STUCK BRAKE DRUM


Q:

I have a 1960 Corvette, and I cannot get one of the rear drums off to inspect the brakes. One side came off easily, but the other side won't budge. I have tried everything I can think of to get it off, and it won't move. There is nothing there to pull on. How do I get this drum off without damage? Shall I heat it with a torch?


A:

I know what you are going through. Sometimes the drums on the early, C-1 Corvettes can be seized, and they can be quite difficult to remove. You should know that the drum is designed to be concentric with its  center hole. For this reason, the center hole is just large enough to fit snugly over the raised center hub of the rear axle. This is what keeps the drum centered, and turning in a concentric circle so the brake pedal doesn't pulsate. Because this center hole is just the same diameter as the hub on the axle, it can get stuck, and it often does. Some similar drums on trucks have built in pullers for easy and safe removal. Those drums have two threaded holes, opposite one another, into which you thread a pair of cap screws.


By turning the two cap screws alternately, you push the drum off of the hub. That is, the bolts that you have threaded through the holes come into contact with the end of the axle, and mechanically force the drum off of the axle hub without damage. If we had this same feature on the Corvette, we would not be having this conversation. It works very well. The Corvette drums, however, don't have such a device.


You should know that the Corvette drum is a two piece drum. That is, it is made out of a disc of steel, where the five stud holes are located, and the cast iron portion, where the brake shoes contact. The casting was poured around the steel disk, and later machined and balanced to finish the drum. The steel disk is very thin, less than one eighth of an inch, and delicate. If it is bent during removal, the brake drum will not turn true, and brake performance will be impaired. This means that you should never use a puller, or a torch to remove this type of a drum. Incidentally, pullers were made and sold in the aftermarket for this purpose, and many drums were damaged because of those pullers.


GM did not recommend the use of a puller for this purpose.


The best way I have ever found to remove this type of drum is with a hammer. That's right, a hammer. Not a regular hammer, a "dead blow hammer". In case you didn't know, there is a hammer available with which you can hit that drum as hard as you can and not do any damage to it at all. The dead blow hammer is a plastic hammer with steel shot loaded inside of the head. When you hit something with this hammer, the shot, being loose inside the head, produces a very heavy secondary impact, and imparts a tremendous force, without causing any surface damage to the work piece. The term "dead blow" indicates that this type of hammer doesn't bounce when it hits. It stays in contact with the work piece after the blow instead of bouncing off, thus the term "dead blow".


These hammers are available in several different weights, and for the drum, you want at least the four pound size. I would use a larger one if I had it, but for now I have been very successful with the four pounder. You want to hit the drum right on the edge where the steel disk meets the cast iron ring. You want the hammer to contact the cast iron portion of the drum just at the outer corner where the shape turns from the flat steel plate to the cast iron ring. This impact will cause the drum to cock slightly.


The rocking motion caused by the impact will break the center ring loose where it is seized onto the hub at the end of the axle, and it will do it without any damage to the drum. Sometimes, when I come across a very stubborn one, I will soak some penetrating oil around the lug stud holes, and around the center hub hole, and let it soak in for an hour or more. This will melt the rust located inside the drum in the center hole area, and enable it to separate more easily. Hit the drum alternately at six o'clock and at twelve o'clock so as to rock the drum in opposite directions. I have removed drums from axles that have been sitting outside for years, and, although it may take several attacks over several hours for the most stubborn ones, I have never failed to get one off by this method. This will also separate frozen brake linings from the inside surface of the drum.


Sometimes, when the car has been sitting for years, with the parking brake set, the brake linings will rust to the inside of the drum, and the drum cannot be turned. This happens when the linings are impregnated with ferrous particles as in the common "metallic linings" often used today. This means that the car cannot be moved until the brake linings are free. Since you can't remove the drum because of the rusted lining, how do you move the car? The dead blow hammer has worked well for this purpose as well, on both cars and trucks.