View Full Version : Brake upgrades for track use, rear discs, 4 pots?
Couple of questions about combatting some braking problems I experienced on my last trackday. Current setup:
Standard rear drum setup, all reconditioned/new 14,000 miles ago
256x24mm front ATE calipers, vented discs, various pads used
The problems I had were:
1) The rear drums stuck on after I came back into the pits
2) The fronts were fading after several laps. (I rigged up ducting pointing at the disc and tried to use the M1144s but it didn't work too well).
What I'm thinking of doing is:
1) Converting the rear brakes to discs/calipers and biasing them correctly, to give a more reliable braking when hot and hopefully not overheat and seize on
2) Upgrading the fronts to a larger disc and "proper" calipers, e.g. a 280mm 4 pot setup.
Questions... Is there anything I can try on the drums to stop them seizing on like they did? Also is there any chance I could upgrade to a "proper" caliper and still have fading problems?
What fluid are you using?
Ideally you'd get some temp indicating paint which comes in 3 flavours, green 430 orange 560 and red 670 iirc? and check what kind of temperature your discs are running at, most performance pads for steel discs should be about 4-500c and they won't start fading before 600ish so a combo of green and orange paint is ideal for checking that... drums I'm not sure on, who the **** uses drums nowadays lol
If you're running within ideal temps and still getting fading issues I'd point a finger at the fluid and a dab of green paint on caliper/lines could let you check temps there. If cooling is to blame you could upgrade to bigger discs and still get fading issues, but obviously you've tried a bit of ducting to solve the problem and it's not made it any better?
ATE Super Blue fluid, bled a little through the front calipers recently too so it was fresh before the day.
Issue with this is I need to put up with another trackday of fade before capturing some results from the temperature paint as I can't reproduce this kind of heat on the road?
I did try the ducting and it wasn't really an accurate before-and-after (Mintex 1144s faded badly without ducting on Donington, and faded with ducting on Blyton Park) but I didn't think it was that effective as you don't get that much speed up at Blyton.
Rear drums, well I don't really like drums anyway so a disc/caliper setup would be much nicer to maintain going forward I think.
craig green
28-05-13, 04:51 PM
I assume the drums seized because you applied the handbrake in the pits?
As for the fronts, proper fluid & pads should be fine, which the begs the question what engine/power have you got?
Simply going bigger (V6 288's) is a lot of extra weight as are 16v rear discs.
ATE Super Blue fluid, bled a little through the front calipers recently too so it was fresh before the day.
Issue with this is I need to put up with another trackday of fade before capturing some results from the temperature paint as I can't reproduce this kind of heat on the road?
I did try the ducting and it wasn't really an accurate before-and-after (Mintex 1144s faded badly without ducting on Donington, and faded with ducting on Blyton Park) but I didn't think it was that effective as you don't get that much speed up at Blyton.
Rear drums, well I don't really like drums anyway so a disc/caliper setup would be much nicer to maintain going forward I think.
Personally I would rather know what I was fixing than blindly changing things and hoping it fixes it, so I'd go for a diagnostic trackday over possibly multiple trackdays with the same issue. Were you running slicks at Donington as well? As slicks will obviously work the brakes a lot harder before they lose grip.
I'd be willing to bet the inertia in a drum setup is similar to or worse than that of a disc tbh! I have seen drums on fire before, where rear brakes shouldn't really get that warm on a Nova, most of the weight is on the nose before you even start braking. I agree on the front though it would be much better to get the 16v setup working effectively than just go bigger.
What rim size are you using ?
Iain i had issues with rear drums binding , i found it to be the self adjusters over adjusting due to the heavy use of brakes ,so i put a split pin through the adjuster to stop it winding the shoes out ,it seems to have solved the problem
meritlover
28-05-13, 05:46 PM
change the fluid, specify what pads you have tested, bin the idea of rear brakes, consider changing your driving style and or suspension to rely less on braking hard in corners. dont use the handbrake when the drums are toasting hot (they shrink as they cool onto the shoes locking them on).
how do the M1144s 'not work too well'?
Im with MK999, its probably fluid boil.
phunkynova
28-05-13, 06:31 PM
Try use Mintex 1155's or there is also 1166
The 256s aren't up to track day use IMO. Go to 280's.
When i did my track day i used 280s with cheapo pads, 1144 and st rear drums. I did snetterton which is a fast track and was out for 15-20 mins a time and did not suffer from any brake fade.
I'd guess you didnt do enough cool down laps as to why your drums over heated.
