Brembos

[petercronin]

Does anybody know how far the pistons will move before they 'pop' out of the calliper?

I'd like to check if they're operating alright. With the pads and disc in between it's obviously hard to tell but it looks like they're not all moving at quite the same time or smoothly. I cant be bothered with the mess of stripping the calliper on my drive to check if they're rusty or if the seals are damaged. I was hoping to put something in the calliper to allow the pistons to move a little bit more but not so much that they come out to check if I'm right before I put it in a garage.

Any ideas would be great thanks.

 

[turkie172]

What are you prepared to do then? or what have you done?

 

[Pav]

Think the pistons are about an inch long..

 

[petercronin]

What are you prepared to do then? or what have you done?

I'm quite happy and capable to do a fair bit but I just can't be bothered with the mess of taking the callipers off on my drive and then having to bleed it all so if this is the only way I'll just have to ask a garage to have a look.

I basically want to check if they are sticking/not pressing equally before I go and buy a seal kit or new callipers. All I've done is watch them squeeze on the pads and disc all assembled as they should be and it doesn't look quite right but with the tiny amount of movement you get it's hard to know for sure. Is there an easy way of watching the pistons extend a bit further than they normally without risk of them coming out of the calliper?

 

[turkie172]

The main thing will be if the brakes are staying on like the brake is slightly on all the time.

You will have to go as far as taking the pads out that means knocking the pins out but that will be as far as you may have to go to check and do some light maintenance. A good quality 4mm punch with a flat face or concave face is better but near impossible to find, copper grease, a fine flat file for quickly smoothing the pad slide faces on the calliper they will corrode as they are exposed aluminium and if they don't have a thin smear of copper grease on them the pads will lock and make you think you have a bad calliper, a spare set of pins just in case you have to cut the old set to get them out not normally a stock item anywhere so to have them and not need them is better than not have them and need them. Below one of my spare callipers I bought more to find out the colour as I'm not a big believer in reworking wheels and callipers they never seem to match originals but the calliper answer is they are bare casting no paint so forget buying silver paint.


To push the pads back I normally put something like a screwdriver in the vent holes in the centre of the disc and use it as a leaver point against the lugs of the steel back on the brake pad never ram in-between the pad back and piston or push on the pistons if the screwdriver slips it will rip the boot or scratch the piston and your in the s**t maybe not there and then but it will long term. And before you start pushing pistons back unscrew the brake reservoir lid so you don't build up pressure remember the fluid has to go somewhere and remember pushing all the pistons back around the car can overfill the reservoir so normally work a pair at a time. But what you are looking for is hard to push back pistons and you will probably find the pads stuck in the slots when I got my 197 I had to cut the pins and beat the pads out the brakes felt wooden but copper grease the pins especially the head, and the edges of the pads and the machined faces and just the piston contact points on the pad backs is all that's needed the more grease the more crap that will stick to it.

 

[turkie172]

before you start press the brake pedal and then go straight to and make sure the disc rotates after expect a little resistance but same both sides, look at the disc both faces should wear at the same rate so equal thickness both sides the central vent holes but like your wife or girlfriend being the prettiest thing you have ever seen not always the case. If putting in new pads you might have to lightly file the face that touches the calliper slot so it moves easily but without slapping around. Pushing the pistons back a few times with a piece of wood or similar might be enough to judge if one has a problem but keep an eye on them pressing one in might force another out so don't let them go out so far it falls out.

Hope this helps you, with my 197 when I got it new discs had been fitted but obviously no one checked what cause was to need the new discs.

 

[petercronin]

before you start press the brake pedal and then go straight to and make sure the disc rotates after expect a little resistance but same both sides, look at the disc both faces should wear at the same rate so equal thickness both sides the central vent holes but like your wife or girlfriend being the prettiest thing you have ever seen not always the case. If putting in new pads you might have to lightly file the face that touches the calliper slot so it moves easily but without slapping around. Pushing the pistons back a few times with a piece of wood or similar might be enough to judge if one has a problem but keep an eye on them pressing one in might force another out so don't let them go out so far it falls out.

Hope this helps you, with my 197 when I got it new discs had been fitted but obviously no one checked what cause was to need the new discs.

Thanks for all you're help there. I had the pads out recently when I cleaned and lubed everything so I'm sure that'll all be fine. The discs are good also.

My main concern is it appears that the pistons aren't all moving together or as smoothly as I imagine they should (but I've never watched them before so this may be ok). On both callipers it looks as though the upper pistons (when fitted) are extending before the lower ones and then shortly after the lower ones suddenly move. I was just hoping to remove the pads and watch the pistons move without any resistance to see what they do then. It looks to me like the lower ones are sticking slightly.

 

[turkie172]

That's reasonably normal the fluid has to pass those pistons first so they will move first until the fluid flows across the link pipe to fill the second chamber. You will find slightly more wear on the inner pad. But when pumped up should be reasonably equal. As long as the seals look ok expect the link pipe on the calliper with 2 right hand bends and smaller diameter to lower the pressure to the other pair of pistons so your good then.


Sent from my iPhone using Tapatalk

 

[petercronin]

That's reasonably normal the fluid has to pass those pistons first so they will move first until the fluid flows across the link pipe to fill the second chamber. You will find slightly more wear on the inner pad. But when pumped up should be reasonably equal. As long as the seals look ok expect the link pipe on the calliper with 2 right hand bends and smaller diameter to lower the pressure to the other pair of pistons so your good then.


Sent from my iPhone using Tapatalk

Good to hear, thanks. I'll have another look at some point but I might just put it in a garage anyway. Something doesn't look quite right.