Brake fade, any ideas?
Discussion
After some spirited driving around Milton Keynes (long straights then roundabouts) the brakes faded and gave me a bit of a scare. Discs are standard size and not that old (drilled and grooved) and neither are the EBC red stuff pads. Car is a 500 and putting out just under 330bhp. Is it likely to be the brake fluid or just insufficient brakes or something else?
jmct said:
After some spirited driving around Milton Keynes (long straights then roundabouts) the brakes faded and gave me a bit of a scare. Discs are standard size and not that old (drilled and grooved) and neither are the EBC red stuff pads. Car is a 500 and putting out just under 330bhp. Is it likely to be the brake fluid or just insufficient brakes or something else?
Sounds like standard brakes getting to hot, suprised the red stuff can’t cope. It does’nt take long or many emergency stops to overheat road brakes,
I found within 3 laps of a shortish race circuit my brakes were gone.
If there getting very hot you might have boiled the fluid a bit which adds to the problem.
Maybe try another type of pad and bleed front brakes with good new fluid.
jmct said:
.............. Also any top tips for flushing through and replacing the fluid.
Depends how valuable your time is.Empty the system with a pressure or vacuum bleeder. Then fill the system and bleed. Time consuming.
Or
Buy a bottle of fluid. Bleed around all four corners topping up with the new fluid as you go. When the bottle is empty you are done.
Steve
Dot 4 has a minimum standard, I don't profess to fully understand it all but I do know there are some very good Dot 4 brake fluids available that exceed the standard requirements, going to a dot 5.1 isn't necessarily the best solution?
A couple that get well recommended are Motul RBF 600.
Or AP Racing Radi-Cal R3
If you want to "push the boat out" there's Castrol SRF
A couple that get well recommended are Motul RBF 600.
Or AP Racing Radi-Cal R3
If you want to "push the boat out" there's Castrol SRF
Edited by phillpot on Monday 30th December 21:53
Steve_D said:
jmct said:
.............. Also any top tips for flushing through and replacing the fluid.
Depends how valuable your time is.Empty the system with a pressure or vacuum bleeder. Then fill the system and bleed. Time consuming.
Or
Buy a bottle of fluid. Bleed around all four corners topping up with the new fluid as you go. When the bottle is empty you are done.
Steve
Get as much as possible out of the reservoir first, if you dont have a vacuum pump then a turkey baster will do fine. Then fill the reservoir with new fluid and bleed all corners, starting with the furthest, topping up as required. If you use a clear tube you will see when you're bleeding out the new fluid compared to the old. You'll probably use between 500ml and a litre bottle.
Macbags said:
No brake fade in my case but cold tyres and damp roads are not the best combination
so you won't have gotten anywhere near the brake temperature to promote fadeAs phillpot above has said buy a good quality brake fluid and not the cheapest from local trader, spec for 5.1 is higher than 4 anyway.
if cost is not a problem then SRF is the best way to go also does not mark paintwork, but is NOT to be mixed wit other fluids.
TVRMs said:
Before spending money, establish if its a pad issue or a fluid issue.
This all day long!If the peddle travel got longer with little resistance then you boiled the fluid and so get a high temp fluid as mentioned above.
Keep it dot4 as that is the correct chemical make up for the car and moving to dot5 is on absolutely no benefit as the temp specs are much the same as standard dot4 but the dot5 could well dissolve seals in your braking system.
If the peddle was still firm then you melted the surface of the pad and you need better pads, I find Pagid RS14 absolutely brilliant on the Cerbera and normally use AP R4 brake fluid and never have braking issues on track or road.
if pedal travel has not changed (increased) there isnt any air inside the system, nor you boiled the fluide....means you cancancel searching the problem at the brake-fluide.
might be that the pads became glazed, hence reduced friction.
get some decent brake pads like mintex, and throw away the EBC´s (never liked them, for me this brand is r*bbish)
might be that the pads became glazed, hence reduced friction.
get some decent brake pads like mintex, and throw away the EBC´s (never liked them, for me this brand is r*bbish)
gruffalo said:
This all day long!
If the peddle travel got longer with little resistance then you boiled the fluid and so get a high temp fluid as mentioned above.
Keep it dot4 as that is the correct chemical make up for the car and moving to dot5 is on absolutely no benefit as the temp specs are much the same as standard dot4 but the dot5 could well dissolve seals in your braking system.
