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So, car is a C5z, running wide wheels, Hoosier A7 and for some reason, the right rear tire locks up prematurely.
I can drive 20 mph, 40 mph, etc, and jamming on brakes, same thing happens, the right rear locks up and activates ABS to that wheel only. I have a scanner that lets me log ABS output solenoids and wheel speed sensors in real time, and every time, the right rear tire locks up and I can see the RR output solenoid on the ABS kick on. The other three wheels, no abs activity. Also, all wheel speed sensors read the same speed. Left and right match.
What would cause a single tire to lock up? Things I thought of and got some feedback from locals:
1) kink in the hard line
2) BPMV has something stuck in it that is preventing fluid flow to the LR
3) something else?
BTW, I replaced calipers, pads, master cylinder, bled and rebled, did the autobleed of the BPMV. other things of note, no DTCs, BPMV pump motor actuates just fine for each corner when autobleed sequence is performed.
This problem is causing me several tenths to a second on one lap because the ABS kicks on the right rear and my stopping distance increases. BTW, for fun, I pulled the ABS fuse and that corner locks up (RR).
Also, I have C6 Z51 brake rotors/brackets front and rear.
Have you considered the real issue is maybe the left rear?
Just a thought, wouldn't be the first time. I had a guy chasing a 'bad corner' problem for weeks only to realize later that corner was working just fine and the other side had bearing grease on the inside of the rotor/pad...
^^^ good point. Also, you can get a brake pressure gauge and check brake fluid pressure at each corner. If everything checks out then maybe it's a suspension issue such as a shock on the right rear with high rebound lifting the right rear under braking.
This thread has so much valuable info, it's pretty awesome. There's OEM equipment, and then there's the top tier racing equipment by AP/Brembo/PFC I see you guys mention quite a bit.
My question: Are there any decent middle of the road recommendations for poor guys like me who just like to HPDE 6 - 10 times a year? I'm in a base C6 on stock everything brake related, except stainless steel brake lines and Hawk HP+ pads, which evidently are garbage when compared to the real racing pads lol.
This is my daily driver, and I'm more than willing to swap parts out for every event...but I don't have thousands of dollars to spend on upgrades that will permanently stay on the car unfortunately.
Am I just SOL? Or is there any solid recommendations for rotors/pistons/pads that will actually help my brakes?
A lot of guys do really well with the stock C5-C6 base setup augmented with DRM stainless pistons and lines and a good pad like a Hawk DTC60, Carbotech 10 or 12 and such an good high temp fluid. Also a good rotor needs to be on the car, like a Centric high carbon.
The stock system is pretty good for all novice and intermediate drivers, really good advanced guys would need better stuff.
Last edited by FASTFATBOY; 04-18-2016 at 12:36 PM.
So, car is a C5z, running wide wheels, Hoosier A7 and for some reason, the right rear tire locks up prematurely.
I can drive 20 mph, 40 mph, etc, and jamming on brakes, same thing happens, the right rear locks up and activates ABS to that wheel only. I have a scanner that lets me log ABS output solenoids and wheel speed sensors in real time, and every time, the right rear tire locks up and I can see the RR output solenoid on the ABS kick on. The other three wheels, no abs activity. Also, all wheel speed sensors read the same speed. Left and right match.
What would cause a single tire to lock up? Things I thought of and got some feedback from locals:
1) kink in the hard line
2) BPMV has something stuck in it that is preventing fluid flow to the LR
3) something else?
BTW, I replaced calipers, pads, master cylinder, bled and rebled, did the autobleed of the BPMV. other things of note, no DTCs, BPMV pump motor actuates just fine for each corner when autobleed sequence is performed.
This problem is causing me several tenths to a second on one lap because the ABS kicks on the right rear and my stopping distance increases. BTW, for fun, I pulled the ABS fuse and that corner locks up (RR).
Also, I have C6 Z51 brake rotors/brackets front and rear.
Please Help!
Put the stock rears back on and see if it resolves itself.
So, car is a C5z, running wide wheels, Hoosier A7 and for some reason, the right rear tire locks up prematurely.
I can drive 20 mph, 40 mph, etc, and jamming on brakes, same thing happens, the right rear locks up and activates ABS to that wheel only. I have a scanner that lets me log ABS output solenoids and wheel speed sensors in real time, and every time, the right rear tire locks up and I can see the RR output solenoid on the ABS kick on. The other three wheels, no abs activity. Also, all wheel speed sensors read the same speed. Left and right match.
