1971 Power steering questions

[dasbulliwagen]

Im new to the sweptlines, and after looking at the PS setup, I have some questions on how it works. I have never seen a setup like this before. It has 4 lines going to a block on the drag link from the pitman arm to the left knucle. Is this some sort of sensing mechanism to tell fluid what direction to go going into the hydraulic ram mounted to the steering crossover rod? Thats all I can think it might be considering it doesnt have a traditional style power steering box setup. A little explanation of this setup would be greatly appreciated. Thanks.

[Johninky]

That's how it works. That block with the 4 lines can be thought of as a control block. Don't cross the lines if you ever have to work on it.

[Hobcobble]

if you ever have to work on it.

From what I gather, its more like if you ever don't have to
work on it. All in all, this assist set up isn't quite on
par with a power steering box system..... but they weren't
available until the Life Style trucks came out.

RobertOb has dissected his power assist system and rebuilt
it with success, as I recall. You might try to find his write up
and study it. It can be found by using the site search feature.
John

[dasbulliwagen]

viewtopic.php?f=20&t=27245&hilit=power+steering

Found the article you were refering to. This thread should be added to the power steering write ups links. All the other links are for adding power steering with non stock components. Thanks for the help.

[robertob]

if you ever have to work on it.

From what I gather, its more like if you ever don't have to
work on it. All in all, this assist set up isn't quite on
par with a power steering box system..... but they weren't
available until the Life Style trucks came out.

RobertOb has dissected his power assist system and rebuilt
it with success, as I recall. You might try to find his write up
and study it. It can be found by using the site search feature.
John

Well all the parts are in a box in the garage while I work on the cosmetics, so I can't really say 'with success' yet.

It's not a very sophisticated system. The control valve has four ports - pressure in, return, left turn and right turn. Inside is a shuttle valve connected to the ball stud that connects to the pitman arm. When you turn the steering box it pushes (left turn) or pulls (right) the shuttle valve, directing pressure to the left or right side of the hydraulic cylinder on the tie rod. When you stop turning, it stops sending pressure and instead diverts it to the return line.

The hoses often leak and are not available new - you either have to find NOS ones at a cost between $50 and $150, or you have to have a hydraulic shop fabricate new ones based on your old hoses. Figure $100+ for that option. The seals are pretty standard o-rings and lip seals, though the seal head of the ram is a little bit special. The grease seal on the ball stud end can be replaced with a Ford part, one of the other members has done that.

The other end of the drag link is not available, but Rare Parts in Stockton, CA can replace the balljoint with a new one for about $100.