Moss Motors, Ltd

How do you know when it's time to rebuild your rear brakes?

I found out when two puddles appeared under my rear wheels. That left two possibilities. I stuck my finder in a puddle and sniffed. I could tell right away that it wasn't 90 weight. The only thing left was brake fluid. Time to rebuild my rear brakes.

Start by jacking up the rear end and putting the car on jack stands or sturdy blocks. Remove the rear wheels. Now take out the two screws that hold the brake drum to the axle. If you're lucky, they come right out, if you're like me, they don't. I found an impact screwdriver did a good job of removing the screws after I cleaned the slots in the screw head. Slide the drum off the lug bolts exposing the brake shoes. Do the same thing on the other side. If you have problems removing the drum, turn the adjusting bolt at the top of the backing plate counter-clockwise, this will loosen the shoes allowing the drum to slide off. Remember, only take off one set of shoes at a time so you have a set to compare with in case you forget how to put them back together.

Next, using a small prybar or large screwdriver, spread the springs on the shoes enough to allow them to be removed from the slots on the adjuster. When the shoes are loose from the top slots they can be removed from the slots on the slave cylinder. The shoes can now be removed intact and set aside for the moment.

Please remember most brake shoes are made from asbestos. There is usually a lot of dust coating all the parts you are handling. Please don't blow off the parts with compressed air as used to be the standard practice. This will result in asbestos fibers being scattered far and wide increasing your exposure tremendously. Instead use clean Stoddard solvent to wash all metal parts. This will evaporate leaving a pile of asbestos dust you can dispose of properly. Don't put solvent on the pads of the shoes if you are going to reuse them. any oil or solvent on the pads will require them to be replaced.

Remove the brake line from the slave cylinder and plug the hose to keep water and dirt out, a golf tee fits very well. The slave cylinder is held to the backing plate with three spring clips. Drive the middle clip out paying attention to how they came apart so you can put them back together the same way. Remove the pin holding the hand brake cable to the lever. The lever can now be removed from the backing plate. When the lever is removed, the two remaining spring clips can be slipped off allowing the slave cylinder to be moved. Wash the cylinder with solvent and take it to a clean work area.

Now remove the dust cover clip and slip the cover off the piston. Remove the piston from the cylinder and remove the seal from the piston. Pay close attention to the direction the seal pointed so you can put the new one on correctly.

Inside the cylinder there will be lots of dirt and corrosion. Use one of the specialized brake parts cleaners to remove it. After it is clean there will be corrosion pits on the cylinder wall. I don't recommend using a cylinder hone. They are too hard to control on a soft alloy cylinder. Instead, use some very fine emory cloth wrapped around a screwdriver till it fits tightly into the bore. Slowly turn while moving in and out, this will allow you to control how much honing you do.

When ordering new parts make sure you take the old parts with you. There are different diameters of cylinders used on TR3s. They are close enough to confuse you unless you compare them.

By car uses 10" drums and shoes. These are made from that rare British alloy called Unobtainium. I got lucky on my shoes. I had a friend who had a friend who knew someone in the brake reline business who just happened to have a set somewhere in New York.

They wouldn't even sell them to me until I gave them my old shoes. It is possible to get your own shoes relined. A truck brake shop will have the equipment to do the job. As for drums, the only reason I would ever do anything at all to them is if they are out of round. Remember, if your drums are worn beyond a certain limit some shops won't let them out of their doors unless they are destroyed. I have found that if the drum is round the new shoes will run in and clean up even the worst of scratches.

Reassemble the cylinder by coating the seal and bore with brake fluid. Slip the seal onto the piston and the dust cover over the other end. Slide the piston into the cylinder until the dust cover reaches its proper position. Put on the steel clip then reinstall on the backing plate. Check the rubber brake lines for damage. You may want to replace them at this point. They aren't very expensive and replacing them may save you some trouble later on.

Put the springs on the new shoes. Look at the other side to make sure they are on correctly. Slide the assembled shoes over the axle and put the ends in their proper slots. Refit the pin in the hand brake lever. Back off the adjuster until it is all the way in. When you finish, leave the drum off unitl the other side is finished so you can compare if you get stuck.

When the other side is finished, refit the drums and bleed your brakes. I suggest you replace the old fluid with DOT 5 silicon fluid. DOT 5 doesn't absorb water, so corrosion won't be such a problem.

After bleeding put the tires back on. Turn the adjuster clockwise until the tire won't turn by hand then loosen the adjuster till the tire can be turned freely without drag, ususally two or three clicks.

Go out on a quiet street and try the brakes a few times to seat the new shoes. You may have to readjust after a few applications.

Enjoy your project.

 
Tom Hughes
Pasco, WA