Brake Pads

[Patton]

I need knew ones,... any comments, suggestions, pointers would be welcomed.

Thanks.

[tomtom72]

I was told that unless the car is used for Auto-X'ing or if you do road course sessions that the stock pads are enough for even some street twisties. I only have 15,000 on my car and I do a lot of "cruises" with the CF/NE crew on the weekends & I think the stock pads work fine. We do our driving on all types of roads and most of us are not racing each other. The one thing I like about the OE pads besides that they work for me is they don't seem to "dust" a lot.

I may not be very qualified to give any more of an evaluation because the type of driving I do is purely street driving. I've never had to throw the anchor out at much over 100 mph. I've never had to use the anti-lock feature so I guess I don't use them that hard. Even when we go to the higher hills in upstate NY & have some fun I have never wished I had better brakes. The stock stuff seems to be fine but then I'm probably not pushing the car. I don't feel like part of the car yet and my skills, if any, are rusty from being away along time. I do know one thing, when I've felt that I was about to overcook a corner the OE stuff has bailed me out in that I can slow the car before I ask it to make the entry point. Sometimes I have not left the car much straight road to work with either & it always makes up for my mistakes. Sorry I'm not better able to give a more scientific evaluation, Mr. F!

:cheers:
Tom

[A1990]

Not sure what kind of driving you do or plan to do. If I didn't just use OEM replacements, I would be looking for something with less dust.

I would look at the Akebono ProAct or the Hawk Performance. They are both ceramic. I found them on tirerack's site

If you read: Better braking = more dust...fact of life I guess....

[Patton]

Tom, and A1990 (I’m sorry I don’t know your name yet!)

Thanks very much for the information guys! I’m not really sure how different brake materials/compounds effect braking yet... The stock stuff is really great and has only let me down once but it was a totally insane extreme that I probably wont be in a position to do very often,...
In my military days, I would drive from Sacramento to San Diego all the time, (in an '89 5.0 IROC) towards the end of my tour I made the run in the ZR1 several times. One of these times I just happened upon an SL500 AMG, I actually posted about it on here a LONG time ago,... Anyway, a couple of acknowledgement nods later we were both at WOT and the bastard hung in there, no more than 1 1/2 car lengths behind and actually felt like he was gaining in the beginning but I guess his legs weren’t long enough because at around 160mph he began falling back more and more,... I continued to the high 170's when I saw traffic up ahead, at those speed your adrenals are pumping soooo much and you are listening to EVERY little sound coming from every corner of the car... So traffic WAY up ahead feels very close, I applied the brakes and just gave it a slow constant pressure to tackle her down from warp 9. As soon as we shot the gaps in the traffic there was a about a mile gap until the next traffic gaggle, we went WOT and hit the brakes hard for the next group and again shot the gaps. Now a HUGE horizon reaching straight-away appeared and we were off once more yet this time in the mid 170's (car takes awhile from 170-180) I got the spine tingling bi-tone bleep of KA radar detection. I got on the brakes vigorously, from 175 or so to 150 was a breeze, but to my utter horror they just melted into absolute jelly and the pedal just mushed effortlessly into the floor, It shocked me so I let up and then applied them again and they gripped for half a second and went to jelly again,... the KA signal strength was growing and the next batch of minivans and 18 wheelers that was on the horizon moments ago was getting closer... I had to tap and release the brakes over and over to very slowly bring me down from 150... That scared my testicles into the nether regions of my abdomen let me tell ya. The KA was coming from a highway patrol on the side of the road ticketing an SRT-4 and I thought, what if the cop wasn't there and forced me to slow down early?? I would have waited to brake later than last traffic pack because my confidence had grown from the last 2 passes... would have been E-brake time at around 130mph, man oh man.

I think that was a rotor issue, not being able to radiate heat fast enough, becoming so hot that any contact by the brake pad is like a molten knife trying to find friction against melted butter. When we pulled off the road for gas/fluids and to just breathe the guy said he could see my rotors glowing. And that his brakes went mushy too. I was really worried my rotors were going to be warped after such a beating but the have never shown any problems. It was that day that I resolved to get more stop before I get ANY more go.

