Problem after Brembo caliper rebuild?
Discussion
I've rebuilt dozens of Brembo calipers on motorbibkes i've had so i'm used to the process.This is the first set of Brembo calipers i've rebuilt from a car (Fiat 20v turbo)and i've run into problems.Pistons were in good nick,cleaned them up,replaced both seals on each of the four pots.I've put them back on the car but after a short run around the streets i could smell hot pads!!!Got home and both of the front discs were hot!!
I took off the caliper from the disc but still had it plumbed in,got my better half to press the brake slightly a few times and observed the pistons,they all moved and just settled back nicely aftr moving,i don't get this,what have a done wrong,it's as if the pads aren't letting go the discs after braking.You can turn the wheel when front of car is in the air,slightly stiff to move but not overly so.Anyone any ideas??
I took off the caliper from the disc but still had it plumbed in,got my better half to press the brake slightly a few times and observed the pistons,they all moved and just settled back nicely aftr moving,i don't get this,what have a done wrong,it's as if the pads aren't letting go the discs after braking.You can turn the wheel when front of car is in the air,slightly stiff to move but not overly so.Anyone any ideas??
Lots of alloy bodied calipers have stainless platforms where the pads slide into.
Unfortunately underneath these corrode and they make that space smaller, and pads often dont fit properly.
And can be worse again as above where pattern pads are often the wrong size too
The corrosion seems worse on calipers where owners go nuts with alloy wheel cleaner. Usually the dirtier they are, the less corrosion there is.
Unfortunately underneath these corrode and they make that space smaller, and pads often dont fit properly.
And can be worse again as above where pattern pads are often the wrong size too
The corrosion seems worse on calipers where owners go nuts with alloy wheel cleaner. Usually the dirtier they are, the less corrosion there is.
stevieturbo said:
Lots of alloy bodied calipers have stainless platforms where the pads slide into.
Unfortunately underneath these corrode and they make that space smaller, and pads often dont fit properly.
And can be worse again as above where pattern pads are often the wrong size too
The corrosion seems worse on calipers where owners go nuts with alloy wheel cleaner. Usually the dirtier they are, the less corrosion there is.
Yes it has these platform,held in place by those,"Go on,try and unscrew me and i'll snap off!"screws.One was particularly high but i managed to pound it flat,plus soaking underneath with wd40 to force out dirt.I took the easy option and filed the pads!Discs just seem to be getting 'too' hot though i think.Unfortunately underneath these corrode and they make that space smaller, and pads often dont fit properly.
And can be worse again as above where pattern pads are often the wrong size too
The corrosion seems worse on calipers where owners go nuts with alloy wheel cleaner. Usually the dirtier they are, the less corrosion there is.
Out of interest, where did you get the seals from? The size, shape (as they can be chamfered) and material of these is critical to the operation of the brakes as they define the piston fallback when the pedal is released and the pushback force (amongst other things).
I'm sure you already know if you're used to doing Motorbike brakes but you should also soak the seals in brake fluid for a few hours before fitting.
Also there's a chance that while bleeding the system it's done something to the master cylinder and the return port is either blocked or the piston isn't returning fully and uncovering it.
It might finally be worth checking if you've got the pressure and wiper seals the wrong way round as that might have some interesting effects!
It's probably horsies and not zebras though and if you've had to file them to fit then your pads are likely binding against whatever abutment fittings there are. It doesn't take much force and if the pad stickies aren't great then they will drag against the disc and cause excess heat.
I'm sure you already know if you're used to doing Motorbike brakes but you should also soak the seals in brake fluid for a few hours before fitting.
Also there's a chance that while bleeding the system it's done something to the master cylinder and the return port is either blocked or the piston isn't returning fully and uncovering it.
It might finally be worth checking if you've got the pressure and wiper seals the wrong way round as that might have some interesting effects!
It's probably horsies and not zebras though and if you've had to file them to fit then your pads are likely binding against whatever abutment fittings there are. It doesn't take much force and if the pad stickies aren't great then they will drag against the disc and cause excess heat.
rumpelstiltskin said:
Yes it has these platform,held in place by those,"Go on,try and unscrew me and i'll snap off!"screws.One was particularly high but i managed to pound it flat,plus soaking underneath with wd40 to force out dirt.I took the easy option and filed the pads!Discs just seem to be getting 'too' hot though i think.
