17 replies to this topic

[Lumbergh]

As it happens I'm restoring an old pair and this is what the hole should look like.....

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[JonnyAlpha]

The way the calipers are made is after casting the pistons are machined out. For the fluid tubes are drilled from
1. piston 1 to the hose connection,
2. from split joint to piston 1
3.from split joint to bleed nipple and
4. from bleed nipple to piston 2.
You have confirmed that both pistons are free and that tubes 1 and 4 are clear. If you split the caliper you will have full access to clean out tubes 2 and 3 with a small drill bit and confirm that you have the two correct halves. If you have no leaks so far and the units are fairly new I would be happy to reuse all seals.

Today I took the faulty caliper apart and everything seemed OK apart from the fact that I could not work out for the life of me how brake fluid was supposed to travel from piston 1 to piston 2 via the split.

So I took the working caliper apart and 'hey presto' all was revealed.

In the working caliper, on the base of the piston housing, there is a small drilling that comes from the base of the bolt hole that is capped off with a bolt, this bolt has a hole in it that then allows brake fluid to travel to the bleed nipple.

Drilling is shown in the pic below on the left hand side of the piston base:





However, on the fault caliper, there is no drilling in the base of the piston housing!!
Therefore I deduce that this caliper was faulty from the factory and whoever had then before never had a working set of brakes!!




The guy I bought them off had said they came on the project car he had just bought and was selling them as he wanted bigger brakes / wheels (these are 7.5").

So if I drill the hole they will work?

Great find. But unless you have confidence in how these are to be drilled/plugged etc to permit correct fluid flow, then I'd chuck them and get something made properly. Not a big expense for piece of mind.

Nothing to be plugged, just needs a 3mm hole drilled down through , exactly the same is the other side?

[JonnyAlpha]

So, 3.2mm drill and Brake Calipers should now work fine.