I have read through the postings on the 411 Master Cylinder, but I would appreciate some clarification and assistance.
Initial symptoms: 411-S1 has stiff rear brakes.
- Problem One: The flex hose to the rear axle was completely blocked. Replaced it with H892 found at Sterling Brakes in Auckland (last one). Now fluid flows to rear, but brakes still stiff.
- Problem Two (maybe) I removed the rear calipers (Girling 12/3HP). They seemed in relatively good shape (they were rebuilt in 2004, but not driven since), but needed a bit of surface cleaning on the top of the pistons due to sitting. Two trips to the brake shop and $200 later, I put them back on car, jacked up both rear wheels, removed wheels, started the engine, the wheels would no turn when in Drive at idle. Applying some power would turn, but clearly the pads were gripping.
- With the engine still running and still in gear, I loosened bleed valve on the caliper, fluid came out, immediately the brakes released.
This points to something upstream keeping pressure on. Options include:
- Master Cylinder needs to be removed, inspected, probably rebuilt
- Hose on the Master Cylinder is partially blocked (works on braking, not on release)
- Servo needs attention of some sort
- There is a pressure relief valve that I don't know about (is there one?)
- If it is the Master Cylinder, it is unclear how one removes it. One comment about an impossible to remove split pin. Is this something I may encounter? I would appreciate a step-by-step removal instructions that I can then summarise for others (the problem with forums is having to read through all of the dialogue to find the core information necessary to solve the problem).
.
A. If it is removed, what is it? How can I find out how to rebuild it. What is the manufacturer (Girling/Lockheed?), what generic part number, what other vehicles use the same master cylinder.
B. Alternatively, what more readily available equivalent is available? I read about Land Rover, sounds like a more difficult procedure, and I read one comment about using a modern master cylinder. What would be the best alternative retrofit?
.
- With the hose, it looks easy - get another one. I'll do that when the shops open.
.
- With the servo, if I disconnect the vacuum and the servo is the problem, does it release the brakes, or do I need to make a bypass line and unbolt the in/out brake line nuts to eliminate the servo as a suspect?
.
- And finally, am I missing anything else?
My hunch is that the rubber hose at the Master Cylinder is partially blocked... it will work when foot pressure is applied, but closes down when back pressure wants to release the pads.
Finally, BODA asked if they could use my postings of the "shadetree mechanic" steps taken, so I have been documenting the findings for future owners in a way that eliminates the back-and-forth, but provides the helpful directions for those of us too far from a qualified repair shop. Clarity in answers will be appreciated by future Bristol custodians (Bristols can last forever, it's the current owners who come and go).