My wife was driving the 500 the other night and she suffered a very nasty brake failure .... She pressed the pedal to brake at a crossroads and the pedal dropped to the floor and the brakes failed completely... She continued across the junction ( luckily there was nothing else coming ) and then came to a stop on the incline... I attended ( dutiful husband ) and having checked the brakes as best I could in the dark, drove it the 5 miles home. I had no issues and the brakes worked ( they are crap though eh !! ). Today I looked around the car and I cannot find anything amiss. The reservoir is full and I can't see any leaks. The brakes work fine. My wife is now refusing to drive the car again so I need to sort it out.... Could anybody give me some tips please ? I am led to believe that the master cylinder ( I'm presuming that's the servo ) has a habit of failing... Thanks in anticipation...

Do the test:

Climb in.. pump pedal as hard as you can.. pedal should be solid.. not drop

Keep your foot on pedal

Wait 30 seconds..push harder.. no more travel?

If it drops.. youve got a leak

With foot still on brake padal

Start engine.. it should drop a little

Servo

But if you still keep pressure on pedal it should drop no more


Let us know

Total failure without an leak is likely to be the master cylinder. Don't risk it, get an OEM replacement fitted buddy. Check the servo paint finish - you may see bubbling paint as the fluid has come into contact with it.

A failed servo (operation described above) will only mean more effort is needed to operate the brakes - not total failure.

If it fails and drops to the floor, it cannot be a small leak or "some" air in the system. It would not come back to work again if it fails in that manner. And you would have lost a noticeable amount of fluid and more as you continue to use it.
Failed servo support would only mean you have to press harder - just the opposite effect of what you described.
It might be a mechanical failure between the pedal and the master cylinder (not sure what the connection looks like in the 500 though)
or - sorry to ask - could it be possible she stepped on the clutch by mistake ?

Playing devils advocate here but is it possible she put her foot on the clutch instead of the brake?

All modern brakes are split so if something fails you have at least some braking, it's a unusual issue in that it can't be 're created.
Has any members ever had a total brake failure?

It's unusual you say the brakes are crap? I find the brakes on my daughter's 2008 diesel quite sharp.

Service the rear drums, front calipers, check for seized cylinders/pistons. Replace brake fluid. It could have been brake fade due to binding drums, causing fluid to boil?

How is the handbrake? It should be able to lock the back wheels if pulled hard enough.

Hope you get it sortied

Have to say the brakes are really quite effective provided the rear drums are still self adjusting.

typecastboy said:

...is it possible she put her foot on the clutch instead of the brake?

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I'd say that's by far the most likely explanation. The 500 pedals are offset, making it easier to do this by mistake than with most other cars. They're also quite close together.

The OP said the pedal went to the floor, but that the brakes worked normally when the car was next driven. I can think of no conceivable mechanical fault which could cause this to happen.

If the brakes fade, the pedal does not go to the floor.

If the servo fails, the pedal does not go to the floor.

If the master cylinder fails completely (a most unusual fault), the brakes do not work normally when the car is next driven.

If you press the clutch by mistake, the pedal goes to the floor, surprisingly easily, because you instinctively press harder if the car isn't slowing down (I've done this myself, very occasionally).

The Younger Mrs S' Uno 55 (back in the day) had a master cylinder failure .. the symptom was like a very spongey pedal that dropped to the bulkhead slowly when you pressed the pedal.

It didn't lose fluid (the fluid was bypassing the seals and ended up back on the reservoir side) but the pedal didn't "collapse".. it fell slowly, had some resistance and the brakes worked (but not very fiercely) while it lasted.

If you were braking for a period of time (down a slope etc) then the pedal would eventually reach the floor and you had to lift it to reapply it, if you wanted to continue braking... otherwise it lost braking force, since it needed pedal pressure to get any brakes.

Once released, the pedal would feel "normal" but it was always still spongey and would drop again as soon as you put pressure on it.

If your brake pedal is firm and stays firm, then I'd say she most likely pressed the clutch by mistake... but have a look for leaks from the caliper seals, at the rubber hoses from each caliper and also those that pass under/over the suspension beam...

Then check the metal pipes at every joint and if you can, all the way along their lengths from the master cylinder to the caliper.. you could have some random/strange split or corrosion going on.. and a lot of metal lines have plastic coating which could hold fluid in, to an extent. Any strange bulging/wetness shouldn't be there.


Ralf S.

Update please Fleurdelyes

I tried pressing the clutch with my brake foot, ok o have size 9 feet but it's really quite hard to get to press the pedal with the right foot

Sorry for the delay.... I have tried all the things you mention...

