Pad Rotor Problem AP Disks

[Dave-ROR]

Originally Posted by ZDan

HPS are by far the worst pads I've ever experienced. FAR inferior to OEM (S2k) pads. Soft pedal feel (i actually re-bled the brakes as it felt like air in the line), poor bite, and immediately faded at the merest hint of action. Centric PosiQuiet are much better street pads in every way.
HP+, on the other hand, I've gotten very good performance out of them at the track on the s2k despite them not being serious track pads, but they dust and squeal like mad on the street...

For the street, I wouldn't be looking at Hawk pads.

They work ok with the Essex kit and are quiet though. Not sure if centric makes pads in this shape, oem is not an option of course.

[ZDan]

They make them for StopTech ST40, which is I think an old Porsche pad shape. Have those on the FD for street. Is the AP pad shape unique to AP?

[Dave-ROR]

Originally Posted by ZDan

They make them for StopTech ST40, which is I think an old Porsche pad shape. Have those on the FD for street. Is the AP pad shape unique to AP?

Same as the Wilwood superlite 4 pot IIRC

[DR 86]

Originally Posted by post_break

I daily the Hawk HPS+ and haven't noticed any issues in rotor warpage. I switched to the DS2500 for the track day and once hot they squealed like crazy but never faded. Swapped the HPS+ back in after the track day, and they bed just fine.

I will say you need to watch out when the HPS pads are cold and wet. They are like wood. Cold they are ok at best, wet they are ok at best, cold and wet? That combination is like rubbing 2x4's together trying to start a fire.

How cold does it get in Houston and what did you need to watch out for? I ran the HPS (stock brake system) all winter in Canada (-20 degrees Celsius) and didn't have any hairy moment, and I drive pretty aggressively. Also, swapping between Carbotech XP8s at the track, I didn't notice any issues with my pads or rotors.

[post_break]

Originally Posted by DR 86

How cold does it get in Houston and what did you need to watch out for? I ran the HPS (stock brake system) all winter in Canada (-20 degrees Celsius) and didn't have any hairy moment, and I drive pretty aggressively. Also, swapping between Carbotech XP8s at the track, I didn't notice any issues with my pads or rotors.

It gets to around 45 degrees which is tshirt and shorts weather for you. But I can tell you, I've had to double pump to get any bite when they were cold and wet around that temperature.

[Tainen]

Originally Posted by DR 86

How cold does it get in Houston and what did you need to watch out for? I ran the HPS (stock brake system) all winter in Canada (-20 degrees Celsius) and didn't have any hairy moment, and I drive pretty aggressively. Also, swapping between Carbotech XP8s at the track, I didn't notice any issues with my pads or rotors.

I guess I want to throw my experience into the mix regarding Hawk HPS pads.


I ran through two sets of them on my WRX. Overall, I feel like they are decent street pads, with a large warning. When it was wet and roughly 40 degrees out, I had to come to a full stop from freeway speeds (after spending a good 5 or 6 miles on the freeway without touching my brakes- so they had no heat in them at all). I hit the brakes, and I got worse than OEM bite, by a wide margin- it felt like I was braking with wood 2x4s in my calipers, like others have described. I smashed into the rear of the F150 and did 5k in damage to the car, and to date, it is the only accident I have ever had that was my fault. I had more than enough stopping room for my usual driving habits, but the brakes just did not perform.


NOW, after that accident, it gave me a certain level of awareness about the heat in the pad. I just stopped slightly more aggressively every now and again to keep some heat in the pads, and they performed very well for street use. On freeways where traffic might be coming up, I'd just make sure to touch the brakes once in a while or give a little extra distance. Even a few degrees into these things will make them work quite well. BUT, if you have NO heat in them at all, they won't work.


I ran a 2nd set of them through the car after that. I felt comfortable enough with their stopping characteristics that I felt it was a non-issue, even after 5k worth of damage, because the pads work quite well in 99% of scenarios. The 1% being ice cold pads/rotors in the wet, or track-like driving.

[dp1]

North East + AP Sprint + J hook rotors + Carbotech 1521 Bobcat for street and XP12 for track = no issues with rotors and even wear. But I don't brake that hard very often. Changing fluid from Motul RBF600 that got flaky on me on a fast track (WGI) to Torque RT700. Will try plain blanks and XP10 on track next as I'm not braking hard enough to wear XP12 much. Looking for steel vented pistons like the ones BOE Fabrication sells for standard front lotus AP calipers to help keep brake fluid cool on track - anyone knows if there is anything like that available for this kit? What is the outer diameter of the pistons @JRitt? Maybe the pistons BOE sells already fit this kit, I can ask them if you give me dimensions. Thx

[dradernh]

Originally Posted by dp1

North East + AP Sprint + J hook rotors + Carbotech 1521 Bobcat for street and XP12 for track = no issues with rotors and even wear. But I don't brake that hard very often. Changing fluid from Motul RBF600 that got flaky on me on a fast track (WGI) to Torque RT700. Will try plain blanks and XP10 on track next as I'm not braking hard enough to wear XP12 much. Looking for steel vented pistons like the ones BOE Fabrication sells for standard front lotus AP calipers to help keep brake fluid cool on track - anyone knows if there is anything like that available for this kit? What is the outer diameter of the pistons @JRitt? Maybe the pistons BOE sells already fit this kit, I can ask them if you give me dimensions. Thx

Curious to see where this goes.

