hot brake judder - bigger brake time?
Discussion
once again i've come back from another trackday, and looking into brake "issues" again.
I've had a bit of a saga with the brakes. long story short, race pads and 6" ducting has got a lot of the heat issues sorted now.
car is FK2R civic, 2peice 350x32 discs (factory size), factory brembo calipers, CL RC6e pads.
I'm usually on donington, but yesterday was silverstone and again saw brake judder when pads got a few laps in. do my session, come in, cool down for 20mins and out again would give no judder until another few laps in. this is very clearly NOT a pad deposit type/warped disc issue.
while it was up around 28c yesterday, ambient temps dont seem to have much bearing on this problem as 8-12c (at donington) has the same issue after similar laps.
i've a number of theories on the current hot judder problem but seeking advice on what to do.
1) pads were used pre-6" ducting and i've possibly killed them. brake feel seems fine so doesnt have the typical feel of cooked pads. Brembos used to turn brown there was so much heat although now theres only a slight hint of colour change since changing ducting. Replace pads and hope for the best? i suspect i'll just see the problem again.
2) normal behavior of the CL pads? unlikely i think.
3) i'm wasting my time with factory size. despite brembo & 350mm discs, i should seriously look into bigger brakes. I can get both brembo & AP 380x32mm + 6pot calipers.
while i could probably go bigger again - 390,400mm discs then it'd push me into 19 & 20" wheel sizes. is 350 to 380mm increase enough to see a noticable difference?
i need to measure more, but even double/triple checking with the 380mm brembo fitment cutout, there does appear to be room for them to fit in my current 18" wheels.
I've had a bit of a saga with the brakes. long story short, race pads and 6" ducting has got a lot of the heat issues sorted now.
car is FK2R civic, 2peice 350x32 discs (factory size), factory brembo calipers, CL RC6e pads.
I'm usually on donington, but yesterday was silverstone and again saw brake judder when pads got a few laps in. do my session, come in, cool down for 20mins and out again would give no judder until another few laps in. this is very clearly NOT a pad deposit type/warped disc issue.
while it was up around 28c yesterday, ambient temps dont seem to have much bearing on this problem as 8-12c (at donington) has the same issue after similar laps.
i've a number of theories on the current hot judder problem but seeking advice on what to do.
1) pads were used pre-6" ducting and i've possibly killed them. brake feel seems fine so doesnt have the typical feel of cooked pads. Brembos used to turn brown there was so much heat although now theres only a slight hint of colour change since changing ducting. Replace pads and hope for the best? i suspect i'll just see the problem again.
2) normal behavior of the CL pads? unlikely i think.
3) i'm wasting my time with factory size. despite brembo & 350mm discs, i should seriously look into bigger brakes. I can get both brembo & AP 380x32mm + 6pot calipers.
while i could probably go bigger again - 390,400mm discs then it'd push me into 19 & 20" wheel sizes. is 350 to 380mm increase enough to see a noticable difference?
i need to measure more, but even double/triple checking with the 380mm brembo fitment cutout, there does appear to be room for them to fit in my current 18" wheels.
It probably is pad deposit / high spots, it happens a lot especially when you have heat issues - those high spots effectively become hardened and will not go away until you change the discs.
Have you changed discs since fixing the cooling?
That said, how bad is it? Lots of people struggle with the same issues and if it's only hot and on track and isn't a significant detriment to performance, then I'd just get on with it.
Bigger brakes are unlikely to solve the issue aside from the fact they'll be new discs.
Have you changed discs since fixing the cooling?
That said, how bad is it? Lots of people struggle with the same issues and if it's only hot and on track and isn't a significant detriment to performance, then I'd just get on with it.
Bigger brakes are unlikely to solve the issue aside from the fact they'll be new discs.
do you warm the brakes up before hard track usage?
what type of driver are you - are you trying to find all your speed through consistently braking very late?
have you tried braking a little earlier but less hard?
what brake fluid are you using?
do you remove any pad glazing between track days?
what type of driver are you - are you trying to find all your speed through consistently braking very late?
have you tried braking a little earlier but less hard?
what brake fluid are you using?
do you remove any pad glazing between track days?
Have you had your braking technique analysed by an instructor?
It could be a combination of your driving/braking style and the brake components.
My driving/braking style along with standard discs and RS29 pads and I can go the whole day without any issues...but if I do the same track on some other harder pads I will get rumbling brakes after about 20 minutes (which goes away for a while when they cool).
My mate told me that I was compensating for the difference in initial bite between the RS29 and the other harder pads by braking harder for longer.
It could be a combination of your driving/braking style and the brake components.
