Outer Limits 4x4 Board

I have just finished setting up full hydraulic steering in my car with a single ended ram, factory discovery v8 power steer pump and forklift orbital valve. Hoses are 3/8 (10mm). I am running on hydraulic oil, Hyspin 46. (should i have used ATF?)

1st problem is that the steering is hard and slow to turn, even at 3000rpm. Is the pump too small? (i know others are using the same setup)

The 2nd is that the steering wheel doesn't end up straight ahead again when you go lock to lock. Is this due to the single ended ram or is there an air lock?


Andy

Slow steering can be caused by the pump not being up to the task but the rover pump usually works ok. Also there are different size orbital valves with different flow rates and this will make a huge difference to the speed they turn at.

Thanks Tony, what were the reasons that Adrians buggy had a bigger pump?

There are 2 screw adjusters on the orbital, one is large on the top above the splined input shaft with a hex cover and the other is an adjustable jet located in the side of one of the ports. I'll have a play with these next.

Andy

Andy,

Like Tony said there are several reasons for a slow wheel response. The pump may not have enough pressure or volume. I've only seen this a couple of times but your suction line to your pump maybe to small or collapsing starving the pump. The suction line could be to long causing the pump to cavitate. The fluid inside of the reservoir maybe swirling/vortex and letting air into the suction line that can cause cavitation in the pump. Is the pump whining while you turn the wheel. If so it could be letting air in or you could still have air in the system. I don't think you want to use ATF. Another thing you may run into is to much heat. The more restriction you have in the system the more heat your going to build up. If you have this problem later even with a cooler bump the return line up to the next size. I hope some of this helps.

Jason

Hay man, had the same prob with a Rangi hydro assist we just did. Scrap the pump and replace with a saganaw pump (they are on everything from holdens, fords ect ect). Also bump the return line size up and get rid of any restrictions. If you want the most pressure from a saganaw pump get a Rolls Royce saganaw pump (sound $$$ but not).
Cheezy

I run hydro assist on a 94 lux with standard pump, been on about 6 months turns 37's lock to lock no worrys, have got a sag pump to go on tho.

Hey cheezy do u make a pump bracket to suit a late model dunnydore pump to a 3L??


sorry for the hyjack

Thanks for the replys.

The return line is 5/8" and the suction line is 1/2", which is standard rover sizes however they are shorter in length than stock. I am so far convinced it is the valve, i'll be pulling it out tomorrow and taking it to a hydro specialist.

If it does end up being the pump, do vt v6 commodores have saginaw pumps? do you keep the stock commo pulley size?




Andy

Dont worry about the valve...it will be the pump. it wont have enough flow and when you start to drive it off road it probably wont have enough pressure either.

If the pump whines then start looking at the resevoir and suction lines.

Search on pirate in the rover section...there are some good threads on how to boost the pressure and flow rate of rover pumps, basically just a matter or adding/removing shims and drilling the pump outlet bigger.

Sam

The steering wheel not returing to centre is because of the single ended ram. You will have to go to a two ram setup or a double ended ram so that the setup uses equal volumes to go left and right.

Sam

tanks sam. i found it.

http://www.pirate4x4.com/forum/showthre ... ump+5%2F32

will have a crack at this today.



Andy

So is a stock standard VR power steer pump up to the task of full hydro with a double ended ram?
Or will I need to mod the pump or fit something heavier duty?
Cheers
Paul.

ausyota wrote:So is a stock standard VR power steer pump up to the task of full hydro with a double ended ram?
Or will I need to mod the pump or fit something heavier duty?
Cheers
Paul.

From what info I have come up with it is, mine is fine with my standard pump, but I am going to fit a vr pump as alot of guys reckon they are far better. And reading the specs on both, the vr has more volume and pressure. If you are keen you can mod the vr pump but you may loose relaibility.

i have done the pump mods above and wound the flow screw on the orbital all the way in and backed it off 2 rotations as advised by a hydro guru (it was origionally 6 rotations all the way out). the steering is quicker, but not like the origional power steer like i hoped. The pump is screeching a bit when i rev it and go lock to lock, so it may be sucking air. Will make a bigger tank this arvo. Starting to think i need a bigger pump too, sam/cheezy exactly what is the pump you have off?commodore? Do you have any flow rates?


Andy

No full hydro system will return the steering wheel to the same spot as it was before, thats why most just use a 3 spoke steering wheel.

the best way I found to stop the cavitation was to semi close loop the hydro circuit(the return straight back to the pump with the reservoir T in and just above the pump) on my rig this stopped that problem and helped with quicker steering.note the oil has a lower life due to its more frequent use.To combat this side effect I run a setup that circulates the oil through the reservoir to avoid the burning and i run a cooler as all hydro setups should have.

also there is a vickers pump (Vain pump) that works better than any other pump around.I will try to dig up the part number or contact Pete at opw.

Chad

I'm now changing to a vn dunnydore pump with Mick Garner modifications, he says he can get them up to 1500psi. Hopefully this will fix the slower steering.

Chad, is there a trick to bleeding your system with the T on the return? I was going to run an autotrans cooler on the return pipe is this where they're normally placed?

Andy

Place the cooler on the return side. If your going to run a trans cooler don't get a stacked row. There's more restriction in them.

Jason

andrew e wrote:I'm now changing to a vn dunnydore pump with Mick Garner modifications, he says he can get them up to 1500psi. Hopefully this will fix the slower steering.

Chad, is there a trick to bleeding your system with the T on the return? I was going to run an autotrans cooler on the return pipe is this where they're normally placed?

Andy

Yep just a bit of time. Its not a completly closed loop so it will bleed off with time.The reservoir still works with the T by ventury(spelling) so there is still oil circulation through the reservoir. another reason it takes a bit longer to bleeed of for me is that i'm running a few more valves than normal so ther is a bit more line.

The way i have it setup I can also flush and replace the fluid in a mater of seconds.

as stated before one of the best things you can do for any hydraulic circuit is have the return line as big and non restricted as you can get it.

just give me a call if or when you start to set it up

Chad

professor wrote: as stated before one of the best things you can do for any hydraulic circuit is have the return line as big and non restricted as you can get it.

Chad

i just changed the return from 1/2" to 16mm (still have the modded rover pump). will test run it in the morning (daytime) to keep it friendly with the neighbours.


Andy

When you say the steering is slow, do you mean too many turns lock to lock or its just hard if you try to turn quick?

If too many turns lock to lock, displacement of orbital valve is to small for cylinder used. Increasing pump flow will not change this.

If steering feels ok when turning wheel slowly, but goes hard if you try to turn it quickly, its more than likely a low pump flow problem.

The pump Professor is talking about is proberly a VTM42 Vickers if its belt driven, as fitted to older trucks (Inters etc). Available is differant pump displacements, easilly adjusted flow rates and pressures.

I took it for a drive today and its not as bad as i first thought. I am still running the modifed rover pump, which has been boosted from 1000psi to over 1500 (the gauge didn't go above 1500) due to those pirate modifications. I'm pretty sure that the orbital is too large for the cylinder aswell, as i only have 1 turn lock to lock which makes it a bitch to drive over 30kph. In all, unless i'm idleing, the steering is quick enough. Thanks for all your help and advice guys.

Andy