Never used the handbrake in the pits or when they were hot
I did one warm up lap and one cool down lap per session
Craig I'm running a mostly standard 20XE pushing maybe slightly more than standard power.
MK999 I see it more like upgrading to cope with problems and give improvements along the way than trying to make 20 year old standard road car items try and cope with my abuse... If I can spend a few hundred and get bigger, better brakes I don't need to worry about then win win IMO.
I'm using 15x6 wheels.
Jezz that sounds quite likely as I think now the handbrake is a click less than when I went on the trackday. I did readjust them just before I went on the day to get the balance right, maybe I need to disable the adjusters...
PhunkyNova I've already tried several pad iterations on these calipers, the Yellowstuff pads I used never faded but had a crap pedal feel and no intitial bite. I've tried DS2500s which the pad material crumbled. I've tried 1144s which feel good until they start to fade.
I thought the Super Blue was a good fluid and I'd struggle to boil it?
The 256s aren't up to track day use IMO. Go to 280's.
This.
Whether you go GM or 4pots, you need bigger discs/pads.
Never had issues on 284s myself.
phunkynova
28-05-13, 07:25 PM
1144's are are fast road pad 1155's are a motorsport pad and 1166's are extreme motorsport pad, they all go up a spec in temp and usage.
But my best tip is to speak with Alan Brown at Questmead : http://www.questmead.co.uk/contact/dealers.aspx
They are the best.
phone: 01706860088
If you can get a hand on light steelies 14 inch you can try how that does it for you. By reducing the wheel weight I think this can save you a lot. Or maybe using 280mm if they will fit 15 inch.
If the pedal was hard but no stopping then the pads were goosed (over worked) 1155's or cl5+'s should sort that.
Power is semi irrelevant when talking brakes IMHO.
Will reducing the wheel weight dramatically change the heat in the brakes? I have 12 15" tyres with various tyres for road and trackdays so changing wheel size isn't so much of an option now...
Stuart the pedal felt firm, with the same pressure on the 1144s there was a lovely intitial bite and the Yellowstuffs felt progressive from 'nothing' to 'something'. DS2500s were similar but not quite as bad and felt nicer when warmed up with even gentle use.
I've had similar discussions on here before about pad choices and kind of wanting to try some new brakes rather than just swapping pads in the same old 256 setup now...
meritlover
28-05-13, 10:07 PM
there is no physical reason why a warm handbrake should bind when it hasn't even been applied.
Sounds like you've already talked yourself into upgrading anyway.
Pistol Pete
28-05-13, 10:18 PM
Will 284's fit under 15" alloys?
I've had similar discussions on here before about pad choices and kind of wanting to try some new brakes rather than just swapping pads in the same old 256 setup now...
But so far you haven't actually just put up the cash for track spec pads, you've skirted around it buying the road spec mintex (1144) similar ferodos, yellowstuffs etc and probably cost yourself double what a set of CL5's or 1155's or the 1166's that phunkynova suggested that I haven't even heard of, which might be precisely what you need.
If you wanna go for 4 pots then just do it and stop asking permission off us :p
Reducing wheel weight is a tiny proportion of what exerts force on the brakes and chances are the larger area of better heat conduction material actually helps, so not sure what that was all about
You clearly brake too much, not got fade in mine yet. :p
Haha I haven't talked myself into anything or asking permission, I guess my underlying question was is getting 4 pots likely to help or are they subject to the exact same fading problems, assuming the fluid is up to the task. Sounds like people have more success with the 280 setups than the 256 setups so sounds like the answer is yes it'll help if for size increase alone.
Granted 1144s aren't the proper pad, DS2500s are written up as trackday/light motorsport use and are what Olly ran on his track car at one point, Yellowstuffs are similarly specced in the EBC range.
The EBC range is completely for idiots though :(
meritlover
29-05-13, 09:47 AM
EBC pads are plain aweful, their 'coloured range' are both unsuitable for driving to the shops and for fast road/track.
Im sure your problem is pad related or you are relying on the brakes too much. either way, even if you 'upgrade' to larger brakes, without a decent understanding of what pad you need you will likely have the same issues again.
Happy to try some different pads, e.g. 1155s, when I upgrade the calipers, just pads aren't cheap and I want to get it right this time without ploughing another £80-100+ into pads for the calipers I now think are too small.
How do you rely too much on the brakes for track driving?
meritlover
29-05-13, 10:14 AM
Happy to try some different pads, e.g. 1155s, when I upgrade the calipers, just pads aren't cheap and I want to get it right this time without ploughing another £80-100+ into pads for the calipers I now think are too small.
agreed, but equally the expence of upgrading calipers and discs when the problem can be solved with pads is certainly something most people would investigate first.
