Hot brakes = Brake Judder?


Bon87

DC2 ITR Owner
Joined
Nov 26, 2007
Messages
1,524
2 days ago, I took my car on track for 25 mins. (taster session)
And near the end of it, I was getting mad brake judder from 90 to 70mph.
But after a few days the judder is gone, but I still have an increased pedal travel from the track day.

To get rid of the judder completely I need new disk and pads.
But judder isnt my problem right now, the deep pedal travel is.
Why is there increased pedal travel?
Now would bleeding the brakes sort it out?
And how do you know if you've boiled standard dot4 brake fluid?
 
Brake judder is normally caused by warped discs, altho it sounds to me like a good fluid change and bleed will sort your problems out.

Did you drive the car hard on the road much or was the track the first time you've given it that level of abuse? Maybe you had warped discs and your session on track highlighted it for the first time.
 
Yes id wager you have got localised boiling of the fluid in the calipers thanks to the heat generated on track...very common after a track day & most track regulars will bleed the brakes as a matter of course after a trackday...

The long pedal is normally a give-away..

Forget the DOT rating of the fluid. The wet & dry boiling points are what are important.

The higher the DOT rating the more resistant the fluid id to water ingress (i.e less hydroscopic)

If you plan on tracking the car again consider a swap to Castrol Response fluid....very good stuff:nice:
 
Fluid was changed 2000miles ago. It was normal halfords stuff. £4 on trade, Im not complaining.
So do you reckon I could get away with just a full brake fluid change?
Brakes are fine, just long travel.
I'll get new disk/ pads later on as its not a must right now...
 
Castrol Brake fluid is very good, but the Castrol SRF is the extreme top stuff! Best of the Best! Dot 5 and about 10 times more expensive than DOT 4.1 performance fluids.

But you only need to use DOT 4 or better DOT 4.1.

I only use Castrol :)
 
I would only recommend DOT 4 or 5.1 fluid, do not use the silicone based DOT 5 fluid as it's incompatible with the stock glycol fluid unless completely (very completely) changed. DOT 5 fluid would also increase pedal travel as it's more compressible than glycol.

And, to clear things up, the term is hygroscopic, and the higher the DOT of the fluid, the MORE susceptible it is to take in water. DOT 4 and 5.1 have much higher wet and dry boiling points than normal brake fluid, but they do have to be changed more often because of the higher water intake. Another reason, besides the expense, that OEM's usually don't use anything but DOT3.

You should be using a good fluid (ATE super blue, motul RBF600) and be doing a simple bleed after every track outing. Once your done with your run try not to stop dead on hot brakes, that will cause brake shudder. We've beat the topic to death, but you won't get warped rotors just uneven deposits of built up pad transfer layer on your discs that cause brake shudder.

You may want to go ahead and switch to a more track worthy pad just for track use, hot pads over their load limit can cause a very unresponsive pedal and braking force.
 
25mins on track with standard discs & pads with basic fluid will have cooked everything for sure. Changing the fluid should sort the travel, get some decent fluid if you plan to track it again - as above.
Your first post says you still have judder, your last post says they are fine? Could be warped discs, maybe get your wheels balanced to be sure.
How was Snetterton? :nice:
 
It is near on impossible to warp discs, the heat generated has probably been enough to melt the pads which has left huge deposits on the discs which are causing the judder.......

BUT a guy i know who used to track his DC2 very regularly got mad vibrations from similar speeds, turns out that he hadn't torqued his front wheels evenly with a torque wrench. came into the pits, loosened off the front wheel nuts, torqued them all up to the right spec with a torque wrench, out for another session and they sorted themselves out once they got roasting!!

As said though, some braided hoses and bled through thuroughly with some decent fluid will help loads

For more track work i'd reccomend some different pads which will be more stable at higher temperatures, standard discs are fine on track, i've used oem discs/plain AP dixcel ones and now on a set of EBC blanks and they work well, it's the pads that make the difference not the discs :nice:
 
Steven has got it bang on....most likely the vibration is pad pick-up...

Some new fluid plus a few hard stops from high speed should clean the discs up nicely...

Certainly well enough for plenty more road use!:nice:
 
K, I'll do fluid change and tourqe the nuts equally, for now and see how i get on, i wont be tracking for a while yet anyway.
I was gonna go for either oem disk or ebc blanks anyway, with some mintex (1155?) pads or similar. or ds2500.. :)

My nuts were not equally tourqed. and the centre of my wheel turned yellow too.... from the heat I guess, I've never come across this .....

DSC04519.jpg
 
Welcome to the world of trackdays & the effects they have!:p
 
They standard 262mm brakes? That will be another reason why...........

My make cooked his brakes big time on track with the wheels going orange on his 96 spec

The bigger brakes front and rear with the larger 1" MC do make a huge difference on the EK9/98 spec

He ended up just upgrading the front brakes with a set of 98 spec calipers/blueprint discs/my old Endless CCX pads and he is now much much happier with the way it slows down :)
 
wow thats some serious heat.

we should think about air routing for the brakes.
 
It is near on impossible to warp discs, the heat generated has probably been enough to melt the pads which has left huge deposits on the discs which are causing the judder.......

BUT a guy i know who used to track his DC2 very regularly got mad vibrations from similar speeds, turns out that he hadn't torqued his front wheels evenly with a torque wrench. came into the pits, loosened off the front wheel nuts, torqued them all up to the right spec with a torque wrench, out for another session and they sorted themselves out once they got roasting!!

