Triumph Repair: Spitfire brakes, replacement seals, power brakes

Question
I have a kit car, which has spitfire running gear.  The brakes are very ineffective.  The pads and shoes still have 4-5mm of material on them. You really have to push hard on the pedal (it's not spongy)to get any response and even then it's not good.  Is it a full re-seal job?

Answer
Hi David,
The amount of material on the pads does not effect the braking power of the brakes until the material is gone. You can however, glaze the surface by a hard high speed stop which will effect them.

First look at the surface of the disk and rear drums to see that there is not a lot of grooving then sand the surface of the shoes and pads. This don't take much. We use to just rub the pads on concrete to deglaze the surface.
If this is not your case, do this test. Find a smooth hard dirt road and make a few brake tests. You only need to go 15 to 20 MPH and apply the brakes progressively until you hear a wheel slide and back up and look at the pattern to see which wheel/s lock up. If the two front locked up then do it again but this time lock the brakes up hard and look at the pattern to see that all four locked up. This would be normal. Next, go on a clean piece of pavement at a low speed (20 MPH) and see if you can lock the brakes up. If the dirt road test was correct and the pavement test was correct, the brakes are normal.
The majority of braking is on the front wheels and they should lock up first on dirt and on pavement. On pavement the rear may not lock up at all by design. This system is not power brakes so you will have to apply the brakes very hard as compared to a power brake car.
The seals in the system can bind up to a point that the brakes are ineffective but these tests must be done first.
With a hard pedal, you have no air in the system. If you have put DOT 3 brake in the system, you MUST get it out right away as DOT 3 will destroy the rubber in the system. ONLY use DOT 4 fluid. Some of the replacement seals may not be damaged by DOT 3 but unless you know for sure that all of the seals and flex lines have been replaced with rubber that can stand DOT 3, you need to assume there is at least some rubber that can not be in contact with DOT 3.
Do these tests and let me know.
Howard