Gary Foster

Right then.

I'm bloody fed up with having brake probs, so instead of going by the 'fast road' 'road race' marketing crap figures most of the manufacturers use, I thought I'd see if I could get some figures. Here's what I turned up for my Pads (Pagid Blues).

Here are some numbers of the Pagid pads:

Type RS4-2 (blue)

friction coeff.: operating u0.45-0,50 / cold u0.40-0.42
fading u0,36-0,38
temperature : continious 400-700C / short 800C
application: hillclimb,Rallye,Slalom,circuit racing


Type RS 9 (yellow)

friction coeff.: operating u0.38-0,42 / cold u0.36-0.38
fading u0,36
temperature : continious 300-650C / short 750C
application: Rallye,long distance circuit racing


Type RS 7 (black) sorry no numbers available

In Germany the different types are used as follows:

RS 9 mostly in long distance races like 4 hours on the
Nrburgring , also used at the rear of cars with a
tendency to overbrake at the rear axle

RS 4-2 very popular for rallye cars and used at circuit
racing for shorter distances , (best type for street use)

RS 7 used on rear axles only , low friction coeff. with
degressive behaviour , specially developed for rear axles
, mostly used on front wheel driven cars

Anyone got similar specs for other manufacturers or the rear 'fast road' pagid pad ?

I shall be testing this out on Saturday by measuring the temp of the rotor after some laps of a race track, to see whether I'm on the limit or not.

Gary

Gary Foster

No brake guru's out there ? I'll probably phone up the suppliers myself I just thought someone might have their old box lying around or something.

It'd be nice to have the information before my next pad change so I can make an informed decision.

Andrew Timmins

Here are a couple of links to some information about EBC brake pads, hope this is helpful.

Hoppy

Gary, I know how you feel!

But there's more to brakes than a set of pads. What have you got? What's the problem? What do you want to achieve?

Richard Hopkins

Gary Foster

OK, bit long winded but, heres the history in terms of track days

1) MY98 Brakes standard front and rear

result - massive amounts of brake fade after 3-4 laps of Donno. Complete set of standard pads worn through before lunch time (back and front).

2) MY99 4 Pots, standard Disks, MY98 Rears and standard (non vented) disk. Pagid Blue's on front, standard pads on rear. Dot 5.1 AP Fluid, braided hoses

result - pedal went very soft after 2 laps of Goodwood, still appeared to brake very well though. At end of day I had 1 cracked front disk (in 2 places !), worn through the rear pads again and scored those disks.

3) Front = MY99 4 Pots, Pagid Disks, Pagid Blue Pads (new), rear = MY99 Callipers, pagid vented disks, pagid 'fast road' pads. Braided hoses, this time Scoobysport recommended fluid (Dot 4 I think) silkolene. Brake support bracket and cooling ducts for the front callipers.

Result - I'll find out on Saturday.

As you can see, the next upgrade will be very expensive.

What I want - to be able to do 5 laps of Goodwood race track with no fade. To get manageable brake costs on track days. Either with pads / disks that last very well or a cheaper combination which wears nearly as well but are cheaper.

The solution I would like would be, same setup as above, cheap pads up front that brake OK but still last 4 track days with no fade. Cheap low friction rear pads at rear which last years and years (don't care about rear braking too much)

Gary

Hoppy

Gary, what you've got now is very similar to my previous set-up. The main differences are that I had DS2000 pads and Bremsport discs. I still managed to bu99er the discs at Dono so went straight to APR 4-pots and, because they're so good, I'm now looking to go to 6-pots. (This next upgrade is actually unnecessary, but I just want them!)

But you've got a very good 'fast road' set up there. You might have problems at Donington as this is the hardest circuit in the UK for brakes (closely followed by Knockhill and Oulton Park). But from your profile Goodwood looks like an easier location. I don't know if this is hard on brakes or not, but Brands, also not so far, is much kinder than Donington. If you really want to give your brakes an easy life, go to Snetterton or Silverstone!

You obviously like to squeeze them hard and I think your expectations of wear are unrealistic. When pads get hot, they wear very quickly. Always take a spare get-me-home set. Your cooling mods are interesting - this is the best thing you can do to maintain consistent performance. If this works, you could be sorted. Please let us know how you get on.

