How much of an improvement might one expect by replacing all four stock rotors with a set of FRPP Lightweight Performance Rotors? Are they acceptable for routine street use? Is there real value in this mod?
FRPP Lightweight Brake Rotors - Make a Big Difference?
- Thread starter ViperJoe
- Start date
snaproll
GT Owner
none, I suspect, unless you're quite a few hot laps into a 24 hour race. They DO look cool though.
There is value. These were used when PeakCompletions car (built by Jason Heffner :biggrin ) drilled the competition at the Car and Driver Super Tuner Shootout. I don't know how much improvement they made, but 200-0 braking in just over 7 seconds and 1100 ft is pretty crazy. I think just taking the weight off is a good idea any time you can.
B O N Y
MODERATOR & FGT OWNER
When we spoke to the ceramic brake folks they said we could expect to shave 4 to 5 feet off a stop. That is a lot, also the unsprung weight difference improves handling. Ed Sims has made the mod to Ford Racing Discs and is very pleased.
STORMCAT
GT
One pound of rotation mass saved is equal to 6 lbs of static weight. I think the FR rotors are about two pounds lighter for $ 3800. I would wait to see what Stop Tech comes up with on these Carbon Ceramic rotors. Weight saving should be about 15 lbs per corner which is tremendous. A reduction that significant will be noticeable for sure. They will be more expensive but it will be like adding 40 or 50 HP to your car. You'll accelerate faster as well as stop better.
Mark my words. The New ZR1 event thought it's as heavy as the GT will have a tremendous advantage in both acceleration and stopping because of the Carbon Ceramic rotors that will be on the car. It's free horse power !!!
Mark my words. The New ZR1 event thought it's as heavy as the GT will have a tremendous advantage in both acceleration and stopping because of the Carbon Ceramic rotors that will be on the car. It's free horse power !!!
cobrar1339
GT Owner
Went through this with Baer several years ago. the 1-6 ratio even higher has been touted over the years. I touted it too based on what I had heard. I was corrected. On a brake rotor the weight is so close to the center of the hub the multiplier effect is not nearly that much, as I recall it was not even double the net weight saved. Think of swinging a weight on the end of a string. The longer the string the more you notice the effect.
Tire weight on the other hand will be noticable and has the highest multiplier effect. Even for wheels it depends on where the weight was saved (hub area or rim area) Lighter is never bad, but I would not get too excited about the FRP rotors for this multiplier effect.
FRP Advantages:
Saves some weight - Always good
The hat disapates heat better for longer lasting hub bearings
Floating design allows for expansion and less prone to warp
Heat treated for a harder surface to improve wear with a aggressive pad.
Looks good
Weakness
Drilled does not last as long on the track dog as slotted only.
Carbon
The carbon rotors will do way more out of the box. 15 lbs is significant. But the POC guys that track the cars are pulling these off in favor of something like the FRP rotors. They are very expensive to replace a couple times a year for a real track dog.
Tires
I spent years thinking brakes stopped the car. Not true. Tires stop the car. Here's the deal....
A softer compound will stop shorter ( Stickier )
A wider tire will stop shorter ( More surface)
A lighter tire will stop shorter ( Less rotational mass)
A wider ,lighter, softer tire will stop alot shorter ( Stickier,+ Surface, less Mass)
All with the same calipers/rotors and pads.
You can feel this in modern cars with ABS. If you brake and the ABS never engages you have room to brake later ( Feet). Call it threshold braking via computer.
Find your latest point where ABS goes nuts with your stock tires. Then swap to Hoosier and the ABS will not engage till several feet later. Step up to lighter Goodyear slicks ( about 12 lbs lighter yet per tire) and it you have several more feet. The ABS engages when the tire slips on the pavement.
As Brian points out the car will accelerate quicker as well. It feels like the motor even got snappier and revs quicker. If the ZR1 saves weight via NO run flats that is even a bigger plus. Now you are talking 25 legit pounds per wheel plus a much better multipler for the Run Flats as well.
If you put a set of 50-65lb monster wheels and tires on your truck you should have a very good idea what additional rotating mass feels like. You should notice the truck is slower to accelerate, stops worse and wears out brake pads much quicker. Taking off the weight is the inverse reaction.
Thank you all for your most insightful responses. You've clearned the fog thereby allowing me to make a much more informed decision. I will proceed with purchasing a rear set of FRPP rotors to match the front set I bought off ebay (NIB for $940 delivered). It's unlikely that I'll get a deal even remotely close to that on a rear set, but my average cost will still be quite low.
mousecatcher
GT Owner
Absolutely right. You generally cannot stop shorter by upgrading brake parts b/c even your old brake parts are capable of threshold stops. To clarify about weight, static sprung weight doesn't matter because as you have less weight, you have less traction available (note F1 cars, which weight "a lot" thanks to aero, stop quite short). Rotating unsprung weight certainly makes a difference.