What would cause a single tire to lock up? Things I thought of and got some feedback from locals:
1) kink in the hard line
2) BPMV has something stuck in it that is preventing fluid flow to the LR
3) something else?
BTW, I replaced calipers, pads, master cylinder, bled and rebled, did the autobleed of the BPMV. other things of note, no DTCs, BPMV pump motor actuates just fine for each corner when autobleed sequence is performed.
This problem is causing me several tenths to a second on one lap because the ABS kicks on the right rear and my stopping distance increases. BTW, for fun, I pulled the ABS fuse and that corner locks up (RR).
Also, I have C6 Z51 brake rotors/brackets front and rear.
Please Help!
Did you replace the calipers with new C5 calipers, new base C6 calipers or new C6 Z51 calipers?
I've I've run into a curious brake behavior that perhaps someone here can explain and provide some suggestions for improvement.
The car is a 2015 C7 Z51, completely stock, including the standard Michelin SS tires. I had done a number of track days with the OEM pads and rotors (with DOT 4 brake fluid). I'm doing nothing extreme, just standard 20 to 25 minute sessions, nothing competitive, so the stock setup was decent. I also drive the car on the street all the time.
The biggest issue I had was the rate at which the pads and rotors wore out. I decided to upgrade the brake pads and rotors to try to improve the life expectancy along with reducing the chances of rotor cracking or any other surprises, not to mention eliminate the need for messing with the cooling rings on the stock front rotors. If the actual performance of the brakes improved, that would be a bonus, but it wasn't the primary objective.
So I upgraded to AP Racing HD J-Hook Two-Piece rotors in the front and DBA T3 ClubSpec 4000 Series Slotted rotors in the rear. I also switched to Hawk HPS 5.0 pads all around. The only other thing that changed was going from GM's DOT4 brake fluid to Valvoline's. Everything was changed at the same time so it was all starting fresh. I did the simple bed-in process Hawk recommends and drove it on the street for about a week before taking it to the track.
So here's the problem: when I got to the track, the stopping power of the brakes was significantly less than the original stock setup. I had to brake about 25% earlier at the end of the straights.
On the bright side, the braking power that was there was very linear and didn't fade at all during the day (didn't get better, either). Also, while the pads wore at about the same rate as the OEM pads, the rotors were almost perfect at the end of the day (the OEM rotors would be noticeably worn and scorched).
I just can't figure out why the braking would be worse. Are the OEM pads better than the HPS 5.0 ones? Is it the pad/rotor combo? Something else? Any ideas are welcome, both about why its behaving this way and what to try to improve things. As much as the "real" solution might be to swap pads for track/street use, I really would like to avoid that hassle.
I've I've run into a curious brake behavior that perhaps someone here can explain and provide some suggestions for improvement.
The car is a 2015 C7 Z51, completely stock, including the standard Michelin SS tires. I had done a number of track days with the OEM pads and rotors (with DOT 4 brake fluid). I'm doing nothing extreme, just standard 20 to 25 minute sessions, nothing competitive, so the stock setup was decent. I also drive the car on the street all the time.
The biggest issue I had was the rate at which the pads and rotors wore out. I decided to upgrade the brake pads and rotors to try to improve the life expectancy along with reducing the chances of rotor cracking or any other surprises, not to mention eliminate the need for messing with the cooling rings on the stock front rotors. If the actual performance of the brakes improved, that would be a bonus, but it wasn't the primary objective.
So I upgraded to AP Racing HD J-Hook Two-Piece rotors in the front and DBA T3 ClubSpec 4000 Series Slotted rotors in the rear. I also switched to Hawk HPS 5.0 pads all around. The only other thing that changed was going from GM's DOT4 brake fluid to Valvoline's. Everything was changed at the same time so it was all starting fresh. I did the simple bed-in process Hawk recommends and drove it on the street for about a week before taking it to the track.
So here's the problem: when I got to the track, the stopping power of the brakes was significantly less than the original stock setup. I had to brake about 25% earlier at the end of the straights.
On the bright side, the braking power that was there was very linear and didn't fade at all during the day (didn't get better, either). Also, while the pads wore at about the same rate as the OEM pads, the rotors were almost perfect at the end of the day (the OEM rotors would be noticeably worn and scorched).
