Wierd Brake pedal after new caliper

[gunman]

Guys, I think I may have an issue with the brakes on my car and I have an MOT tomorrow morning first thing.

First off, all my brakes are standard all round. I have replaced the OSR caliper with a new one as the handbrake was siezing and the caliper had developed a leak too (probably due to the heat from the sticking handbrake). I have bled the caliper (many times) and get a solid brake pedal, however If I leave the car for 30 mins or so and start the engine I can put the pedal to the floor, although there is some resistance).

When driving the pedal goes down just over an inch or so before the wheels lock and the ABS kicks in. The brakes seem OK on test drive. Is this pedal normal? Cant say I noticed before if it was.

If I turn the engine off and pump the pedal about 20-30 times It goes rock solid again so I dont think there's air in it. I have checked all calipers and joints and cant see any leaks.

Am I worrying about nothing?

[Error404]

sounds like you tried to bleed it with the handbrake on mate
Pedal should never sink to the floor, although it will give a little as the hydraulics pressurise on start-up.

[gunman]

I'll admit that yes, I did first time around, but not after that. I got a decent pedal and left if for a week as I fitted new discs and pads to the rear. After they bedded in I adjusted up the rear calipers again by winding the pistons back in and then out to be a tight slide over the pads. Pedal went back to spongy again yet I never did anything to disturb the hydraulics.

I'm wondering if my new caliper is dodgy.

[gunman]

I'm hoping this is just me having a dose of madness. Maybe the pedal isnt going right to the floor. My wife was pumping the pedal as we were bleeding the brakes, she says the pedal was traveling much further when they were being bled. Maybe the pedal has a bit of travel then goes solid. I thought it was a stop on the pedal. Put it this way, they aren't getting any better before my MOT as we have les than 90 mins of daylight and I need to wash it as it's covered in cack.

[Error404]

you really need to partially bleed the brakes, i.e. get fluid to the new caliper. then pump the pedal to seat the pistons to the back of the pads and the pad up to the discs. Then bleed the about 1 pint / half a litre of fluid through and it should be fine.
Have you bled the whole system or just the one corner? If you didn't use a decent hose clamp when you changed the caliper it's possible air pockets have got in the other lines and need bleeding out.
If they stop the car properly and the handbrake works they should be fine for the MOT, regardless of the amount of travel on the pedal AFAIK.

[gunman]

I think if I need to bleed the NSR caliper I will need a new caliper for it too as the bleed nipple is rusted to hell and is rounded off just for good measure. I might in the near future change to braided flexi hoses and bleed the whole system. As for the hose clamp I used needle nosed vice grips .

[sidrick]

I've seen ABS systems pump air all around the car. I've had this issue when changing my o/s/r/ caliper (sticking handbrake too).

If I change a caliper I bleed every corner.

[gunman]

Well, the brakes seem to be enough for the MOT anyway as I got a pass this morning. I was in the car when it was put over the rolling road. Interestingly the new caliper was slightly weaker on handbrake and footbrake that the old rusted up one on the other side but were well within tolerances. Fronts were virtually no imbalance. Front calipers were about 3.7Nm and the rears about 1.8 - 2.0Nm. I'd be interested in finding out how this realtes in real terms to how effective the brakes are as I know you'd want the brakes better than the minimum standard for MOT.

Cheers.

[Christophski]

Well done on the pass slip

[Fat Audi 80]

I would suggest the next step is to bleed all four corners in the correct order. Well done on the MOT pass, always a relief!

[bilko0795]

didn,t think they put 4x4 systems on the rollers mine always goes for a drive with a gadjit in the passenger footwell.

[Error404]

[gunman]

In N.Ireland the MOT testing is a bit different. There are Government testing centres with 6-8 lanes each. MOTs are not done by the local garage. There are seperate lanes for 4x4s and cars fitted with LSDs (and additional ones for lorries).

[gunman]

I've just bought a good set of front calipers while I have a full seal kit for so I'll fit these and bleed the whole system (so long as I can get the bleed nipple out of the RNS caliper ).

As my MOT didn't end up costing me a fortune I may overhaul some of the car, I am thinking of getting powerflex bushes for my spare rear wishbones and refurbing and fitting them. Also considering braided hoses but not sure If they'll be much different to the std flexi hoses.