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 Posted: Mar 28, 2018 06:29AM
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CA
Having a leak of any size in the brake system is a symptom for immediate concern - with hydraulics a tiny leak can suddenly become a massive one. However, I do appreciate that occasionally the location of a leak can remain a mystery if it isn't in an obvious location such as a hose or wheel cylinder. Our Suzuki Grand Vitara has a hydraulically operated clutch which loses fluid over time, though even a shop visit (excellent local garage) could not determine where. The only symptom is incomplete disengagement of the clutch, occurring about once a year or longer. A top-up of the reservoir solves the problem.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Mar 28, 2018 06:04AM
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GB
The clip isn't 100% neccessary.  I know people who don't run them are they are a PITA, and I have to admit that on Gertie they are so difficult to install (due to the conversion) that last time I changed the cylinders I didn't bother...  Not correct, but the hard line holds the cylinder in enough of the right place for assembly and once assembled it can't move.

We'll probably never know what happened to you, but my guess remains with one end of a shoe not in the right place on reassembly.

 Posted: Mar 28, 2018 03:45AM
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I don't post here to sound like a genius, I post to the masses that work on their cars and enjoy them. Most of those masses never post but do read and learn.

What I was experiencing was a small leak. When the car was used daily it didn't require any bleeding. The fact that I JUST got it out of storage and was doing tuning for the season meant I knew I would have some issues to sort.

My belief is the clip on the back was the failure. When I installed a new wheel cylinder the clip was bent when put on and didn't stay. I'm shocked still there was enough room to allow the piston to fully escape the cylinder.

I have since purchased two wheel cylinders, 4 new springs and the nifty tool to install the clips. Now the clips are in proper shape and position, the springs are doing their job and the brakes work great.

I'm sure there are many better mechanics out there who could tear my car apart and build it better than me. But it's my car. It's me and I enjoy it almost daily.

Thank you to those with constructive comments (and criticism) and good luck to those who just read and learn. Over 300 people read this while 20 or so commented. Case in point.

Mark Looman, Ada Michigan 1967 Austin Cooper S
 Posted: Mar 23, 2018 09:06AM
mur
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The telling detail is where he considers regular bleeding acceptable; it is underscored by his line: ...I bleed it out and it was fine....

Brakes fail because parts fail and because mistakes can be made when servicing and repairing these systems. It is important to accept that we all make mistakes.

Things get really bad when a mistake is made, and it is ignored because of the culture; in this case, the ideas this fellow has about automotive hydraulic systems.

I am not writing this to be mean. My goal is to illustrate the gravity of the mindset problem. This is far more dangerous than simply assembling the brakes incorrectly.

Minis are cars, and like every other car on the road improper service can result in crashes that can cause injury or death.

 Posted: Mar 23, 2018 06:29AM
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US
Not at all surprised Help has a history of running issues to complete failure. Steve (CTR)

 Posted: Mar 22, 2018 12:23PM
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It’s kind of a training wheel approach, but I like to do one side at a time. Take a look at the other side and see if you can spot any difference. Nice to have a sanity check.

 Posted: Mar 22, 2018 01:37AM
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GB

Did you replace the adjusting tappets ?

The little stepped wedges ?

The only fail mechanism I can think of is an incorrect assembly, so you need to figure out what you did wrong.


As pointed out, multiple bleedings should have flagged up a massive warning - hydraulic systems shouldn't need more than one, maybe two, bleeds and will sit for years.

 Posted: Mar 21, 2018 01:40PM
 Edited:  Mar 22, 2018 06:13AM
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CA
Quote:
Originally Posted by Alex
Quote:
Originally Posted by Dan Moffet
Yikes!!! You mention adjusting the adjuster. Did you also adjust the handbrake? The adjuster works on one end of the shoes and the handbrake mechanism on the other. They need to be set up equally. The turning drum may have pulled the shoe around to where it slipped off the piston tip.

Sorry Dan, but that is utter bollocks.
...

Too right my friend! I don't know what I was thinking... ( probably not much!). In my defense, it has been years since I had the drums off. I was trying to visualize what could be incorrectly assembled or adjusted. I suppose if the handbrake was loose the piston might retract far enough to disengage the shoe.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Mar 21, 2018 12:52PM
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CA
Holy Frack !  Glad you're OK Mark !

  ~ 30 minutes in a Mini is more therapeutic than 3 sessions @ the shrink. ~

  Mike  Cool  NB, Canada   

 Posted: Mar 21, 2018 12:22PM
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Without seeing the offending hub/brakes it is impossible to say what happened, But what I can't believe is that knowing you had a problem and had to bleed the brakes more than once to get a pedal you continued to drive it until it failed before you actually took a look at what was wrong!! As you say thank God you didn't wreck a nice Original Cooper S let alone hurt anybody else.................................

Mini's are like buses they come along in a bunch

 Posted: Mar 21, 2018 10:43AM
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GB
Quote:
Originally Posted by Dan Moffet
Yikes!!! You mention adjusting the adjuster. Did you also adjust the handbrake? The adjuster works on one end of the shoes and the handbrake mechanism on the other. They need to be set up equally. The turning drum may have pulled the shoe around to where it slipped off the piston tip.

