RR-Racing Sport Performance and AP-Racing Essex Initial Comparison

[Gear_One_Performance]

Originally Posted by JRitt

Okay, at this point I have to officially apologize for the thread-jacking. Sorry to the OP. I owe you a beer or three if we ever meet in person.

We're OK with that!

[ajc209]

Not sure why there is a problem with RR racing not publishing data on brake bias. Theres a gragh on page 11 of their thread where they were showing the ratio front to back.

The calipers are all standard wilwood calipers. Took me all of about 5 minutes to look up piston sizes on their website.

Its the rear brakes that move the bias back ~8-10%. The RR racing fronts have a piston area of 52cm^2 which is very similar to the CP8350 (~50cm^2 IIRC)


I agree that this "comparason" is not really very in-depth or technical. My suspion is that you'd be hard pressed to tell much difference between the $1600 RR and $2100 AP kit front kits.

Obviously at some point one will fail for whatever reason, but for the average weekend track junkies they will both do a good job.

[JRitt]

Originally Posted by ajc209

Not sure why there is a problem with RR racing not publishing data on brake bias. Theres a gragh on page 11 of their thread where they were showing the ratio front to back.

That graph is essentially meaningless. It shows relative bias within the product line. That chart only allows comparison among the RR Racing kits. There are no absolute values to use for the calculations vs. OEM or anything else. Using that chart to compare bias to anything else is essentially the same thing as comparing an engine dyno plot from one type of machine to another (Dynojet vs. Mustang). It's basically meaningless.

The calipers are all standard wilwood calipers. Took me all of about 5 minutes to look up piston sizes on their website.

Its the rear brakes that move the bias back ~8-10%. The RR racing fronts have a piston area of 52cm^2 which is very similar to the CP8350 (~50cm^2 IIRC)

Yes, but disc diameter also comes into play. They use 328 and 330mm discs on the front, which also adds more front brake torque on the front axle (in addition to larger piston bores).

I dug the numbers up on Wilwood's site and we're going to run them and see what we're looking at in terms of how they impact bias. That should give an actual scientific look, with real numbers, at how their kits compare to ours (which I believe was the original purpose of this thread).

Does anybody know what the piston bores are on RR's two rear kits? Wilwood has three piston options on the Wilwood Powerlite, and two piston options on the rear Superlite. I'd rather not have to run all possible simulations if we don't have to do so. Thanks.

[ajc209]

Hardly meaningless, it shows the RR front / OE rear combo as ~ 2.6:1 which is ~72% front. Stock car is about 71%.

The powerlite used in the sport performance are 1.25" IIRC and its a ~316mm brembo STI disc.

Here's my graph - I have a 355mm AP kit from an imprezza so that why I have that included in the numbers but you can see the effect the various rear brakes have in comparason.

[JRitt]

Originally Posted by ajc209

Hardly meaningless, it shows the RR front / OE rear combo as ~ 2.6:1 which is ~72% front. Stock car is about 71%.

The powerlite used in the sport performance are 1.25" IIRC and its a ~316mm brembo STI disc.

Here's my graph - I have a 355mm AP kit from an imprezza so that why I have that included in the numbers but you can see the effect the various rear brakes have in comparason.

Hmmm...I swore when I looked at it, it didn't have a scale. Regardless, I'm going to run the numbers anyway and see what we come up with. The OP's comments about our kit being "too front biased" in particular was very odd to me. My memory was that we were very, very close to stock bias. Thanks for the tip on the rear piston bores!

[ajc209]

Originally Posted by JRitt

Hmmm...I swore when I looked at it, it didn't have a scale. Regardless, I'm going to run the numbers anyway and see what we come up with. The OP's comments about our kit being "too front biased" in particular was very odd to me. My memory was that we were very, very close to stock bias. Thanks for the tip on the rear piston bores!

I ran the numbers on your kit a while back and they were both within a percent of stock. Sprint slightly less, endurance slightly more. I missed the comment about too much front bias otherwise i'd have spoken up.