I just can't figure out why the braking would be worse. Are the OEM pads better than the HPS 5.0 ones? Is it the pad/rotor combo? Something else? Any ideas are welcome, both about why its behaving this way and what to try to improve things. As much as the "real" solution might be to swap pads for track/street use, I really would like to avoid that hassle.
Thanks
First, thanks for the purchase on the Essex/AP Racing front discs!
You answered your own question. Yes, the OEM pads on the Z51 are better than Hawk HPS...considerably better. The OEM pads are very similar to the Ferodo DS2500. They have a higher coefficient of friction and higher max operating temperature than the HPS. HPS should never be run on the track. They're street pads for the street. They have a fairly low max temperature. When they exceed that temp they burn very quickly. I'm actually really surprised you didn't fade them.
You need the proper tools for the job. That means race pads for the track. A great/popular combo is either Ferodo DS1.11 or DSUNO for the track, and DS2500 for autoX/street. The DS1.11 and DSUNO are going to have a considerably higher mu (what you're calling braking power), and much higher max operating temperature range. They're going to be considerably more expensive, but they also won't burn up anywhere near as quickly. Your track miles per dollar will be much higher with the race pads. They're also going to feel much better, and give you a huge boost in confidence heading into turns.
Also, please make sure you try to scrape the Hawk material off when you switch to proper race pads. Don't try bedding in your new pads until you do so. I did a video on swapping between street and track pads...and also bedding, which you can see on the Essex site.
Swapping pads for track and street is a bit more work, but is going to give you a far better experience, and save you money in the long-run.
I guess I'm surprised because at Spring Mountain they are using the Hawk HPS (not the 5.0) and I didn't notice much of a difference at all between the OEM pads and the HPS pads. Unless the HPS pads are actually are better than the 5.0.
So, for the street, is there a real difference between the Ferodo 2500 and the OEM pads? (ie why buy the Ferodo instead of the OEM)
I suspect the HPS 5.0 pads didn't fade because I was baking earlier and lighter and when combined with the better cooling of the rotors it just never got that hot. Most of the day wasn't very warm either.
when it's your job and your livelihood on the line you want the best right? that's why snap-on exists.
and grams do matter, Rational mass is 4x as important as sprung mass. SO for example the 350z 2 piece rotors that PFC offers. they save a whooping 15lbs per corner. now that rotational mass is 4x as important. 15lbs X4(corners) = 60lbs of rotational mass.
60lbs x4 =240lbs. SO if you save 15lbs from each spinning wheel the car will react like you removed 240 lbs out of the passenger compartment. that's like kicking fat Albert out of the car all from a rotor swap.
so if you're in a class (like nascar) and you have a minimum weight of 3000lbs. all the cars are 3000 lbs when they roll across the scales. the tires are spec size and weight, so are the wheels. that leaves the brakes. now lets say you remove 4lbs out of the brakes,( a pound out of each corner) and add 4 lbs in roll bar tubing. your opponents kept the 4 lbs in the brakes and ran some cut rate rotor. now if we do the math. 4x4=16. your car will behave like it weighs 2948lbs, your opponents will behave like it's 3000 lbs. who would you say would win? mind you, if you lose everyone is fired.
so in a series that requires a min weight of the chassis. you can really pick up performance by removing grams out of the wheels, and adding it into the chassis to meat minimum weight.
that and Drag.
On out TA2 cars. the PFC Brake kits have so much less drag when compared to a willwood we are seeing 4mph advantage at road Atlanta. 4mph in a spec race is a huge advantage. if that kit gives you .2 of a second faster lap time. take .2 X 50 laps.= 10 second advantage. that's a victory by miles. if it's your job to win races you'll gladly buy the stuff that gives you .2 seconds.
on a side note
Congratulations to Ernie Ty Francis Jr. On his ta3 victory this weekend. Ernie and Breathless Performance run PFC brakes. 11 compound.
You should measure moment of inertia compared to the oem rotor by spinning the rotor vs. Stock. The reality is the weight reduction is mostly at the hub where it doesn't make nearly as much difference.
I guess I'm surprised because at Spring Mountain they are using the Hawk HPS (not the 5.0) and I didn't notice much of a difference at all between the OEM pads and the HPS pads. Unless the HPS pads are actually are better than the 5.0.
So, for the street, is there a real difference between the Ferodo 2500 and the OEM pads? (ie why buy the Ferodo instead of the OEM)
I suspect the HPS 5.0 pads didn't fade because I was baking earlier and lighter and when combined with the better cooling of the rotors it just never got that hot. Most of the day wasn't very warm either.
