P&L STI Lightweight rear brake kit

[diss7]

All I know, is that my poo spec rear brakes, will Wilwood 6 pots up front, running semi slicks at the track, barely got hot at all. I had new TRD pads in the back, and I wish I had taken before and after measurements, because they still looked new.

In the same 50 laps, The wilwood 6 pots and destroyed a brand new set of pads down to the metal.

However, I do think part of this was caused by me being inbetween suspension at that track day, so I used my oem suspension. Which heavily unloaded the rear under heavy braking, making the rears work easier than they should be.

My new suspension has arrived so I'll try go to the track again with that in, take some before and after measurements of the rear pads, and if they show little/no wear, I'll take that as that they are indeed doing naff all, and bite the bullet on this kit.

[diss7]

Re brake bias concerns, while valid, this is more often than not to be another thing that is over analysed and stressed about on forums. Often the arguement starts from someone selling brake kits, trying to tie you into a rear kit you dont really need.

As another has pointed out, you can toy around with compounds, and find a balance you're happy with. Heck, if that didnt solve it, its not hard to put in a brake proportioning valve; thats what I can in my ae86 before I went full pedal box.

[jack43]

Trying to figure out the actual weight loss potential.

Actual weights posted:
stock caliper 2.8lb, bracket 3lb, disc rotor 13.2lb, pad .8lb = 19.8lb (1 side)
x2 = 39.6lb for stock rear brakes

Anyone know what the rest weighs?

[Dave-ROR]

Originally Posted by diss7

Re brake bias concerns, while valid, this is more often than not to be another thing that is over analysed and stressed about on forums. Often the arguement starts from someone selling brake kits, trying to tie you into a rear kit you dont really need.

As another has pointed out, you can toy around with compounds, and find a balance you're happy with. Heck, if that didnt solve it, its not hard to put in a brake proportioning valve; thats what I can in my ae86 before I went full pedal box.

You can mess with pad choice for sure, but not all pads are consistant across temp ranges so that's not always the best choice either.

Having been on track with too little rear brake (rear pads glazed), it's something I will never understress again. Too much rear brake is just as bad of course.

Adjustable prop valve may not work well on a car with EBFD either, unless you always disable it.

People can do whatever they want, but I see a VERY limited market and usefulness for a product like this. From a track perspective I see absolutely no value in it. From a street perspective I see no value (I don't care much about street performance and having to test and tune to find proper bias again on a street car isn't very appealing, nor is the custom disk and who knows how much pad choice/selection). For an autocross car or drag race car I see value in it.

[Dave-ROR]

Originally Posted by industrial

You're right, I don't know how the bias is affected. I'd imagine these brakes would bite really hard just looking at the rotor. It was designed for dirt tracks and drag racers so I'd imagine they'd work fairly well.

Huh? It's an iron surface. Appearance isn't all that telling in how it will perform, beyond all the additional stress risers. And that they will be noisy due to the design.

I'd like to hypothesize that the brake bias wouldn't be radically affected by the overall system. Nothing that couldn't be fixed with a pad swap or something to that effect. I really don't know at this point. Hard telling not knowing. I can say with a large degree of certainty that 95% of the people on this forum wouldn't reach the thermal limit of these brakes on their daily commute. That's the main point I was contending with. I have little interest in running this exact setup but I do have an inquiry with P&L about using their custom brackets with a slightly larger caliper which can take a .81" thick rotor which opens up a ton of options from wilwood's catalog of rotors. From there, it will take some experimenting to see what works well.

You can adjust pads. Assuming you have a lot of choice in that size. I agree that people won't overheat these in daily driving. There's very little thermal mass in that rotor, but no one should be killing their rear brakes that much when daily driving, unless they have too much power, a heavy right foot, and TCS turned on... that could heat them up quick

I'm sure you know but it seems that robispec runs a similar setup on his timetrial car. Granted, it's a brakeman setup but it's similar. He has also claimed similar weight loss numbers and seems to be doing just fine racing their setup. The 40 pound figure is just for the rear brakes on the sti. I'm not sure what the figure is for us but it's going to be significant. The wrx front kit that some are running saves 32 pounds so it doesn't seem like 40 pounds is that far out there.

The entire rear brake system is about 40lbs, not including a few lbs of lines and nuts.. so... yeah.. 40lbs seems pretty far out there.

[diss7]

Originally Posted by Dave-ROR

From a track perspective I see absolutely no value in it.

No track value in removing 35-40lbs of unsprung and rotational weight?

I politely disagree sir.

[CSG David]

Originally Posted by diss7

No track value in removing 35-40lbs of unsprung and rotational weight?

I politely disagree sir.

What Dave says is true. Our very good friend Robispec runs the Brakeman custom kits. Originally he had a 4lb setup in the rear. Blew up that rotor in a session and proceeded to upgrade to a 7lb setup. Also, his car is caged with 400lbs+ less than a stock car. If your car is at that point, then you can try it. He also changes rotors often enough because he does crack those rotors. If the cost of changing doesn't bother you, then go for it. Robi also doesn't run full sessions too. For the record, his setups usually net podium finishes all over the country so he knows a thing or two, however, he does get a little angry whenever we beat him just by a few tenths every time (all in good competitive spirits).

