Brake pedal biting at the floor

[JaamesVRS]

Had my car on the rollers yesterday to see what it was making rolled 166.8bhp and 325ftlb however after it come off the dyno I noticed that the brake pedal was travelling further before biting thought nothing of it, however today I jumped on the brakes now the brakes don't bite until they are almost on the floor, if I very gently pump the pedal then brake it comes back up again until braking again then back to the floor. Is this a case of simple bleed the brakes? Or is there adjustment etc? 

 

Note; the handbrake was actually on at the time of braking so has that come out of adjustment causing excess travel? Used to my works van with auto handbrake and was in a rush forgot to take it off when a neighbour shot out they're driveway infront of me which is why I had to anchor on (oops) 

Edited 10 December, 2017 by JaamesVRS

[JaamesVRS]

Bump

[CWARD]

Try bleeding it and if the pedal continues to sink to the floor whilst you have pressure on it then it will probably be the master cylinder

[KenONeill]

@JaamesVRS - The handbrake operates on the back wheels, so the only reason they need to spin is to prevent ASR or ESP cutting in and killing the power. ASR is switchable, so it shouldn't be operational during a dyno run.

 

Anyway, if you think the HB is out of adjustment, with the engine running, push the footbrake down hard, and work the HB until you get the travel down to 6 to 8 clicks if you can. If that doesn't get your pedal back up then as @CWARD says in #2.

[TripleMcB]

How's the fluid level? Any leaks around calipers? Any leaks around the master cylinder? What's the state of your pads 'n' discs all around. 

 

If you pump the pedal with the engine off does it go hard? Then start the engine the pedal should go softer and move towards the floor. If not then you have a servo fault, or collapsed servo hoses. 

Edited 11 December, 2017 by TripleMcB

[JaamesVRS]

I've just noticed The rear caliper is leaking from the handbrake cable l, probably anchoring on the brakes has drawn air through the leak possibly? The pedal goes hard when the engine is off and brakes are pumped as normal just when engine is running the pedal goes to the floor before the brakes bite. I was thinking of upgrading the braking system in the near future anyway to the 312(?) setup up front and the larger rears obviously the rears first due to the leak, is this advised? Or just upgrade the fronts and replace rears with OE spec calipers? All of my cars to date have had huge brakes with track spec pads so I'm used to stopping on a penny even my first car 8 years ago (corsa) I fitted the VXR setup and the car went from 100-0 quicker than 0-30 :lol:

 

the pads and discs all round are in good condition with plenty of meat left on them. I'll try give the system a bleed and see what happens! 

[JaamesVRS]

I've also read you cannot bleed these cars the conventional up down way? You need an easy bleed due to the seals on the MC? Is that true or ******? As I don't own an ezbleed kit and just been laid off 2 weeks before xmas! Never rains but poors!

[CWARD]

No idea on the bleeding but I do have an Ezbleed kit in the garage somewhere not been used anymore as I use a Mittyvac now. If I can find you can have it for the cost of postage.

 

If it is leaking from where the hand brake arm enters the caliper you will continue to get air in the system so you'll need to repair this first. You'll need to replace the caliper or if you're confident enough just replace the seal on the shaft which will be an o-ring but will need the piston and hand brake mechanism remove to do so in which case replace all the seals.

[JaamesVRS]

It's okay mate I just used my trade card at Halfords and got it for tenner! Bargain tbh! Yeah I did think this, so it's worth buying a repair kit then? And do the seals etc? Haynes spanner difficulty? How many spanners would you say? Out of 5? If so I'll do both sides to rule out any further issues. What's the cost of the repair kit do you know? 

[JaamesVRS]

Is this the correct kit? 

 

P.s - Thankyou for the offer for the eezibleed much appreciated!! 

[CWARD]

Couldn't say if it the correct version but I have used that supplier (recognise the picture layout) before for doing my brother Shogun Sport and they are good kits and if they are stating it's right for your car I would trust them. 

 

Have you ever pulled a caliper apart?

[JaamesVRS]

I haven't pulled one apart personally however few friends of mine have which I'm sure would be happy to help! The handbrake used to be around 3 clicks and is now about 8 clicks, could this be causing the issue? Only been high since the RR so maybe the dyno operator pulled it up a bit too high which has affected my pedal? Can it be manually adjusted? 