My driving/braking style along with standard discs and RS29 pads and I can go the whole day without any issues...but if I do the same track on some other harder pads I will get rumbling brakes after about 20 minutes (which goes away for a while when they cool).
My mate told me that I was compensating for the difference in initial bite between the RS29 and the other harder pads by braking harder for longer.
Edited by mmm-five on Wednesday 8th September 11:14
I did have this once because I was being too gentle on the brakes. They were glazing after a few laps.
Are you hitting them hard or are you braking a bit less than you could do in order to make them last longer before they overheat?
When it happened to me, I struggled with judder all morning then went out as passenger in a similar car. Saw how hard the driver was braking. Did the same in mine after lunch and it didn’t happen again.
Are you hitting them hard or are you braking a bit less than you could do in order to make them last longer before they overheat?
When it happened to me, I struggled with judder all morning then went out as passenger in a similar car. Saw how hard the driver was braking. Did the same in mine after lunch and it didn’t happen again.
I'd say I'm absolutely hammering the brakes.
copse corner would be something like this:
This was my first time at silverstone and while ambient heat was a problem with power, i'd be hitting around 115 at my braking point (green on the above screenshot next to the longer white paint marker, I've highlighted red as that seemed to be a common point for some), coming down to around 82 for apex and exit of 92+. Into maggotts where i'd line up to brake as straight as possible. brooklands would be the start of the right side rumble strip.
i cannot fault the brake performance itself. never fail or fade just the juddering is somewhat intense. If the green additional strips at the exit of copse or donningtons esses on national layout is 100% vibration, i'd estimate the juddering is maybe 50% of that. Very noticeable and shakes the car a bit - cannot be good for various components, surely?
the CL RC6e's are a bit different than most pads - sintered so afaik they dont work by using pad deposits. Yes the discs are new (EBC 2piece, but had the identical same behaviour on Girodiscs too). Currently running the regular brembo street pads, and swapping to the RC6e's at the track.
i swapped back at the end of the day to drive home on the street pads. zero judder or brake issues at all to lead me to believe it's a disc side issue.
warm up; yes. i tend to run a lap at maybe 60-85% pace before going full bore. partly to warm things up again, but also get my points, track state (no dumped oil from last time etc) and 'settled in' to the stint again.
copse corner would be something like this:
This was my first time at silverstone and while ambient heat was a problem with power, i'd be hitting around 115 at my braking point (green on the above screenshot next to the longer white paint marker, I've highlighted red as that seemed to be a common point for some), coming down to around 82 for apex and exit of 92+. Into maggotts where i'd line up to brake as straight as possible. brooklands would be the start of the right side rumble strip.
i cannot fault the brake performance itself. never fail or fade just the juddering is somewhat intense. If the green additional strips at the exit of copse or donningtons esses on national layout is 100% vibration, i'd estimate the juddering is maybe 50% of that. Very noticeable and shakes the car a bit - cannot be good for various components, surely?
the CL RC6e's are a bit different than most pads - sintered so afaik they dont work by using pad deposits. Yes the discs are new (EBC 2piece, but had the identical same behaviour on Girodiscs too). Currently running the regular brembo street pads, and swapping to the RC6e's at the track.
i swapped back at the end of the day to drive home on the street pads. zero judder or brake issues at all to lead me to believe it's a disc side issue.
warm up; yes. i tend to run a lap at maybe 60-85% pace before going full bore. partly to warm things up again, but also get my points, track state (no dumped oil from last time etc) and 'settled in' to the stint again.
Before you pull the trigger on a BBK have you tried a different track compound, Pagid RS29 as per mmm-five is an obvious comparator. Whatever PFC compound fits would be another solid choice.
You really shouldn't be getting judder after so few laps. I've run something similar but heavier and with more power with RS29 pads on track which had 350mm dia front discs and 4 pot brembo's without having ever having judder (and cup2 tyres). The CL 6e as an abrasive pad works by abrading the disk down so pickup etc would or should be worn away by them so that can't be the issue.
Silly question but have you tried them with the OE disc's to rule out any strange interaction with the hat on your two pieces?
Do you have pyrometer to check front and rear face temps are equal? or temperature paint to see what temps your getting on the disc and temperature strips on the calliper? Before spending big on parts I'd try to get to bottom of what is going on.
You really shouldn't be getting judder after so few laps. I've run something similar but heavier and with more power with RS29 pads on track which had 350mm dia front discs and 4 pot brembo's without having ever having judder (and cup2 tyres). The CL 6e as an abrasive pad works by abrading the disk down so pickup etc would or should be worn away by them so that can't be the issue.