The pedal is stiff when you first apply pressure and pump .... 30 seconds later it didn't go any further ( other than the fact that I was trying to put it through the floor ).
I kept my foot on the brake and then started the engine ... It dropped as expected and then became as solid as expected ( useable ).

Thanks for the update..

Probably good enough to carefully drive to a garage for a proper inspection

A favourite.. given you say the brakes are not great.

The friction pad will have fallen off a disc pad

This is 2 fold.. its leap from the car means the pedal needs 2 full pumps to 'take up the slack'

Then once you've restored pedal travel..

Its metal to metal on one side of the disc.

Could be a lot worse

I am going to get the wheels off properly and have a good look... I will change the pads and shoes and then see what occurs. Cheers.

Fleurdelyes said:

I am going to get the wheels off properly and have a good look... I will change the pads and shoes and then see what occurs. Cheers.

Click to expand...

You might want to read this thread before you start.

jrkitching said:

You might want to read this thread before you start.

Click to expand...

You can buy Pagid pads & discs from ECP for about £50 all in; from experience, they perform and last well. Given the low cost of the discs, I'd change these at the same time.

Brembo pads & disc's can be got for about £43 upto midnight tonight at ECP!
But a total check of the whole brake system needs doing inc renewing the fluid.

If you're going to put new pads in there, I'd recommend Brembo. If you shop around you can often find them at prices not too much higher than the most bargain basement pads out there.

They tend to be better made than cheapo pads, so the backing plate fits in the caliper more precisely and doesn't jam when it's rusted slightly, as a lot of less well fitting pads can.

Pagid are also not bad but the ones I've had have always needed a mid-life remove/free-off/re-fit to keep them going (although this is on the rear calipers.... front calipers usually have enough force to bully any slacker pads back into line).


Ralf S.

Are you sitting comfortably ? Then I shall begin.

I ordered a set of front discs and pads and a set of rear shoes ( Euro car parts half price Pagid ) , anticipating that I would need at least these parts. I set about getting the wheels off and then finding out how to take the disc off of the hub ( I’ve never seen a design like that in my life and I have changed a good few different models in my time ) I did not see the hex shape at the base of the spigot as it was so corroded that it was basically part of the disc ! A few telephone calls and a visit to the local Fiat dealer ( not very helpful at all ) and I realised that I need to undo the spigots. I set about this task having sprayed some penetrant on them before a well-earned cup of tea. The first one started to move and then…. Thud !! It snapped in the hub…. Brilliant. Another call to the Fiat garage to find out if they had any stock…. No was the answer and they are £6.51 + VAT each and will take two days to get here…. So… Head scratching ensued and then a trip to my local tool dealer for some Gucci new tap and die set. It is an M8 thread so all it needed was for me to re thread the hole as it would not budge. Drilled out with an M6 and then re threaded to M8. Steal one of the spigots from the rear and we are away….. I pulled the caliper off of the hub and found ( both sides ) that the rubber had perished so now I need two new caliper…. Great ! Ordered from my local stock all shop ( £173 if I take the old ones in or there is a surcharge of £77 on each one !! Why is the sliding bolt placed directly in line with the brake line so as to make it virtually impossible to get a 8mm hex socket in ? I took the reaction frame out and my God I’ve never seen corrosion like it…. I used wet and dry like I had shares and a drill bit brush…. They still did not come up to my satisfaction but I had had enough. They were far woprse than the thread I looked at... I could not get the pads out at first due to the corrosion and I very much doubt that the pads have been returning for some time. I had to take a hammer to the pads to get them out…
Caliper arrived this morning and I set about fitting them. All went relatively well and eventually I got the brakes constructed and on the car. I now had to bleed the brakes. This went fine until there was a large air bubble and a huge amount of white cloudy liquid came out of the offside caliper bleed after it. No more air and so all tightened up.
I Moved to the rear of the car… tried to get the drum off but it was so badly corroded into place that it would not move … I Sprayed some penetrant on the holes and gave it another cup of tea time lapse… I watched a video on You Tube and found that I just needed to be forceful with a hammer … I lumped it and it came off…. Really bad corrosion once again so set about cleaning it all up… Replaced the drum and then the road test…. All seems good.
So to sum up….
You need a M8 tap just in case, You need a lot of elbow grease and a lot of wet and dry, you need a lot of copper grease and a good socket set … If I did the job now with everything as it should be, greased and clean, I reckon the job would take me 15 minutes tops… It’s taken me two days and I have yet to find if it’s cured the problem… Thanks for the links and help.