Bleedin' Brakes
How to get around a natural air trap in your braking system...

I recently had the pleasure of trying to remove all the air out of the brake system of a Wolseley 24/80 (Austin Freeway). I use the term pleasure quite loosely as what I thought should be a routine job turned out to be a frustrating waste of a couple of litres of brake fluid and a learning experience.

Speaking to numerous people and searching the internet revealed that it wasn't unknown for some Austin A60's, Freeways & Wolseleys to have really stubborn braking systems that were difficult to bleed. There were a number of vague suggestions for solutions, from the need to have 6 people to do the brakes properly, slackening off all the brake adjusters, or using vacuum bleeder tools.

As it turns out there's a natural air trap in the brake setup of theses cars, but once you know where it is, it's very easy to overcome.

Some of the brake cylinders are actually mounted inverted, meaning that the bleed nipples are at the lowest part of the cylinder rather than at the top where the air naturally wants to go. The trick then is to make sure the pistons are fully retracted into the cylinder so there's no space left for the air to be trapped in.

Starting with the back wheels. Jack up one side and turn the brake shoe adjuster to fully lock the brakes on. This has the effect of pushing the piston fully into the brake cylinder. Bleed the wheel, then adjust the brake shoes back to their normal position. Repeat the procedure on the opposite side.

Moving to the front wheels, we need to do things a little differently. Although there are two pistons on each front wheel we only need to work on the last piston with the bleed nipple. Unlike the back wheels, when the front brake shoes are adjusted outwards it causes the brake pistons to expand outwards too, trapping more air, so we need to go the other way. While turning the brake adjuster fully retracted does help to push the piston in, I found it didn't go back in far enough.

The simple fix, wedge a screwdriver between the piston and shoe. This pushes the piston all the way in. You'll now need to secure the brake shoes in place, easiest way is to slip on a large G-clamp. Bleed the wheel, watch all the air bubbles come out, re-assemble the wheel and adjust the brake shoes to their normal position. Repeat the procedure on the opposite side.

You should now have a very positive feeling brake pedal.

Does anyone have any further comments they'd like to this?

Article written by: Eriks Skinkis


 
   
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