[JaamesVRS]

I've also read online the master cylinder may need to be bled too? I understand there is 2 bleed nipples and the 90 degree boost hose needs to be removed

 

is it a case of the same process as brake caliper? Hook up the easy bleed kit and crack off the master cylinder nipples? 

[CWARD]

Handbrake lever travel will be either the cable that needs adjusting or pad wear. The hand brake mechanism within the caliper adapts to the pad wear by the means of screw attach to the piston, hence the need to wind the piston back when changing pads.. It's mechanically applied rather than hydraulic like the foot pedal so no affected by air in the system.

 

I only asked if you'd done them before as you need to completely disassemble the caliper and the hand brake mechanism can fall apart when removing it so may need putting back together in the correct order.

[KenONeill]

@JaamesVRS - The absolutely critical point in doing a caliper rebuild is complete cleanliness during the rebuild. Clean the caliper before you start dismantling, and work inside on a table covered in old newspapers.

[JaamesVRS]

Lovely thanks gents - I have plenty of degreaser/brake cleaner/ use of airline etc for the operation, I may just upgrade the rear braking system for for the larger alternative yet I'm still undecided. If it breaks upgrade etc! 

 

In in terms of bleeding the MC is it carried out the same way as bleeding the brakes? Using the eezibleed and cracking off the nipples? 

[CWARD]

Master Cylinder, I would assume done the same but would be the last to be bled.

 

If you have an airline and easy way to get the piston out is to wind back. Tap the bolt that the hand brake arms attaches to with a rubber/wooden mallet until it is flush with the caliper. Drain all the brake fluid out and close the bleed nipple. With the air gun attachment place it in the hole for the brake pipe and give a blast of air. The piston complete with the handbrake mechanism will pop straight out. Best to pack in front of the piston to prevent it shooting out straight across the garage. 9 out 10 times it just pops out and prevents damage to the piston.  

Edited 12 December, 2017 by CWARD

[JaamesVRS]

Lovely thanks for the help! I'm in two Minds currently whether to replace these calipers for the larger setup or rebuild these ones, may just uograde can never have enough stopping power 

[CWARD]

Not sure what your options are regarding upgrading the Fabia brakes so can't comment. I would start at the suspension though before upgrading brakes as this can improve stopping power by increasing tyre adhesion.

[stevobeavo]

Wouldn't bother upgrading the rear brakes. They do rather little braking hence why the discs rust up and corrode pretty quickly. 

[CWARD]

13 minutes ago, stevobeavo said:

Wouldn't bother upgrading the rear brakes. They do rather little braking hence why the discs rust up and corrode pretty quickly. 

 

Not quite true as they are required to provide stability otherwise you end with the back end shaking about under braking. Agree though in not much point in upgrading them without additional tyre traction otherwise you'll just end up making the ABS work more.

[bmbmdmb]

Why not just replace the caliper as a whole unit? All mine were replaced . try Avs at Norwich. Got mine for 70 quid.1x rear caliper.  You might find the piston is scored with dirt getting past seal. Use new brake hose union o rings . buy copper.  Don't buy recondition. I did originally. Piston was found to be  sticking like my old one. False economy. Check other side of same axle. Rubber seals soften and then leak. Probably want to replace both sides sooner than later.

Use bungee cord to avoid 'hanging the caliper'. You can fit new caliper then and simply swap brake hose over.

No doubts then about condition of your old caliper.. You can spray paint caliper yourself. I found good green paint match to Skoda green or use red. Rosso red

Edited 15 December, 2017 by bmbmdmb

[rum4mo]

I've bought reconditioned callipers, they were branded Pagid I think, got them at ECP and returned the old callipers to them, they came with new copper hose end seals.

 

Maybe not an issue with this age of car, but I think that the piston size changed at some point in these rear callipers.

 

Edit:- if you are keeping that car for another couple of years, I'd have to agree with the idea of replacing both sides, in my case I knew that my car was being sold on in less than a year, so I only fixed the seized side, though the other side did seize up a year or so later, this I know as I was brave/stupid enough to sell it to an ex work mate - and 4 years on, that car is still running with possibly a BCM or wiring issue (2000 VW Passat 4Motion 2.8 V6)

Edited 16 December, 2017 by rum4mo

[JaamesVRS]

Thanks for all the replys. Yes I would replace the rears as a pair, no point doing one side as could cause imbalance or the other side to fail shortly after do it right first time etc