How to Rebuild Brake Calipers | Austin-Healey Bugeye Sprite Project

Early Sprites, like our Bugeye project, had drum brakes all around, but fitting the disc brakes from a later car–a 1962 and newer Sprite or MG Midget–is quite straightforward.

You will need the calipers, spindles, kingpins and hubs. You might also want the brake rotor dust shields, but they are not required to make the conversion work.

Now to rebuild the calipers.


First, assuming that the pistons are frozen in place, you need to get them moving again. Generally, you can carefully force some compressed air through the caliper to pop out the pistons.

Once you get the pistons moving again, you can remove the pads and clean the whole assembly. A parts washer will work, and an ultrasonic cleaner will make short work of brake components.

Moss Motors has caliper rebuild kits which contain new seals.

Unless the caliper is leaking, we do not split the calipers apart.

With the caliper clean and stripped down, you put in the new seals. The outer, grooved seal goes to the outside–towards the brake pads.

Then install the pads and retainers into the calipers. We used Porterfield R4-S pads. We have found these pads to be quite rotor-friendly, with a minimum of dust and squeal. They are also great for autocross events or canyon carving, which are conditions that will fade a lesser brake pad.

Only after you have your caliper assembled–because the brake fluid used to lubricate the new seals during assembly will ruin fresh paint–can you paint your calipers. We used a high-temp, dull-silver paint from POR-15.

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han5l778
han5l778 New Reader
11/17/21 1:17 p.m.

Any shop manual, and your comment here about not splitting the caliper unless it is leaking simply doesn't work for me.  One of the first thingS I do when rebuilding these calipers, after I get the piston on the side opposite the bleeder free is to split the caliper.  I am not and have not ever been a mechanic for a living so I can use the, possible, extra time it takes to split the caliper.  It make rebuilding it so much easier, and in approximately 50 years of working on, restoring and racing these cars I have never had one leak after I rebuilt it.  Moss does sell the seal(Fluid Channel Seal) that needs to be replaced between the halves, but unfortuneatly it is not included with the rebuild kit.  They can be bought seperatly from Moss, part number 180-285.  

I would either paint or powder coat the calipers.  When painting them I use a VHT high temp exhaust header paint.  Usually less expensive than specific caliper paint.  

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