[WB9MCW]

HAH I REMEMBER THAT STORY....only i dont remember all the detail on the brakes...lol..it was when u told me i was scared to go wot in my z...and u know ur right i have never gone wot..only 130 myself althoug my mech/best friend took it to 145 to show his parts supplier what a zr-1 was all about. the lee auto parts mgr now knows what the koth is indeed!!! LOLOL see Patton i can write in lower case after all!!!!! :-({|=

[Patton]

LOL, YUP BRYAN I REMEMBER OUR LITTLE CONVO ON THAT THREAD. I REMEMBER NOT MENTIONING THE BRAKES... DONT KNOW WHY I DIDNT, I WAS SO IMPRESSED THAT I HUNG WITH AND BEAT AN AT THE TIME BRAND NEW SL55 AMG THAT PUT OUT 469HP. IT WILL BE A VIVID MEMORY FOR THE REST OF MY LIFE. JUST WISH I COULD HAVE SEEN THOSE ROTORS GLOWING FOR MYSELF. I DONT BLAME YOU ABOUT WOT IN THE Z THOUGH, SHE CAN BE A REAL HANDFUL AT TIMES IN THE LOWER GEARS. HOWEVER I SERIOUSLY RECOMMEND YOU FIND YOURSELF A NICE DESOLATE STRETCH OF STRAIGHT ROAD, JUST FVCKING NAIL THE THROTTLE AND MOVER HER COMPLETELY THROUGH THE FIRST 3 GEARS AT WOT. YOU'LL FREAKIN LOVE IT, BUT BECAREFUL BECAUSE IF YOU ARE ANYTHING LIKE ME, ONCE YOU FEEL THAT RUSH YOU'LL BE ADDICTED!

The caps was all for you old buddy.

Hey, you know what else I remember about that post? I remember at first I remembered wrong and called the car a SL500 AMG when there wasn’t any such thing and you corrected me ever so eloquently :sign10: it was an SL55 AMG and after all this time I called it an SL500 AMG in my recounting AGAIN... weird how the brain works. lol. I’m surprised you didn’t rub my face in it again! LOL :thumbsup:

But seriously, you aren’t an actual human being until you've wot'ed through the first 2 gears at least! Give it a shot, its a rush and very therapeutic after a shitty day at the office. :dancing
The high speed thing gets a little scary and unnerving on public roads, but the quick 1/4 mile type runs are relatively safe and fun as crap.

[tomtom72]

I'm glad I'm sooo chicken after reading about your experience Francisco! Holy cr@p! Seems like the system does not disapate rotor heat quickly enough??? Would the answer be bigger, drilled & slotted rotors with calipers that have more pistons?? Oh well I'm glad nothing bad happened! :thumbsup:

[Tom]

Since your description said the pedal went to the floor you probably boiled the brake fluid from the heat generated from your high speed brake applications. The brake fluid needs to be flushed regularly to keep the moisture content down since the boiling temperature of the fluid is greatly reduced when there is moisture in the fluid. Some track days require a brake fluid flush within a certain time period before the event in order to try to prevent this exact problem.

[Patton]

Aha! Thanks very much Tom#2 ;)
That is very good information to know. I have flushed it since, but not because I knew exactly that, just as preventative maintenance.
Now that I think of it, physics wise that makes sense. If the fluid is extremely hot, one would think the PSI would increase and you might get better braking however one must not forget what the heat is doing to the vessels which house the fluid,... EXPAND. Thus increasing the volume that the fluid must displace, for every inch of tubing. Which explains the brake going to the floor. However, the brakes got very loose just before the pedal went to the floor. I wonder if it was overheating all around?

Good stuff :thumbsup:

[Jeffvette]

Go with a high quality fluid. Motul 600 or even Ford Blue fluid. That will help solve the problem of the soft pedal as mentioned before.


As for pads take a look at the Hawk HPS pads, they will do well for street use (don't require to much heat to function) and they will also serve as a good auto X or a couple of track days.

[A1990]

Go with a high quality fluid. Motul 600 or even Ford Blue fluid. That will help solve the problem of the soft pedal as mentioned before.


As for pads take a look at the Hawk HPS pads, they will do well for street use (don't require to much heat to function) and they will also serve as a good auto X or a couple of track days.

Are these the ones on DRM's site?

[Jeffvette]

You can get them from tirerack which has a good price, along with great shipping.

[Tom]

The volume change with temperature of the calipers/lines/parts is minimal when compared to the displacement of the master cylinder. The temperature increase will not cause an increase in pressure like in a fixed volume gas pressure vessel where pv=nrt applies since the brake system is not a fixed volume system. The v is variable since you have moving pistons in the calipers and a moving piston in the master cylinder where the seal moves over a port open to the reservoir. Your mushy pedal that goes to the floor is caused by the fluid/moisture/contaminant mixture boiling and creating bubbles. The master cylinder does not have enough displacement to collapse the bubbles and adequatly pressurize the system before the pedal hits the floor. When the fluid cools and quits boiling the bubbles disappear and the pedal feel returns close to normal. This phenomenon used to be fairly common in mountain driving, like descending Pikes Peak, before modern brake systems that meet current government brake performance standards. Here is a link I put in another thread that shows how a tandem master cylinder works normally and with one system leaking: http://auto.howstuffworks.com/master-brake1.htm

