defiant1

Okay- I got the standard Saginaw power steering gear box in the '70 Cutlass.

I am in the process of replacing steering components. So, right now the center link, tie rods, and idler arm are removed. Basically nothing is attached to the pitman arm.

I grabbed the steering shaft and rotated it back and forth. I noticed the pitman arm move very slightly. I figured I rotated the shaft at least 3/8" and the pitman arm maybe moved 1/16".

So - I guess I am asking is the relationship between the input of the steering shaft and the output of the pitman arm suppose to be 1:1??

I have a dead spot in my steering, where I would be driving down the road and I could feel the steering release and then catch itself (minor movement, but I could tell it was there). The guy who did my alignment said my idler arm had a little play in it (but it was not critical to replace).

At any rate before I put brand new parts on, I would like to determine if I have a bad rag joint, or steering box.

I have read that there is an adjustment screw on top of the power steering gear box, but you are not supposed to use this to adjust any play out of the steering.

d1

Run to Rund

You can carefully tighten the adjuster on top until most of the play is removed. don't overtighten or the internals will wear excessively.

defiant1

Yeah, I went back and looked at it again. I used a magnetic pointer attached to the pitman arm to help see the movement better. It's actually better than I thought it was initially. Although, I did notice the lower bearing on the steering column is shot. I have a lot of play in the shaft at that point. I am having problems finding the correct bearing however.

I may use the adjustment screw after I get everything back together and back on the road. I will see how the steering performs then.

d1

Coltonis

Oh come on... its like six bolts and two hoses...

Take the gear box off - buy this forty dollar torque wrench on amazon - Measure drag torque - adjust worm bearing preload per the factory service manual specs - Measure drag torque - Set the sector shaft gear mesh per the factory service manual specs - double check final drag torque - bolt that sob back on - learn stuff - be amazing - and your done.

(I just completely redid the gear box on my truck, its practically identical to the cutlass box. Adjusting it was the easy part.)

defiant1

Can the worm bearing preload be set to specs if it is worn? Is there enough leeway/tolerance to return it to factory specs?

Coltonis

Yes its quite possible, but it does depend entirely on how worn the internals are. The worm bearing and spool valve (which is essentially the input side of the gearbox) don't see nearly as much wear and tear as the sector shaft and rack piston (output side of the box).

Honestly, adjusting the sector shaft's "gear mesh" (ie that Lock nut and threaded rod on top of the box) will indeed do more to take the play out, BUT you can't properly adjust that without first knowing the drag torque at the input shaft. You can't know the drag torque without setting the worm bearing pre-load.

It it is also very easy to over tighten the gear mesh if your eyeballing it - I read a lot of stories when researching for my rebuild that all said the same thing, "oh yeah i just tightened that little adjuster and it was great/tight for about a month or two then it got really loose again...".

The worm bearing pre-load is set by tightening the big adjuster plug that surrounds the input shaft and houses the input shaft seals. There are three bearings that keep that side of the gearbox spinning.

One is a ring bearing in the adjuster plug that surrounds the input shaft and keeps it straight.

The other two are thrust bearings that essentially sandwich the connected spool valve and worm shaft (One bearing on top and one on the bottom). The bottom thrust bearing is referred to as the "worm bearing" since the worm shaft rides on top of it. However, tightening down the adjuster plug (ie setting the worm bearing pre-load) simply removes the play that these two thrust bearings have.

--If the plug is too far out (loose), then the input shaft may spin great, but the spool valve and worm shaft can bounce around in the housing and wear things out.

--If the plug is too far in (tight), then the input shaft will be tough to turn, and the extra friction will probably chew up those two thrust bearings right quick.

That is why you have to measure the drag torque of the input shaft (drag torque = how hard it is to turn the input shaft). This way you know the friction/play is just right.

If things are severely worn on the input side, the worst case is going to be that even with the adjuster plug all the way in, you still wouldn't have a high enough drag torque. At which point, its either going to be close enough to live with and move on to setting gear mesh (within a couple in-lbs of specs) or its going to need to be opened up and a few bearings be replaced/shimmed.

Once that is set properly you can then adjust the sector shaft gear mesh.

The sector shaft and rack piston both have big gear teeth that interlock. The full mechanical+hydraulic force used to turn the tires is placed on those teeth, which is why they are likely to wear down. (This should take years not weeks like what occurs when that lock nut adjuster is over tightened) Tooth wear cause more play in between the teeth and thus steering and wheel play.

Luckily the teeth are manufactured with a three dimensional tooth profile that allows the tooth mesh (ie how tightly those teeth interlock) to be controlled by the vertical position of the sector shaft. That threaded rod with the lock nut adjusts the vertical position of the sector shaft and consequently the gear mesh. Some play in the tooth mesh is required to prevent accelerated wear. If the teeth wear down severely or somebody were to repeatedly over tighten the mesh adjuster screw eventually you run out of vertical space (and tooth profile surface). At which point you'll need a new sector shaft and rack piston.

Now that I explained the gear mesh I realize its not really important since all you do to properly set the sector shaft gear mesh is little-by-little adjust the threaded rod with the tightened lock nut until the input shaft's drag torque is a certain amount above the drag reading when just the pre-load was set.

oh boy, that got long - sorry... All the needed drag specs are in the service manual.

defiant1

Coltonis

Thanks for the explanation. I will give it a shot. I have to replace the lower bearing and rag joint any way, so I might as well give the gear box a try. I will break out the service manual and give it hell.

d1

Bluevista

The steering box is 40 years old, they wear out and no adjustment is going to fix it, been there... done that.
Do yourself a favor and replace it or have it rebuilt, it's one of the biggest resto bangs for the buck in terms of how much difference it makes, especially if you go to a quicker ratio.

The car will go from "The Wanderer", to the "I Wonder Why" I didn't do this a long time ago.

About two old guys here will get those lame song references, all bow...Dion's in the house.