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Bleeding the hydraulic system: Austin-Healey Sprite project car

by Kyle Smith
12 October 2020

Bleeding is a term I have been hearing a lot lately in my garage, mainly when referring to the exodus of cash from my wallet since I have so many classic car projects on the go. However, in this instance the bleeding taking place is less monetary and more hydraulic. The Austin-Healey Sprite project continues as I dive into the brakes and clutch to get it back on the road as simply as possible. The car seems to have other plans.

The key to hydraulic systems like modern brakes is the incompressible nature of the fluid in the system. Should that system be infiltrated by even small air pockets, the function will be affected. A soft or low brake pedal can often be traced to air in the brake lines. The Austin-Healey not only has hydraulic brakes, but also a hydraulic clutch. Two systems to bleed, one man. What could go wrong?

A lot, actually. Even after replacing the rear bleed screws and pulling a fresh slug of fluid through the system, pedal pressure was sad at best, and the driver’s side rear drum was providing no stopping force. Knowing there was a deeper problem and I wanted to chalk up at least one win during the the evening, I switched my attention to the clutch system.

The clutch on Sprite and Midget cars is known to be a pain to bleed. The location of the bleeder screw makes it difficult to bleed the slave cylinder in place. I figured if I was going to remove it from the transmission I was going to make the bleeding process as easy as possible. That meant building a fixture to lock the slave cylinder solid while also making it the highest point in the system. Air bubbles want to rise, so this allowed me to try and accomplish the task without fighting nature.

In all, it wasn’t the most successful night in the garage, but that is how working on cars goes. Some nights you get to start your project for the first time, but most nights you are buried in a quagmire of endless problem solving. I think I know how I’ll be escaping this particular set of problems; if you want to know how it works out, subscribe to Hagerty’s YouTube channel and wait for next week’s video.

Via Hagerty US

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