Brake leaver going soft on track...

Brake leaver going soft on track...

Author
Discussion

Hooli

32,278 posts

199 months

Saturday 5th April 2014
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Ferodo?

Made in the Peak District where they know all about braking with those hills.

Mike600F

1,049 posts

155 months

Saturday 5th April 2014
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hehe yeah, that could be it!

Mr2Mike

20,143 posts

254 months

Saturday 5th April 2014
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Bizzle said:
Immediately i thought it's boiling the fluid - so i swapped it out for the new fresh AP stuff which improved a little bit - but the problem still persists.
Hugely unlikely to be a brake fluid problem. If the fluid gets hot enough to boil you lose all braking effort, and it happens very quickly.

Bizzle said:
I was talking with my friend Si (MrKippling on here) who suggested that i should swap out the pads for something that doesn't get quite as hot.
There's no such thing; all pads get hot by the very nature of friction. The higher performance pads simply continue to work well at higher temperatures.

Before you replace the pads, check the existing ones can move freely within the caliper with a reasonable amount of clearance. If they can't then they will bind within the caliper as they get hot which will give a poor feel at the lever. If that's fine then put a decent set of pads on your shopping list.

I'm assuming you already have a quality set of aeroquip hoses rather than 13 year old rubber ones.

George29

14,706 posts

163 months

Saturday 5th April 2014
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I'd just replace the pads with a new set of standard Suzuki ones.

Padgetts used standard Yamaha pads in my bike when it was raced at national Superstock level. There is no need to go to race/track only brake pads.

Bizzle

Original Poster:

544 posts

200 months

Saturday 5th April 2014
quotequote all
Okaydokey,
Thanks all. I can't say i'm a huge fan of the idea of putting standard Suzuki pads in it. I'm told the more recent Yamaha pads are actually pretty damn good though.

I have ordered up a set of those SBK Duel Carbon's and they are getting here this week. There is some talk of us doing Rockingham next weekend so i'll let you know if it makes a difference.

Cheers

Chris

George29

14,706 posts

163 months

Saturday 5th April 2014
quotequote all
Bizzle said:
Okaydokey,
Thanks all. I can't say i'm a huge fan of the idea of putting standard Suzuki pads in it. I'm told the more recent Yamaha pads are actually pretty damn good though.
Who do you think spends more money on brake pad development? Suzuki or an aftermarket company? Standard pads are fine, as I said, if bikes can compete at national super stock level with them then they will be more than sufficient for someone who goes on track days or even club racing.

Bizzle

Original Poster:

544 posts

200 months

Saturday 5th April 2014
quotequote all
Suzuki, most definitely. Developing a pad that has to perform as an exceptional compromise for all types of riders, in all types of conditions. I'm not saying they are bad - i'm saying that knowing that, i personally would rather put in a different pad. :-)

Mr2Mike

20,143 posts

254 months

Saturday 5th April 2014
quotequote all
George29 said:
Who do you think spends more money on brake pad development? Suzuki or an aftermarket company? Standard pads are fine, as I said, if bikes can compete at national super stock level with them then they will be more than sufficient for someone who goes on track days or even club racing.
It's extremely unlikely that bike manufacturers develop their own pad materials, in the same way they don't develop their own tyres. Why would they when there are numerous companies that specialise in this area?

StuB

6,695 posts

238 months

Saturday 5th April 2014
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Mr2Mike said:
It's extremely unlikely that bike manufacturers develop their own pad materials, in the same way they don't develop their own tyres. Why would they when there are numerous companies that specialise in this area?
It's also likely that price & overall cost are big factors more than some of the material properties which make brake pads more effective.

I'd suggest specialists like AP, Brembo & other specialists know more about brakes & friction materials than an engineer at Suzuki.

George29

14,706 posts

163 months

Saturday 5th April 2014
quotequote all
StuB said:
It's also likely that price & overall cost are big factors more than some of the material properties which make brake pads more effective.

I'd suggest specialists like AP, Brembo & other specialists know more about brakes & friction materials than an engineer at Suzuki.
I'm not denying they can make more efficient brakes. Buy Brembo mono block calipers and discs if you want that, then Brembo pads will make sense.

Standard pads and callipers it makes the most sense imo to use the original pad that was designed to work with them.

If John McGuiness can win TTs with them I'm sure they are good enough for 99.99% of people.

Also aftermarket pads can wear discs at an increased rate.

Biker's Nemesis

38,536 posts

207 months

Saturday 5th April 2014
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George29 said:
StuB said:
It's also likely that price & overall cost are big factors more than some of the material properties which make brake pads more effective.

I'd suggest specialists like AP, Brembo & other specialists know more about brakes & friction materials than an engineer at Suzuki.
I'm not denying they can make more efficient brakes. Buy Brembo mono block calipers and discs if you want that, then Brembo pads will make sense.

Standard pads and callipers it makes the most sense imo to use the original pad that was designed to work with them.

If John McGuiness can win TTs with them I'm sure they are good enough for 99.99% of people.

Also aftermarket pads can wear discs at an increased rate.
Not all aftermarket pads, I use the EBC HH's or Standard pads in all my bikes.

theshrew

6,008 posts

183 months

Saturday 5th April 2014
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Mr2Mike said:
There's no such thing; all pads get hot by the very nature of friction. The higher performance pads simply continue to work well at higher temperatures.

Before you replace the pads, check the existing ones can move freely within the caliper with a reasonable amount of clearance. If they can't then they will bind within the caliper as they get hot which will give a poor feel at the lever. If that's fine then put a decent set of pads on your shopping list.

