Monday 1 March 2021

Rear Brakes Rebuild

With new parts delivered I could start rebuilding the rear brakes.

I mentioned before that the rear bearings are in good condition so I won't be replacing them. Before I could rebuild the brakes I needed to put the rear axle and hub back on with new oil seals and gaskets.

Both surfaces of the hub needed a good clean. I used fine wet and dry paper to remove all the old crud.

As part of the preparation I had removed as much of the surface rust from the back plate and then applied a couple of coats of rust converter and then a couple of top coats of black chassis paint. It was now ready to start to install the new parts.

First up was the oil seal and gasket. I made sure the groove was very clean and then put a small amount of oil in the groove to help settle the seal.

Gasket goes on easily.

Then carefully slide the half shaft in the differential and then on to the inner hub mounting bolts. If you have wire wheels like me make sure that you put the correct hub and half shaft in the right end of the axle. Then make sure the screw hole is aligned and then tighten the screw.

Once that is in place I moved on to the wheel cylinder that contains the two pistons that force the brake pads on to the drum. I should point out that I did paint the pistons before putting them back into the cylinder to stop them rusting as they did before.

In order to keep the cylinder in place you have two options. Could can either use a washer and circlip or you can use a clip as I have used. This is partly because a new washer is not currently available from Moss and it needs to be exactly the right width. The clip I used is slightly bent to ensure everything is tight and stops the cylinder moving around.

I have seen some people use a tools to get this clip on but a screwdriver and a little bit of pressure and it clips on well, even if it did scratch the paint, which I tidied up afterwards.

Next up is to put the handbrake arm and new seal in place. Quite easy to do.

Then the pads themselves. This is a fiddley job!

I have to admit that I had two goes at this and it took me a while to try to understand why on one side the pads were reasonably tight and in place and on the other the pads were flopping around all over the place.

It turned out that although the springs looked ok, one wasn't even the right spring and was longer which caused the looseness, but also over time springs lose their strength, so I bought a new set from MGB Hive

I still cannot believe that someone had fitted the old pads with this top spring. The braking must have been all over the place.

The best way to show how to correctly fit the pads is to use this diagram:

When I fitted the pads I put the top spring in place first and then slid the pads over the hub and slotted the handbrake arm into the slots as shown below and then set the top of the pads into the cylinder pistons.

You need to make sure you clip the spring around the handbrake arm, which helps to stops vibrations and the brakes squeaking.

The bottom spring is tricky to get on. Although the photos show the pads in place, I actually fitted the bottom spring with the bottom of the pads off the adjuster just behind the hub. This allowed the pads to be closer together and the spring was easier to clip into place. Then you pull the pads back into their slots on the adjuster.

Once that has all been checked and making sure it is all tight you can fit the drums on. 

If like me there is some rubbing when first fitting, you should check the adjuster to make sure it isn't over tightened. But some initial rubbing is normal until you get a chance to drive the car to test the brakes. They should settle in with a few miles. If not you need to check the installation again.

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