The Coupe is a fairly weighty car and the brakes will get pretty hot if you are using them a lot. You don't have to try very hard to fade them, especially if you are using cheap pattern pads.If you aren't driving it hard and the pads are genuinely overheating then they must be binding. I owned a 20VT for a long time and filing the pads down is a bodge that doesn't last with these calipers. Any corrosion already present just gets worse.
Was this problem present before you rebuilt the calipers, or did it only happen afterwards?
Mr2Mike said:
The Coupe is a fairly weighty car and the brakes will get pretty hot if you are using them a lot. You don't have to try very hard to fade them, especially if you are using cheap pattern pads.
If you aren't driving it hard and the pads are genuinely overheating then they must be binding. I owned a 20VT for a long time and filing the pads down is a bodge that doesn't last with these calipers. Any corrosion already present just gets worse.
Was this problem present before you rebuilt the calipers, or did it only happen afterwards?
Brakes were ok before i done the caliper.It feels brakes are dragging although as i said with the front wheels in th air i can turn the wheels 'fairly' easily,they aren't jammed solid or anything.Pads are Mintex incidentally which came with the vented,drilled and grooved discs.I've driven a car with pads jammed against discs before and the pads reeked to high heaven.The discs are getting hot but not much smell of pads now.If you aren't driving it hard and the pads are genuinely overheating then they must be binding. I owned a 20VT for a long time and filing the pads down is a bodge that doesn't last with these calipers. Any corrosion already present just gets worse.
Was this problem present before you rebuilt the calipers, or did it only happen afterwards?
After much fretting and with the brakes still dragging i decided to replace every rigid brake pipe,and the flexi right back to the abs unit.Just incase anything freaky was happening within the flexi.After i bled the brakes the disc turned freely within the caliper for the first time since i rebuilt caliper!,great i thought.Stuck the wheel back on,turned wheel by hand and it dragged again??There is no play in the wheel bearing and wishbones/balljoints etc are fine.
As obvious as it sounds, you need to go through things step by step! If its all moving freely until the wheel is bolted up, I'd be inclined to unbolt the caliper and then fit the wheel, torque it up and see if it still rotates ok. Whilst its more than likely to be a brake issue, it could be something totally unrelated- the tyre rubbing slightly on the strut for example. Once you've narrowed it down to definitely being the caliper, could you swap them to the other side (might make bleeding a challenge but usually possible) and see if the binding moves to the other wheel. Work from there and keep us posted...
I had this problem on a Discovery, the discs were machined incorrectly but they were cheap discs.
I have also seen motorbike rear brakes binding badly because the reservoir was overfilled, there is no air vent in a motorbike reservoir and the pistons are pushed out when the fluid becomes hot and expands.
The first thing I would do is refit the old pads and see what happens, it's a quick and free check. I won't insult you by asking if the seal grooves are free of corrosion and the pistons spotless.
I have also seen motorbike rear brakes binding badly because the reservoir was overfilled, there is no air vent in a motorbike reservoir and the pistons are pushed out when the fluid becomes hot and expands.
The first thing I would do is refit the old pads and see what happens, it's a quick and free check. I won't insult you by asking if the seal grooves are free of corrosion and the pistons spotless.
kev b said:
I had this problem on a Discovery, the discs were machined incorrectly but they were cheap discs.
I have also seen motorbike rear brakes binding badly because the reservoir was overfilled, there is no air vent in a motorbike reservoir and the pistons are pushed out when the fluid becomes hot and expands.
The first thing I would do is refit the old pads and see what happens, it's a quick and free check. I won't insult you by asking if the seal grooves are free of corrosion and the pistons spotless.
I've rebuilt Brembos on bikes many times and never had any issues,yes everything was spotless,seal recesses etc.I'll try all other suggestions though,thanks!I have also seen motorbike rear brakes binding badly because the reservoir was overfilled, there is no air vent in a motorbike reservoir and the pistons are pushed out when the fluid becomes hot and expands.
The first thing I would do is refit the old pads and see what happens, it's a quick and free check. I won't insult you by asking if the seal grooves are free of corrosion and the pistons spotless.
Have a read of this - sounds like plate lift is the issue, as has been mentioned
http://www.jackals-forge.com/lotus/968cs/968_plate...
http://www.jackals-forge.com/lotus/968cs/968_plate...
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