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How to Rebuild the Manual Steering Gear Box on a 1966 Mustang

by Dr. Marvin Phillips

The 1966 Mustang sported three steering boxes. Two were manual and one was power. The steering box is identified by a aluminum tag that is attached to one of the cover bolts. The tag will have two lines with the top line the identifier code. The code for manual steering should be HCC-AT or HCC-AW. The former was used in lower performance Mustangs and had a turning ratio of 19.9:1 with 4 5/8 turns lock to lock. The latter was used in the high performance cars like the Shelby and had a turning ratio of 16:1 with 3 3/4 turns lock to lock.

Removing the Steering Box

Place the vehicle on a smooth, level surface, turn off the car, put it in park, set the parking brake, and put the wheel chocks on the rear wheels. Put on safety glasses and mechanic's gloves.

Remove the horn ring by pushing down and turning counterclockwise. The horn ring should just lift out. Using the socket wrench, remove the steering wheel nut. Install the steering wheel puller with the correct bolts. Tighten down on the center bolt of the puller to pop the steering wheel off the shaft. Remove the steering wheel. Unplug the column wiring harness. With the socket wrench, remove the two nuts holding the steering column brace to the dash. Remove the steering column from the shaft with a twisting motion straight up the steering shaft.

Jack the car up and place on jack stands. With a 1/2-inch drive socket wrench, remove the pitman arm nut. Slide the pitman arm puller over the shaft and tighten the center bolt until the pitman arm pulls free. With the 3/8-inch drive socket wrench, remove the three bolts holding the steering box to the frame. The whole steering box and shaft should lift out of the car in most cases. In some cases the motor mounts will need to be removed and the engine jacked up.

Dismantling the Steering Box

Place the steering box assembly on a clean work table. Remove the three bolts on the top plate with a socket wrench. With a hammer and a drift punch, loosen the adjustment nut lock ring and remove. With the crescent wrench, remove the adjustment nut from the input shaft. The sector shaft should now lift out from the rack block. Carefully remove the input shaft rack block and the rest of the internal parts. Count and take care not to lose any of the recirculating ball bearings.

Place the smaller parts in a cleaning basket and all the larger parts in the parts washer or bucket of mineral spirits and let soak for a couple of hours to dissolve all the old grease. Clean all the parts with a brush to remove all old grease and contaminants. Blow off all parts with compressed air. Any of the outside surfaces that will be painted that have rust or corrosion can be media blasted or cleaned and prepped with Prep and Etch. Mask off any gasket or seal surfaces and holes. Media blast the external surface only of the main steering box, top plate, and external nuts and bolts. Alternatively, spray with Prep and Etch, allow to dry, then neutralize with water and baking soda. Blow all the items dry with compressed air.

Inspect all the internal components for pits and corrosion. Pay particular attention to the surfaces of the rack block, sector shaft and recirculating balls. If all surfaces of these parts are not bright and smooth, replace with a new part. Make sure the recirculating ball guides are not split.

Reassembly of Steering Box

Hang the cleaned and prepped exterior parts on hooks and paint with Cast Blast and allow to dry. Put the exterior bolts into hardware cloth and paint with Cast Blast and allow to dry. If the bearing surfaces of the sector shaft and input shaft are scored, sand smooth with 600 grit sand paper, then buff with emery on the buffing machine. Finish buff with white rouge. The surfaces should be smooth and polished-looking.

Pack all the bearings with lithium grease. Following the specific directions in your rebuild kit, carefully press in the worm bearing cup and the sector shaft bushings. Lubricate the shaft with lithium grease and center the rack on the shaft. Install the bearing tubes and 31 bearings on each side. Do not turn the shaft or rack until all 62 bearing are installed. After all bearings are installed, rotate the rack back and forth and make sure no bearings fall out. If they do, tear the assembly back apart and start over.

Insert the rack and worm assembly into the box and thread in the worm bearing adjuster cap. Tighten to 4-5 inch-pounds and install the locknut. Tap in the bottom plug. Lubricate the sector shaft with lithium grease and insert into housing. Replace the cover gasket, cover and loosely install cover bolt. Check for some lash play before tightening cover bolts. Tighten the cover bolts to 20 foot-pounds Remove the grease plug and the cover bolt on the opposite end of the box from the grease plug. With the grease gun, pack grease into the grease plug hole until it comes out the cover hole. Replace and tighten cover bolt and grease plug to 20 foot-pounds. Do not forget to put the identification tag on the cover bolt.

The adjustment of the sector shaft end play and the gear mesh load are precise and detailed adjustments. Follow the directions in the rebuild kit or the adjustment directions at Stangerssite.com.

Mount Steering Box in Vehicle

Maneuver the input shaft through the fire wall and position the steering box at the frame. Install three box bolts. Make sure the input shaft is at the center of travel and the wheels are straight. Replace the pitman arm and nut. Tighten the box to the frame bolts to 50-65 foot-pounds. Tighten the pitman arm to the sector shaft nut to 85-110 foot-pounds. Replace motor mounts if removed. Take car off jack stands and lower.

Reinstall the steering column. Thread on the support bracket nuts and tighten. Reattach the wiring harness clip. Install the steering wheel and nut. Tighten the steering wheel nut to 25-35 foot-pounds. Reinstall the horn ring and spring. Remove wheel chocks. Test drive car.

Enjoy new play-free and accurate steering.

Tips

  • For the best tip, have the mechanics at Stangersite rebuild the box itself. It will be cheaper; you cannot buy the correct torque wrench for the price that they charge. See stangerssite.com/GBrebuilding.html.
  • If not maintaining originality, order a new collapsible steering assembly and install. The Mustangs and other Fords with this particular steering box were known as "The Thoracic Harpoon."

Warnings

  • Always wear safety glasses. Always be careful with a car on jack stands.
  • Adjusting the steering box loads are precise and require a torque wrench in the 0-10 inch-pounds. These adjustments cannot be done by feel. If you do not have this item, do not attempt to do by feel.

Items you will need

About the Author

Dr. Marvin Phillips, known affectionately as Dr. Phil, retired from the practice of pediatrics in 1999. He currently is the CEO of a start-up ambulance service, and has been writing since college. He has published works in "Circulation Research" and "The Anatomical Record." He has professional experience in building, electrical,plumbing, woodworking, cabinetry and automobile restorations.

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