Pad fade or fluid fade
Discussion
This isn't actually a track car question at all, but I figured it would be a familiar problem to people in this section of the forum!
It's relatively easy to cook the brakes on my Focus on the road. You don't have to be going that quickly to get fade issues if you're very heavily laden and/or going down a long descent. It's the base model 1.6 with vented discs on the front and drums on the back, but still I don't think this should be happening on a modern car in normal(ish) road use. There's plenty of life left in the pads (and as far as I'm aware the shoes at the back), but I've got some better quality items to try next.
It's happened three times now and each time it's been fairly textbook fade symptoms - first the smell, then the wooden pedal combined with a noticeable drop in braking force. I've always let it cool off a little at that point!
As I understand it 'pad fade' and 'fluid fade', while obviously linked, are actually two different things. I presume in this instance it's just the pad material overheating, and therefore everything should be back to normal once it's cooled down? ...Do you think there's any need to change the fluid?
It's relatively easy to cook the brakes on my Focus on the road. You don't have to be going that quickly to get fade issues if you're very heavily laden and/or going down a long descent. It's the base model 1.6 with vented discs on the front and drums on the back, but still I don't think this should be happening on a modern car in normal(ish) road use. There's plenty of life left in the pads (and as far as I'm aware the shoes at the back), but I've got some better quality items to try next.
It's happened three times now and each time it's been fairly textbook fade symptoms - first the smell, then the wooden pedal combined with a noticeable drop in braking force. I've always let it cool off a little at that point!
As I understand it 'pad fade' and 'fluid fade', while obviously linked, are actually two different things. I presume in this instance it's just the pad material overheating, and therefore everything should be back to normal once it's cooled down? ...Do you think there's any need to change the fluid?
You are suffering from pad fade.
Pad fade has all the symptoms you describe - as the pad overheats, it gives off gasses, which causes the pad to aquaplane across the disc on the gasses. Cross drilling and grooves aid disc cooling but also allows these gasses to escape.
Fluid fade has different symptoms - you get a spongy pedal as the fluid boils, since you compress the air in the fluid rather than the fluid transferring the pedal movement to the pads. The chances of fluid fade increase over time as the fluid is hygroscopic, meaning that it absorbs moisture, which obviously has a lower boiling point than the fluid. To solve this problem, change you fluid regularly, and use good quality stuff.
Looking for DOT 4 or DOT 5.1 is misleading, you need to look at the dry and wet boiling points of the fluid on the back of the container - the higher the better. Motul RBF 600 or the Millers stuff are a good bet (600F) and isn't ridiculously expensive compared to the likes of the Castrol offerings.
HTH
Jonny
Pad fade has all the symptoms you describe - as the pad overheats, it gives off gasses, which causes the pad to aquaplane across the disc on the gasses. Cross drilling and grooves aid disc cooling but also allows these gasses to escape.
Fluid fade has different symptoms - you get a spongy pedal as the fluid boils, since you compress the air in the fluid rather than the fluid transferring the pedal movement to the pads. The chances of fluid fade increase over time as the fluid is hygroscopic, meaning that it absorbs moisture, which obviously has a lower boiling point than the fluid. To solve this problem, change you fluid regularly, and use good quality stuff.
Looking for DOT 4 or DOT 5.1 is misleading, you need to look at the dry and wet boiling points of the fluid on the back of the container - the higher the better. Motul RBF 600 or the Millers stuff are a good bet (600F) and isn't ridiculously expensive compared to the likes of the Castrol offerings.
HTH
Jonny
I suspected the smell would indicated pads (something out in the air rather than a sealed fluid...) but I wondered if the heat transfer could then cause the fluid to go too?
I'm just amazed that a healthy set of pads would fade on the road on an average car. I probably drive a bit quicker than the average base-spec Focus buyer, but I wasn't thrashing it, hence I wondered if there could be an underlying problem like aged or contaminated fluid.
I'm just amazed that a healthy set of pads would fade on the road on an average car. I probably drive a bit quicker than the average base-spec Focus buyer, but I wasn't thrashing it, hence I wondered if there could be an underlying problem like aged or contaminated fluid.
I can vouch for ''Millers Racing Brake Fluid'', it's about £14/litre from Opie Oils and the boiling points are 192'C Wet and 312'C Dry if my memory serves me well...
EDIT Link; http://www.opieoils.co.uk/p-60239-millers-oils-rac...
EDIT Link; http://www.opieoils.co.uk/p-60239-millers-oils-rac...
Edited by FLD_WILLIS on Tuesday 18th January 14:14
Ojc said:
DOT 5.1 and a set of better pads, Mintex 1144, DS2500 or something from Carbotechs range will improve things.
Make sure you change the discs if you are fitting a set of new pads from the above though.
Don't forget that most 'track/race' pads are not ECE R90 certified, so if you're in an accident and questions over braking come into play, then you may find you have a bit of explaining to do.Make sure you change the discs if you are fitting a set of new pads from the above though.
If you do upgrade your pads, make sure you go for road legal 'fast road' pads
Chris71 said:
I'm just amazed that a healthy set of pads would fade on the road on an average car.
You jest squire, IMHO its rare to find a base car where they won't, even M3s M5s etc have pad not up to a good road let alone track thrash in stock form, let alone humdrum cars.I'll wager you don't have genuine Ford pads in there either, the manufacturers spec pads will normally be a proper brand & be better than some cheapy motor factor jobs, standard bmw rear pads can last fine on an e30 track car, stuck on my local motor factors items when in need of some in a hurry & they lasted half a day!
iguana said:
Chris71 said:
I'm just amazed that a healthy set of pads would fade on the road on an average car.
You jest squire, IMHO its rare to find a base car where they won't, even M3s M5s etc have pad not up to a good road let alone track thrash in stock form, let alone humdrum cars.I'll wager you don't have genuine Ford pads in there either, the manufacturers spec pads will normally be a proper brand & be better than some cheapy motor factor jobs, standard bmw rear pads can last fine on an e30 track car, stuck on my local motor factors items when in need of some in a hurry & they lasted half a day!
Chris71 said:
but do you know if brake fluid is still a service item? I thought those days were gone for normal road cars.
My wife has the very same car.I find the brakes rather under servo'd, but I like that.
The rear brake shoes last forever.
If you've NOT changed your fluid for a few years, that's probably where your problem is.
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