Some Observations on Brake Hydraulics

John and some T series MG's

John and some of his friends

Sometimes the planets just align.  Tuesday it was the “T” series MG’s that aligned.  From right to left they are MG’s TC, TD, & TF, and also John.  Not since we had six (yes really !) red MGA’s here all at the same time have we had a line up like this to contemplate.

These cars constitute the bedrock of the british sports car world.  The TC of course bridges the gap between the pre-war and post war MG’s, the TD represents MG’s headlong dive into the U.S. market after WW II, and the TF was the hurriedly cobbled-together place holder, the stop-gap which was almost never built, between the TD and the MGA.

mangled brake tubing flare

A mangled brake tubing flare. click to enlarge

new flare on our NAMRICK flaring tool

New flare on our NAMRICK flaring tool. click to enlarge

The black TD is here for brake work, among other things.  John was highly suspicious of the brake line on the right, so he pulled it out for a closer look, although there isn’t much to see, it’s been pretty thoroughly mangled.  Someone is very lucky this didn’t lead to a catastrophic failure.  God may protect children and small dogs.  Apparently, he also protects fools.  In this case the former owner, an individual capable of doing great harm to himself and others.

Well, we just happened to have a complete TD brake pipe kit lying around so John got right to work replacing ALL the lines.  Of course , if we didn’t we could have just made them up, which is something we do nearly all the time.  It’s a job made much easier by the use of a vice mounted English flaring tool.  It actually takes longer to cut the pipe to length than it does to make the flares.

Grotty old brake fluid

Grotty old brake fluid -click-

fresh fluid coming thru the bleed tube

fresh brake fluid replaces it -click-

So let’s talk for a moment about what’s inside those brake pipes.  Cutting straight to the chase, brake fluid is HYGROSCOPIC, which in plain english means that it absorbs moisture.

That’s great news if you’re in the brake repair business because that dirty, wet old brake fluid is working assiduously to destroy the brake cylinders, pistons and seals thru corrosion and acidity.

In this shop we strongly advise changing brake & clutch fluid every two years.  The brown grunge being pumped out of the E-type clutch slave cylinder on the left has been long neglected.  It’s not terminal yet.  That stage is identifiable by small particles of the brake seals floating along in suspension, eaten away by acidic brake fluid.  The color of that fluid is black.

Think of this maintenance as being analogous to changing the oil in your engine, which removes the contaminants which are the by-products of combustion.  We use Castrol GTLMA brake fluid.  You should, too.  Forget about silicon fluid with its host of problems, it’s by changing it that you gain the benefits of periodic maintenance.

Patrick’s next assignment: This Austin Healey side shift transmission and overdrive after cleaning and before final layout for assembly.Healey side shift Tx laid out for assembly

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