Mixed-pad combinations?

[dan_b]

Some advice/views appreciated on this thorny topic...

Most people here uprate the front brakes to something fairly significant (multi-pots, massive discs) but generally leave the rear setup standard (useless caliper, paper-thin disc).

By doing so, we're shifting the brake effort even more in favour of the front of the car, which we all understand.

My question is this - what about pad friction? And therefore, what about using a different pad at the back to the front?

The classic example is EBC Red at the front, with EBC Green at the back: Green has a significantly higher coefficient of friction than Red, so physically grabs at the disc much more vigourously, but can't run the high temperatures that Red can manage.

This is the situation I have at the moment. I did have Reds on the back as well, but the disc needed changing and I thought "well might as well give it a try, it might improve cold-bite a bit as well"...

I can envisage the situation though that having different CoFs on the different axles could cause big problems with braking, and screwing up the ABS system - if the rear axle, which is less heavily loaded than the front anyway, has a higher CoF than the front, is there a chance that the rears are going to slow quicker than the fronts, maybe lock up also becuase it's less heavily loaded, and then you're in to skid-mode, even if your front brakes still have capacity?

Could this confuse the ABS system in to engaging Anti-lock mode too early because one axle is slowing quicker than the other?


Thinking further on this - I've just had a pad failure with EBC Reds after 2 months of pottering about driving, so I've gone and bought some Ferrodo DS2500s to go on the front. Of course, I've still got the EBC Greens on the back. Am I going to be causing problems for myself? Should I get (yet) another set of pads for the back too?


I had a very long chat with an engineer at EBC today about the problems of having different pad compounds front and rear - he said that this was a really bad thing to do, that they would absoluotely never recommend the Red/Green combination, and that for a car as heavy and powerful as the S2, the Red is the absolute minimum pad spec to use.

The same engineer went on to discuss the view that the most important aspect of improving brake performance is in Friction, and not actually in Caliper power or disc diameter/thickness, and that the classic big-brake upgrades can cause as many problems as you think they might solve?

What we did agree on was that X-drilled discs are truely bad. He said they actually INCREASE the pad temperature, rather than doing what people think is the opposite - this can lead to premature overheating of the pad, causing premature brake fade, and incrased thermal stress on the disc, which leads to increased chance of the disc cracking.

Does anyone know what the Friction coefficient of the DS2500s is compared to the EBC Reds/Greens? Those of you running the Ferrodos here, do you have them just on the front or on the back too? What's the price?!

Views welcome -there are some very clever people here, and there are a lot of us who have dabbled in brake mods, but it would be interesting/useful to actually find out the truth.

[Fat Audi 80]

Personally I can't imagine why different pad compounds ( and therefore Cof) would affect the ABS system. The ABS system in its basic form looks for a locking wheel by analysing the speed from the sensors in each wheel. If it detect the slow down of any particular wheel or wheels it momenrarily releases the caliper on that particular wheel or wheels to avoing it locking up. The Front brakes are always going to be doing more work than the back regardless of compound.

The above statement is based on my knowledge of general ABS systems, so feel free to correct me if I am wrong

On the subject of mixed compounds, I could imagine why he cannot recommend it, as the two sets of brakes will be not be building up to temperature in the same time and would have overall working temperature differences.

There is a brilliant article referenced on here somewhere that I have not read recently that may also shed some more light on some of these issues.

Over the rest of you.

Personally I find my standard brakes okay for general day to day driving but useless if pushing on hard....

cheers,

Steve

[audiman]

The ABS system will only act when the wheel locks, and it only acts on the wheel that does lock and non of the others. From what Dan said, that engineer is saying big brake upgrades are pointless, fit high CoF pads and that will work better??

So i that why Audi and Porsche, when making the RS2 kept the stock brakes with monster pads?? I think not.

[audiman]

It may affect the way the car behaves coming hard into a corner. If the front brakes hard and the back brakes not as hard then it tends to make the back end feels very light and can induce a slide.

[charlie]

You should also consider that unlike most other cars, The braking circuit is split front and rear separately and not diagonally. This has a few advantages
especially in snow or mud conditions

[NoNonsense]

It may affect the way the car behaves coming hard into a corner. If the front brakes hard and the back brakes not as hard then it tends to make the back end feels very light and can induce a slide.

