Disc Brake Conversion

Bugeye Sprites never came from the factory with disc brakes, although the Healeys did offer a conversion kit that they used on their racing Sprites. These conversion kits are now very rare and expensive, but there are newer alternatives that work just as well. The most common is to use the brake setup from a later Sprite or Midget, which is essentially a drop in replacement.

The conversion has 3 sections:

1. Replace or rebore your master cylinder with one with a 3/4" bore. These can come from a later Spridget or the Bugeye one can be rebored.
2. Replace the Bugeye rear drums with the later style ones.
3. Replace the front spindles with the disc brake ones.

As part of this project I also cleaned up the rear differential and swapped it for the 3.9 one from the donor car. This was also a good time to rebuild the rest of the front suspension and replace the brake lines, so those will get done as well.

1. Master cylinder

I had my master cylinder rebored for the use of the disc brakes. At the same time it was cadmium plated -- looks fantastic!

2. Rear brakes and differential

The first task was to clean up the donor 3.9 diff. An evening or two were spent with a scrubbing pad and some solvent, cleaning grime off. Not difficult, just took some effort.

Cleaned (mostly) 3.9 diff

It proved to be more difficult to find the paint I wanted than I originally thought, but after a bit of driving/riding around I was able to get hold of the paint. It is a high-heat engine paint, black and cast aluminum. I know the diffs were originally all black, but I like the cast aluminum look.

Painted up

Next up were the new backing plates. More cleaning and degreasing, then some paint and all was ready for assembly. I reused the old washer and circlip for the slave cylinders, and with the help of some photos from the BCF was able to get all the brake bits in their proper places.

Painted backing plates

Once all the parts were cleaned and painted it was time to install all the pieces. First up was the differential. Everything was put back in place, and with a vise, cardboard box, and a wrench everything was back together. Then the diff was reinstalled and the brake backing plates were installed.

One thing did come up here -- the old parking brake rods are too short to be used with the later style backing plates. The later plates sit at a bit of an angle from where the original ones sat, so the old rods don't work. I'll need to have them lengthened somehow, probably by cutting them in half and threading the cut ends so that I can use some sort of turnbuckle to set them at the proper length and angle. A project for later.

Everything installed

3. Front brakes and suspension

The first steps here were to grab the parts from the donor car, and clean everything up. I took off everything from the steering arms to the A-arms. The A-arms and kingpins were rebuilt by World Wide Imports, and rebuilt disc brake calipers were sourced from there as well.

Next came a thorough cleaning of all of the bits, and a bit of painting. The brake dust shields and spring perches were painted, as were the steering arms from the Bugeye (these get reused).

Dust shield and spring perch painted