Brake experts -- your opinions, please

strother · 05-11-2005, 06:19 PM

I have a stock 1982 SC. At my last DE, I boiled my brake fluid twice. I want to avoid that next time. I had old, old Pirellis on the car that were as effective at keeping my car on the track as banana peels soaked in vaseline. I've since put Bridgestone SO-2s on. I hope that I won't need to brake as much, since I'll be able to take the corners at higher speeds.

I don't know what fluid I have in the brakes now, but I'm going to flush it out and replace it with Ate Super Blue. I'm considering another change to prevent the boiling, but I don't have chunks of change right now to do big upgrades or to do all the changes.

Which of these changes would help the most if I were to only do one?

JeremyD · JeremyD's Garage

Sticky tires will make it worse...

strother · 05-11-2005, 07:07 PM

Jeremy, fill me in. I was thinking that I'd use my brakes for a shorter time now, and I wouldn't be getting them as hot.

For instance, let's say I'm heading towards a corner going 75 mph. On my crap tires, I would brake earlier and longer so that I'd reduce my speed to what the tires could handle. Let's say I braked to get to 35 mph. (These were REALLY crappy tires -- I was told it was like I was running in high heels.) On my new tires, let's say I only have to brake to 55 mph to take the same corner. Doesn't that mean I'm using my brakes less frequently and getting them less hot?

I guess I'm coming out of that corner faster and braking harder in the next turn...

JeremyD · JeremyD's Garage

Quote:

Originally posted by strother

I guess I'm coming out of that corner faster and braking harder in the next turn...

Bingo! And stickier tires will tax the thermal capacity even more - because they won;t let loose.

MotoSook · 05-11-2005, 07:16 PM

Even with the SO3's...boiling your fluid seems more a fluid problem than the tires. SC brakes are fairly capable..unless you are really driving the car....but at a DE? I have a client who's SC ran DE sessions back to back (6 sessions with PF-97's, Ate Blue...and no brake fade or other issues.)

I run my cars pretty hard at the track and I never boiled Ate or Motul....lighter weight Bastard and Fat Bastard...I burned up pad and backing material..yet the hydraulic was fine.

Not know what you have in there (fluid) is maybe the route of your trouble.

zotman72 · 07:20 PM

If your SO2s if still very new, they will get chewed up rather quickly if you drive really hard. I made this mistake and actually melted the tread areas on my SC's SO3s. If you have got the track bug, you have to get another set of wheels for dedicated track tires. They do not have to be Fuchs. Do change your brake fluid for sure. I have tried Pagids, Hawk Blues and decided on the Performance Friction Golds for my dual use car (my '72). These pads do well in both environments. Cooling ducts/scoops to the center of the rotors work as well. HTH

89911 · 05-11-2005, 07:19 PM

Jeremy's right (I hate agreeing with him

). All the load of braking on "crappy tires" will most likely be limited by the tire/road interface. The tires will skid at the point were the rubber can't grip the road, in your case, this is reached very quickly. With track or R compound tires, this adhesion point is greatly increased. Now, the increased forces are aimed at the next point of friction, the brakes. The biggest, cheapest, easiest upgrade for an SC is Carrera brakes which you don't list. I would do this first.

JeremyD · JeremyD's Garage

depends on the track too - the high speed tracks - you better bring your brake "a" game.

MotoSook · 05-11-2005, 07:21 PM

OH..yeah, I ran with SO3's....

Sure a brake upgrade would be nice, but I'd run with a known fluid first, then cooling, then caliper and rotor (Carrera is the next step up as Bill and Jeremy said).

strother · 05-11-2005, 07:37 PM

You guys are all a great help. Muchas gracias. In addition to changing the fluid, I need to upgrade the driver... I'm sure my braking approach is still too "don't tip the groceries" for the track.

Souk, your point is well-taken about boiling fluid at a DE. It makes me think it is a driver problem more than anything else.

How much do the parts for a upgrade to Carrera brakes cost?

MotoSook · 05-11-2005, 07:51 PM

Used Carrera rotors and calipers can be had for 250+ depends on what time of year, shape and how many guys are upgrading to bigger brakes

The hand-me-down effect of 911's

(I'd get used calipers and spring for new rotors....but try the fluid and cooling first...easier and cost effective)

Steve Marshall · 05-11-2005, 07:52 PM

Yes, while sticky tires may work your brakes harder, they will enable you to take turns at a higher speed, thus require less braking before the turn. But that is only part of the equation. Good clean premium brake fluid is just common sense. Ate blue or gold is a good place to start. Cooling ducts and back plates are worth while.

But the most important issue is braking technique. I ride with a lot of people that cook their brakes by dragging the brake into the turn. I see it every weekend. Proper braking requires you to brake intensely initially and then back off as later in the braking zone. People that cook their brakes tend to brake lightly early then increase braking intensity deeper in the braking zone, until they smoke their brakes.