How do you rely too much on the brakes for track driving?
driving style, poor tyres, poor suspension, poor lines....
obviously i dont know how you drive, but its a major conrtibutor and as said before its something that you should consider.
Put it this way.
The VX 200 and Elise both use calipers that have tiny tiny pads and with 1144's you get good stopping on the road but fade under heavy load but 1155/CL5+/PFB97's etc you dont get any of that.
OK the callipers are two pot and the discs are bigger, but fade isnt related to disc size or calliper piston count really. Fade is simply a function of size and compound (willing to be corrected)
Hopefully tyres and suspension are right, I've spent a while and some cash getting those how I want them (full Michelin slicks, Gaz coilovers, spherical bearings, poly bushes, tweaked spring rates etc)
Stuart I've attempted to follow your excellent advice before, I tried to order a set of CL5+s and stock was out for months, and I struggled with finding Mintex 1155s for the Vauxhall 256 setup cheaply and on the shelf. Another reason I'm tempted to move to a 'standard' pad size (e.g. Wilwood pad shape)
Disc size will drop the heat levels, as it's a larger conducting area to expel heat. Also the bigger disc will do less physical work at the point of contact, because it's got a larger lever. For a given mu value of the pad the clamping force will be lower on a smaller disc to produce a smaller braking force at the pad, but the same moment.
However it's also a trade off for weight and inertial mass, people underestimate just how much performance is in smaller, lighter brakes because 'big brake kits' are pushed as performance upgrades and supercars boast discs bigger than your wheels. I would much rather have a 256, or 256 sized at least or even smaller! (if you go for 4 pots maybe) that outperforms the 288 ATE's, than 288 that you can use standard pads in because they're overspecced.
Also Merit, poor tyres will work the brakes less, as you can't use them as hard, same as poor suspension and poor lines really, all result in less grip or less straightline braking... only way you can pull effort away from the brakes in driving is using more engine braking.
meritlover
29-05-13, 12:32 PM
just do it then. 3 pages of great advice, but it doesnt really seem to tell you what you want to hear.
what on earth is this thread actually about when you continually discount all the relevant issues and suggestions being submitted.
if you tried to get pads months ago then they would have probably arrived by now if you had just gone ahead and bought them instead of giving up and buying the cheapest/worst off the shelf equivelant.
out of the whole UK you couldnt get a set of CL5 off the shelf?
you say you 'struggled' to get 1155s ...but struggled is different to 'couldnt get them', so they can be obtained.
why did you not buy them and use them?
meritlover
29-05-13, 12:36 PM
Also Merit, poor tyres will work the brakes less, as you can't use them as hard, same as poor suspension and poor lines really, all result in less grip or less straightline braking... only way you can pull effort away from the brakes in driving is using more engine braking.
i disagree to some extent. You are right, but having poor lines/tyres/suspension forces drivers to work harder on the straights and brake later. the corner speed is generally lower with a poor setup but straight line speed can be the same (depending on power and length of straight/track layout etc) and therefor more speed has to be shed through braking to allow for a reduced corner speed.
You cannot achieve the same straight line speed with a lower cornering speed, unless that car is topped out at the end of every straight, where does the extra acceleration come from?
And how do you 'work harder' on the straights, than being WOT?
With a poor setup you will have less grip which forces you to brake earlier, and for longer, but at a much lower rate so much less energy in the braking system.
Calm down Mr Merit, I've not discounted or ignored any advice lol I basically wanted to know if upgrading to 4 pots or larger discs would potentially lead to a solution, the answer is yes, therefore I am happy.
I tried to order CL5+s and failed, so I rang several suppliers of Mintex pads who couldn't get 1155s, I think they said that compound was custom made for the Vauxhall pads. So I bought a different pad and put up with crap pedal feel for a few trackdays, I'm not gonna put in a CL5+ order at the same time as buying the other pads am I...
And other than the explanation of cool down laps and the auto adjusters messing about, I see no reason to move to rear discs still too lol
meritlover
29-05-13, 01:10 PM
You cannot achieve the same straight line speed with a lower cornering speed, unless that car is topped out at the end of every straight, where does the extra acceleration come from?
And how do you 'work harder' on the straights, than being WOT?
