Steering Gear Adjustment- 1950 Mercury

[jackson]

The steering on my Merc is sloppy.... lots of excess play. It's doubtful if the steering gear assembly has ever been serviced. I need to tear it down and do a rebuild. But, in the meantime, is there a way I can take some slack out of the steering? My shop manual says to properly adjust the sector thrust screw I need to remove the steering gear arm. I was hoping I could do a quick and dirty adjustment by simply removing the housing cap and turning the adjusting screw... (which way?). Any advice is appreciated.

Jackson

[51 MERC-CT]

Originally Posted by jackson

The steering on my Merc is sloppy.... lots of excess play. It's doubtful if the steering gear assembly has ever been serviced. I need to tear it down and do a rebuild. But, in the meantime, is there a way I can take some slack out of the steering? My shop manual says to properly adjust the sector thrust screw I need to remove the steering gear arm. I was hoping I could do a quick and dirty adjustment by simply removing the housing cap and turning the adjusting screw... (which way?). Any advice is appreciated.

Jackson

At this point it's not really necessary to remove steering arm.
With the wheels straight forward remove locking cap and star washer.
With screw driver tighten (clockwise) screw until it feels like it bottoms out.
Then back off until the star washer will fit.
With the front wheels off the ground turn the steering wheel.
If you feel any binding it's probably an indication that the worm gear has a badly worn spot. Back off the screw until the binding goes away. The worm gear probably needs to be replaced.
If no binding then re-assemble.

[jackson]

Thanks, I'll give it a try Monday. If I can get a bit of the slack out with an adjustment..enough to last through the summer, I'll rebuild the unit in the winter (assuming parts are still available).

Jackson

[Mike51Merc]

At least get your front wheels off the ground. You need to feel the resistance that the box gives which you can't do if the tires have weight on them. Overtightening the box will lead to rapid wear of your brass worm gear.

The box is designed to give the most resistance with the wheels centered and less resistance the more the wheels turn.

Center the wheels. Remove the locking cap. Turn the screw gently until you feel just a little drag moving the steering wheel off center. Replace cap. Test full range of motion.

I adjust mine with my fingertips instead of a screwdriver.

[34PKUP]

Originally Posted by Mike51Merc

At least get your front wheels off the ground. You need to feel the resistance that the box gives which you can't do if the tires have weight on them. Overtightening the box will lead to rapid wear of your brass worm gear.

The box is designed to give the most resistance with the wheels centered and less resistance the more the wheels turn.

Center the wheels. Remove the locking cap. Turn the screw gently until you feel just a little drag moving the steering wheel off center. Replace cap. Test full range of motion.

I adjust mine with my fingertips instead of a screwdriver.

The worm gear is not brass.
You seem to have overlooked the fact that the anti-rotation star washer only allows for the adjusting
screw to be locked in one of six positions.
Finger adjust? On a box that has never been serviced, I doubt it.

[51 MERC-CT]

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Originally Posted by Motorhead6

I have not worked on a '50 Merc, but I suspect that box may be like a Ford. If so, there are four bolts that hold the two halves of the steering box housing together. They go up into the case from the bottom so you have to raise the car and get under it. They are in four slotted holes in the bottom half of the housing. Loosen all four of them and then gently tap the bottom half of the housing clock-wise as you look at it from underneath to increase pre-load. It only takes a little movement, so keep checking the pre-load after each slight rotation of the housing. Re-tighten the bolts when you get the feel you want.

Removal of the cap on top of the box does not reveal the back lash adjusting screw. The sector shaft does not move up and down to adjust back lash as on later model steering boxes. The back lash adjustment is by turning the lower half of the housing as described above. This causes the sector shaft and worm gear to move close to or away from each other due to the fact that the sector shaft is not concentric with the center of this housing. This whole process is really not as complicated as it seems.

You really should disconnect the drag link from the pitman arm (steering gear arm as called above) so you can get a good feel in the steering wheel for pre-load. You want just enough to be certain that you can feel it on the middle of the left and right extremes. There is a prescribed amount of pre-load for this, but you would have to use a scale and all that which you probably don't have. If you merely jack the front wheels off of the ground, it is almost impossible to get a good feel for it due to the drag of the steering components.

All steering boxes are made such that as you rotate the steering wheel away from the center(as if you are making a left or right turn) the back lash will increase. this is normal and it is designed to do so. If you cannot get a slight pre-load feel in the center of rotation, then that means that your sector shaft is worn and you will have to replace it or just opt for the best comprmise you can attain.

This procedure is directly out of the Ford manual. Good luck.

You're right, you have not worked on '50 Merc. box and the adjustments to the box that you describe are nothing like the '50 Merc. box.

[Motorhead6]

Thanks for the correction. Is the Merc box like the later Fords or something completely different?

[51 MERC-CT]

Originally Posted by Motorhead6

Thanks for the correction. Is the Merc box like the later Fords or something completely different?

Here ya' go.

[rotorwrench]

Merc box is cross between a truck (sector shaft) and a car (worm shaft) but it is a Gemmer II design and uses the same worm that all the Gemmer IIs had back to 1937. You can adjust bearing preload with shim gaskets and firm up the sector to worm free play at center possition only. Most of the old Merc boxes I've torn down have divots or galling of the worm gear. If it's worn out, no amount of adjustment is going to fix it.

Worms are available but replacing it takes some work and special tools may be required (home made) if you use a press to do the job. I see them on flea-pay now and then and have purchased some NOS ones from there. The sectors last pretty well since the roller & pin are a lot harder than the worm gear. The sector shaft bushings are from a truck application but they are out there. All the bearings and shims cross over to other Gemmer II designs like the F1 box and the 48 & earlier passenger car boxes. The sector seal is available since it was used in several applications too.

[Karl Wolf]

Rather than look for drag in the box, I look for decreased slack (free play) right at the place where the wheel centers... The adjusting screw has huge leverage on the situation, it's very easy to overtighten. Many boxes have been ruined by this.

Remove the cap and star washer... The adjustment is by turning the screw clockwise... Wiggle the steering wheel back and forth about 4 inches and look to get the free play at about 1", maybe a bit more. Go gradually, it's sneaky...

--This all to be done after checking for loose tie rod ends, etc. Have a helper just wiggle the steering, while you put a finger on both sides of the joints, you can feel a disparity easily.
Karl

[jackson]

Thanks for all the info... Sorry I disappeared for a week, got tied up with work. Doubt it makes much difference, but I should have noted in the original post that I replaced all the steering linkage when I had the body off. I installed a Jamco ball joint conversion (mainly to get the disk brakes and new front short coils) and at the same time added Fatman steering. The Jamco conversion required a new, much heavier idler arm, which came with the kit.

That's when I should have addressed the steering gear box, but alas I didn't. I'll save this thread, and later this summer will pull the gear box and see what I've got.

The car is a mild custom. Lowered a little on stock suspension (except for the modified a-arms with ball joints welded on the ends) No chop, stock tranny with OD. Engine is the stock block, re-built .040 over, 3/4 cam, aluminum heads, Edelbrock super dual manifold with dual Stromberg 48s.

again, thanks. Jackson