Silly question but have you tried them with the OE disc's to rule out any strange interaction with the hat on your two pieces?
Do you have pyrometer to check front and rear face temps are equal? or temperature paint to see what temps your getting on the disc and temperature strips on the calliper? Before spending big on parts I'd try to get to bottom of what is going on.
Taking a logical approach, there are plenty of civics kicking around trackdays without mega brake upgrades. Therefore, it's unlikely that the issue really requires bigger brakes, although replacing the entire system may well solve it (baby out with the bathwater).
The reason to get bigger brakes would mainly be if the existing ones can't sink the amount of energy required. Again, see point 1, and get some temperature paint to confirm. But even then, there's no reason why being 'too hot' would cause judder, unless it's lead to warped discs (doubtful). I've 'coloured' plenty of discs without any issues.
Does the judder frequency change throughout the braking phase - i.e. is it related to the rotational speed of the wheels?
TBH, I'd bet money on the discs, whether deposits or some other factor. As they're 2 piece (I assume you mean floating), have you checked they're free to move on all the bobbins? If it's stuck.. go figure. Personally I'd not really want floating discs unless really necessary - IME they're a pain on motorbikes.
The reason to get bigger brakes would mainly be if the existing ones can't sink the amount of energy required. Again, see point 1, and get some temperature paint to confirm. But even then, there's no reason why being 'too hot' would cause judder, unless it's lead to warped discs (doubtful). I've 'coloured' plenty of discs without any issues.
Does the judder frequency change throughout the braking phase - i.e. is it related to the rotational speed of the wheels?
TBH, I'd bet money on the discs, whether deposits or some other factor. As they're 2 piece (I assume you mean floating), have you checked they're free to move on all the bobbins? If it's stuck.. go figure. Personally I'd not really want floating discs unless really necessary - IME they're a pain on motorbikes.
A bit more info on the discs would help, are they drilled, grooved etc?
I had an issue with calipers being so close to the wheel that on heavy braking in certain corners the minute amount of flex in the wheel caused rubbing on the calipers, obviously a set of 3mm spacers sorted it........
They were REALLY close! To get them to actually fit I had to grind the "AP" off the caliper front.
I had an issue with calipers being so close to the wheel that on heavy braking in certain corners the minute amount of flex in the wheel caused rubbing on the calipers, obviously a set of 3mm spacers sorted it........
They were REALLY close! To get them to actually fit I had to grind the "AP" off the caliper front.
b0rk said:
Before you pull the trigger on a BBK have you tried a different track compound, Pagid RS29 as per mmm-five is an obvious comparator. Whatever PFC compound fits would be another solid choice.
You really shouldn't be getting judder after so few laps. I've run something similar but heavier and with more power with RS29 pads on track which had 350mm dia front discs and 4 pot brembo's without having ever having judder (and cup2 tyres). The CL 6e as an abrasive pad works by abrading the disk down so pickup etc would or should be worn away by them so that can't be the issue.
Silly question but have you tried them with the OE disc's to rule out any strange interaction with the hat on your two pieces?
Do you have pyrometer to check front and rear face temps are equal? or temperature paint to see what temps your getting on the disc and temperature strips on the calliper? Before spending big on parts I'd try to get to bottom of what is going on.
i'm on nankang AR1 tyres. I've considered RSL29's but since i've been struggling with temps in the past i couldnt face blowing £300+ on pads i'd likely cook. the 6e pads are the only ones i've had luck with on the front. I've cooked EBC Blue NDX last time, pMu HC800+, PBS pro-race etc. admittedly apart from the NDX, the others were pre-brake ducting. Due to the design of the front hub, theres no way to get direct ducting in place so i'm running 6" through from bumper to get as much air as possible into the arch, and allow the discs and air redirectors to do their job.You really shouldn't be getting judder after so few laps. I've run something similar but heavier and with more power with RS29 pads on track which had 350mm dia front discs and 4 pot brembo's without having ever having judder (and cup2 tyres). The CL 6e as an abrasive pad works by abrading the disk down so pickup etc would or should be worn away by them so that can't be the issue.
Silly question but have you tried them with the OE disc's to rule out any strange interaction with the hat on your two pieces?
Do you have pyrometer to check front and rear face temps are equal? or temperature paint to see what temps your getting on the disc and temperature strips on the calliper? Before spending big on parts I'd try to get to bottom of what is going on.
factory discs - they're long gone. although i do have some dba 4000t3 1peice discs sat on the shelf.
I've currently no way to check temperatures. pyrometers & paint have been considered but not pulled the trigger on those yet. maybe get some 650c paint and see if i'm hitting that.
upsidedownmark said:
Taking a logical approach, there are plenty of civics kicking around trackdays without mega brake upgrades. Therefore, it's unlikely that the issue really requires bigger brakes, although replacing the entire system may well solve it (baby out with the bathwater).