With a poor setup you will have less grip which forces you to brake earlier, and for longer, but at a much lower rate so much less energy in the braking system.
its perfectly reasonable for 2 cars with different brake setups to be doing the same straight line speed on the right track. especially since most are geared for 110-120 max
this is where the advantage comes from. yes the car with more corner speed will be ahead, but the top speed can be the same because he reaches it quicker.
having been to many track days and watching many people with budget cars 'drive quick' its no wonder many of the same people complain about brakes and how they could go faster with better brakes. There is often nothing smooth or consistent about how they are driving and all the energy as expelled through brakes rather than just taking a smooth clean line and lifting off before the corner. Not just throwing an anchor out the window last minute and hoping for the best.
VX220 and Elise track days are priceless for this.
You clearly brake too much, not got fade in mine yet. :p
You clearly can't carry enough speed through the corners to justify braking at the end of the next straight :p
You clearly can't carry enough speed through the corners to justify braking at the end of the next straight :p
I'm guessing the drivers of the caterham/vx220/s2000... Other good handling cars would disagree that mine doesn't do corners.
http://www.youtube.com/watch?v=PorTDHSnazo&sns=em
:p
turbojolt
29-05-13, 04:18 PM
You clearly can't carry enough speed through the corners to justify braking at the end of the next straight :p
oooooooooooooooooooh burned!!!!!!
I'm guessing the drivers of the caterham/vx220/s2000... Other good handling cars would disagree that mine doesn't do corners.
http://www.youtube.com/watch?v=PorTDHSnazo&sns=em
:p
Lol. Interesting to see what lap times are like compared to a 4pot. Can't really draw a conclusion on a wet day like that one. Anyway that's another thread. :)
Christ Iain's trying to build a cheap track toy not break lap records. He has a great car and has found that he is suffering from brske fade so has asked what other people are using and what results they have. How we've got into a scientific debate about 'mu' and clamping forces and iain's driving lines!
If he was serious about trackday-ing and lap speed records then a) he wouldnt be doing it in a Nova and b) he wouldnt be taking advice from us.
He is building a Nova not a Ginetta cup car!
Southie
29-05-13, 06:47 PM
Iain are you running bias brakes or a standard Nova master cylinder? Might of missed this somewhere.
If bias have you got the rears setup with too much braking?
If standard then are the adjusters too tight?
Missed out the rest of the braking setup sorry, here it is completely:
Corsa master cylinder/brake servo
Braided brake lines from MC to all four corners
Wilwood rear brake bias valve
ATE 256mm front calipers, vented discs, Mintex 1144 pads
Standard rear drums
The bias valve only reduces pressure and doesn't increase it so I don't think it'll be set up too much to the rear? Adjusters were perfect before I took it on track, I *think* it has reduced a handbrake click now so it could have done what Toymex said and adjusted itself when hot?
Southie
29-05-13, 06:59 PM
Also how new are your hand brake cables, they maybe pulling too tight.
Only coming up with suggestions btw ;)
chris gsi
29-05-13, 07:08 PM
The spec of your car is similar to my old one and I never suffered brake fade and I ran courtenay sport 16 grove discs 256/24 and mintex 1155s and standard rear drums and dot 5.1 fluid (the tracks I did were castle combe and llandow) hope this helps
Everything on the braking setup was brand new 14,000 miles/2 years ago apart from the calipers and Corsa servo/MC.
Yes thanks Chris, I'm pretty set on trying the 1155 pads it's whether or not I go for new/bigger calipers or try them in my current setup hmmmmmmmmmm
Sorry for the spam, Iain
how did you do the thing with the wilwood rear brake bias valve, how many lines are going out of the master cylinder for the rear brakes ? Any pics ?
Thanks
Couple of pics here: http://www.pngclub.com/forum/showthread.php?114446-Iain-s-20XE-Trackday-Nova/page155
The Corsa brake servo only has 2 outlets so one is taken through the car, and the bias valve, then T'd off to the drums. Similar for the fronts.
turbojolt
30-05-13, 09:53 AM
could you not borrow a set of widder opened alloys, to help get more air to the brakes?
could you not borrow a set of widder opened alloys, to help get more air to the brakes?
Actually the wheels act like a heat sink, and a larger surface area means they cool faster. Hence the popularity of BBS style or multispoke wheels over 5 spokes etc for racing because they have a large surface area for their low weight. So some multispokes might help, but having thinner 5 spokes, i.e more open. would actually drop the cooling capacity imo.
blue_peg_16v
30-05-13, 08:36 PM
I ran 280mm willwoods front and drums on the back (now discs but not been on track with them) and never had any problems after going straight on into a gravel trap with 256s through brake fade I decided to upgrade and have never had the problem since bear in mind my car has full stereo install and leather interior so wasn't the lighter and was running 196bhp xe at the time carnt wait to get the van on track now though last bit of paint next week hopefully
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