Weight transfer is also very important as evidenced by Ferrari (and now McLaren
) who have dynamic brake bias which moves the bias rearwards as you slow down. So in general, lowering your car will also help decrease stopping distance as well, but this depends on the factory brake bias and whether or not you're willing to change it.Shorter stopping distance is not what you're looking for when you upgrade brakes though.
You're looking for better feel, modulation and consistency (braking aspect) and better handling (weight aspect). Also, of course, better fade resistance so that you can threshold brake all day long instead of just once.
What a floating rotor buys you is no knockback, and "cheaper" replacement since you only replace the ring. (This argument is a tough one because you can always find cheapie 1 piece rotors which cost MUCH less than just the ring part of a 2 piece.) Oh and the weight savings, of course, from an aluminum hat.
People generally go with 1.5-3x multiplier for unsprung weight. More for rotating mass. This is because of the handling improvement. Even if you're not on the track, there is an improvement in ride quality which is desirable.
When considering unsprung weight reduction, not only do you have to consider the absolute amount, you have to consider the ratio change. 8lbs on one car is not equivalent to 8lbs on another car.
To answer the question: it depends.
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mousecatcher
GT Owner
I take it back! Because stock brakes can apply enough torque to lock up even "heavy" tires, reducing this weight has no effect on stopping distance.
911teo
GT Owner
Wally and Mouse
very well said.
Usually my first concern with brakes is the fading. A relatively cheap way to upgrade your braking system SIGNIFICANTLY is to change the brake fluid AND the brake pads to racing ones (or performance ones if using the car on the street also).
Also when chosing the brake fluid pay attention to the wet boiling point (takes into account the fluid tendency to absorb moisture and water), not the dry one. When you grade the fluids out there by wet boiling point you see that there are a couple that stand out.
I like the Castrol SRF as it is the ultimate with a wbp of 518 degrees but it is nearly $80 per liter.
I found that an oil with a great compromise between cost and performance and readily avaliable is the ATE superblue (at $10 per bottle).
As per the pads it depends on how heavy you are on the brakes. I like the Pagid pads, and I have been using the orange RS 4-4 Orange and RS 4-2 Blue on the GT with good results.
All my experience has been done with the stock Goodyear tires.
As Wally said above if you swap tires for stickier/wider ones you'll increase the efficiency of your brake system but the temps will go higher. Here is where a better rotor (beside higher compounds in pads) will come handy.
The last thing one needs to change (in my opinion) is the caliper. Those huge and cool looking calipers weigh usually more and only add pad surface.
I think your stock tires will melt before you cook the hardest compound pads avaliable for our caliper....
very well said.
Usually my first concern with brakes is the fading. A relatively cheap way to upgrade your braking system SIGNIFICANTLY is to change the brake fluid AND the brake pads to racing ones (or performance ones if using the car on the street also).
Also when chosing the brake fluid pay attention to the wet boiling point (takes into account the fluid tendency to absorb moisture and water), not the dry one. When you grade the fluids out there by wet boiling point you see that there are a couple that stand out.
I like the Castrol SRF as it is the ultimate with a wbp of 518 degrees but it is nearly $80 per liter.
I found that an oil with a great compromise between cost and performance and readily avaliable is the ATE superblue (at $10 per bottle).
As per the pads it depends on how heavy you are on the brakes. I like the Pagid pads, and I have been using the orange RS 4-4 Orange and RS 4-2 Blue on the GT with good results.
All my experience has been done with the stock Goodyear tires.
As Wally said above if you swap tires for stickier/wider ones you'll increase the efficiency of your brake system but the temps will go higher. Here is where a better rotor (beside higher compounds in pads) will come handy.
The last thing one needs to change (in my opinion) is the caliper. Those huge and cool looking calipers weigh usually more and only add pad surface.
I think your stock tires will melt before you cook the hardest compound pads avaliable for our caliper....
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STORMCAT
GT
I pulled the rotational mass figure from the Dymag wheel site. I understand that the weight savings factor for a rim or tire would have a greater affect or higher factor because of it's distance from the center of rotation. All I know is less weight good , more weight bad...:bored
satx
Well-known member
incorrect, downforce and the vehicle weight had different effects on vehicle handling dynamics. Add 1000lbs to that F1 car and it will take longer to stop due to momentum. Think "objects in motion tend to stay in motion". Downforce is pushing the car down without the downside of vehicle weight. This is why race cars are lightweight with lots of downforce.
mousecatcher
GT Owner
probably not, due to the reason we've been highlighting in this thread -- the brakes have sufficient power to lock up the wheels. yes there would be more momentum but there would be more traction as well.
but your point is well taken. downforce is different than static weight.