The reason to get bigger brakes would mainly be if the existing ones can't sink the amount of energy required. Again, see point 1, and get some temperature paint to confirm. But even then, there's no reason why being 'too hot' would cause judder, unless it's lead to warped discs (doubtful). I've 'coloured' plenty of discs without any issues.
Does the judder frequency change throughout the braking phase - i.e. is it related to the rotational speed of the wheels?
TBH, I'd bet money on the discs, whether deposits or some other factor. As they're 2 piece (I assume you mean floating), have you checked they're free to move on all the bobbins? If it's stuck.. go figure. Personally I'd not really want floating discs unless really necessary - IME they're a pain on motorbikes.
yes, the discs are floating type. The old girodiscs are 7 grooves. The new EBC are split groove (https://d2hw29brqn7o70.cloudfront.net/media/catalog/product/cache/1/thumbnail/720x/9df78eab33525d08d6e5fb8d27136e95/e/b/ebc-racing-2-piece-rotor_33.jpg). Ended up with EBC because i couldnt get girodisc replacements in a sensible/confirmed timeframe.The reason to get bigger brakes would mainly be if the existing ones can't sink the amount of energy required. Again, see point 1, and get some temperature paint to confirm. But even then, there's no reason why being 'too hot' would cause judder, unless it's lead to warped discs (doubtful). I've 'coloured' plenty of discs without any issues.
Does the judder frequency change throughout the braking phase - i.e. is it related to the rotational speed of the wheels?
TBH, I'd bet money on the discs, whether deposits or some other factor. As they're 2 piece (I assume you mean floating), have you checked they're free to move on all the bobbins? If it's stuck.. go figure. Personally I'd not really want floating discs unless really necessary - IME they're a pain on motorbikes.
good question on the frequency. i cant actually remember although i am swaying towards a rotational issue.
caliper clearance is all good and plenty of room - running 18" TD prorace 1.3's
time for some more pictures...
pads
closeup of the left most pad
driver side disc - trailing edge of grooves appears to have some pickup possibly related to the cause of the judder?
braddo said:
Are you ever feeling the ABS start to kick in into slow corners, e.g. braking to the chicane after Stowe? That is a reliable sign that you're using maximum braking performance.
Yes, there has been times when abs kicks in. i do aim for threshold braking but also try to keep off the ABS as i'm sure it's not great for pad deposits with hot pads and monemtarily stopped discs.Firstly, I must stress that I am no brake expert, but if they were mine & I was having that issue I would be thinking the following.
You won't cook RS29 or DS1.11, they are full on endurance pads, they are money well spent, and will last longer than many other pads that claim to be racing pads.
I have managed a year on both with enough left on them to keep as spares.
The pads are well cooked & the discs look very shiny, as I say if they were mine I think the pads are the issue, but there may well be more specialist knowledge to follow my opinion.
You won't cook RS29 or DS1.11, they are full on endurance pads, they are money well spent, and will last longer than many other pads that claim to be racing pads.
I have managed a year on both with enough left on them to keep as spares.
The pads are well cooked & the discs look very shiny, as I say if they were mine I think the pads are the issue, but there may well be more specialist knowledge to follow my opinion.
veehexx said:
Currently running the regular brembo street pads, and swapping to the RC6e's at the track.
i swapped back at the end of the day to drive home on the street pads. zero judder or brake issues at all to lead me to believe it's a disc side issue.
This is likely the source of your issue. i swapped back at the end of the day to drive home on the street pads. zero judder or brake issues at all to lead me to believe it's a disc side issue.
You can't just swap and change between two different compounds, especially two wildly different types of compound. They are simply incompatible - I learnt this the hard way switching from Stoptech's street compound on a BBK to RS29s and it just vibrated like nothing else, far worse than normal pad deposit issues.
The damage might already be done to your new discs but it's worth getting them redressed/skimmed somewhere and then picking one brake compound and sticking to it after following the manufacturer's bedding in instructions to the letter.
So many variables that's it's tricky to know what the issue is with.
I would probably go back to square 1 and fit OE plain discs with perhaps DS1. 11 (cheaper than Rs29) and run the pads all year round.
A thin pad will overheat exponentially and exacerbate the binding agent in the pads being suckled away onto the discs. That's perhaps what happened. But perhaps not.
I would probably go back to square 1 and fit OE plain discs with perhaps DS1. 11 (cheaper than Rs29) and run the pads all year round.
