CORVETTE TIPS AND TECHNIQUES

1953-1962 CORVETTE STEERING GEAR OVERHAUL

Part 2

In the first part of this article (see Winter 1994, pages 32-35), I outlined the general design and operational essentials of the early Corvette steering gear box. I mentioned some of the features of this design, and how they pertain to those of us who are involved with the restoration of these cars. I also mentioned that I would not be re- writing the 1953-62 Corvette Servicing Guide (publication ST-12). It remains the premier source for information pertaining to this assembly. 

In addition to the servicing guide, there have been other interesting and informative articles written in The Corvette Restorer Magazine, among which is a recent article by David Harrington, which appeared in the Spring 1993 issue (Volume 19, Number 4). 

I hope to supplement the other writings by showing some workable methods for the actual replacement of some of the parts. 

As you will see if you look in the ST-12 Corvette Servicing Guide, the need for special tools is clearly shown. I have tried to put together some ideas on how you could do this job without the need to buy or borrow these special tools. 

The parts with which to overhaul this gearbox are available in a kit from Corvette Central and other parts suppliers. They include all the bearings, seal and gasket. 

As I see it, there are five areas where the average home restorer would have difficulty in completing the job:

(1) Ball Bearings (22 ball bearings on the sector roller)

(2) Roller Bearings (worm gear, one on each end)

(3) Needle Bearings (sector shaft, two sizes and locations)

(4) Lash Adjuster washer (maintains sector shaft end play)

(5) Adjustment (pre-load of bearings, and gear lash or mesh) 


I would like to treat these five subjects in the order shown above so as to keep them clear. I have, therefore, numbered the photos so as to relate to these categories. All photos numbered with the number 1 will relate to the ball bearings in the sector roller assembly; the number 2 will relate to the roller bearings on the worm gear, etc.

Ball Bearings 


These 22 ball bearings are used to support the sector roller with precision. There are two rows of 11 balls, one on each side of the roller. These ball bearings run on races, which are a part of the roller, that is, the outer races are machined into the roller itself. The races are not separate, and therefore, not able to be changed separately if damage has occurred to them. In order to remove the inner races and the 22 ball bearings, you can pry with two screwdrivers as shown in photo 1- A. These small inner races will pop out as they are held in place by a simple stainless steel retainer, which holds them when they are assembled. Use care, as the balls will spill when the races are removed. I find it helpful to do this over a large cloth. 




















After the bearings have been removed, clean the races, both inner and outer, and look for any galling, roughness, discoloration or rust and deter- mine if the original roller is usable again. If the roller is in good condition, and both the inner and outer races are smooth, you will be able to install the 22 new ball bearings by using a heavy grease to stick them to the inner, smaller races as shown in photo 1-B. After they are all stuck in place, use a vise to force the two small inner races straight together so the small stainless clip will snap them together as shown in photo 1-C. This roller is critical to the smooth operation of the steering gear. It is very important all the surfaces be smooth. It is the outside diameter of this roller, which is in constant contact with the worm gear, and therefore, any roughness will be transmitted up the steering column to the driver. If you hold the roller in contact with the worm gear, you’ll see it will touch in two places. It makes constant contact throughout the turn as it rolls. These two contact points carry the whole load of the steering effort. Look it over carefully to determine if there is any reason it would cause poor handling. 

The roller is mounted on a hardened and ground shaft, which fits into the sector shaft. It is designed to hold the roller bearing inner races, but should not show any signs of the races having turned on this shaft. This shaft has threads on the end, and after the nut is threaded onto the shaft, and tightened to 45 to 55 foot pounds of torque, the exposed threads are peened over with a hammer. This is done as a safety measure to be certain it will not loosen in service. The roller, shaft, inner races, and balls are all shown in photo 1. 

Roller Bearings 

The roller bearings support the worm gear and the lower end of the steering column in the steering gear box. Note the roller bearings have removable outer races, which come with the kit, but the inner races for these bearings are machined onto the worm gear itself. (A condition similar to that of the roller mentioned in section one above.) Therefore, if the bearing races on the worm gear are damaged, the entire worm gear must be replaced. 

