[Spridgets] Brake Questions

[Bob Kitterer]

To begin, this entire hydraulic system is from a 1957 Mk IV but installed in a Bugeye.  The brakes and the clutch are separate systems.  Also It has used silicon break fluid since the restoration in 1997.  Jump forward to 2009, on the way to the gas station suffered a complete loss of brakes. No leaks, no loss of fluid.  Assumed that the seals in the master cylinder had “suddenly” ceased to seal, may be a bad assumption.   Anyway did a complete rebuild of both the brake and clutch master cylinders, wheel and slave cylinders and calipers.  Afterwards was unable to get any pressure on either system.  This may have been due to the one person system bleeding method which may have introduced air into the system, a problem with silicon fluid.  The car went into storage so I could do some bucket list stuff.

So now I have just finished disassembling the entire hydraulic system.  

First all the seals look new, that is setting in silicon brake fluid for eight years has not had an adverse effect.  

Next there is some wear on the master cylinder pistons, wheel cylinder pistons and slave cylinder piston.  This wear seems to be just enough to remove the black finish on those parts.  I measure less than 0.001” wear.  So would assume that they are still serviceable.

There is some corrosion, particularly in the rear cylinders, which needs to be honed out.

Besides any questions, comments on the above, does anyone know what the maximum service diameters are for the various cylinders?

Brake Master Cylinder Bore = 0.747”
Rear Wheel Cylinders Bore = 0.748”
Clutch Master Cylinder Bore = 0.696”
Clutch Slave Cylinder Bore = 0.998”

Thanks


Bob  Kitterer

1960 Austin Healey Sprite (Mk IV in disguise)
1966 Austin Healey Sprite Mk III (Trevor) - still in boxes
2013 Miata

Pay it forward.
Thanks Frank