For side note, while our damper setup is superior to his (he will admit this flat out), he barely pulls on straights when was E85, big radiator/oil cooler, 400lbs lighter, stock motor, and his epic uber light brake rotors. Again, I don't see the correlation to going with lighter brakes will improved performance. There are other things you can do improve performance on your car, such as picking up high quality dampers that will improve your cornering speed and help lay down additional grip for higher corner entry speeds.

While weight matters, our tuning philosophy never compromises on safety equipment. I've seen quite a bit of brake failures with multiple setups. If you find this absolutely necessary for your application, then there's no way to stop you from doing it.

[diss7]

schooled

[Dave-ROR]

Originally Posted by diss7

No track value in removing 35-40lbs of unsprung and rotational weight?

I politely disagree sir.

Again, the rear brakes weigh about 40lbs total based on information in this thread. If that's true, then these brakes will NOT save 35-40lbs.

And not all of that weight is rotational. About 13.2 lbs per side is rotational based on that information. If this rotor/hat setup weighs 5 lbs then it's 8.2lbs rotational, the rest of the savings is in the bracket, drum, caliper, etc.

Furthermore, ignoring the bias issues, I don't run time trials for a few laps on A6 hoosiers. I run 30-60 minute sessions. There's no way I'd track my car with these on the back. Absolutely no way in hell.

Having said that, if they meet your needs then rock on.

[industrial]

Originally Posted by Dave-ROR

Again, the rear brakes weigh about 40lbs total based on information in this thread. If that's true, then these brakes will NOT save 35-40lbs.

And not all of that weight is rotational. About 13.2 lbs per side is rotational based on that information. If this rotor/hat setup weighs 5 lbs then it's 8.2lbs rotational, the rest of the savings is in the bracket, drum, caliper, etc.

Furthermore, ignoring the bias issues, I don't run time trials for a few laps on A6 hoosiers. I run 30-60 minute sessions. There's no way I'd track my car with these on the back. Absolutely no way in hell.

Having said that, if they meet your needs then rock on.

40 pounds not including the drum brake hardware I believe. That stuff can be pretty heavy. I don't think anyone is saying these wilwoods in question would work for heavy track use.

I just want to remove the parking brake and go with a lighter two piece rotor. Don't know why you guys are so vehemently against touching the rear brakes. Seems strange to me especially considering the op has a similar undersized setup stock.

[Dave-ROR]

Originally Posted by industrial

40 pounds not including the drum brake hardware I believe. That stuff can be pretty heavy. I don't think anyone is saying these wilwoods in question would work for heavy track use.

I just want to remove the parking brake and go with a lighter two piece rotor. Don't know why you guys are so vehemently against touching the rear brakes. Seems strange to me especially considering the op has a similar undersized setup stock...

I just said if it meets your needs then rock on. I'm just cautioning that it's not the best idea IMO for various reasons for most people.

I didn't notice that he didn't include the drum bits. Rotational weight will still be limited to the rotor though, most of that is in the hat and that weight removal is less important than weight further out (wheels for example).

[industrial]

Originally Posted by CSG David

For side note, while our damper setup is superior to his (he will admit this flat out), he barely pulls on straights when was E85, big radiator/oil cooler, 400lbs lighter, stock motor, and his epic uber light brake rotors. Again, I don't see the correlation to going with lighter brakes will improved performance. There are other things you can do improve performance on your car, such as picking up high quality dampers that will improve your cornering speed and help lay down additional grip for higher corner entry speeds.

While weight matters, our tuning philosophy never compromises on safety equipment. I've seen quite a bit of brake failures with multiple setups. If you find this absolutely necessary for your application, then there's no way to stop you from doing it.

I'm just curious, how is your car setup for comparisons sake? You guys don't have any weight reduction, brake upgrades or engine tuning?

[industrial]

Originally Posted by Dave-ROR

I just said if it meets your needs then rock on. I'm just cautioning that it's not the best idea IMO for various reasons for most people.

I didn't notice that he didn't include the drum bits. Rotational weight will still be limited to the rotor though, most of that is in the hat and that weight removal is less important than weight further out (wheels for example).

Yeah, I hear you. Weight is weight and if I can drop some without compromise(other than cost to a limit) I plan to do it. Your caution is echoed by p&l who sells the kit too. I share your concern as well which is why I'd like to find out if this kit can be made to work with a proper vented rotor.

[CSG David]

Originally Posted by industrial

I'm just curious, how is your car setup for comparisons sake? You guys don't have any weight reduction, brake upgrades or engine tuning?

No weight saving measures have been performed...even the spare tire and jack are left in the car...(please don't do this when you go out on track).

This is the following mods on the car:

TEIN SRC with CSG Spec prototype valving
Subaru crash bolts
Essex AP Racing Sprint Kit
Carbotech XP12 or Project Mu 999 F/R brake pad
225/45/17 RS3 on RPF1 17x8 +45 or TC105N 17x9 +35
Berk prototype axleback exhaust

Stock engine/ECU