General Brake Failure

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General Brake Failure

ksf60

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Hi Fiat forum, its been ages....

So my Punto is due an MOT next week so am at "dad's garage" for a check over.

Front wheels off, osf wheel bolts ridiculously tight. Local garage changed a coil spring about a year ago, so vastly over tightened.

Anyway, all good on NSF, applied brakes so the disk won't spin whilst wheel bolts were freed and lubed, all good, wheel back on.

Same treatment for the OSF. Placed foot on brakes like NSF attending to very stiff bolts and BANG! something dripping on face. It wasn't water... Brake peddle straight to the floor. Bugger.

Brake hose has blown off the union! The metal pipe is unioned to the metal end of the flexi hose, being swagged, the metal swagging part under the thick rubber strain relief part of the hose.

Very bad corrosion as seen in the picture.

Very lucky to have this happen whilst stationary. Had this happened in an emergency situation, the minded boggles at the thought.

Be warned, they may look fine, yet be ready to fail.

Hose now out of the caliper as is the nipple and the union free of the rusty flexy pipe end.

Typical this should be a long bank holiday weekend. Hopefully local shops should be open again tomorrow for two new brake pipes.

A 60 plate vehicle with 72k miles. Once front is done, the rears will get a service. New shoes a possibility, cylinders if needed and flexi hoses replaced.

Cross fingers, eyes and toes....
 
Picture mentioned above
 

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Picture mentioned above
Oh my goodness.
That is a shocker.
From picture looks like the swaged part of the union parted company from the union years ago due to corrosion. only the very small metal tube inserted into the hose was holding it together.

I will make a metal note.

Thanks
 
Yes, a really lucky escape, could have well been a tragedy waiting to happen.

All other brake hoses will be changed.
 
Yes, a really lucky escape, could have well been a tragedy waiting to happen.

All other brake hoses will be changed.

Lucky indeed, but this is down to lack of servicing. Sorry if this sounds too frank, but facts are facts. Brakes seem to be top of the list of being least looked at. Glad you’re going to be changing other hoses.
 
The thing is it look fine, the thick rubber strain relief tube covers the swagged part, so no real way of checking...no leak, no staining, it just blew off.

But yes, moral is, change hoses every 5 years or so from now on.

Merc service/change interval is 3 years, but if you can afford a Merc you can afford the bills...
 
But yes, moral is, change hoses every 5 years or so from now on.

Merc service/change interval is 3 years,

That punto has travelled away from Italy for 11 years..;)
there does appear to be a fair degree of corrosion :(

Ive got 2 x 2013's they still have the zinc inplace


Merc changing it all at 3 years..
They will be up in court for environmental misuse ;)

Edit : your failure seems 'unique'..

But I was thinking..'nobody ever changes the clutch hose'- WRONG..

The modern 500 has an appetite for the union on the innerwing 1 to 3 years appears 'normal' :(
 
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Rather a shocking failure this which I've actually never come across before. Thinking about it though it's entirely logical that it might fail in this way.

Back in my instructor days I was always very strict with my lads that they fully support things like calipers and not let them hang on the flex hose. This was usually accepted without question but on one occasion two "smart Alecs" decided to "get clever" about it so I set them a wee project to write up a wee instruction for me to use in lectures as to why one should or should not allow weight to be taken by the hose.

One of the things they found out, which is highly relevant here, is how the metal ends are fitted and secured to the flexible rubber pipes when manufactured. The metal end has a "spigot" over which the hose is pushed and around this is a much larger diameter metal "collar", all part of the metal end, which is then crimped over the hose to hold it. Think now about how this works in service - when the fluid in the hose is pressurized it will try to expand the hose and leak out between the spigot and the end of the hose. The crimped collar tends to stop this happening anyway but the internal pressure is attempting to expand the rubber hose against the collar. This actually locks it even more securely in place and stops the hose coming off the spigot. If the crimped collar wasn't there the hose would expand and just blow off the spigot, Which, because it was badly corroded, is exactly what happened here.

Think now though about what you are doing to this crimped connection if you let a heavy caliper "dangle" from it. You are now applying a force in tension to the rubber hose and it's not designed to withstand this. By pulling on the hose you are elongating and "thinning" the side wall rubber of the tube which could pull it out of, or, more dangerously, partially out of, the crimped fitting making it much more likely to then fail when pressure is applied during braking. So, DON'T LET "STUFF" DANGLE FROM BRAKE HOSES!

I have to admit I'm always careful to take a good look at metal brake pipes when working on any of the cars and I usually flex the hoses to look for external cracks but, I've just realized, I don't look all that closely at the flex hose ends. So now I'll be taking a very careful look at Becky's hoses in the near future when I'm tackling the rear axle corrosion.
 
I now have the car for a week if need be, he is on holiday, in Thier house !

Anyway new nipples arrived last week, 8mm X 1.25 pitch. Got them from vehicles wiring products mail order.

The new nsF brake hose ( and the pads ) seem to have gone walkabout ( I'm sure I gave them to him to look after ! ) So got another new hose on Tuesday, ready for this week end.

Anyways the car arrived with me at 4pm, only 6 hours late !

New nsf hose and new nipples on, will finish tomorrow if the new pads are found, else another new pad set grrrrrrrrrr

We replaced the rear shoes and cylinders before the mot. Had great fun getting the rear drums off ?.

See the picture of the NSF hose, again ready to fail in an emergency.

Maybe these didn't have any plating when they were fitted in the factory ?

Need to research mail order fiat parts, suspect g/box selector shaft oil leak....and starter motor off to investigate the iffy starter, been ok since we cable ties the solenoid energiser wire, suspect bad/loose connection.

Other than that the Punto is running fine.

Famouse last words...
 

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I now have the car for a week if need be, he is on holiday, in Thier house !

Anyway new nipples arrived last week, 8mm X 1.25 pitch. Got them from vehicles wiring products mail order.

The new nsF brake hose ( and the pads ) seem to have gone walkabout ( I'm sure I gave them to him to look after ! ) So got another new hose on Tuesday, ready for this week end.

Anyways the car arrived with me at 4pm, only 6 hours late !

New nsf hose and new nipples on, will finish tomorrow if the new pads are found, else another new pad set grrrrrrrrrr

We replaced the rear shoes and cylinders before the mot. Had great fun getting the rear drums off ?.

See the picture of the NSF hose, again ready to fail in an emergency.

Maybe these didn't have any plating when they were fitted in the factory ?

Need to research mail order fiat parts, suspect g/box selector shaft oil leak....and starter motor off to investigate the iffy starter, been ok since we cable ties the solenoid energiser wire, suspect bad/loose connection.

Other than that the Punto is running fine.

Famouse last words...

Wow that was definitely due to fail like the other in the next few years

This is why I've slapped a load on anti sieze paste over the end of my brake hoses
That being said on a 2017 car it should be years until anything get that rusty
 
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