How am I so sure of this? I used to cook my brakes every weekend. Now I've run with out ducting and had no problems. Why? I simply learned how to brake.

I can say that Pagid Orange pads are the best money I've spent in the pursuit of braking improvement.

MotoSook · 05-11-2005, 07:58 PM

Never used Padgids before (probably scared of the cost)...

I think Ferodo 2500's and PF-97's are great performers for their cost..and are perfect for DE cars that double as street cars

.... I hear Padgids are hard on rotors.... tend to be noisy on the street...had a few friends dump Padgids for PFs or Ferodos. We provided PF's for a couple of cars at the last Chicago PCA-DE ... one was M-calipers all around, the other was A and M calipers ... no braking issues. Another client ran Ferodo 2500's on A and M calipers.. again..no braking issues.

Ray B · 05-12-2005, 03:55 AM

Also- get rid of those brake dust deflectors. I'm running SC brakes, super blue-no problems.

strother · 05-12-2005, 04:07 AM

Anyone try these (or have an opinion on them)? http://www.seinesystems.com/BrakeFade-2.htm

For those that don't want to click through, Seine makes titanium heat shields to go between the brake pad and the caliper piston.

Wavey · 05-12-2005, 04:42 AM

Definitely change the fluid first. Once the fluid boils, it's boiling point is lower the next time.

911teo · 05-12-2005, 04:47 AM

I had exactly the same problem at my first DE. Changed fluid to ATE superblue and pads to Hawk Super Plus (street/track.... they squealed a little on the street) and problem was solved.

$20 for 2 tanks of ATE fluid and $200 for the pads...

Quicksilver · 05-12-2005, 05:23 AM

There are a few ways to think about brakes that will help you to decide what to do about them.

Brakes convert your cars forward motion into heat with 100% efficiency. The disk rotors are acting as a heat sink to absorb the huge quantity of energy that is being forced into it. The faster you stop the faster you are feeding energy into it. When a car is going down the road you can actually think of it as having a certain number of BTUs in it based on its speed and weight.
You can also think of brakes in the terms of 'negative' horsepower. More horsepower flings a car up to more speed, faster. That requires more brakes to slow it back down. The more grip the car has then the faster you can force heat into the rotor. This will push the peak brake temperature higher.

Think about where you are putting this heat. You are putting it into the contact point of the rotor and the pad. The rotor is spinning so you are spreading the energy around plus the rotor is very conductive of heat so it will 'soak' full of heat. At the beginning of braking the rotor is cool so the heat build up in the pad is actually cooled by the rotors relatively cooler surface. The pad also doesn't conduct heat very well so it is harder for the heat to pass that way.

The rotor's heat spikes during brake application and because it is so much hotter then anything around it, it cools between braking events. As it gets cooler the rate of cooling goes down because of the reduced temperature differential.

The basic things to worry about are:
- Have enough heat sink to absorb the biggest, fastest stop the car will make.
- Have enough cooling/time between braking applications to allow the heat sink to cool to a point that the system is ready for another braking event.
- And finally to have enough 'heat rejection'/'heat resistance' coupled with a low enough average temperature that the other systems don't go over their temperature. (This last bit means calipers and wheel bearings.)

Question: When was the last time the brake fluid was replaced? You should completely replace the brake fluid before each track event. Most cars have brake fluid that is way past its prime. Use something good like Motul or ATE Blue.

The heat shields will help lower the caliper temp but the heat will go elsewhere. This could push your pad temp higher to cause the pads to fade or just wear extremely fast. If the pads go over temp you can switch to something with a higher temp. Pagid is popular but pricey. I like Porterfield R4S. They are much cheaper and if you push them over temp then you should look farther down this list.

The real major fix is bigger rotors. Calipers are very popular mostly because the upgrade ones are really cool looking (oooh, the colors!) but really they should just be designed to fit the rotor. In extreme cases a larger pad can help spread the heat load but a larger rotor is also shielding the rotor from cooling.

Brake cooling will give you a relatively small increase in braking capacity but it is usually most effective when you have increased the capacity of the rest of the system. When everything else in the system is setup for high temps a cooling system can actually keep the brakes from getting enough heat to work correctly during normal street driving.

Miguel Antonett · 05-12-2005, 05:55 AM

ATE Blue is your first move.

JonT · 05-12-2005, 06:19 AM

I'm no brake expert but only have personal experience to rely on. You don't need any expensive brake equipment upgrades. Better pads and fresh ATE super blue fluid is the fix. Your braking technique will need improving as well--I'm guessing you are doing (as already described) riding the brakes into the braking zone because you are not confident in your brakes and are being cautious. Expensive pads are not necessary either -- Metalmaster pads are $25 per set and worked fine for me at my last DE. I do have the AJUSA brake cooling kit as well so this might be an option for you as $$ comes available.