Technical Seicento Brakes HELL!

[shotokan18]

Hey Guys,

Why is it that every time i do a job on my sei something always goes wrong?... You ready for this?

Ok got the tyres changed the other day and while they were off noticed the front brake shoes needed replacing.

Following day got a kit and proceeded to change the brakes. When done we started the car and tried them and noticed the pedal went straight to the floor. After a little pumping we noticed the brakes got better so we assumed there was air that got into the hoses somehow and the spongy-ness was the air being compressed until it couldnt no more and finally we had braking.

So naturally we bled the front brakes and after a while felt as normal until i turned the engine on and tried when my foot went straight to the floor again! so we went to bleed the back brake hoses when we noticed the nut on the nipple had seized.

Took it to a mates garage, he had the same problem with the rear brake nipple nut, so decided to replace the housing unit as a new nipple wasnt available (even from fiat!) once that was done he bled the whole system and still no result, and then somehow found out that the master cylinder had gone so he got a new one ordered and fitted that hoping it would fix it. WRONG! Now he hasnt got a clue what else it could be as he's checked the whole braking system over from start to finish and cant find anything else it could be.
So I turn to you, knowledgeable members of fiat forum, has anyone ever had trouble like this or is there a curse on this car? any help/ advice would be deeply appreciated as my gf's baby is making her very sad as she has to rely on me now to drive her around. PLEASE HELP!

Gavin:bang:

 

[Fivehundred]

It's normal for the pedal to go "long" after you replace the pads. Obviously you need to lever the pistons back to the new pads will physically go in. The first time you press the pedal you need to move the pistons significantly so they sit snug against the pads, and the pads snug against the disks.

It may be that he seals in the master cylinder were damaged because as you pressed the pedal it reached part of the bore they never normally reach. It's also possible to turn master cylinder seals inside out by levering the pistons back without opening the bleed nipple. I've never had a Cinq do it, but certain Volvos are notorious for it.

The braking system in a cinq is capable of self bleeding, leave the nipples open and the fluid drains out. I normally bench bleed master cylinders before fitting. Fill it up with fluid off the car, qwork it, then when the air is purged fit it on the car.

When you bleed work from the longest brake line down to the shortest, or use a power bleeder.

Pete

 

[Liam]

Quite a common problem this weather, read this thread https://www.fiatforum.com/cinq-sei-technical/62321-bloomfieldliams-brake-overhaul-2.html?highlight=bleeding+brakes and do a search in the cento section and see what comes up.

Liam

 

[Malin Dixon]

How flat are the disks?

If the disks aren't flat, it will take ages for the pads to wear to the shape of the disks. There are 2 main reasons that the disks don't stay flat.

1. A lot of cars have soft brake disks, that wear as fast as the pads. This means that it is longer before the pads need replacing, but the disks may need replacing as well. It saves a lot in labour to do it that way.

2. If you get any rust on the edges of the braking area on the disk, this slowly cuts into the pads, leaving you with a bit less braking area, but a very odd shape of pad. The new pads will be flat, and won't work properly until you have got them to the disk's shape.

Either way, changing the disks and the pads together is often a good idea.

Are the sliding calipers sliding OK? If one is jammed, it will twist and not slide. Then it twists back when you take your foot off the brake pedal, and leaves lots of play. If the pads were worn, the new pads are much thicker and the back-plates will be resting on a part of the caliper that hasn't had anything on it in ages and may be rusty, leading to jamming. Scrape the rust off and make sure it all slides.

The pads have nothing to hold them in place when you take your foot off the pedal, so any movement of the disk can push the pads back, and lead to excess play. This could be a failed wheel bearing, or a warped disk.

Have you damaged a hose? If one was about to go, the extra bending when you take off the caliper to change the pad, could have finished it off. It might now be expanding when you press on the pedal.

Good luck.

 

[shotokan18]

hey dude,

i think the seals may have turned inside out as i was unaware we needed to open the bleed valve to change the pads. but the guy in the garage has supposedly got a new master cylinder now and fitted it so wouldnt that fix the prob? btw its not a cinq its a sei and i needed to pump the brakes to get the fluid out when bleeding. NE more ideas?

 

[shotokan18]

didnt notice the other posts, i'll see if i can get the car back off the garage tomorrow and i'll take a look at the discs
keep the ideas coming guys!

Thanks

 

[Malin Dixon]

The fluid should be free to run back into the reservoir when you take your foot off the pedal. If it isn't, when the fluid heats up and expands, which is normal, it has nowhere to go and puts the brakes on a bit.

Also, when it cools down, the fluid will contract, and so a bit of extra will be needed from the reservoir.

There are ports in the master cylinder which should be open when your foot is off the brake pedal, which let the fluid flow between the brake lines and the reservoir. If not you get problems.

On our Cinquecento, the pads wouldn't move back into the caliper until I opened a bleed nipple, and the brakes were getting hot even in gentle driving. It was a failed master cylinder. Both problems are now gone.

Other possible causes are the brake servo or pedal not pulling all the way back when you take your foot off. This leaves the ports closed all the time. Or a hose inner can fold up and make a valve.

http://www.brakesint.co.uk/technical.html has good advice.

 

[shotokan18]

Ok guys,

The guy in the garage found the problem

When we changed the pads over on the front discs, I let the missus do one side after watchin me do the other, so she knew how to do it herself, it turns out that when she fitted her side the barckets that hold the pads in place were not fitted correctly and as a result were twisting the metal away from the ferodo therefore only a minimal amount of the pad was actually touching the brake!

He fitted new pads again, bled the system just to check all was good and the brakes now work better than ever!

Once again I have a happy missus coz she got her baby working fine again and doesnt need me to drive her round anywhere.

Moral of the story: DONT LET YOUR MISSUS WORK ON THE CAR!!! LOL!

Thanks for all the advice

Gavin

 

[randomizered]

Thats what happened to me a while ago (see my membership date) and drew me to FF. Sorry I didn't see this thread earlier, as I could have saved you some time.

Sadly I had no one to blame but myself

Cheers,

Kristian