[MaximeT]

Originally Posted by ajc209

I ran the numbers on your kit a while back and they were both within a percent of stock. Sprint slightly less, endurance slightly more. I missed the comment about too much front bias otherwise i'd have spoken up.

By "too much", I think what was meant was "same as stock".

[ajc209]

Well FWIW I tried a slightly higher friction pad in the back of my car to try it out and I didn't notice any ill effects. I think you probably need to do the pedal dance to really notice it (which I didn't).

[Gear_One_Performance]

Originally Posted by MaximeT

By "too much", I think what was meant was "same as stock".

Pretty much, but again these weren't track conditions or anything super scientific. That was just our initial feel after having them on the car for a few weeks, once we get some warm weather and clear roads we'll throw the datalogger in the car and take it back out.

[JRitt]

Originally Posted by Gear_One_Performance

Pretty much, but again these weren't track conditions or anything super scientific. That was just our initial feel after having them on the car for a few weeks, once we get some warm weather and clear roads we'll throw the datalogger in the car and take it back out.

We finally had the chance to run the calculations for the front RR Racing/Wilwood BBK's. The figures below are the % of front brake with the rear OEM brakes left alone. Our Essex Sprint Kit actually has less front brake than stock, shifting a little bias rearward (the exact opposite of what was claimed in this post). Our Endurance Kit has a little more front bias than stock, but still less than all of the RR Racing kits. The RR Sport Performance Kit would probably be a bit too front biased for most of our customers. Heat would be increased in the front brakes, and the fronts would likely lock up while the rears were still rolling.

We haven't had a chance to do the calculations on their rear kits yet, but hopefully soon. As you can see though, any talk of our Essex/AP kits being more front biased are untrue. The opposite is in fact true. Thanks.

% of front brake:

Stock 67.1
Essex Sprint 66.3
Essex Endurance 68.5
RR Sport Performance 72.9
RR Stage 1 69.4
RR Stage 2 69.4
RR Stage 3 69.6
RR Stage 4 69.6

[churchx]

I guess, RR's are intended for car setups with more rear aero downforce, while Essex's for no aero or balanced aero setup. Thanks for all the testing performed. I guess it took lot of $ & time.

[infinity21]

Originally Posted by JRitt

We finally had the chance to run the calculations for the front RR Racing/Wilwood BBK's. The figures below are the % of front brake with the rear OEM brakes left alone. Our Essex Sprint Kit actually has less front brake than stock, shifting a little bias rearward (the exact opposite of what was claimed in this post). Our Endurance Kit has a little more front bias than stock, but still less than all of the RR Racing kits. The RR Sport Performance Kit would probably be a bit too front biased for most of our customers. Heat would be increased in the front brakes, and the fronts would likely lock up while the rears were still rolling.

We haven't had a chance to do the calculations on their rear kits yet, but hopefully soon. As you can see though, any talk of our Essex/AP kits being more front biased are untrue. The opposite is in fact true. Thanks.

% of front brake:

Stock 67.1
Essex Sprint 66.3
Essex Endurance 68.5
RR Sport Performance 72.9
RR Stage 1 69.4
RR Stage 2 69.4
RR Stage 3 69.6
RR Stage 4 69.6

What causes the difference between stage 1/2 and 3/4? I thought that the calipers are the same and rotors are the same size. is the coefficient of friction different between the two rotors?

[JRitt]

Originally Posted by infinity21

What causes the difference between stage 1/2 and 3/4? I thought that the calipers are the same and rotors are the same size. is the coefficient of friction different between the two rotors?

According to RR's published data, Stage 1 & 2 use a 328mm disc, while stage 3 & 4 use a 330mm diameter...hence the difference.

[Pat]

Originally Posted by JRitt

According to RR's published data, Stage 1 & 2 use a 328mm disc, while stage 3 & 4 use a 330mm diameter...hence the difference.

Shouldn't the calculations use the same diameter, as the pad is the same distance from the hub with all four stages? If one disc is larger than another, yet uses the same pad/caliper/carrier, I don't think that changes the outcome. That just means there is some unswept area outside of the pad.
What am I missing here?