School Me on Brakes

[TXPD]

i ran blues on the front of my cobra r and blacks in the back. then i moved to pfc and ran 06 up front and 97 in the back. now...i am on cobalt friction and i trust andee. i call and tell him what package, tire and track and he chooses my compounds for me.

 

[racebronco2]

Sorry to be a contrarian here but I run Cobra R front pads and Hawk Blues in the rear. I think the braking is better with that combo for my hillclimbing. When timed correctly, you can really initiate a nice rotation into a corner. So I believe you can bias a bit with pads. I wouldn't go crazy though and if you're new to this type of driving, I'd wait and get used to a matched set first. I'm 6 years into this type of racing.

I would say you are not a contrarian. Your braking needs are just the same as the rest of us. Racing uphill requires less braking because of gravity.

 

[David Hester]

I've raced SCCA since 1984 (autocross since 84, time trials since 94, road raced since 2003.) I've tried all kinds of pads...all of Hawks, anyway.
Concerning PBR calipers... We (Ford and GM guys) had to run them for years in SCCA A/Sedan. Some of the National guys talked about them clamming open, but none of the regional guys had that complaint. Certainly not me. They are easy to rebuild. BTW.
Now we can use Wilwood or whatever. Rob and I have raced together for several years. He likes Cobalt, but I used Hawks for years and always liked them. I do use Wilwoods on my present car, but have Hawks on my DD.
I've used every compound they make from HPS to DTC-70...understand they have a DTC-5 and 30 now....Guessing to replace the HP+ some day.
Sounds like you boiled fluid. As was mentioned, you can pick up Motul 600 at bigger bike shops, or order on line. I like Raceshopper.com
You can try some Motul 600 (or Wilwood 600) and some HP+. That will buy you some extra stopping, and still work decent on the street. From there, move up to the Blue for track use only. They are crap on the street. Don't get hot enough.
I agree with Rob Slots, and holes FOR SURE! do not belong on a track. The Porch crowd may think they look racy, and bikes and formula cars can use them, but they crack REAL quick on a 3200-3500 lb car. like in one weekend at Sebring when they still had the hairpin.
I used HP+ on the rear of my A/Sedan car. Fronts (DTC-70) would get to 1000+ degrees, but I never saw over 600-700 on rears, well within HP+ heat range. You DO NOT want rears locking up. I used a slight chirp from fronts to judge maximum braking into a corner. Locked rear will spin you.
Note rear pads will always be smaller than fronts with smaller caliper. I agree with Rob, dont fub with them. Just swap your pads and fluid.

 

[nekasrof]

I would say you are not a contrarian. Your braking needs are just the same as the rest of us. Racing uphill requires less braking because of gravity.

For the most part, you are correct and it depends upon course and corner. At this hp level, we're haulin aZZ into corners.

I'm not familiar with the suspension characteristics of the cobra under braking. For this car however, it was necessary to decrease the crazy nose dive it had in order to brake better. I did the pad bias as a test and it felt like the car did a better job at braking even on the Jefferson Circuit @ Summit Point. Sooner or later, we're gonna change the rear calipers to a larger one and try that. If it works poorly, we'll go back to this set up.

Back to the nose dive thing. I think it's important to look at nose dive and consider addressing that at the same time you're addressing the braking issue. Keep that rear end down as much as possible so those back tires contribute to stopping better.

 

[MFE]

Since brake dive is largely a function of braking forces acting upon the car's mass about the car's center of gravity, and also a function of the the anti-dive characteristics of the suspension, if all you did was change the braking bias and the result was less brake dive, then it seems to me that the change resulted in a net reduction of total braking force.

 

[David Hester]

Yeah, I agree.
Grigg's Arm helped my old Fox body with putting power down and braking.
I thinking stiffer springs/ shocks to control weight transfer would be more important than pad manipulation. But we've moved off the original post again.


Getting back to original poster, I think we get lost sometimes with people on here that have progressed to building all out track cars, and forget someone running PDX or HPDE may ALSO have to use their car on the street.
You really don't need super big brakes on the street, unless you are compensating.... moving on.
You can have alot of fun with a simple pad/ fluid upgrade. When you start running out of brakes after you have moved up to a DTC-70 or similar pad, THEN start thinkng about bigger brakes. By then you will have taken your car off the street and joined us other addicts. ;-)

BTW, Rob- Still haven't done anything with those racing calipers I got from you. Ain't compensating. LOL

 

[Todd TCE]

Since brake dive is largely a function of braking forces acting upon the car's mass about the car's center of gravity, and also a function of the the anti-dive characteristics of the suspension, if all you did was change the braking bias and the result was less brake dive, then it seems to me that the change resulted in a net reduction of total braking force.

Certainly possible. But if the change nets a more effective rear brake function he may well be exploiting more total brake force than before. For example; if the car has HUGE front brakes that generate X amount of torque at a specific pressure point the car can have so much front brake that the rears are doing nothing at all. Continued use like that usually results in overheating up front and the answer of course is more front brake...no.

You'd not want so much front at a low pressure that they nearly lock up. That could mean the rears are not getting enough brake. Conversely if you put too little front brake in the equation you'd need to ramp up the pressure (ie. effort) and line pressure. That puts you into the knee point of the prop valve too soon and cuts line pressure to the rear. You may not be able to alter the total weight transfer, slow it maybe) but that doesn't effect the tires grip to the road.

True that more front is more effective for the most part but not matching it or even increasing the rears can simply mean that the fronts are doing all the work. At the least a good pad change (thus not so pressure sensitive) would be in order to pair with the front.