Power Steering Question

JackConrad · August 30, 2011, 09:44:36 AM

I removed the OEM hydraulic cylinder assist power steering on our MC-8 and installed a Ross HFB64 integral power steering. Got everything hooked up, filled reservoir and started the engine. With front wheels still blocked up, I turned lock to lock several times to bleed all air out of system. Everything seemed to be working OK. After removing the blocking, with weight on front wheels, I am getting very little power assist. I used ATF for the fluid (one of the fluids recommended on Bab Steering web site for this model & what was in the steering unit when I got it). I installed a gauge in the line and am showing 1100 PSI. Do I need to replace the pump with a higher pressure unit? If so, anyone have a brand and model number for the correct pump? Jack

luvrbus · August 30, 2011, 10:06:27 AM

Jack you should be good with 1000 to 1500 lbs try getting the poppet valves to set automatic by turning the wheel to the left with 40ft lbs of torque on the wheel do the same to the right turn,poppet valves let the pressure by pass if not set right the pressure is not there.
If the unit came from a different type vehicle they will need to be set again, wheels need to be off the ground to set the poppet valves

good luck

JackConrad · August 30, 2011, 10:14:21 AM

Thanks Clifford. Are the poppet valve adjustable from the outside of the steering box? Are they a screw with a locknut?

bevans6 · August 30, 2011, 10:23:39 AM

Probably does not translate but the Sheppard (stock later MCI) integral PS on my bus had virtually no boost when not moving with a stock pump, which was around 1200 psi. I had to replace with a Vickers VTM 40 set at 2000 PSI to get assist standing still.

FWIW, etc.

Brian

luvrbus · August 30, 2011, 10:40:48 AM

You change the pump for flow if he needs more pressure you just buy the valve set at the pressure you want you just remove the roll pin and replace it.
Some of the Vickers have a adjustable pressure valve but now most are pre set cost you around 35 bucks a few years back.
I have a 1800 lb valve Jack I can send you if you need it

good luck

Len Silva · August 30, 2011, 11:04:13 AM

Jack,

It's been well over ten years now but when I had some steering questions, I talked to the support folks at Bab. They were most helpful and knowledgeable. At least one guy there knew everything there was to know about the ram steering on my 4104.

I don't know if they still have the same attitude today, but it is worth a call.

luvrbus · August 30, 2011, 11:12:58 AM

Straight Line Steering is the place to go shoot Mark a pm from their site and he will send you the answers or call them 408-289-9850

good luck

kaptar · August 30, 2011, 11:15:13 AM

Does anyone know if this Ross box can be used on a 4104? Haven't had any luck finding which Ross box to look for.

bevans6 · August 30, 2011, 11:23:08 AM

Jack i have a 2000 PSI valve around here somewhere, you are welcome to it. I bought it to upgrade my existing pump but the old valve was corroded in and I screwed it up trying to get it out. I should have just let the pump pressure shoot in out, but that didn't work.

Brian

luvrbus · August 30, 2011, 11:41:54 AM

Next time you have that problem Brian hook a grease gun to it comes out nice and easy I tried using the steering pressure to blow one out was not a nice sight never did find all the parts LOL

good luck

roadrunnertex · August 30, 2011, 12:24:20 PM

Jack,
This is very old information from R.H.Sheppard Co.INC for the change over on the PD4104 to Sheppard steering.
They Sheppard suggest using a Vickers VTM 42 pump with a pressure relief of 1750 PSI and a flow rate of 4.36 GPM at idle and
5.3GPM at fast Idle.
Hope this helps.
jlv

luvrbus · August 30, 2011, 12:29:24 PM

Guys he installed a Ross not a Sheppard unit

good luck

tomhamrick · September 01, 2011, 11:48:22 AM

Jack, Let me know what you find out. I am having the same problem with my upgrade from an HF64 to the HFB64 using the Eaton B pump.
Tom Hamrick

JackConrad · September 01, 2011, 01:54:35 PM

Quote from: tomhamrick on September 01, 2011, 11:48:22 AM
Jack, Let me know what you find out. I am having the same problem with my upgrade from an HF64 to the HFB64 using the Eaton B pump.
Tom Hamrick

Tom,
How much pressure are you getting at the pump? I am still researching, trying to get more information about how to adjust the valves. With front end blocked up, it works OK . But with weight on the wheels, sitting still, virtually no assist. Give me a call tomorrow morning 863-444-3400 so we can compare notes. Not sure what pump I am using other than it is the OEM pump used with the saginaw hydraulic cylinder assist steering. Jack

Hard Headed Ken · September 01, 2011, 02:13:42 PM

Quote from: kaptar on August 30, 2011, 11:15:13 AM
Does anyone know if this Ross box can be used on a 4104? Haven't had any luck finding which Ross box to look for.

Ross only made one axle mount gear that I know of, it was used on the MCI 96A2. They are very hard to find. If you could find one I think it makes a better driving bus because the free play is adjustable.

Ken