The car may slide anyway because the balance is upset. A car will stop hard because when you apply the brakes, the weight transfers to the front of the car. this applies more weight to the front wheels which is why we need larger front brakes than rear. If braking is all about the powers of FRICTION, then larger calipers and rotors increase friction because they increase the surface area of the brake pads, thus increasing friction.
When a car goes into a turn, if there is no throttle or brake being applied, it will handle a great deal of turning before it slides. this is because the weight transfer is to the outside two wheels. When braking (weight --> front wheels) and turning (weight --> side wheels) the cars weight is mainly on only one wheel.
Finally, I do not see the problem with putting two different compound pads between front and rear. As long as you do not upset your brake bias in that your rear wheels lock up, you will increase your ability to modulate the brakes.
I have been researching putting 4-pot calipers in the rear, and obviously even larger 6-pot calipers up front, but in our cars, this can only be done with a cockpit controlled bias because having such strong brakes in the rear will call for different braking strengths under different conditions.

[dan_b]

So basically having Ferrodo DS2500s up front (4-pots), and EBC Greens on the back (stock rear) is not going to be the death of me?!

[NoNonsense]

So basically having Ferrodo DS2500s up front (4-pots), and EBC Greens on the back (stock rear) is not going to be the death of me?!

Basically, yes.
That's very similar to what i run with my 996 calipers now.

[dan_b]

Just got the bill for the Ferrodos - damn they're not cheap! Anyone using them on the rear too?

[audiman]

Not yet But i will. You will find that a decent product is normally expensive. Thats why they are proven to work.

[dan_b]

I'm more than prepared to pay for quality when it comes to most things, and especially things like brakes and tyres...

[charlie]

I'm more than prepared to pay for quality when it comes to most things, and especially things like brakes and tyres...

What is ur driving style and r u gonna be needing or using the full potential
of the new brakes. I find it hard to justify the high price tag of Ferrodos.
This is mainly its considered an upgrade item and hence is supplied through
other outlets. Aproved Ferrodo suppliers can get pads that conform to
"legislation 91" :mischeif:

[dan_b]

My driving style is one where I found the stock S2 brakes completely worse than useless with 280BHP, but I wouldn't say I'm a "last of the late brakers" maniac. I use my car a lot in London and you soon find that you need to do BIG Stops a lot because of the sheer number of complete numpties on the road. I've found the brake upgrade to be fantastic in the sense that I've got much better braking capacity, but I've found the Reds lack of bite disconcerting -sure they pull you down from speed very well, but I also need/want that agressive bite at urban speeds/temperatures.

When I go on cross-country blats, which is when I really get to enjoy my car, then sure, it's all hands on the anchors -you want as much capacity as you can get, and you want it every time. I would say again with the Reds I've not had any problems with fade or hot performance generally, and they work bloody well when warm.

What I want is the best of both worlds -cold bite, high friction and high temperature capacity because that best reflects my driving style, and the vaguries of British traffic conditions. I want to enjoy my car, but I also don't want to run over any body, or find myself wrapped round a lamp post. You never know when you need to perform a BIG Stop.

It's the same with tyres- get the best you can buy -those 4 tiny strips of rubber are all that's keeping you, your 1.6tons and your 300ish horses on the black stuff. Grip is everything, especially in the wet, which is afterall most of the time in the UK: you never know when you'll need that extra capacity.

Too many lunatics/idiots/blind stupid people out there, too many badly designed roads, too many poorly repaired roads, too much mixed traffic for you not to have the best tyres and brakes if you ask me.

[charlie]

My driving style is one where I found the stock S2 brakes completely worse than useless with 280BHP, but I wouldn't say I'm a "last of the late brakers" maniac. I use my car a lot in London and you soon find that you need to do BIG Stops a lot because of the sheer number of complete numpties on the road. I've found the brake upgrade to be fantastic in the sense that I've got much better braking capacity, but I've found the Reds lack of bite disconcerting -sure they pull you down from speed very well, but I also need/want that agressive bite at urban speeds/temperatures.

When I go on cross-country blats, which is when I really get to enjoy my car, then sure, it's all hands on the anchors -you want as much capacity as you can get, and you want it every time. I would say again with the Reds I've not had any problems with fade or hot performance generally, and they work bloody well when warm.

What I want is the best of both worlds -cold bite, high friction and high temperature capacity because that best reflects my driving style, and the vaguries of British traffic conditions. I want to enjoy my car, but I also don't want to run over any body, or find myself wrapped round a lamp post. You never know when you need to perform a BIG Stop.

It's the same with tyres- get the best you can buy -those 4 tiny strips of rubber are all that's keeping you, your 1.6tons and your 300ish horses on the black stuff. Grip is everything, especially in the wet, which is afterall most of the time in the UK: you never know when you'll need that extra capacity.

Too many lunatics/idiots/blind stupid people out there, too many badly designed roads, too many poorly repaired roads, too much mixed traffic for you not to have the best tyres and brakes if you ask me.

Point taken

[dan_b]

If I gave the impression of a bit of a rant there I completely apologise, have had a complete dogs ar*e of a week - thank goodness it's the weekend! Got the Ferrodos on the front today so will see how she fares with DS2500s at the front, and EBC Greens on the back!