[petefias]

The volume change with temperature of the calipers/lines/parts is minimal when compared to the displacement of the master cylinder. The temperature increase will not cause an increase in pressure like in a fixed volume gas pressure vessel where pv=nrt applies since the brake system is not a fixed volume system. The v is variable since you have moving pistons in the calipers and a moving piston in the master cylinder where the seal moves over a port open to the reservoir. Your mushy pedal that goes to the floor is caused by the fluid/moisture/contaminant mixture boiling and creating bubbles. The master cylinder does not have enough displacement to collapse the bubbles and adequatly pressurize the system before the pedal hits the floor. When the fluid cools and quits boiling the bubbles disappear and the pedal feel returns close to normal. This phenomenon used to be fairly common in mountain driving, like descending Pikes Peak, before modern brake systems that meet current government brake performance standards. Here is a link I put in another thread that shows how a tandem master cylinder works normally and with one system leaking: http://auto.howstuffworks.com/master-brake1.htm

Exactly, the brake goes to the floor because the air bubbles caused by boiling brake fluid can compress. The normal liquid brake fluid does not compress and it operates the wheel cylinder/caliper pistons.

Here is an interesting question: why does the brake pedal go to the floor when you bleed the brakes one wheel at a time with a dual-piston master cylinder? According to howstuffworks the pedal should only go half way to the floor because of the separate circuits.

Peter '95 #442

[Patton]

Tom,... Funny, I just read exactly that from How stuff works right before reading your link, I love that site. Thanks very informative!

Jeffvette, thanks for the product suggestion!

Also, I am wondering what performance differance are there from pad to pad? Since i guess any pad has the ability to lock your wheel up so "grip" isnt really a performance trait... however consistent grip after heating to the surface of the sun is a different matter... also, the dust issue is a small concern of mine, function is my priorty. however which dusts the least while still maintaining the high temp performance without needing to be warmed up like you said jeff?? Still the Hawk?

Thanks guys.

[tomtom72]

Don't mean to hi-jack your thread, Francisco but this is very interesting. I have a Q for the guys that have been there & done this. Way back in the C2 & early C3 era there was a brake option called "J-56", if i'm not mistaken. Any way the pistons on the calipers had phenolic insulators on each piston to slow the heat transfer to the piston & fluid from the rotor. What would the C4's solution to that problem have been from the factory?

If I get what happened to Francisco, the fluid boiled from rotor heat transfer, right? Drilled & slotted rotors solve that problem along with the better brake fluid?

Thanks & my apologies to Mr. F :o
:cheers:
Tom

[Tom]

With one system leaking the pedal will go most of the way to the floor. You still have to move the other master cylinder piston seal past the port, move the caliper pistons, and use some travel to make up the volume increase under pressure of the components, like the flexible lines, and since one system is out you will generate higher pressures in the remaining system to get normal stop deceleration levels. You can typically generate pressures up to around 2,000 psi in hydraulic brake systems. I've driven vehicles with one system out and the long pedal travel is very disconcerting especially when the front system is leaking on a vehicle where the front brakes are on one circuit and rear brakes are on the other circuit. The government brake system performance standards have a one system out performance standard. In order to meet this standard some small, front wheel drive cars have a diagonally split system. The right front and left rear are on one hydraulic circuit and the left front and right rear are on the other since the two small rear brakes alone can not meet the stopping requirements. The temperatures at the interface between the pad and rotor during hard stops are very high. This heat is dissipated through both the rotor and the pad raising the temperature of both. This heat finds it way into the caliper and hence the brake fluid through conduction throught the pad material, to the pad backing place, to the pistons, and hence to the fluid as well as some through radiation from the hot rotor and pad to the caliper. Brake temperatures during testing are commonly measured by placing thermocouples in the brake pads. The thermocouples are placed at various depths below the surface and when you wear the pad away and expose the thermocouple to the interface surface you switch to the next deeper thermocouple. You can put thermocouples on the rotors but this is more difficult and not usually done since you have to get the signal across the interface from the spinning rotor to the non-spinning side.

[Patton]

Jesus, its Tom mania!

Umm,... Tom Alpha, dont worry about it, you arent hijacking at all! I like the question too, I figure the answer is yes btw.

Tom Bravo, Very interesting retrograde acceleration tidbits. I actually had no idea that they configured them diagonally on some cars. I think that would lead to a very dramatic momemtary yank to one side if there was a leak and a hard stop occured, wouldnt it?