I suspect you're correct about the fade. Our AP Racing discs have 72 vanes and flow a ton of air. They were most definitely running far cooler than the OEM discs. We see this a lot with our discs and BBK's actually. A customer who previously was overheating a certain pad compound or was boiling a certain brand of fluid no longer does when they switch to our equipment. Still though, I have rather low expectations for the HPS as a track compound.
As for Ferodo vs. stock, you're fine with the stock pads on the street. I'm not certain on the precise differences between the OEM pads and the DS2500, but they're fairly close. For puttering around on the street, stock is fine. If you're going to invest in one set of pads, switching the fronts to a premier race pad will provide the greatest ROI. I am certain you will be extremely pleased with the results.
I guess I'm surprised because at Spring Mountain they are using the Hawk HPS (not the 5.0) and I didn't notice much of a difference at all between the OEM pads and the HPS pads. Unless the HPS pads are actually are better than the 5.0.
So, for the street, is there a real difference between the Ferodo 2500 and the OEM pads? (ie why buy the Ferodo instead of the OEM)
I suspect the HPS 5.0 pads didn't fade because I was baking earlier and lighter and when combined with the better cooling of the rotors it just never got that hot. Most of the day wasn't very warm either.
The 5.0 pads are supposed to have more bite than the older HPS. That was a complaint from many with sportier cars i.e. Z06 etc.
However HPS (and the new 5.0) ARE more aggressive than your average Honda pad - but really at best similar to a Brembo supplied pad on your C7. (Brembo uses many suppliers for pads by the way)
Not sure why you felt the HPS was more aggressive though.
I guess I'm surprised because at Spring Mountain they are using the Hawk HPS (not the 5.0) and I didn't notice much of a difference at all between the OEM pads and the HPS pads. Unless the HPS pads are actually are better than the 5.0.
So, for the street, is there a real difference between the Ferodo 2500 and the OEM pads? (ie why buy the Ferodo instead of the OEM)
I suspect the HPS 5.0 pads didn't fade because I was baking earlier and lighter and when combined with the better cooling of the rotors it just never got that hot. Most of the day wasn't very warm either.
PS
The OEM pad will have a shim I think - the DS2500 will not.
The DS2500 may have street level bite - but likely a higher MOT.
DS2500 may squeal some.
DS2500's have long been my favorite mixed use pad. Nothing is perfect but if you insist on one size fits all this is what I suggest.
Pricey though.
PSS -
Watch out at GM. In the past - AC Delco has made various compound replacement pads for Corvettes and they are not the same as OEM.
The 5.0 pads are supposed to have more bite than the older HPS. That was a complaint from many with sportier cars i.e. Z06 etc.
However HPS (and the new 5.0) ARE more aggressive than your average Honda pad - but really at best similar to a Brembo supplied pad on your C7. (Brembo uses many suppliers for pads by the way)
Not sure why you felt the HPS was more aggressive though.
Don't know the why, but I know that while I was at Spring Mountain using their cars with the HPS pads, it felt about the same as using the OEM pads. But on my car, when I put on the HPS 5.0, braking distance was significantly longer.
I saw the video about about swapping between race and street pads. However, to start with, I'm going to switch between the HPS pads and some other street pad, in which case I don't think your technique will work. I was told that I could just use some sand paper on the rotors to clear off the old material. Is that the best way to do it?
Don't know the why, but I know that while I was at Spring Mountain using their cars with the HPS pads, it felt about the same as using the OEM pads. But on my car, when I put on the HPS 5.0, baking distance was significantly longer.
I am shocked to hear that SM uses HPS pads.
C-70 400°-1600° F 800°-1200° F HIGH
DTC-60 400°-1600° F 700°-1100° F HIGH
HT-14 300°-1400° F 500°-1100° F HIGH
HT-10 300°-1300° F 500°- 1100° F HIGH
DTC-30 100°-1200° F 100°-800° F MEDIUM
Blue 9012 100°-1200° F 100°-800° F MEDIUM
Black 100°-900° F 200°-700° F MEDIUM
DTC-15 200°-800° F 300°-600° F MEDIUM
HP Plus 100°-800° F 300°-600° F LOW
DTC-05 100°-700° F 100°-50
It's not considered a motorsports pad even by Hawk.
04-18-2016, 12:13 AM
Need help for Rear Brake issue on C5z
