Power Steering (Changing Boxes)

Joebus · August 30, 2009, 05:34:45 AM

I have a 1977 MC8, with the original "power assist" steering box. I am changing to a box from a MC9 (I believe a "Sheppard". I purchased the mounting plate kit from Sam Caylor, and it looks like it shouldn't be to hard to do...... Question: what if anything do I need to do to the power steering pump....less pressure....more pressure...do nothing?

Thanks Joe

Busted Knuckle · August 30, 2009, 05:58:38 AM

Joe,
I honestly don't know the correct answer, but I'd say "nothing". But if you wanted to be sure a call to Sam w/details of what bus # (or at least yr) the 9 box came off of he sould be able to tell ya! Sam has done that mod so many times the sheep now do it while he counts them while falling asleep!

BK

luvrbus · August 30, 2009, 06:11:32 AM

Joe
I am not sure about the Shepperd system but changing to a ROSS the pump has to be changed more about flow than pressure.
Check with Sam but he would have told you about changes he doesn't miss much.

good luck

edroelle · August 30, 2009, 07:41:11 AM

Joe,

MCI used Ross integral power steering gears after about 1982. This was a change from hydraulic assist used in pre-1982 buses. Most power steering pumps do NOT need any adjustments or changes. Try yours first after you change the gear, before you do anything to the pump.

Ed Roelle
Flint, MI

TomC · August 30, 2009, 08:56:16 AM

When I changed out my air assist steering, the pump put out around 1600psi-which wasn't enough. Put in a new pump that pumped out 2200psi-no problem. I use 15w-40 engine oil in the pump (as suggested by the rebuilder). The pump will whine when cold, and does make some noise when turning, but it isn't objectionable. I really like the Sheppard-it is finger tip steering, fast ratio (great last trip in the Sierra Nevadas [wouldn't believe where I went]). But- it is hard to get it adjusted tight enough so there isn't wonder at highway speed. Don't get me wrong-the Sheppard is a 1000% better then the air assist steering, but there is still a noticeable difference between my bus and the very direct, easy steering of my Kenworth truck. Good Luck, TomC

JohnEd · August 30, 2009, 11:14:07 AM

Is there a direct correlation between the play in the King Pins and wander? Seems there should be. I went under mine and had a friend rock the steering back and forth briskly. I gripped every ball joint and coupling under the thing. The only, absolutely ONLY thing that had play was the steering box input shaft.
Adjusting that play to zero lash was a piece of cake after I took the box out like they said I would have to do. I then jacked her up with my mondo mucho overkill 20 ton air over hydraulic jack. With a 2X4 under the wheel I sampled the King Pin play and found so little I actually smiled.

Now for the rest of the story: Driving the thing down the road is a job for two people. It drifts.....you pipe in a small correction and she centers up and then you feel the rear "swing" around and she darts off in the correction direction and you repeat this till your arms and back hurt. Unhappy Camper. The bright side is that I have rebuilt the thing where needed and checked and verified that all in the FRONT END is as it should be. I think I remember someone saying that bad bushings in the tag would give the same performance in a ten wheel bus. Well, Dick Kaiser and Karen will resolve this in a week. I am dumping enough money in this Winnie resuscitation t6hat I will have to keep her for another 10 years as a guest cottage.

Can't stop now....right?

John

rusty · August 30, 2009, 03:56:22 PM

JohnEd, When I redid my Eagle I had a similar problem. Come to find out the steering box was not centered. When this happens the box is not at rest and is always putting power to assist the steering. Check to make sure when you are going straight that the steering box is in the center. Also have the caster checked that will help the wandering.

good Luck Wayne

JohnEd · August 30, 2009, 04:17:45 PM

Rusty,

That is good advice...all of it. No, I didn't do anything to the box that wasn't in the Dodge manual. When I last had the front end aligned the tech said I was a long way from having the correct caster. He put soooooo many shims in the front end to tilt the axle that it looked scary. They are all still there and the steering has been deteriorating over the years that I used it. It is now so bad I would not want to drive her far. My rear end feels like it is held in place by a bungee cord. And when the cord gets stretched, even a little, she "darts" to one side or the other.

I asked a friend if Dodge ever put some sort of bar from the differential to the frame and he said NO! He said that the rear springs in the 15,000 pound RM400 are so beefy that lateral movement isn't possible if it is all there. I think the years in Pennsyltucky with all the salt might have dissolved some of that "beef" that keeps things stable.

Thanks for your comment,

John

Lin · August 30, 2009, 05:50:28 PM

John,

I had to have all the leaf springs rebuilt on my old bus. I'm sure you must have checked this, but I will mention it anyway. Have you checked to make sure there is nothing weird going on with a tire or two?

Joe,
When researching the assist to integral change, which I have not done yet, Caylor said I would not need another pump. Nimco Nick said I would. When I get around to it, I will probably go without the pump first to see if it works.