CORVETTE TIPS AND TECHNIQUES

1956-1962 Clutch Linkage Composite Bushing Replacement


I always find it interesting to look at the design of an item and try to figure out why the engineer decided to do it that way. I am sure he or she had reasons for each and every part. The engineer or designer works through a series of steps, each one improving on the other, until the final design is settled upon. Many factors are taken into consideration in this process, and it is sometimes a balancing act to try and satisfy several different pressure groups within the company in the process. We all know that cost is one of the major factors in the design of every product, and the best designs are the ones where a low cost has been achieved as well as superior performance. 


The engineers at Chevrolet used an expensive little part in the clutch linkage of each Corvette with a manual transmission from 1956 through 1962. Not only was this an expensive part to manufacturer and install, but it has a relatively high rate of failure. For these reasons, I have always wondered why it was used in the first place. As a matter of fact, if you have one of these cars, your clutch bushing is either bad, or you have already replaced it. 


This little part is a composite bushing shown in photo #1. It is made up of three parts: 


1.  The outer jacket or sleeve is steel. It is pressed into the large hole in the clutch bell crank (photo #2) and, when installed, it looks like the one in photo #3. 


2. The inner bushing is an "oilite" type bronze bushing with an inside diameter of 3/8 inch. It is designed to receive the special "shoulder bolt" shown with it in photo #4. The shoulder bolt is designed to turn in the oilite bushing. This is important to keep in mind. The main force on the clutch pedal is directed down the long rod, through the firewall of the car, to the shoulder bolt which is bolted tightly to the rod as shown in photo #5. As the clutch is pushed down, the shoulder bolt turns in the brass bushing. 


  1. 3.The rubber insulator, which binds the two steel pieces together, is the part that fails. It fails because of several reasons. The first is time. The rubber will dry out and crack in time, causing it to fan out. When that happens, the clutch will go out of adjustment. It may be that the transmission will become difficult to shift. This is because the clutch is not being completely disengaged when the driver pushes the pedal down. 


Another reason the rubber fails is when it gets grease on it. Some grease can cause the rubber to swell up and become soft and squish out of place.




































Using a clutch with extra-heavy springs will cause the rubber to fail because it is not designed for such heavy pressure. Misalignment of the linkage can also be a cause of failure because the bushing can only handle straight forces applied equally across the face of the part. 


Whatever the reason, this little part can cause a lot of trouble. 


Because it is pressed into the bell crank, it is not just a simple matter of slipping a new one in. It takes force to remove the old outer jacket, and then it takes force to install the new one, and this force must be applied straight in line with the bushing or it will bind.


The normal way to install one of these bushings is to remove the entire bell crank from the car, and, using a hydraulic press, push the old sleeve out of the lever and then press the new one in. This is a fairly substantial job. I have devised a simple means of changing the bushing while leaving the entire bell crank in the car. 




































The first step is to remove the steel sleeve which will still be in the lever of the bell crank as shown in photos #6 and #7.1 use a pair of heavy-duty slip joint pliers to twist out the sleeve as shown in photos #8 and #9. You will need a good pair of pliers with very sharp teeth to grip the little raised flange visible in photo #7. If too difficult to get out using this method, you could use a plain hacksaw blade with 32 teeth-per-inch to cut a slot in the sleeve. Put the blade through the hole in the sleeve, and cut the steel just until you sever the sleeve. Then it will be easy to grab the lip with pliers and pull it out. 


To install the new bushing I use a homemade tool which is simply a 4-1/2" piece of fine thread 3/8" threaded rod, sockets, and two heavy washers as shown in photo #10. The fine thread rod is much better than a course thread because you will get much more force against the steel bushing when tightening the nuts. The sockets I use are both 3/8-inch drive. This means the threaded rod will fit closely through the drive holes of both sockets, and it will also fit closely through the new composite bushing. This will keep everything lined up straight for an even push. This is very important. One socket, the one that will be pushing the bushing is an 11/16-inch standard depth socket. The other one, the one that will be receiving the bushing is a 3/4 inch size. Photo #11 shows the socket and the bushing over the threaded rod. Note that the socket will be push- ing evenly on the lip of the steel sleeve.















































In the next two photos, #12 and #13, the setup is shown, as it will be used.



















































The final two photos, #14 and #15, show the actual operation of pressing the bushing into the lever of the bell crank. I have turned the whole assembly over, and the new bushing is moving from right to left as it enters the lever. I am using a ratchet with a deep socket in my left hand to tighten the nut. I have placed a box wrench on the nut at the right side, and I let it swing around and contact a part of the bell crank as you can see. This will hold the nut tightly as I turn the socket. At first it is important to check to be sure the bushing is entering the hole straight, but once it starts it will go in very easily. If you look carefully, you can see that the bushing is fully pressed into the lever, and the thin flange of the new bushing is rest- ing right up against the lever. I have removed this bell crank from the car in order to photograph it properly, but I have done many of these in the car, and I believe it is easier and faster than the old method.


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