A thin pad will overheat exponentially and exacerbate the binding agent in the pads being suckled away onto the discs. That's perhaps what happened. But perhaps not.
right, ok... CL RC6e's are being dropped. as been mentioned, they look cooked and while i'd agree, their performance remains solid so i've been doubtful if they were actually shot... i've still much to learn with how sintered, organic/semi-metallic and ceramic pads behave.
Think i'm going to run track pads&discs too based on the way this discussion has gone. bit of a faff swapping discs arounds twice a year, but definately cheaper than 380mm brakes and having to replace 18" with 19" wheels.
I'm going to clean off the current 2peice EBC's (probably run the RC6e's for a week or 2 on the road as they'll be in their cold abrasive mode) then pull 'em ready for the next set of pads, and fit the 1peice DBA's with road pads till then. Come next year (or maybe a final run late oct/nov) then i'll run the EBC discs with ds1.11/rsl29's.
quick question on the ds1.11/rsl29's... how year-round are they? I use the civic for daily use and somewhere around 6-9k/yr, so while i dont care about noise or squeal, when i ran the RC6e's on the road i chewed through 1/3rd of the girodiscs in 6weeks due to how abrasive they were - WAY more agressive than i expected. Performed fine, but definately not a pad to use year-round so i'm concious on wear rates of track pads.
Think i'm going to run track pads&discs too based on the way this discussion has gone. bit of a faff swapping discs arounds twice a year, but definately cheaper than 380mm brakes and having to replace 18" with 19" wheels.
I'm going to clean off the current 2peice EBC's (probably run the RC6e's for a week or 2 on the road as they'll be in their cold abrasive mode) then pull 'em ready for the next set of pads, and fit the 1peice DBA's with road pads till then. Come next year (or maybe a final run late oct/nov) then i'll run the EBC discs with ds1.11/rsl29's.
quick question on the ds1.11/rsl29's... how year-round are they? I use the civic for daily use and somewhere around 6-9k/yr, so while i dont care about noise or squeal, when i ran the RC6e's on the road i chewed through 1/3rd of the girodiscs in 6weeks due to how abrasive they were - WAY more agressive than i expected. Performed fine, but definately not a pad to use year-round so i'm concious on wear rates of track pads.
veehexx said:
quick question on the ds1.11/rsl29's... how year-round are they? I use the civic for daily use and somewhere around 6-9k/yr, so while i dont care about noise or squeal, when i ran the RC6e's on the road i chewed through 1/3rd of the girodiscs in 6weeks due to how abrasive they were - WAY more agressive than i expected. Performed fine, but definately not a pad to use year-round so i'm concious on wear rates of track pads.
Absolutely no issues at all, I have used both as my all year round pads on both e36 328 & r53 Mini with zero issues & both have good initial bite regardless of use/temperature.If I was being REALLY pedantic I would say the DS1.11 were slightly preferred on road & the RS29 slightly preferred on track, but the difference is miniscule.
Both last more than a year and with each I just changed discs & pads each year/18 months depending on usage, typically 8 - 12 TD + 5/8k miles/year on each set up/car.
Oh, and regardless of which you choose do NOT use drilled discs.
Edited by E-bmw on Thursday 9th September 12:03
I'm surprised anyone that's tried almost any other pad enjoys RS29s on track.
They are great in terms of longevity and fade resistance, even on very hot brakes but I think you'd get more bite and brake feel by fitting wood in your calipers.
I forget whether it was DS1.11 or DSUNO I tried in my M2 and they were golden on track and off, very little squeal but I got through a set in two days on track. That's in a 1600kg car with relatively small stock calipers though, they were definitely too hot! I'm sure they'd last better on something lighter with some brake cooling.
They are great in terms of longevity and fade resistance, even on very hot brakes but I think you'd get more bite and brake feel by fitting wood in your calipers.
I forget whether it was DS1.11 or DSUNO I tried in my M2 and they were golden on track and off, very little squeal but I got through a set in two days on track. That's in a 1600kg car with relatively small stock calipers though, they were definitely too hot! I'm sure they'd last better on something lighter with some brake cooling.
mpit said:
I'm surprised anyone that's tried almost any other pad enjoys RS29s on track.
That's in a 1600kg car with relatively small stock calipers though, they were definitely too hot! I'm sure they'd last better on something lighter with some brake cooling.
There is the difference right there. That's in a 1600kg car with relatively small stock calipers though, they were definitely too hot! I'm sure they'd last better on something lighter with some brake cooling.
FOB 4-pot Tuscan racer AP calipers on an e36 @1180kg all up.
Gassing Station | Track Days | Top of Page | What's New | My Stuff