Rear Pads

[Alfa156Melb 9]

Smaky, I'm replacing my rear rotors and pads tomorrow and was wondering:

 

Can I take the lid of the fluid res to allow the fluid to creep up when i wind the piston back, or would you advise i release the calliper nipple and re-bleed instead?

 

I've heard that there is a risk of damaging valves if you push the fluid backwards.. is that true?

[Alfa156Melb 9]

All good Smaky. I found an answer you prepared earlier.. here it is for the benefit of all:

 

Originally Posted by jug

its nothing to do with alfas, all modern cars have a proportioning valve. if you force it backwards it will allow too much brake effort to go to the back brakes (no more brake balance control). the reason rear caliper pistons are far more commonly wound back in (compared to front) is to protect the proportioning valve, but you can still damage it if you wind it back in too quickly because the valve is only meant to take pressure in one direction.

 

i was always taught to bleed the caliper every time you push the piston back in, that way you can never apply force the wrong way on the valve. starting work at a garage doesnt mean you should ignore all the teaching you received prior to starting work, but i know it is normal practice in industry to simply force the piston back and then not bleed the brakes at all to save time regardless of age or mileage or if you're charging an extra £8 for brake fluid that you dont even use. i understand why that is done, but that does not mean it is a good thing, and it is not a good enough reason to join in, especially on your own car.

I'd have to agree that your reasoning is codswallop, if the fluid was meant to travel in one direction only then the brakes would never release. The way the proportioner works is by closing off the side with with the most flow to equalize the pressure to both sides/ends to equalize braking effect. If the fluid did not pass BACK THROUGH it when the pedal was released then you'd be locked up PERMINANTLY. For this reason you can just wind the caliper back in with the cap of the fluid reservoir,but not with an air wrench (for christs sake) you'll do it too fast and the valve will slam over as the flow will be quicker than if you do it manually, as a result it may well blow a seal inside, but manually it will never damage that valve.

[Smaky 73]

You are correct Melb, BUT these cars dont have proportioning valves, it's all done by the ABS unit and the reason we wind them rears in is....because of the handbrake self adjust mechanism which has an ACME thread which itf you just push in will shag the calliper.

 

So yes, just remove the cap and wind them in.

 

I also take this opportunity to remove the brake cable and grease it up inside to prevent it sticking come the winter.

[Alfa156Melb 9]

Well I was expecting it to be much harder than it turned out to be.. Simple job. I didn't grease the cables, but they were in good order anyway, actually everything back there was pretty much like new, but for some dirt and dust.

 

I have new rotors on the front along with ds2500 ferodo pads and although there was an improvement, it wasn't as good as Ive heard.. but now - the car's transformed.. which i guess is to be expected .. lol