Sector Shaft Vertical Slack?

[Mike51Merc]

My steering sector shaft moves up and down when my wheels are turned, but not when the wheels are centered. I can move the Pitman Arm about 3/4 inch by hand. Sometimes it clunks if I hit a bump while making a turn (like into my driveway).

I have a general idea that the box is supposed to be tight on center and loosen as you go through the range of motion, which is why you have to adjust your box with the wheels centered.

Is the up/down motion normal or do I have an internal problem?

[alanwoodieman]

sound like bearings are bad or they are broken, what year are you working on?

[Mike51Merc]

Originally Posted by alanwoodieman

sound like bearings are bad or they are broken, what year are you working on?

Avatar car. 51 Merc

[ford1]

there is no up and down movement for that shaft, if i goes up and down something is worn out or broken,

[columbiA]

By up& down do you mean side-to-side shaft movement? or endways movement?If side-to-side,then sector bushings and/or shaft are worn.If end-ways play then adjuster screw needs to be turned in to have minimum end play.

[Dale Fairfax]

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If the steering shaft (the one with the wheel attached) moves up and down, its slop in the bearings. Either the bearings are worn or the races. On a Gemmer, the only way you can tighten it up is remove shims from under the top housing adapter. Sometimes you get lucky and that's all it takes. The greater problem is that you have to remove the steering gear from the car to do it. Once you do that you might as well tear it down, inspect, and rebuild as necessary. The Gemmer gears have a tendency to wear and gald their wear surfaces-the worm and the roller on the sector. Find a good reference (Ford or Mercury shop manual, Motor's Manual.) before you start.

[Mike51Merc]

Originally Posted by columbiA

By up& down do you mean side-to-side shaft movement? or endways movement?If side-to-side,then sector bushings and/or shaft are worn.If end-ways play then adjuster screw needs to be turned in to have minimum end play.

Sorry. I tried to be specific. I'll try again. The sector shaft (the shaft that the pitman arm mounts to) goes up and down (vertical) about 3/4 inch.

It only happens when the wheels are turned, not when they're straight. If you lay under the car and grab the pitman arm with your hand, you can push the pitman arm up and down about 3/4 inch.

Not side to side.

[Mike51Merc]

Originally Posted by Dale Fairfax

If the steering shaft (the one with the wheel attached) moves up and down, its slop in the bearings. Either the bearings are worn or the races. On a Gemmer, the only way you can tighten it up is remove shims from under the top housing adapter. Sometimes you get lucky and that's all it takes. The greater problem is that you have to remove the steering gear from the car to do it. Once you do that you might as well tear it down, inspect, and rebuild as necessary. The Gemmer gears have a tendency to wear and gald their wear surfaces-the worm and the roller on the sector. Find a good reference (Ford or Mercury shop manual, Motor's Manual.) before you start.

All respect Dale. I never mentioned the steering shaft and I have a shop manual. Thanks.

[Andy]

I have never worked on a Merc box so bear with me. I think they are probably like 55-up Chevies and then Mustang boxes.There should be a secrw in a pressed steel cover that sets the gear engagement and also holds the sector shaft down into the worm assy. With that much play, I suspect your adjustment screw has loosened and fallen out. See if there is a hole in your top cover.

[Mike51Merc]

Originally Posted by Andy

I have never worked on a Merc box so bear with me. I think they are probably like 55-up Chevies and then Mustang boxes.There should be a secrw in a pressed steel cover that sets the gear engagement and also holds the sector shaft down into the worm assy. With that much play, I suspect your adjustment screw has loosened and fallen out. See if there is a hole in your top cover.

Andy:
Thanks for your response.
The adjustment screw controls a "cage" that holds the head of the sector shaft/pivot roller. The screw moves the cage up and down to adjust the roller's interference with the worm. The adjustment screw is in place and the box is adjusted to provide resistance at center and decreasing resistance as you turn the wheels to either side.

[Andy]

Mike, It sounds like it is just like the 37-48 boxes. The box sounds like it is not worn out and is adjusted correctly. Since the adjustment screw controls the up and down movement and that seems OK, I have to wonder if the main box housing is broken. When you push the sector up and down, does the steering shaft to the wheel move with it?

[rotorwrench]

The sector is only slack free when the steering wheel is centered. Once it goes off center either way, you pick up a lot of slack. When the car is in a turn, it has pressure on both wheels so this allows one wheel to turn a little more than the other to keep the steering symetry correct. Otherwise the tires would squeal anytime you turned the wheel off center very much.

