CORVETTE TIPS AND TECHNIQUES

1953-1962 CORVETTE FRONT WHEEL BEARINGS


PART 1


While driving along the freeway a few months ago, I was passed by a wheel. Yes, I said a wheel. It was actually a wheel, tire, hub and drum. It came off of a car that was following me. It rolled right past my left side just as it might have done had it still been attached to the car. Fortunately, no one was hurt as it rolled into some low growing brush and came to a stop. Needless to say the car now missing a wheel was having some trouble of its own. It cut a groove into the highway surface several hundred feet long as the driver struggled to maintain control, bringing the car to a stop. As I returned to the location of the stranded car, I was able to see quite easily how this accident happened. The wheel bearings were so badly damaged from neglect they had finally crumbled into a kind of metallic dust, and since the bearings are the only thing holding the hub onto the spindle, the wheel had spun right off the car.


This incident made me think about the wheel bearings on our Corvettes. The front wheel bearings on the early cars, up through 1962 are all ball bearings. Back in those days ball bearings were quite common as front wheel bearings. Today, roller bearings have taken over as the most common type. While both types of bearings do the same job, they are very different from one another in some important ways.


Ball bearings have developed a bad reputation for failing in service more often than roller bearings. It is quite common for an early Corvette owner to replace all four front ball bearings with a new set of roller bearings, usually at a cost of over $150 for parts alone, when one bearing fails. This is because of the bad reputation of the ball bearings. The fact is the most common reason for bearing failure is improper installation and maintenance. In fact, ball bearings are actually better than roller bearings in some ways. They produce less friction from turning, and they are properly installed with zero endplay, so the wheel is held in more perfect alignment. I am not saying anything against roller bearings, but I wouldn't change all four ball bearings just because one of them failed. I believe if you properly install and service the ball bearings, they an be expected to deliver just as long a service life as the roller type.











Photo #1 shows a set of ball bearings for an early Corvette. Let's take a moment to look at the nomenclature. The bearings on top are the inner bearings, the larger ones. The ones on the bottom of the photo are the outer bearings, the smaller ones. (Guess which set carries most of the weight of the car?) Each set of bearings is made up of three major components. The inner race, the caged balls, and the outer race. The races provide the machined and hardened path for the ball bearings to run in. The cage provides the spacer necessary to hold the balls apart, even distribution of force, and a space remains between each ball for grease to lubricate and cool the bearing. It also helps to keep the balls together for handling and installation. The races on the right ball bearings, the smaller ones, are the inner races. They slip over the spindle, and provide a means for adjustment as well as a surface for the grease seal to mate with. It is important to note these bearings can be replaced if any one part goes bad. In many new cars, the races are now an integral part of the hub and spindle. That is, the race is machined into the hub, and on the spindle itself, and then the parts are heat treated so the manufacturer does not have to provide separate races. This saves money in manufacturing, and lets them sell the car for less money initially, but, if you develop a bad wheel bearing, you will have to replace the entire hub, or spindle to repair the problem. This costs much more money at that time. You can see this is a trade off. The design we have in the early Corvette allows us to replace only the part, which failed, which will help in lowering the cost of restoration and maintenance of the car.

















I mentioned the inner races provide a means of adjustment and a surface upon which the seal may act. Photo #2 shows an inboard inner race, and the felt seal, which is designed to operate with it. The race has a smooth machined surface as its largest diameter, and that surface is used for the sealing surface. Once again, it is a replaceable part in case of failure.


If you will notice, I mentioned that was the INBOARD inner race. The wheel bearings are fitted to the inboard or outboard positions and each has an inner and outer race. This allows us to refer to individual parts by definition.


























The faces must not spin in the hub, or on the spindle. The races are designed to stay put, and the movement should all take place between the balls and the races. If a race has been spinning in the hub, or on the spindle, it is certain to have damaged those parts, and they will have to be replaced along with the bearings.


Photo #3 shows a front spindle with the inboard inner race and the oil slinger fitted to it. The oil slinger is part of a device, which will help to keep grease off of the brakes if the grease fails. That is, if the grease breaks down into a liquid, which it is not supposed to do, and it is forced past the seal, it will be caught by the slinger and its counterpart, the oil shroud, which is riveted into the center of the drum, Photo #4. Once inside the shroud, centrifugal force will cause it to find its way out of a drain hole in the drum and exit between the wheel and the drum. It will make a mess, but it will not get onto the brakes, which would be very serious.


















Also, Photo #4 shows the inboard wheel bearing fitted into the hub and in position under the grease seal. The seal is only intended to be used once. Removing it damages it, and it is important that it be perfectly straight and concentric in its bore so as to keep the grease in the hub. Note the spring surrounding the drum. This spring fits into a machined groove around the drum, and is used to reduce brake squeal and chatter. The spring is often missing on early Corvettes.


Photo #5 shows a new grease seal and a seal installer tool. The tool is simply a means of providing equal force all the way around the circumference of the seal while you are forcing it into the hub, and limiting the depth of installation into the hub. It is used with a rawhide or plastic hammer to drive the seal in. Photo #6 shows the seal centered on the seal installer tool ready to be used. Some people use a film of gasket sealer around the outside diameter of the seal so no grease can leak around the outer edge of the seal, between the seal and hub. Photo #7 shows the tool in position over the hub, with the seal in position to be tapped into place. The way the tool is made, it will only force the seal down into the hub until it is level with the top surface of the hub. At that time, the tool will contact the hub so the seal cannot go in any further. This is important because the seal itself has no means of limiting its movement down into the top of the hub.
























If you don't have a seal installer tool, you can easily use something else, but be sure the tool you devise will put equal force all the way around the seal and limit the depth the seal will travel down into the hub.