I'm assuming you already have a quality set of aeroquip hoses rather than 13 year old rubber ones.
Your correct he should check everything is free and it gets very hot really quick the discs will heat very quickly and actually glow red. As the discs get hotter and hotter they bind even more if it was that bad he would tell while riding the bike + he would be able to smell it.

There is as you say a huge difference in brake pads in the material that's in them which makes them perform in different ways. Some brake better, give loads of dust off some deal with heat better etc etc

I cant see how this is pad related. Interested what happens when the new ones are fitted.

Lets think about this with a bit of logic, a disc is metal which will expand when hot but even if red hot its still a solid. Im guessing a pad is designed to withstand huge temps and that it doesn't change its form while hot either. So if im correct you have 2 solid surfaces against each other that wont change no matter what ( until a point the rider wouldn't reach ). Which is why I cant see how that can cause the OP's issue its doing the exact same thing as it is when its cold. If anything the leaver should have a tiny tiny tiny bit less travel because the disc is slightly bigger its expanded due to the heat the pads will have less distance to travel. ( maybe im wrong )

This is a strange problem but in my experience pretty much every time you have a random problem its always related to rubbish fluid, MC or maybe even pipes. As BN pointed out these might have rubbish MC so that's worth looking at.

Im interested how this turns out keep us updated and ffs be careful if your having problems like this on track OP



Hooli

32,278 posts

199 months

Saturday 5th April 2014
quotequote all
theshrew said:
Lets think about this with a bit of logic, a disc is metal which will expand when hot but even if red hot its still a solid. Im guessing a pad is designed to withstand huge temps and that it doesn't change its form while hot either. So if im correct you have 2 solid surfaces against each other that wont change no matter what ( until a point the rider wouldn't reach ).
Actually the pads vaporise from the heat hence the need for cross-drilling or groves on performance discs.

theshrew

6,008 posts

183 months

Sunday 6th April 2014
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Hooli said:
Actually the pads vaporise from the heat hence the need for cross-drilling or groves on performance discs.
That will probably explain why pads made of different materials perform better / worse at high temps.

Anyway I'm interested to see how OP gets on with this.

Hooli

32,278 posts

199 months

Sunday 6th April 2014
quotequote all
theshrew said:
Hooli said:
Actually the pads vaporise from the heat hence the need for cross-drilling or groves on performance discs.
That will probably explain why pads made of different materials perform better / worse at high temps.

Anyway I'm interested to see how OP gets on with this.
Different materials work at different temp ranges, hence race pads don't work cold etc. I believe the main reason pads 'overheat' is they vapourise too quick when hot & the build up of gasses holds them off the disc & reduces braking power. Hence the groves/holes to allow the gasses to escape.

Mike600F

1,049 posts

155 months

Monday 7th April 2014
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Hooli said:
Different materials work at different temp ranges, hence race pads don't work cold etc. I believe the main reason pads 'overheat' is they vapourise too quick when hot & the build up of gasses holds them off the disc & reduces braking power. Hence the groves/holes to allow the gasses to escape.
That sounds like the problem to me! just like a aquaplaning but between pad and disc rather than tyre and road.

You are full of interesting information sir!

ETA, just bought a set of HH compound pads to test on track this weekend, I'll post if they solve the problem or not.

Edited by Mike600F on Monday 7th April 11:02

Mr2Mike

20,143 posts

254 months

Monday 7th April 2014
quotequote all
IIRC the pad outgassing theory for brake fade fade was discredited due to the large amount of gas that would need to be generated to sustain a "gas bearing" on a moving disc. It's primarily because the coefficient of friction drops quite rapidly above the pads operating temperature range.

Mike600F

1,049 posts

155 months

Monday 7th April 2014
quotequote all
Mr2Mike said:
IIRC the pad outgassing theory for brake fade fade was discredited due to the large amount of gas that would need to be generated to sustain a "gas bearing" on a moving disc. It's primarily because the coefficient of friction drops quite rapidly above the pads operating temperature range.
Balls. I liked the gas theory; it's more interesting than regular old fricton.

On the up side new pads will fix that too.

fergus

6,430 posts

274 months

Monday 7th April 2014
quotequote all
As the system gets hot, the pad compound may not be able to handle the heat generated. It can lose its friction coefficient at high temps. The distance the pistons in the calipers need to move is the same (pad thickness hasn't magically reduced to that extent over the course of a session), hence the volume of fuild that the m/c must displace is the same.

Typically when pads overheat, the lever can remain firm, but with less retardation. If the lever is coming back to the bars, it's related to a hydraulic issue rather than a friction issue.

Have you tried tying the lever back to the bars for a decent period of time with a tie wrap? Has the m/c got a top bleed nipple on it?

It sounds wierd that with new fluid (i.e. no water in the fluid to boil) and a decent lever (i.e. no air to compress) the lever comes back to the bars as things get hot? I'm not sure how "bad" (i.e. not thermally stable pads) allow the lever to come back to the bars, as decent brake fluid can't be compressed any more when it's hot as opposed to when it's cold.

Why not give one of the AP reps, etc a call and ask for their advice?

My money is on fluid fade.

Edited by fergus on Monday 7th April 12:29

Hooli

32,278 posts

199 months

Monday 7th April 2014
quotequote all
Mr2Mike said:
IIRC the pad outgassing theory for brake fade fade was discredited due to the large amount of gas that would need to be generated to sustain a "gas bearing" on a moving disc. It's primarily because the coefficient of friction drops quite rapidly above the pads operating temperature range.
I hadn't heard that, bang goes me looking intelligent for once.