[JRitt]

Originally Posted by dp1

North East + AP Sprint + J hook rotors + Carbotech 1521 Bobcat for street and XP12 for track = no issues with rotors and even wear. But I don't brake that hard very often. Changing fluid from Motul RBF600 that got flaky on me on a fast track (WGI) to Torque RT700. Will try plain blanks and XP10 on track next as I'm not braking hard enough to wear XP12 much. Looking for steel vented pistons like the ones BOE Fabrication sells for standard front lotus AP calipers to help keep brake fluid cool on track - anyone knows if there is anything like that available for this kit? What is the outer diameter of the pistons @JRitt? Maybe the pistons BOE sells already fit this kit, I can ask them if you give me dimensions. Thx

Personally, I wouldn't spend any money on different pistons. I looked at BOE's site and they are $300. The ones in our Sprint kit as it comes are extremely high quality stainless steel. The vents will add a little bit of benefit, but the benefits gained from stainless over aluminum are far greater (which you're already getting in the kit as standard).

Good fluid is critical to preventing fluid fade. Probably no big surprise there! I'd definitely try something with a higher dry boiling point if the Motul isn't working for you. I have no experience with Torque, but we have a whole list of fluids that are superior to RBF600...I'd take the AP Racing R4, PRF, Super 600, or Ferodo Super Formula over the Motul.

Do you have brake ducts on your car? I would go there before messing with pistons. Even though they are only interacting with the discs when set up properly (dumping directly into the center of the disc), brake ducts cool everything downstream as well. In other words, cooler discs means cooler pads, means cooler pistons, means cooler calipers, means cooler brake fluid.

We have 500hp cars thrashing the same disc and caliper that we have in our Sprint Kit. There's no need to mess with the hardware. Good fluid and ducts will lower your temps and eliminate fluid fade. You can probably buy both for under $500, and you'll receive a whole bunch of other benefits as described above.

Again though, I'd start with good fluid and go from there. My hunch is that will cure any fluid fade you may have experienced.

[dp1]

Originally Posted by JRitt

Personally, I wouldn't spend any money on different pistons. I looked at BOE's site and they are $300. The ones in our Sprint kit as it comes are extremely high quality stainless steel. The vents will add a little bit of benefit, but the benefits gained from stainless over aluminum are far greater (which you're already getting in the kit as standard).

Good fluid is critical to preventing fluid fade. Probably no big surprise there! I'd definitely try something with a higher dry boiling point if the Motul isn't working for you. I have no experience with Torque, but we have a whole list of fluids that are superior to RBF600...I'd take the AP Racing R4, PRF, Super 600, or Ferodo Super Formula over the Motul.

Do you have brake ducts on your car? I would go there before messing with pistons. Even though they are only interacting with the discs when set up properly (dumping directly into the center of the disc), brake ducts cool everything downstream as well. In other words, cooler discs means cooler pads, means cooler pistons, means cooler calipers, means cooler brake fluid.

We have 500hp cars thrashing the same disc and caliper that we have in our Sprint Kit. There's no need to mess with the hardware. Good fluid and ducts will lower your temps and eliminate fluid fade. You can probably buy both for under $500, and you'll receive a whole bunch of other benefits as described above.

Again though, I'd start with good fluid and go from there. My hunch is that will cure any fluid fade you may have experienced.

Great feedback, thanks! Will swap to Torque RT700 brake fluid tomorrow. Good suggestion but no brake ducts for me as it's a year-round north east primarily street driven car.

[dp1]

AP Racing Sprint BBK with Torque RT700 and Carbotech XP12 performed flawlessly at the NJMP Lighning course. No need for vented pistons or brake ducts.

[evanescent03]

Originally Posted by CSG Mike

Grooves that run radially are normal...

Hi mike. I sent you a PM but couldnt' attach a picture. Here are my stock rotors after about ~120 minutes of track time (1.5 days in dry-ish conditions). Using the R12 pads that i didn't bed in but i've skipped that before and haven't had a result like this.

Thanks again!

Matt

:edit: i see OEM rotors from parts.toyota.com are only $73/ea. that's comforting since my camaro's were like 3-4x that much.

Edit#2 : Mike at CSG got back to one of my private messages and said that it looks like I greatly exceeded the capability of the pads. Apparently uneven pad where is a tell tale sign of this.

Thought someone may find this useful..