I mentioned the inner races provide for an adjustment of the wheel bearings. This is because they will slide over the spindle to the correct position for this adjustment. The spindle is threaded to allow for a castle nut to be used as the means of adjustment and final fastening. Photo #8 shows the castle nut and the tang washer that goes under it. The nut is used with a cotter pin to provide an adjustment when the bearings are installed. We will cover the adjustment later.






























The most common failure I see in these ball bearings is galling. In Photo #9 you will see an example of galling, where a tiny imperfection has grown larger until it has developed the rough path you see on the running surface of this outboard inner race. Sometimes you can hear the noise produced by the balls running over the rough surface when you are riving the car. Occasionally, the race will turn around so the balls are sometimes running on a smooth surface and sometimes on a galled one. This causes an intermittent noise, some days it is quiet, and some days it makes noise. Rear wheel bearings will do the same thing, and cause similar noise. I use a stethoscope to listen to the turning wheel by placing the pickup of the scope on the backing plate or axle housing while the wheel is in motion. It is usually done with the car up on a service station hoist where you can listen while the engine is providing the power to turn the wheels. You can compare the sounds and often pick out the offending side.


To listen to the rear wheel bearings, I put the car in second gear and let out the clutch, or, if it is an automatic, I will usually let it idle in drive. The wheels will turn. I pull on one parking brake cable to stop one wheel, and then I listen to the other side. By listening to one and then another, a comparison can be made. If it is a Positraction axle, both wheels will turn equally, so the parking brake trick isn't necessary. This works just the same. It is not a perfect science by any means, but it usually helps to isolate the bad side. To listen to the front bearings, I will back off the brake adjustment so the wheels will spin freely, and I spin the wheel by hand or with the help of a spin balancer to be able to hear the sounds of the bearings in motion. With front wheel bearings, if they cannot be checked by spinning, they can be removed and wiped clean, and inspected visually to see if there is any significant galling or other discoloration.


If they are good, or after the bad ones have been replaced, the ball bearing cage must be packed with clean WHEEL BEARING grease and re-installed with new seals before adjustment. Many bearing companies recommend the bearings not be washed with any solvent. They are concerned that some of the solvent will remain in the bearing cage after the bearing has been packed and installed, and the solvent will dilute the grease and cause it to fail. I often clean the cages by holding the bearing in a shop rag, and, using compressed air, blow into the bearing cage. Hopefully, the grease is forced out and caught in the rag, cleaning the cage, and allowing for complete inspection of the bearings. After determining they are good, only new, fresh grease will be packed around the balls. It is important here to note it is never safe to blow compressed air at a bearing that will spin. The compressed air is capable of spinning the bearing so fast it is very possible it will explode in your hand. Many people have been injured, and some have been killed this way because the expanding air can accelerate the bearing so fast it will disintegrate before one can realize what has happened.


Photos #10 and #11 show the radio static suppressors, which were installed in every Corvette with a radio. If you will notice, one is wound clockwise, and the other counterclockwise. In Photo #11, one suppressor has been installed in a hubcap. This suppressor is intended to be used on the right front wheel. It will keep an electrical connection between the hub and the spindle. This will not allow any static electricity to build up in the hub. This was designed to improve radio reception.


Chances are your radio equipped Corvette doesn't have these installed. Or, maybe a part of one still remains in the hubcap. The reason is when the wheel bearings were repacked; the cotter pin was wrapped around the end of the spindle. This obstructed the point were the contact button is intended to ride. The contact button is the brass button in the center of the device. For this reason, there are hardly any of these still in service.


If the cotter pin is positioned properly, the suppressor will contact the center of the spindle without touching the cotter pin, and will last indefinitely.


This all brings me to the main reason for this article, which is the proper adjustment of the front wheel bearings. Photo #12 shows an old tool I was given by my good friends at CORVETTE CONNECTION in Campbell, California. Kevin Ireland and Bob Griffin, who are not new to the Corvette hobby, found this tool packed away in the old inventory of a parts house in San Jose. It appears it was never used.


It is a wheel bearing adjusting tool especially designed to be used on ball bearing front wheel bearings. This torque wrench was sold through United Motors Service which was the major supplier of New Departure bearings. It was very interesting to me because it shows how important the proper adjustment of these bearings is to their longevity.


Photo #13 shows the instruction sheet, and a view of the wrench showing the fact it is a socket wrench, designed to be used with a one-half-inch drive socket from the mechanic's tool box (Photo #14).


In Photo #15, the wrench is being used. The needle is pointing to position 2 on the scale as the bearing is being torqued to the proper setting which is about 12 foot-pounds. After this has been done, the cotter pin is placed into one of two holes in the end of the spindle (Photos #16 and #17). If it won't go through either hole, the nut is backed off just far enough to get the cotter pin to go through the nearest hole.


You certainly don't need this wrench to do the job. Any torque wrench capable of holding the proper socket and measuring 33 foot-pounds, and then reading 12 foot-pounds is perfectly fine. The idea of first bringing the nut up to 33 pounds is simply to seat the bearings fully into position. It forces the races into position, especially the inboard inner race, to be certain the torque setting remains applied to the bearing at all times during the service period.


The procedure is outlined in the Corvette Servicing Guide (ST-12) on page 3-2. I have included a copy of the text here.


































The proper method of bending the cotter pin so as not to damage the static suppressor is shown in Photo #13, in diagram #3. As you can see, the pin clears the center of the spindle so the suppressor won't be damaged.


In Part 2 I will show how you can remove and replace both the inboard and the outboard outer races in the hub, at home with ordinary tools. I will also show other facts pertaining to these bearings in case you ever have trouble with yours and you want to repair them yourself.


Click to download file

WheelBearings1.pdf



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