RR Racing Brake Development -- Competition and Street

[jamal]

Alright, so I'm looking at the OP, and it appears all the front kits use the same size rotors, and the only difference is some use a wider caliper/pad?

Drawing a rotor over the caliper and then a smaller circle through the center of the pistons gets me the same effective rotor diameter as subtracting half the pad height, within about 1mm. I also compared that method to what is in the brake math spreadsheet for stock brakes and came up with about the same numbers as Josh has.

So, anyhow, that gets me an effective radius of 141mm for the wilwood 6pots and 328mm rotors.

I'm also going to assume that the bore sizes are 1.625 and 1.125 since those are round numbers. Then I converted it to mm, and came up with what I'm going to call a "brake torque coefficient" which is piston area x effective radius (so mm^3) and then divided by 100000 to get a reasonable number.

So here is what that works out to for a number of brakes:
Stock: 3.51
FHI 4-pot: 3.10
STI brembo: 3.91
CTSV 4-pot: 3.71
Wilwood 6-pot: 3.695
Wilwood 4-pot: 3.77

So given the same pads and line pressure the kit will give about 5% more brake torque than stock, which is pretty much the same as what @sickmint79 came up with, although I got about the same change from cts-v 4-pots.

[Lynxis]

Originally Posted by jamal

Alright, so I'm looking at the OP, and it appears all the front kits use the same size rotors, and the only difference is some use a wider caliper/pad?

Drawing a rotor over the caliper and then a smaller circle through the center of the pistons gets me the same effective rotor diameter as subtracting half the pad height, within about 1mm. I also compared that method to what is in the brake math spreadsheet for stock brakes and came up with about the same numbers as Josh has.

So, anyhow, that gets me an effective radius of 141mm for the wilwood 6pots and 328mm rotors.

I'm also going to assume that the bore sizes are 1.625 and 1.125 since those are round numbers. Then I converted it to mm, and came up with what I'm going to call a "brake torque coefficient" which is piston area x effective radius (so mm^3) and then divided by 100000 to get a reasonable number.

So here is what that works out to for a number of brakes:
Stock: 3.51
FHI 4-pot: 3.10
STI brembo: 3.91
CTSV 4-pot: 3.71
Wilwood 6-pot: 3.695

So given the same pads and line pressure the kit will give about 5% more brake torque than stock, which is pretty much the same as what @sickmint79 came up with, although I got about the same change from cts-v 4-pots.

Regarding the RR kits, those numbers are right in line with what @JRitt found so there are now 2 sources for these values so I think we can consider that accurate.

Out of curiosity, what do the numbers look like with this caliper:

http://www.wilwood.com/Calipers/Cali...o=120-12003-BK
Piston 1 Bore(In): 1.38
Piston 2 Bore(In): 1.12
Piston 3 Bore(In): 1.12
Total Piston Area (in²): 3.46

I'm curious how far it will send torque the other way. A bit unusual that I can only find this piston sizing for the narrow caliper and doesn't seem to be available on the full sized caliper.

[jamal]

Going to assume they are actually 1.375 and 1.125.

That makes the "coefficient" 3.159, or a 10% reduction compared to stock.

If you combined that with a 355mm rotor instead I bet it would be a pretty good combo.

[Lynxis]

Originally Posted by jamal

Going to assume they are actually 1.375 and 1.125.

That makes the "coefficient" 3.159, or a 10% reduction compared to stock.

If you combined that with a 355mm rotor instead I bet it would be a pretty good combo.

Yeah 10% is way too far the other way. 355mm rotor might work but there are a variety of problems with that, I think I would rather go the other way and downsize my rotor. The reason RR Racing can offer the kits so cheap is because they use off-the-shelf parts for their kits.

Now this makes me wonder what the brake torque is on the rear kits to see what the various rear kits do to bias..

[jamal]

Well, a 5-10% change at one axle is not the same as the overall bias change. I get about 72:28 for these kits while stock is 71:29. Using the smaller pistons brings it to 69:31.

I'm not entirely clear on the rear piston sizes or I could put those in too.

And also the differences in ideal brake distribution with different tires and braking forces and aero is also much bigger than what any of these kits are causing. So really it comes down to a case by case basis. if you are on track and keep getting front abs engagement before the rears seem like they are doing anything the smaller piston calipers might be the best choice.