Al this sounds like I know what I'm talking about, which is scary! But you asked for feedback.

Richard Hopkins

PS I've also got braided hoses and the support bracket intended to enhance 'feel'. Watse of money. How can you improve feel when you've got a power-assisted system running through ABS as well?! I think I'm right in saying that the Prodrive/Alcon 17in brake upgrade still runs on rubber hoses. Driving God Simon de Banke (webmaster) says the Prodrive brakes are the best he has ever experienced.

[This message has been edited by Hoppy (edited 01 March 2001).]

Gary Foster

Hoppy

I said that's the brake pad wear I would *like* not what I think I'll have to live with

I didn't think I used the brakes much - obviously I do , I found Goodwood worse than Donno on brakes TBH possibly because the speeds were higher, possibly it was me not being kind to them. I try to be nice to them honest.

I am sure the ridiculous pad wear (ie 15-20 minutes) is due to the pad / disk overheating. I'm guessing the pad wears away very quickly once it's gone above it's max temp. This is why I was interested in the max working temp for the pads.

My theory being - as long as you are always within the useable range for the pad, wear should be 'OK'.

Eg, Goodwood Pagid Blues on front wore down by about 20-25% of the pads. The standard rears wore down 100% (and quite a bit of the metal backing plate). Given that the rears don't brake much, my conclusion was that the rears are either getting hotter than the fronts (unlikely even with solid disk) or they are going above their maximum temperature.

If the brake ducts / brake support braket (sounds like that was a waste of £50) arrive I'll get them fitted tommorrow.

Just arrived is some AP Temperature paint, so if it all goes to **** again at least I can provide some useful feedback on the temperatures reached.

Gary

Ps Are the AP's really that good - are they the 330mm ones ?, and do you not find that because those are so good the rears fry themselves now ?

Pps Give me first refusal when you come to sell ?

Ppps DS2000's arent really the same as pagid blues, I think DS2000's are just a fast road pad.

Gary Foster

Cheers for that Pete, it almost sounds like you know what you are talking about

Seriously though, I have to congratulate Scoobysport (Pete) on this, I really appreciate a tuning company which actually researches their equipment in a proper and scientific manner. We are really lucky to have Pete testing and supplying this stuff.

It would be very easy for him to simply read the marketing gumph from these companies and spool that straight of to us customers.

(I'm not sure I'd be so generous with the information gained, but hey

I would be quite happy to change my pads before and after every track day, this looks like it may be the way to go.

Interesting what Pete's said about the Brembos ! 350 deg is cold in brake terms only just working temparature for a lot of pads. I had assumed there would be little difference between standard as the disk size is only 10-15mm bigger hmm, that brake upgrade may be affordable after all ...

But wouldn't even bigger disks mean less wear on disk / pad so a longer life ? Or is this negligeable ?

Pete - What about lower friction pads on the back for track day use ?

Interesting about blocking of the rears, was talking to a track driver about this and he said they use a brake bias valve in the cars and if they are having problems with overheating the rears in qualifying they would just dial slightly more front bias in before the race.

Gary

Pete Croney

Gary

Most fast road pads tend to have a high wear rate, above their maximum operating temperature. On the road, this beneficial.

Now you are wondering

If you overheat the pad, the resins that bind the friction material together will boil. If the pad is designed not to wear away in this event (such as Mintex 1155) then the face of the pad remains, but without the resin the co-efficient of friction plummets.

On the track, you need a pad with a very high temperature range and these may not be suitable for road use.

Ideally, we should use one set of pads for the track and one for the road.

With regard to rear disc temps... we did some measuring at Cadwell, two years ago, with Brembo.

The measurements were made after 4 laps, with the car having driven into the pit lane. On the standard two pot set up, front disc temps would reach 640degC and the rears would reach 710degC.

With a brake kit fitted, the fronts were 350degC but the rears were still 630degC.

The measuring was done with Brembo's F1 probe device and the fronts were measured first. This means the rears had longer to cool and were some amount hotter, for a true comparison.

The cars used had the UK solid rear disc. One of the main problems with the rear brakes is that the hub shields the disc and prevents a decent airflow. As this part is structural, there are no easy solutions. We have supplied Gary with the parts to up-grade the solid rear discs to a vented set up and will should help.