If the peddle was still firm then you melted the surface of the pad and you need better pads, I find Pagid RS14 absolutely brilliant on the Cerbera and normally use AP R4 brake fluid and never have braking issues on track or road.
Do you mean DOT 5.0 - which is entirely different to DOT 4.0 and DOT 5.1?If the peddle travel got longer with little resistance then you boiled the fluid and so get a high temp fluid as mentioned above.
Keep it dot4 as that is the correct chemical make up for the car and moving to dot5 is on absolutely no benefit as the temp specs are much the same as standard dot4 but the dot5 could well dissolve seals in your braking system.
If the peddle was still firm then you melted the surface of the pad and you need better pads, I find Pagid RS14 absolutely brilliant on the Cerbera and normally use AP R4 brake fluid and never have braking issues on track or road.
O/T - as linked to above. A good quality DOT 4.0 fluid will be more than up to the job for road use unless you're driving really inappropriately on the 'road'.
Brake - and clutch - fluid is a service item so should be changed regularly. If I were changing the discs and pads alround, I would be changing the fluid as well.
The standard brake set up was designed for a much heavier car so is more than adequate.
GinG15 said:
if pedal travel has not changed (increased) there isnt any air inside the system, nor you boiled the fluide....means you cancancel searching the problem at the brake-fluide.
might be that the pads became glazed, hence reduced friction.
get some decent brake pads like mintex, and throw away the EBC´s (never liked them, for me this brand is r*bbish)
I agree with your thoughts on EBC.might be that the pads became glazed, hence reduced friction.
get some decent brake pads like mintex, and throw away the EBC´s (never liked them, for me this brand is r*bbish)
Rubbish or not, I’ve never heard of anyone cooking pads on today’s roads.
I've driven on track both a chim 450 with standard 260mm discs (my first TVR) and a 4.3 precat griff with standard 240mm discs. I've never had brake fade from overheating. Pad glazing is more likely IMHO. Take out the pads and clean off the top layer with some wet&dry (rub the pad on the paper on a flat surface), put them back in and try to replicate the problem. Make sure the discs are not out of spec, ie thin and corroded or that if they are drilled, the holes full of crap. I find grooved discs are better nearer the heat limit.
Brake upgrades are often an unsprung weight downdgrade and the real problem is the discs or pads or calipers (could be a sticky caliper causing the pad to over heat) need servicing or replacing.
Just my humble opinion of course.
Brake upgrades are often an unsprung weight downdgrade and the real problem is the discs or pads or calipers (could be a sticky caliper causing the pad to over heat) need servicing or replacing.
Just my humble opinion of course.
Edited by leerdam23 on Thursday 2nd January 18:07
I have done many track days. I use bigger brakes (324mm grooved disks) with Hawk pads, which are between road and race spec.
I also use dot 4 fluid, but a good quality one. I did use dot 5.1 for a while, but it is more hygroscopic, so needs to be changed more regularly
I have never suffered brake fade with that set up, but have on the one occasion I put a set of new Carbon Lorraine full race pads in without changing the fluid. After about 5 laps of hard braking on a twisty circuit I started to notice longer pedal travel, and at the end of a straight when i braked hard for a 90 left I lost the brakes completely at 120 mph and spun out.
Back to the pits, changed underwear and pads - the pads back to the worn Hawk pads, topped up the fluid and completed the track day with no further loss of brakes.
So, from my experience I would suggest you might be boiling the fluid, especially if it actually wasn't changed at the last service. But if you did, you should have seen some evidence of brake fluid spilling out of the reservoir. If you didn't, then you must suspect glazed pads or worn discs.
I also use dot 4 fluid, but a good quality one. I did use dot 5.1 for a while, but it is more hygroscopic, so needs to be changed more regularly
I have never suffered brake fade with that set up, but have on the one occasion I put a set of new Carbon Lorraine full race pads in without changing the fluid. After about 5 laps of hard braking on a twisty circuit I started to notice longer pedal travel, and at the end of a straight when i braked hard for a 90 left I lost the brakes completely at 120 mph and spun out.
Back to the pits, changed underwear and pads - the pads back to the worn Hawk pads, topped up the fluid and completed the track day with no further loss of brakes.
So, from my experience I would suggest you might be boiling the fluid, especially if it actually wasn't changed at the last service. But if you did, you should have seen some evidence of brake fluid spilling out of the reservoir. If you didn't, then you must suspect glazed pads or worn discs.
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