NO brakes.....what could go wrong?

[derekchace]

Was driving my 66 IIa ambulance tonight. I had the great feeling of going down a main road and hit the brakes only to have it go to the floor. Frantic pumping and cursing insue. The more I pump with out result the cursing turns to pure terror. Luckily I found a brake in traffic and maniged to switch lanes and turn into a gas station. I am very glad it did not happen on a steep hill a couple miles before.

So I have pumped the pedal no pressure at all. Resivor is holding fluid. Prior to this brake pedal was very stiff....then started fading on the drive tonight. So thinking brake master. what do you guys think?

[coyoteair]

I had that happen to my IIa and it was the master cylinder that decided to take a vacation. Had a rebuild kit under the seat and was on the way not much later.

[RoverDover]

If the fluid drops in the reservoir you are losing fluid (usually from a wheel cylinder) if the pedal goes soft they need to be bled. If the pedal goes to the floor with no apparent leaks, 9/10 times the master is shot.

[willincalgary]

I had a similar thing happen in an old Mazda truck. Turns out the hand brake (which on that truck operates the rear brakes) had stuck on causing them to drag and boil the fluid. Wicked case of brake fade. Happened on a steep highway off ramp at 60 mph. There was much cursing involved. I let the brakes cool unstuck the handbrake and I was on my way.

Nothing feels worse than brake failure.

[SalemRover]

I have lost my brakes on the 109 once and on an MGB once. The 109 was on the trails and I just used the hand brake to get me back safely. Since then I always make sure my handbrake is in good working order. The 2.5 diesel also makes for a decent brake. You could say it excels at deceleration.

[derekchace]

Rebuild kit or new master?
Also what one does the IIa ambulance take?

[SafeAirOne]

Rebuild kit or new master?


Depends on what it looks like inside once you disassemble it. If the bore looks good you might be able to get away with a light honing and a rebuild kit.

[yorker]

Rebuild kit or new master?
Also what one does the IIa ambulance take?

It has been 46 years since this thing rolled off he assembly line- who knows what master cylinder it has by now? Open the hood and take a look.:thumb-up:

[pjsank]

Glad that didn't happen when I drove it Friday :eek:

[disco2hse]

Master cylinder can fail like that, or the result of cumulative leakage from a broken/corroded brake line, or leaking wheel cylinder,...

Time for a full check over. Repair/replace as necessary.

As a point, in NZ, copper brake lines are illegal for a reason.

[derekchace]

I am going to get a new master. Also well I have the wheels of to mount snow tires I am going to check all the drums and lines.

[daveb]

and this is pertinent how? and what is the reason?



As a point, in NZ, copper brake lines are illegal for a reason.

[greenmeanie]

Copper work hardens with vibration and some argue through presure cycles from brake operation. In some countries (UK) copper is still legal but in lots of others (Australia, NZ, Canada) it is no longer acceptable.

There are plenty of people who claim copper is also illegal in the US as it doesn't meet DOT standards. I had a quick glance through the FVMSS 105,106 & 135 and could not find a definitive statement so it must be something where it doesn't meet part of the requirement and by default is illegal.

Coppe also affects corrosion in brake systems and is one of the things that should be tested for if you don't just adhere to the standrd replacement times for the DOT fluids. It results in pitting of the steel components like your master cylinder.

Lots of fun info here:
http://www.mossmotors.com/SiteGraphics/Pages/Brake_Fluid/brake_fluid_long.html

Kunifer and SS are easier to obtain anyway.

[derekchace]

For the third time this year no brakes again. Drove great all weekend over a clouple hundred miles. Then this morning pedal was very soft and before I left my road no brakes again. Fluid level is fine and no leaks. Getting really tired of throwing brake cylenders at it.

[disco2hse]

I feel your pain. Been there.

It is probable there is a leak in the system somewhere.

As a point of interest, I went through three sets of Brit Part wheel cylinders before finally getting a full set that have not failed, yet.

[4flattires]

Hmm,

Post #1 noted reservoir holding fluid (thus you are not leaking externally)
Post #11 noted checking drums and lines. (psst, its not the drums)


Fluid level is fine and no leaks. Getting really tired of throwing brake cylenders at it.

Tell us what you found that was leaking. You've noted no leaks twice.

Sure sounds like the classic bypassing within the master cylinder.

[derekchace]

I'm thinking master again.....third on in 5 months....I'm not very impressed.

[disco2hse]

Tell us what you found that was leaking. You've noted no leaks twice.

Sorry, missed a word :rolleyes:

I meant to say, "air leak". That is, air is getting into the system. May not result in a drop in fluid levels, but air can be sucked into lines where there are poor connections, split pipes, main and slave,...