I have thought that track braking may be better, if the rear brakes were blocked off. The fluid would stay at the cooler front calliper temps and the rear hubs would suffer no pad knock off.

Hoppy... unless you are using slicks and a set of track suspension, that will keep the car very flat under braking, I doubt you will get much more stoppage from going to 330mm. It is easy to have 305mm discs holding slicks just off the point of lock. This is the maximum braking that can be achieved and a bigger disc won't help. The one thing you will get is a fair increase in unsprung weight. No problem on a smooth track, but a big issue on country lanes.

You can have too much of a good thing

DS2000 is definitely a fast road pad and is not really up to the temps of a track day, unless on a very big disc. Pagid RS42 is much closer in feel to DS3000, but without the aggresive disc wear.

Stef

Pete.
How does using a bigger brake kit reduce the temperatures? When my AP kit was first fitted, temperature paint was applied to all components. They all still got VERY hot. I can't see how using a bigger brake kit without any additional cooling can reduce temperatures? With bigger brakes you can brake harder, stay out longer and use pads that are designed to work better at high temperatures? Surely this would increase the operating temperatures, not reduce it?

Stef.

Pete Croney

The point is the readings were taken in the pit lane, approx 10 seconds after the last big use (the left hander going towards the mountain).

Heat paint showed that we were just touching 700degC on the fronts, but the temps in the pit lane showed us how quickly the brakes were recovering. This is the important thing. If a braking excercise is going to add 400degC to the discs, it's not much fun if they are already at 500degC.

Think of the discs as a water butt, with a drain hole in the bottom.

The hole represents the rate at which the water (which we will use to represent heat) can be lost. The example over simplifies things, as the true rate of heat loss is not so linear. With normal driving, we pour water in and it drains out. The level in the barrel can fluctuate, but provided it doesn't overflow, we don't get brake fade.

On track, we throw the water in with stable buckets, probably with a mate helping.

Provided the amount of water added in a given period is less than the flow rate through the hole for the elapsed time + the holding capacity of the barrel, it doesn't overflow.

What we need is a bigger hole in the barrel...

...or discs with more surface area and better cooling abilities. Step forward the various brake kits on the market, with greater surface area, larger cooling gaps between the friction plates and turbo shaped vanes in these gaps.

Bigger brakes are like a bigger barrel and a bigger hole.

Hoppy

Gary, I can't add anything more to this thread. Pete Croney has said some of the things I was thinkign about, but he's been there, done that, and has got the data to prove it. I also have it on the very highest of high authority that Pete really does know what he's on about.

Pete, thanks for your input. I know my reasons for fitting APR 6-pots are not entirely objective. My excuse is that I've got 17in wheels and slicks, and I just want them

Comments I would make are that while my APR 4-pots stop the car very well, triggering the ABS quite often, I have to push the pedal so hard that sheer physical effort wipes out any useful feedback from the pedal. I would like to have too much brake, so that it's down to me how well the car stops without just planting my foot and letting the ABS take care of my clumbsyness.

I'm with you on the track suspension thing. When funds allow, I am hoping to fit adjustable dampers for comfort on the road combined with much firmer performance settings for track. Leda is a name that comes to mind. Do you know any Leda retailers ? Seriously, I would appreciate your advice.

Richard Hopkins

PS I also need some driving lessons, having been down 'Stef Straight' (aka Craner Curves) on my last track day !

Gary Foster

Pete's rear MY99 brake upgrade appears to have done the job (and maybe too well I don't think even the green heat paint has turned ! Well this is a better result than I could have hoped for.

All the coloured paint on the front has gone a sort of pasty colour of the original colour, so I assume this means they ran way over 700 deg C

I'll check for pad wear tommorrow, but I think I've killed 1/3 to 1/2 of the front pads off today (not cheap !).

In addition, after a lap or deux, the pedal becomes very very spongy, but there is still braking there (I had no fade all day - 15min sessions) - anyone know what that means ?

Gary

Gary Foster

Re-reading Stef / Pete's comments, it looks like I should have taken a temperature probe thingy to get some useful information, guess the heat paint is not a very useful figure.

Oh well. Just need to fix the spongy pedal thing though now.