Replacing Sprite 7" Front Brake Drums with Morris 8" Brake Drums

The standard 7" brake drums give poor braking and a +/- 35% increase can be achieved by replacing them with Morris 8" drums.

I bought a ($700.00) conversion kit for an Austin A30 from "Gimmy the Cricket" in Perth. Why someone would have a business name like that only he would know. The kit and modification description was ok except for the width of the back plate spacer.

The kit consisted of an 8" back plate, news drums, new brake shoes with springs, new brake cylinders (same ones used on 7" drums) and new link brake pipe between cylinders. The hole in center of the 8" back plate had to be enlarged to that of the 7" back plate and bolt holes drilled to the same pattern as the 7" back plate.

A 6mm spacer plate has to be manufactured to position the 8" back plate to line up with the 8" drums. The 8" drums are much narrower than the 7" drums. Longer back plate bolts are also required. The existing flexible brake pipes can be reused as well as the existing wheel hubs.

The existing 7" arrangement is removed and the 8" installed, like for like, except the 6mm spacer being added. Adjustment is via a hole in the drum the same as the 7" arrangement.

Not a complicated conversion and with a vacuum brake booster added the brakes are very effective but not quite that of a disc installation. In my case it was a nightmare trying to get the 8" drums to line up with the new shoes.

If you ever decide to do this modification, first look at the 7" brake shoe trace on the drum surface and if it is wider than the actual shoe, you will have problems. It indicates your stub axles are bent and original replacements are not available but you will know you are driving a possible crash, they could break.

I had to trade my stub axles for upgraded "super stubs" from Colin Dodds, an extra $800.00.