How much play in the ball joint (attached to pitman arm) is considered excessive??? I seem to have a dead spot in the steering when I'm coming out of a long curve. A little frightening when the steering wheel is moved a little and nothing happens. Having the wife move the wheel back and forth while I'm looking underneath shows movement in the pitman arm but no movement transferred to the wheels. 3/8 to 1/2 inch of slop on top of the control valve.

 

There is an internal adjustment to tighten the slack between the ball-stud & the half-shells. The valve has to be disassembled to make this adjustment. A new gasket is needed between the two halves of the valve when you disassemble it. So, to adjust it, you need a gasket kit.

When the ball-stud is adjusted properly (0 clearance), when turning, the internal assembly slides internally just a smidgen to move the hydraulic valve (spool) to one side to produce hydraulic steering assist.

Some movement is "normal".... depends on where it is coming from & how much.

 

Tom,

I have this problem on my new '75. However, on mine the clamp also came off the rubber boot and it leaks all the fluid out. I plan to rebuild mine, based upon what I learned from your note here. Any suggestions on tightening up this adjustment on the ball? I hate to overdo it.

Thanks for your guidance.

 

If there is "fluid" leaking out past the grease seal, then the valve is leaking internally. The internal seals are designed to keep the grease and the PS fluid separated. When you put it back together, assemble the ball stud, "clam" shells and spiral wound spring so there is zero play.... just snug. It's a threaded adjustment.

 

Yes, the fluid is pouring past the rubber seal. Does that mean that the internal seals are bad and rebuilding it with new seals should fix the problem? If so, I'll order up the seal kit and rebuild it.

Thanks for your assistance here

 

Yes, there is one internal seal that has probably gone bad. The valve consists of 2 housings. The housing with the ball stud contains grease, the housing where the 4 hydraulic hoses attach contains p/s fluid. There is one seal that prevents fluid under pressure from entering into the grease side of the housing (see pic below). That seal has most likely failed. Most auto parts stores sell a seal kit that is common for Ford and Chevy, but it might only contain the internal seals, other kits from Paragon for example, contain all internal seals, plus a new dust boot, and new ball stud and ball seats.

I would disassemble your valve first to determine if it's rebuildable. If the spool valve housing is scored or the spool valve is worn you won't be able to rebuild it successfully. When you disassemble your valve, take lots of pics to show the order of the parts for reassembly. There are exploded views of the valve in the Chevy overhaul manual as well as instructions. Somewhere on the forum Jim Shea has some tech papers and the manual pages that will also help you. The valve is going to be a sloppy mess inside and all the parts need to be washed, so it will be easy to forget how it goes back together if you don't keep some type of notes. Also, it might be helpful to get an extra pair of hands when reassembling the valve, because it can be tricky the first time.

 

Yup. That's it in a nutshell.

 

Thanks for the great guidance here. I'll post back if I see anything out of the ordinary.

 

How did you separate it from the pitman arm. Both my pitman arm puller and tie rod puller were slighly too large and I couldn't fit the larger puller in the space available.

 

Asto Pneumatic (Old Forge) makes the puller I use. It's the 2 jaw puller on the right. It will fit up into the frame pocket area, apply a little pressure and let it sit a few seconds, the stud will pop out of the pitman arm with no damage to any parts. Kit #7838.

 

Thanks. I'll look for one of those.

 

I thought I would post my results for everyone's benefit. I got the unit off last night and found the slop was from the gear box and not Control unit as I suspected. The ball unit was nice and tight. Upon tear down, the ball is scored somewhat, but should be reusable with some polishing.

I think I may have found the source of the leak. there was pitting, likely due to corrosion from lack use, in the plate that separates that two pieces. This corrosion was around the place where this plate meets up with the o-ring on the other half of the unit (wet side). Likely the corrosion happened during a long sitting period and when started, the fluid was able to pass by the o-ring, due to the pitted metal.

In looking at the rebuild kit from Zip, they include either this plate, or a small gasket for this plate that should resolve this issue. I'll post results after rebuidling and installiing.