Steering

[pawillie]

How to properly adjust 7 tooth Sector Thrust Screw on 29 A

[Marshall V. Daut]

This adjustment will not gain you much in correcting loose steering in a seven-tooth steering box, but you might try it anyway. Jack the front end of the car up, turn the steering wheel to the middle neutral position and try to push and pull the pitman arm and sector in and out. If you feel the sector move, the adjustment is necessary. If not, do it anyway because the adjustment might be too tight to start with. You're just establishing a baseline here to see what needs to be done. With the front end still up, loosen the 3/4" lock nut over the adjusting stud on the engine side of the steering box and with a wide flatblade screwdriver, turn the slotted stud inwards until it just makes contact with the end of the sector shaft. Test in and out free play again; there should be none. Tighten the lock nut and turn the steering wheel lock to lock to check for stiffness or binding. If none and the steering wheel turns smoothly, you are done. If, however, there is binding or the steering wheel turns hard, back the adjusting stud out a little and try again. The idea is to take up all inward and outward movement of the sector shaft inside the housing to keep the sector's teeth in proper mesh with the worm gear. Experiment to find the sweet spot for your car.
Marshall

[nkaminar]

Marshall has the correct response. The only thing I can add is to keep the screwdriver in the slot when you tighten the lock nut to keep the screw from turning.

The only other adjustment that can be made is to tighten up the tapered roller bearings for the worm. Try to move the steering wheel up and down. If there is any movement, take a shim out at the cover on the bottom of the box (capture the oil that will spill out) and try to move the steering wheel again.

[Synchro909]

I agree with both Marshal and Neil. All I would add requires the steering column out of the car and dismantled. The 2 tooth steering boxes have an additional adjustment - the engagement between the sector and the worm. The only way to adjust that in a 7 tooth box is to have eccentric sector shaft bushes made, fitted and adjusted. Any decent machinist should be able to do that for you.
That said, the 7 tooth steering box, IMO, is a much under rated part of the Model A.

[Marshall V. Daut]

I am not a fan of the seven-tooth steering design, but will admit when they are set up properly (and with extra non-factory machine work as Synchro909 states), they can steer nicely and be a pleasure to drive. You don't get to that point by simply slapping in new parts, though. The basic design has built-in, non-adjustable slop that only worsens as wear sets in. The very fact that Ford changed horses in midstream in early-mid 1929 by replacing this design with the more adjustable two-tooth box says even Henry was de facto admitting that the seven-tooth design had not been as successful as hoped. Making a tooling and supplier change like that in mid-year production of almost 2,000,000 Model A's worldwide in 1929 was a very expensive move that Henry must have felt was justified, as customer and dealer complaints of loose steering mounted up.
When I worked for four (miserable) months in an antique Ford restoration shop in the late 1970's, NOS Model A parts could still be acquired relatively easily. For years most antique Ford vendors sold NOS steering sectors and worm gears that had been turned up by combing through older established Ford dealership parts bins. Replacing these two steering parts was a matter of course when restoring a seven-tooth box that came in a customer's car. More often than not, NOS parts were installed. For show cars, we had to take an extra step to pass judging standards. Even with NOS parts, there was noticeable, disconcerting slop at the steering wheel right off the bat that resulted in deducted judging points. Apparently, the judges back then believed there was to be virtually no steering wheel play - although both the seven-tooth and two-tooth designs call for a little play in the mid-range (neutral, straight ahead). There MUST be some minor play at the mid-position or else the driver would constantly be compensating for the car wandering via the steering wheel. To meet judging standards of the Jimmy Carter era, we (meaning me!) had to apply JB Weld on both sides of the NEW sector teeth and then file/sand them flat while trial fitting for slop. What a pain in the C.K. Yang, believe-you-me!!! Finally, when there was no slop at the steering wheel - after hours of sanding and testing - the seven-tooth box was deemed "show acceptable" by the shop owner. Of course, with time and use, the thin layers of JB Weld wore away and the designed slop returned. But for strictly show car use and limited driving time, it would be a long time before the slop appeared - many trophies later.
Because of this experience, to this day I cringe when I see a seven-tooth steering box that needs to be rebuilt. I can tell you one thing, though - If I rebuild it, no JB Weld is coming within three city blocks of it! The owner will just have to live with a little built-in slop that will only become worse with time and use.
Marshall

[Synchro909]

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Marshall, That shows what lengths some people will go to just to win a piece of silver. When I assembled the 7 tooth steering box in my 1928 Tudor, there was NO PLAY in it at all, in fact, it was tight. Now, some 15 or 20 thousand miles later, I have about an inch freeplay at the edge of the steering wheel.
That said, I have a rebuilt 2 tooth column ready to go. (RHD 2 tooth columns are not easy to find here.)

[Marshall V. Daut]

Synchro909 -
If you have not yet experienced a two-tooth steering box, you will love its adaptability as time and usage move on. You can actually make periodic adjustments to compensate for wear, something one cannot do with the seven-tooth design to any serious degree. Team this up with a shortened pitman arm, Teflon steering plug bushings and proper lube, and you will have achieved the best that can be expected from a 100+ year-old steering design. I left the fold years ago regarding the needle bearing steering housing conversion due to the horror stories concerning bruiniling into the sector shaft. But over the winter, I reluctantly rebuilt a local Model A owner's two-tooth box with the supplied needle bearing conversion he insisted upon installing. I know all the arguments against making this conversion, but I was reminded afterwards how much easier the sector shaft turned inside the needle bearings versus inside bronze bushings. I doubt that most of us will ever drive our Model A's long enough to really see the effect of this so-called bruiniling of the needle bearings into the sector shaft. Like anything else that moves, these parts must be kept lubricated or problems will undoubtedly develop.
Marshall

[Synchro909]

Originally Posted by Marshall V. Daut

Synchro909 -
If you have not yet experienced a two-tooth steering box, you will love its adaptability as time and usage move on. You can actually make periodic adjustments to compensate for wear, something one cannot do with the seven-tooth design to any serious degree. Team this up with a shortened pitman arm, Teflon steering plug bushings and proper lube, and you will have achieved the best that can be expected from a 100+ year-old steering design. I left the fold years ago regarding the needle bearing steering housing conversion due to the horror stories concerning bruiniling into the sector shaft. But over the winter, I reluctantly rebuilt a local Model A owner's two-tooth box with the supplied needle bearing conversion he insisted upon installing. I know all the arguments against making this conversion, but I was reminded afterwards how much easier the sector shaft turned inside the needle bearings versus inside bronze bushings. I doubt that most of us will ever drive our Model A's long enough to really see the effect of this so-called bruiniling of the needle bearings into the sector shaft. Like anything else that moves, these parts must be kept lubricated or problems will undoubtedly develop.
Marshall

RHD 2 tooth steering boxes are not very common here but I have one in each of 3 of my 4 Model As and I agree they are better than the 7 tooth ones. I've never been tempted to use roller bearings on the sector shaft.