Sorry Dan, but that is utter bollocks.

The 'dead' end of the shoes sit on the adjusting tappets and are moved in and out by the adjusting screw symmetrically.

The 'live' end of the shoes are moved by either the wheel cylinder or the the handbrake mechanism.  The handbrake has no part at all in setting up the brakes for bleeding or adjustment as the mechanism is slack in the shoes when the handbrake is off.  If the handbrake is on the shoes will drag.

With everything fitted correctly it is also impossible for the shoes to move.

The only thing i can think of is that on reassembly you didn't hook one of the shoes into the piston properly - probably onto the edge of the slot instead of inot the slot - and it came out under load.

 Posted: Mar 21, 2018 08:34AM
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did you put the circlip on the other side of the backplate where the wheel cylinder mounts? 

 Posted: Mar 21, 2018 07:31AM
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CA
Quote:
Originally Posted by helpmymini
Is the handbrake adjustment in the car at the handle? I did notice the cable had play. I can't imagine the shoe came out of the piston; it has a deep slot.
Yes, the handbrake adjustment is at the handbrake handle in the cabin. Depending on the age of your car, it may have one or two adjusting nuts - the older type (pre 1976) has one for each cable and newer ones combine it. The cable quadrants etc. also need to be clean and movable. If it was really slack, the end of the shoe might have slipped off the piston slot. Shoes must be installed the right way around, the return springs need to be installed the right way around and the shoe-to-cylinder retaining springs should also be in place.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Mar 21, 2018 07:25AM
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Quote:
Originally Posted by helpmymini
I have had a problem with a rear wheel cylinder. I first had an old one with a small leak, so I swapped it out with a new one. That was last fall. When we had a thaw I went to get my mini out of storage and the pedal went to the floor. I bleed it out and it was fine. This happened any time I left the car for more than a few days. Recently I bleed the brakes until I had clear fluid then tightened the bleeder. I took off on my trek then about 2 miles away I was coming to a stop sign and the pedal had extra travel then on second pump went to the floor. Luckily I thought quickly and down shifted to as slow as possible, looked both ways and blew the sign turning right. There was no traffic and all is good. I limped back home (again, no traffic anywhere out in the sticks) and pulled the wheel. One of the pistons had come completely out of the cylinder!!!! I cleaned everything up, reinstalled the piston and adjusted the brakes with the square top adjuster. It was almost all the way in or back or not pushing out the shoes. My question is: If the pads are like new, and the adjuster is all the way out can there be enough play in the shoes to allow the piston to do this normally? Is there something else wrong? Could the cylinder have moved on the back plate? If nothing else, check your brakes often. This scared the hell out of me. My car is an original Cooper S with original paint. I could have permanently damaged it beyond repair.
I cannot imagine how there would be enough space for a piston to drop out of a wheel cylinder with everything in place. The wheel cylinder is fixed in place and the way the bleed nipple is located it would only have slight movement if any.
Even if the drums were worn out and there were no shoe linings left on the shoes i still don't think there could be enough space for it to happen. Something else must be going on with the brakes inside that drum.
I would start by measuring the drums to see if they are in spec.

If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Mar 21, 2018 05:18AM
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US
no mention of the retaining springs.

 Posted: Mar 21, 2018 04:25AM
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Is the handbrake adjustment in the car at the handle? I did notice the cable had play. I can't imagine the shoe came out of the piston; it has a deep slot.

Mark Looman, Ada Michigan 1967 Austin Cooper S
 Posted: Mar 21, 2018 04:20AM
 Edited:  Mar 21, 2018 01:37PM
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CA
Yikes!!! You mention adjusting the adjuster. Did you also adjust the handbrake? The adjuster works on one end of the shoes and the handbrake mechanism on the other. They need to be set up equally. The turning drum may have pulled the shoe around to where it slipped off the piston tip.

See Alex's reply above. "utter bollocks' occurs when one isn't fully awake!

.

"Hang on a minute lads....I've got a great idea."

 Posted: Mar 21, 2018 04:10AM
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I have had a problem with a rear wheel cylinder. I first had an old one with a small leak, so I swapped it out with a new one. That was last fall. When we had a thaw I went to get my mini out of storage and the pedal went to the floor. I bleed it out and it was fine. This happened any time I left the car for more than a few days. Recently I bleed the brakes until I had clear fluid then tightened the bleeder. I took off on my trek then about 2 miles away I was coming to a stop sign and the pedal had extra travel then on second pump went to the floor. Luckily I thought quickly and down shifted to as slow as possible, looked both ways and blew the sign turning right. There was no traffic and all is good. I limped back home (again, no traffic anywhere out in the sticks) and pulled the wheel. One of the pistons had come completely out of the cylinder!!!! I cleaned everything up, reinstalled the piston and adjusted the brakes with the square top adjuster. It was almost all the way in or back or not pushing out the shoes.

My question is: If the pads are like new, and the adjuster is all the way out can there be enough play in the shoes to allow the piston to do this normally? Is there something else wrong? Could the cylinder have moved on the back plate?

If nothing else, check your brakes often. This scared the hell out of me. My car is an original Cooper S with original paint. I could have permanently damaged it beyond repair.

Mark Looman, Ada Michigan 1967 Austin Cooper S