As said though, some braided hoses and bled through thuroughly with some decent fluid will help loads

For more track work i'd reccomend some different pads which will be more stable at higher temperatures, standard discs are fine on track, i've used oem discs/plain AP dixcel ones and now on a set of EBC blanks and they work well, it's the pads that make the difference not the discs :nice:

Y0 Steven, I torqued up my nuts... still got the judder :(
I'm going for EBC blanks and Mintex 1155 pads, soon.
 
On DC2, upgrade to BBB6 caliper and 282mm rotor. Pagid RS4-2 (blue) with Motul RBF600 fluid, and you'll never have a problem again, if you're only doing the odd track day. RS-14 if you're track only. You can use them for street, but they're noisy, and take a while to warm up, so be careful until they do. Remember to upgrade your brake lines to braided lines also. Goodridge make direct bolt in kits which (in New Zealand at any rate) go through compliance no sweat.

I've tested lots of different pads for many different cars, and Pagid have out performed everything else in all applications.

They're not cheap, but the extra you pay means you won't be sorry!
 
Hi Bon,

If the brake judder is the build up of brake pad material on the disc then this will fix it. I encourage customers of mine to do the same thing to bed the brakes in faster if theyre going to their next track event soon after fitment.

Location
find a long quiet road, preferably in an industrial estate

Proceedure.

At between 70-90 brake very hard down to about 5mph WITHOUT STOPPING then bring your speed back up and repeat! You need to do this 8-10 times then simply roll your car to a stop WITHOUT using the brakes as they will be very hot by now. DONT use the handbrake, once youve stopped put it in gear with the engine off.

Relax and let it cool down for 10 minutes.

Then drive off braking gentlyfor the first couple of miles then test. Problem solved every time,

People get this alot too when they over heat the pads (glazed) and or brake very hard to a stop at traffic lights. Then you get a BURNED on imprint of the pad shape onto the disc. This uneven layer of material stuck in the disc is what gives you the brake judder.

let me know how you get on :nice:


Notes:
*Cheap blueprint/pattern parts/econo ebc or similar pads WILL glaze over with this proceedure, factory pads wont. Just to bear in mind.

*Harder the pad/disc setup the more you MAY have to do it to get rid of the juddering. Most track pads wont give you this problem though because of their temperature range

*If pedal travel has been greatly increased after a track-day and your brake system is in mechanically-great health then this is a sure sign youve boiled the fluid. I give my customers a free brake-fluid test that measure the ammountof water in the fluid and also indicated if it has exceeded its boiling point. This test is with a handheld machine and takes barely a minute overally :nice:

*If you have braided brake lines and they dont have a heatshrink cover then make sure you inspect them periodically. The factories dont use braied lines without a sheathe as dirt and grit gets between the braid and the teflon tube then before you know it you get a hydraulic leak from the damaged PTFE liner. !

*using the wrong kind of brake fluid (like silicone based fluids that are very hygroscopic) in your car or mixing fluids without a pressure flush can leave you with worn/leaving seals! Most topend racing brake fluids have to be changed every event because of this! which is why its good to find a happy medium for the street

:nice:
 
Hi Bon,

If the brake judder is the build up of brake pad material on the disc then this will fix it. I encourage customers of mine to do the same thing to bed the brakes in faster if theyre going to their next track event soon after fitment.

Location
find a long quiet road, preferably in an industrial estate

Proceedure.

At between 70-90 brake very hard down to about 5mph WITHOUT STOPPING then bring your speed back up and repeat! You need to do this 8-10 times then simply roll your car to a stop WITHOUT using the brakes as they will be very hot by now. DONT use the handbrake, once youve stopped put it in gear with the engine off.

Relax and let it cool down for 10 minutes.

Then drive off braking gentlyfor the first couple of miles then test. Problem solved every time,

People get this alot too when they over heat the pads (glazed) and or brake very hard to a stop at traffic lights. Then you get a BURNED on imprint of the pad shape onto the disc. This uneven layer of material stuck in the disc is what gives you the brake judder.

let me know how you get on :nice:


Notes:
*Cheap blueprint/pattern parts/econo ebc or similar pads WILL glaze over with this proceedure, factory pads wont. Just to bear in mind.

*Harder the pad/disc setup the more you MAY have to do it to get rid of the juddering. Most track pads wont give you this problem though because of their temperature range

*If pedal travel has been greatly increased after a track-day and your brake system is in mechanically-great health then this is a sure sign youve boiled the fluid. I give my customers a free brake-fluid test that measure the ammountof water in the fluid and also indicated if it has exceeded its boiling point. This test is with a handheld machine and takes barely a minute overally :nice:

*If you have braided brake lines and they dont have a heatshrink cover then make sure you inspect them periodically. The factories dont use braied lines without a sheathe as dirt and grit gets between the braid and the teflon tube then before you know it you get a hydraulic leak from the damaged PTFE liner. !

*using the wrong kind of brake fluid (like silicone based fluids that are very hygroscopic) in your car or mixing fluids without a pressure flush can leave you with worn/leaving seals! Most topend racing brake fluids have to be changed every event because of this! which is why its good to find a happy medium for the street

:nice:

The 1st thing that came to me is, "did I boil the fluid?!"
And you basically confirmed it for me.
Damn.
 
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