes when you need to change direction without losing momentum it actually has an impact on where I can go.

I think I have my answer. Call station and get a new pump/control unit. Doing it halfway will only cause different problems. I guess I'll start saving for it now, unless I break something else at Harlan at the end of the month.
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Old 03-20-2007, 09:33 PM   #5 (permalink)
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stock pump has always worked fine for me.

save a few bucks and go to motion industries and get a larger droler plate
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Old 03-20-2007, 09:53 PM   #6 (permalink)
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If you swap to a larger valve, you will get fewer turns lock to lock.
If your pump can't keep up, you'll only be able to spin the wheel "so fast".
Swapping to a higher flow pump will help that.

If you can only spin the wheel "so fast" now, *and* it's too many turns lock to lock, the time lock to lock won't change with a larger valve... only how many times your hand passes 12-o-clock on the way from lock to lock.

The only thing that will make it faster (in time, not turns) lock to lock, is a higher flow pump.

Make sense?
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Old 03-20-2007, 11:40 PM   #7 (permalink)
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Originally Posted by heep86 View Post
stock pump has always worked fine for me.

save a few bucks and go to motion industries and get a larger droler plate
links?
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Old 03-21-2007, 12:31 AM   #8 (permalink)
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better think about power off steering....the more turns the easier it is to steer when your dead....
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Old 03-21-2007, 12:50 AM   #9 (permalink)
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I am supprised no one has said it, but the problem is the orbital. You need bigger one. Station sells almost all 9.7 orbitals, I special ordered a 12.

The bigger orbital will make it much less turns lock to lock, like somehwere close to half of what you got now...
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Old 03-21-2007, 05:52 AM   #10 (permalink)
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IMO, 9.7 is too big for a 2" ram. 2.5" (with 1.5" shaft), sure.
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Old 03-21-2007, 06:04 AM   #11 (permalink)
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Quote:
Originally Posted by [email protected] View Post
If you swap to a larger valve, you will get fewer turns lock to lock.
If your pump can't keep up, you'll only be able to spin the wheel "so fast".
Swapping to a higher flow pump will help that.

If you can only spin the wheel "so fast" now, *and* it's too many turns lock to lock, the time lock to lock won't change with a larger valve... only how many times your hand passes 12-o-clock on the way from lock to lock.

The only thing that will make it faster (in time, not turns) lock to lock, is a higher flow pump.

Make sense?
I had to read it a few times but I understand now. I can actually turn the wheel pretty fast now, in terms of RPM. It's just that even though I'm spinning as fast as I can sometimes it just takes too long to get 5 full revolutions on those obstacles where you "aim for this tree, hit the throttle, then turn right before you get to it."

So, the impact of a higher CI steering control unit is going to be a lower max RPM of the steering wheel, not more required strength to turn it. It sounds like I should just buy the unit and see how it works. If I need a new pump then the steering control unit isn't wasted money, I needed it anyway. And the impact of having a pump that's too weak isn't that bad, it's just a low "steering wheel RPM" which can't be any worse than my current situation where the RPM is held back by my ability to turn the wheel fast enough.

BTW, thanks for the replies everybody. This has been really helpful.
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Old 03-21-2007, 06:08 AM   #12 (permalink)
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Quote:
Originally Posted by X-Rated View Post
I am supprised no one has said it, but the problem is the orbital. <snip>
The bigger orbital will make it much less turns lock to lock, like somehwere close to half of what you got now...
Actually a few guys have said it. We're just saying "more cubic inches in the steering control unit" instead of "bigger orbital".

I call it the "billavista effect". He's teaching us all the proper vocabulary. Soon I'll be running around taking about Double-Cardan-style universal joint driveshafts.
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