The ST-12 Corvette Servicing Guide shows a special puller being used to remove the race in the bearing cup (Fig. 15, Pg. 9-B). This type of puller is available from the major tool companies in several forms. It is called a “Blind Bearing Puller” as it is designed to pull out of a blind, or closed bore. One of these pullers is shown in photo 2-A and 2-B. The pencil shaped pin fits down the center of the main barrel and, as it is screwed into the threads, it forces against a ball bearing, which is located inside of the barrel. The ball bearing forces the three legs of the barrel outward, expanding it to a larger size until it fits under the lip of the bearing race. After this has been done, the puller, along with the race, is drawn out of the bore by means of either a slide hammer puller, or by a conventional force screw puller. See photo 2-C, which shows the expanded puller with the old race still locked on it after being pulled from the bore. You can see the ball in the center of the puller legs where it has been forced to expand the three legs. This is the conventional method of removing a race like this one.




























Another method is somewhat unconventional, but I have used it for many years with great success. It simply involves the application of an arc weld along the surfaces of the race, as shown in photo 2-D. I usually run two beads opposite one another as you can see. After a few minutes of cool-down time, the race will drop out of the housing. This will not harm the housing, but you have to be careful to not weld the race to the housing. The arc bead must be applied to the race only. It has never failed. I would recommend you use a MIG or wire welder, as it will cause little spatter. You can see in the photo how clean the area around the weld has remained. If necessary, however, I have used a DC arc welder and stick electrodes with success. As a matter of fact, the stick electrode makes it much easier to get into the gearbox to remove the race on the upper end of the worm gear. Photo 2-E shows the empty gearbox, and we are looking in through the side cover at the machined ledge where the race would normally be located. In photo 2-F, you will see the worm bearing adjuster cap with the race still installed. I would remove this one the same way. 

In order to install the new races, you could use a bearing and seal installation tool of the proper size, or you could simply use a long punch, and tap alternately on opposite sides of the new race as you work it down into its cavity. If you use a punch, make sure it has good square shoulders so the punch will exert the force only upon the edge of the race, and not on the running surfaces. (A bearing installation tool is shown later in the article.) 

Needle Bearings


These needle bearings are located on each end of the sector shaft. Photo 3-A shows the sector shaft, without the sector roller, and the two needle bearings next to it. If you will notice, the needle bearings have their outer races built right around them, and the races act as a cage also. A cage is used to keep the loose balls or rollers from falling out while the device is being assembled, and has no function during operation. Notice the two bearings are different. The longer one is installed closest to the spline. They fit on the sector shaft as shown in photo 3-B. The sector shaft, being used as the inner race for these bearings, as well as the surface on which the seal will act, must be smooth and sound. The splines must be straight. I have seen at least one steering gearbox where the sector shaft was so damaged the splines were spiraled like a barber pole. 


















Removal of the needle bearings is accomplished by driving the caged needles out of the housing with a bearing installer tool, as shown in photo 3-C, This is done after the seal has been removed. The needle bearings in the side cover housing can be removed by using a cape chisel as shown in photo 3-D. This will distort the race and allow it to be pulled out with a pair of pliers. 

I always dress the flat surface on the side of the gearbox with a sanding block to remove any irregularities as in photo 3-E. The side cover housing should get the same treatment with a mill file as shown in photo 3-F. 





















Installation of the new needle bearings must be done by means of a device, which will place the force on the entire circumference of the cage, like the one shown in photo 3-C. As you can see, the new bearing will be pushed straight into the bore, and no damage will come to the race. The use of a punch will always damage the outer race because it is made out of thin stainless steel only. 

Lash Adjuster

 

This little button head bolt with a simple looking washer around its head is one of the most important parts in the assembly. This adjuster screw holds the sector shaft in place. You will remember that the sector roller must be held in contact with the worm gear at all times. This screw holds it.



