The other thing is that the EBD system uses wheel speed to take away rear brake pressure so it should be able to handle changes to the bias from calipers within reason.

Also, my numbers for the essex kit put the bias even farther rearward.

[sickmint79]

Originally Posted by Lynxis

Yeah 10% is way too far the other way. 355mm rotor might work but there are a variety of problems with that, I think I would rather go the other way and downsize my rotor. The reason RR Racing can offer the kits so cheap is because they use off-the-shelf parts for their kits.

Now this makes me wonder what the brake torque is on the rear kits to see what the various rear kits do to bias..

i have some of the rear kits added in my article. i'm guessing you want a wang at some point with these. also note the narrow calipers fit more wheels but that's about all the positives for them - i'm guessing they retain more heat and they definitely have thinner pads.

[Lynxis]

Originally Posted by sickmint79

i have some of the rear kits added in my article. i'm guessing you want a wang at some point with these. also note the narrow calipers fit more wheels but that's about all the positives for them - i'm guessing they retain more heat and they definitely have thinner pads.

Yeah I wouldn't run the narrow caliper unless I had to for wheel clearance and I only wanted the BBK for bling factor. I chose to change wheels when the SP kit didn't fit behind the ones I was using and I think most others would too.

[Cartman]

So I decided to Install a set of Ferodo DS1.11 on the Calipers along with my old set of Raybestos ST45, and I have to say the braking performance is mind boggling! I'm at the point of considering a 5 point harness as I'm being lifted off my seat under braking.

Here's a vid of yesterdays event running that pad setup.

[ame="https://www.youtube.com/watch?v=FghdEBOh8TU"]FRS Salinas speedway Feb 5 2016 - YouTube[/ame]

For comparison, this vid is running Ferodo DS2500 on all 4 corners

[ame="https://www.youtube.com/watch?v=KpgEWLfvjRk"]Salinas Sept 18 2016 FR S - YouTube[/ame]

The braking point straight away shows the difference.

[Pat]

Fantastic. Welcome to the world of race pads. So much fun, right?
Now take that crap off your mirror for God's sake.

[maregt]

Originally Posted by Cartman

So I decided to Install a set of Ferodo DS1.11 on the Calipers along with my old set of Raybestos ST45, and I have to say the braking performance is mind boggling! I'm at the point of considering a 5 point harness as I'm being lifted off my seat under braking.

Here's a vid of yesterdays event running that pad setup.

For comparison, this vid is running Ferodo DS2500 on all 4 corners

The braking point straight away shows the difference.

Wonderful, I'll start with ds2500 like you cause they are very cheap, but I'll take your review for a future upgrade.

Just two questions:
- have you experienced pad fade using ds2500? Do you have ducting?
- i've read raybestos st45 has lower mu than ds2500 and ds1.11. what is your experience with this configuration?

I'm asking cause I'd like to run ds2500 on all 4 corner on the street and swap the front only (DSUNO) while on track

Thank you!

[Cartman]

Originally Posted by maregt

Wonderful, I'll start with ds2500 like you cause they are very cheap, but I'll take your review for a future upgrade.

Just two questions:
- have you experienced pad fade using ds2500? Do you have ducting?
- i've read raybestos st45 has lower mu than ds2500 and ds1.11. what is your experience with this configuration?

I'm asking cause I'd like to run ds2500 on all 4 corner on the street and swap the front only (DSUNO) while on track

Thank you!

I found the ds 2500 have very little bite, and I was not a fan of that. I have GT3 ducts and didnt experience fade on thay track.

As for the ST45 mu, the specs ive found only mention mu at 1200f... In my experience, running the st45 along with the BP20s would cause the rear to lock up under braking.

With that in mind, i find the ds1.11 match the st45 very well. I didnt feel any shift in brakinng bias.

[churchx]

Cartman: yep, stock alike little bite. But then again stock alike no squeel and working find in cold temps too, yet slight more capability for rare ocasional track days then stock. Imho DS2500 fine for drivers daily driving 99% like some .. oem+ pads.

[Cartman]

DS2500 squealed almost as bad as the ds1.11... I just switch pads for my events. I daily on ebc greenstuff...

[Cartman]

Originally Posted by Pat

Fantastic. Welcome to the world of race pads. So much fun, right?
Now take that crap off your mirror for God's sake.

I used to run st43 when I had my oem brakes... I missed the feeling

And no... I need my G sensor and timer, soon to be replaced with an aim