This play would allow the sector shaft to chuck a bit when end pressure is applied while the steering shaft is off center. Some movement would be normal but a lot would point to a problem with the adjusting shoe that pivots on the end on the end of the adjustment screw and fits into the sector shaft end slot.

[Dale Fairfax]

Boy, did I muff that-I just flat didn't read it (missed the word "sector"). I'm so accustomed to steering gears laid on their side ala F-1, F-100, that when I see "vertical" I automatically think of the steering shaft. All cross steer cars have the SECTOR shaft VERTICAL. Sorry 'bout that.

Originally Posted by Mike51Merc

All respect Dale. I never mentioned the steering shaft and I have a shop manual. Thanks.

[Mike51Merc]

Originally Posted by rotorwrench

The sector is only slack free when the steering wheel is centered. Once it goes off center either way, you pick up a lot of slack. When the car is in a turn, it has pressure on both wheels so this allows one wheel to turn a little more than the other to keep the steering symetry correct. Otherwise the tires would squeal anytime you turned the wheel off center very much.

This play would allow the sector shaft to chuck a bit when end pressure is applied while the steering shaft is off center. Some movement would be normal but a lot would point to a problem with the ajusting shoe that pivots on the end on the end of the adjustment screw and fits into the sector shaft end slot.

Rotor-- Thanks. THAT'S what I'm talking about. Question is how much is too much and should I worry about the clunking sound when turning?

[rotorwrench]

It sounds like it's time to take a look in there. I'd start by taking the adjuster cap off to see if there is an issue with the adjuster foot or the end of the sector gear or possibly even a problem with the sector roller. You can pull the sector out if you take the pitman arm off the bottom of the shaft. It should slide out if you have the battery tray removed & out of the way.

The most common issue with the 49/51 Merc Gemmer units is spalling of the worm gear. The next item would be excess wear in the sector shaft bushings. The Merc sector shaft is a big unit that is similar to ones used in big trucks of that era. The bushings are a truck part number so finding them is more of a challenge. Job Lot or one of the other parts sources that purchased a lot of old stock would be the place to look for these. The worm in the same as all the Gemmer II type boxes but the steering shaft is unique so the shaft has to be pressed from the worm (or cut the worm off) to replace it. The sector shaft is a hard one to source. I haven't had any luck finding out if anyone makes a roller gear kit for these or not. Most of the time they are still in good shape but you may have an issue with it with the symptoms you mention. I have a spare that is usable if you need one. All the other bearings, shims & gaskets are same as any Gemmer II type unit and all are available from multiple sources.

If your box needs an overhaul, your biggest problem is getting the steering unit out of the car. It's a job when the engine is out but a bigger one if the engine is in. It's not difficult but it's a lot of stuff to remove to get it out since the whole steering column has to come out.

Kerby

[Mike51Merc]

Thanks again Kerby. I've had the unit out before and I don't look forward to doing it again. This weekend I'll open it up and tell you what I find.

Since you know about this stuff, I've seen adaptations of F100 power steering boxes and Volvo 120 boxes, but are there other manual steer boxes (like an F100 manual) that are fairly easy swaps?

[rotorwrench]

I've never done a swap on a 49/51 Merc but some of the guys on the HAMB have. Many of the custom Mercs end up with different frames but I think I'd stick with the stock one. I know of several later type rag joint drive power steering boxes that are similar in design and shape to the Merc but haven't compared them seriously. Some are Saginaw units. A few folks don't take to using Chevy parts on the Fords. I figure whatever works for you is OK by me.

I've managed to put one original box together with good serviceable & NOS parts and I have one left to go. Hopefully I have enough inventory to get that one done too. They steer real nice when they are right. That big ol Merc wheel doesn't hurt for Henry's method of power steering. When I was a little kid, I used to climb up on the steering wheel and go for a spin. I'm sure a few cracks in that wheel were my fault.

[Mike51Merc]

Hey guys, just an update, problem solved. Whoever previously installed the cap and adjustment screw didn't seat the "shoe" on the adjuster properly into the head of the sector cage. The adjuster was providing the downward force to keep tension on the worm in the straight forward position, but the sector shaft was dropping in the turned position because the adjuster wasn't holding the shaft up. The drooping shaft had upward slack.

Topped it off with some STP and one more item of Spring maintenance is done.

Excuse me while I go remove something else that needs attention.