In photo 4-A you will see the method of measuring the play in the head of the adjuster screw. You should not be able to get anything thicker than a .002” feeler gage into this space. I have never seen one with less than .006” of wear in a used gear set. The factory prescribed method of bringing this into specs was to buy a set of different thickness washers, and then selecting the correct thickness washer to bring the gap down to less than .002”. Since that is no longer possible, and since just about every single one will need to be corrected, I have come up with a simple method of correcting the endplay. I use a wave washer as shown in photo 4-B. The wave washer, or spring washer, is the thin one in the photo to the right of the selective fit washer (thick one). Photo 4-C shows both washers on the bolt ready for a trial fitting. The two washers together will be too thick to allow the button head to slip into the slot in the head of the sector shaft. I sand the head of the bolt with a sanding belt to reduce its thickness just a few thousandths at a time, photo 4-D. Each time I remove a small amount of metal, never allowing the bolt head to become very hot, I trial fit it into the slot. Soon I find I can just fit it in by hand, photo 4-E. This method will allow the freedom of movement necessary for the sector to turn, but it will not have any measurable endplay. This has been a good alter- native to some other methods involving such things as weld build up on the head of the bolt, and I have quite a few of these steering gears in service with excellent results. The washer measures .470” (15/32”) I.D. by .665” (21/32”) O.D., with a thickness of .018”. I buy them from clutch and brake houses or friction material supply houses. On trucks with drum brakes they are used where the emergency brake lever attaches to the brake shoe web.

Adjustments


The ST-12 Corvette Servicing Guide shows how to adjust the worm bearings and the sector roller to worm gear adjustment. (This is the adjustment done with the lash screw.) I use a hang- ing scale similar to a fish scale to measure the turning forces at the steering wheel spokes. These scales are very inexpensive and I don’t know any other way to get the adjustments done correctly. I install the needle bearings and the seal into the housing and then the steering shaft and the worm bearing adjuster cap. I recommend you coat the threads of the cap with “Never Seize”. I do this to prevent the possibility of a leak at these threads. At this point, photo 5-A, I adjust the worm bearing pre-load. I install the steering wheel and measure the resistance to turning with the fish scale and set the load to ½ Ib. Then I install the sector shaft and fit the lash adjuster screw through the side cover. I use some gear oil on the shaft to lubricate the seal and needle bearings. I use a good grade of silicone gasket sealer on the side cover gasket. I don’t want any leaks. 

Look for the mark on the top of the steering shaft. This is a small hash mark, which looks like the hands of a clock. It should be pointing to 12 o’clock when the steering sector shaft is in the center of its movement. 

Following the ST-12 Corvette Servicing Guide, adjust the lash as the steering wheel is turned through the center point. There is extra force required to turn the wheel through the center, and this extra force is what you are measuring, and what is most important in the adjustment procedure.
















The bearing at the upper end of the column is a rubber mounted bearing which serves two pur- poses: It supports the upper end of the steering shaft, and it provides a ground track for the horn contact brush. Look for a brass track around the top of the bearing. It will tie the surface upon which the horn brush rotates. Clean it off with a wire brush, and be aware it must be kept clean in- side. If it is in poor condition, merely prying upward on the horn contact track can easily change it, and the entire bearing will come up out of the mast jacket. The installation of the new one is just as simple. 

The steering wheel goes onto the steering shaft in the following way: First, be sure the upper bearing is complete. It has a small curved washer, which goes over the bearing for the spring to push against. Next, the spring goes over the steering shaft, and then the steering wheel. When the steering shaft is at the 12 o’clock position, the steering wheel should be mounted so that the two pins (turn signal cancelling pins) are closest to the driver’s door. That is, one spoke will be pointing straight down when the two pins, which are away from you, pointing into the turn signal housing will be at the 8 and the 10 o’clock position. This is the correct way to install the steering wheel. The nut has a flat washer under it and it should be tightened to about 30 foot pounds torque.

The success of the steering box overhaul will depend upon the condition of the rest of the front steering linkage and the suspension. The third arm bearing, drag link, tie rod ends, king pins and wheel bearings will all affect the steering, as will the front end alignment angles. If you follow up on all these items, and make sure that they are all in good operating condition (including frequent lubrication of the 22 grease fittings), you will be surprised at how easily and responsively the car will handle. 


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Steering2.pdf


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