Have any of you seen the video or read the article on the "Turbo Encabulator"? :sign10:

[Jeffvette]

Also, I am wondering what performance differance are there from pad to pad? Since i guess any pad has the ability to lock your wheel up so "grip" isnt really a performance trait... however consistent grip after heating to the surface of the sun is a different matter... also, the dust issue is a small concern of mine, function is my priorty. however which dusts the least while still maintaining the high temp performance without needing to be warmed up like you said jeff?? Still the Hawk?

The difference in pads is the compund and how much "bite" they provide. Track pads are made to bite at higher temps that they encounter, and are horrible for street use, as they are not in their operating range.

Dust and braking capabilities go hand in hand. You want less dust, you get less perfomance, such as with the ceramic pads. You want great stopping power, buy PFC pads and watch the dust fly.

I still like the Hawk pads and it's what I use on my 4 piston set up.

[Jeffvette]

Don't mean to hi-jack your thread, Francisco but this is very interesting. I have a Q for the guys that have been there & done this. Way back in the C2 & early C3 era there was a brake option called "J-56", if i'm not mistaken. Any way the pistons on the calipers had phenolic insulators on each piston to slow the heat transfer to the piston & fluid from the rotor. What would the C4's solution to that problem have been from the factory?

If I get what happened to Francisco, the fluid boiled from rotor heat transfer, right? Drilled & slotted rotors solve that problem along with the better brake fluid?

Thanks & my apologies to Mr. F :o
:cheers:
Tom


The way to counter this in a modern caliper is with Stainless Piston compared to the stock aluminum.

The real issue with what happened is the fluid boiled due to not being changed frequent enough. it should be on your list to do every year, and more if you track your car (every event)

[tomtom72]

Thank you Jeff for the explaination and the pointers. I will put the brake fluid on my annual to do list from now on. :thumbsup:

Thanks Tom for all that research material you shared! :thumbsup:

This is great, I learn so much everytime I log on!

thanks guys!
:cheers:
Tom

[Patton]

Jeff,

I ordered the Hawk HPS's 160 with shipping from tire rack. (front and rear)
I am going to change the pads this weekend, I have never changed disc pads before, I have done a drum though. I have a Haynes repair manual, it doesnt have ZR-1 specific instructions but I think I have the general idea. Any pointers or things to watchout for?
Thanks guys.

[WB9MCW]

have the rotors checked for trueness..may want to rebuild the calipers..make sure they are smooth acting and not hanging up at all... may want to use the new one man bleeding tool then u can do all by yourself...rest is easy..gud luck :icon_scra

[Patton]

Thanks buddy :thumbsup:

[Jeffvette]

Changing them out is fairly simple in the front.

Get the whole vehicle up in the air, so 4 jackstands (makes bleeding easier)

Remember to compress the pistons in with the old pad in place with a large C-clamp. You can pop the bleeder valve when you do this to make it easier, but make sure you have a rag over the top of it.

DO NOT TURN THE ROTORS, they are thin enough as is, and if they are currently warped, turning them will only make them warp quicker and easier, but new replacements. If your rotors are fine, use some fine grit sandpaper or emroy cloth to scuff the surface for the new pads.

Your seals should be fine, but do check your dust boots for tears or holes. If they do have holes, consider doing the seal kit on that caliper. I think they are around 15 bucks from GM.

Changing fluid, use a turkey baster (don't put it back in the kitchen drawer) suck out as much fluid as you can. Fill with new clean fluid and start either sucking or pumping to change the fluid out. I prefer the manual way as opposed to the vacuum kits.

Just take your time, make sure you have the right tools and it's fairly simple.


Rears, do not disassemble the parking brake!!!!!!!!!!!!!!
You can change the pads without messing with it.

[cuisinartvette]

Not to hijack, but Jeff you mentioned the rotors should not be turned...Are there stock replacements available?

[Patton]

Na, thats not a hijack, relevant question.
TireRack has brembo replacement rotors for 52 bucks each (front) and 49 each rear. TireRack also has what I will get eventually, Baer Eradispeed 2 piece, drilled/slotted/zinc washed. dammit those look nice, and get great marks on radiation. $499 for both fronts and $479 for the rears, OUCH. Hmmm,... there are many other things I can think of spending a grand on before brakes that I might only need once or twice. :mrgreen:

[Jeffvette]

Yes replacement rotors are available from NPA, GM, Brembo or a few other places.

[Patton]

What rotors do you recommend Jeff?

[Jeffvette]

Probably the stock replacement Brembos. Not to bad price wise.

The baer Eradispeeds look nice, but I dunno, they see mto do fine when I've driven on a few cars with them.

[Patton]

Yeah, they are just way to expensive. Baer says they reduce 13Lbs of unsprung weight per wheel. That is significant.

What about the whole multi-piston calipers deal. I figure if you have enough pressure to cause the wheel to stop turning and break traction than you should divert your attention to heat management,... Brodening your heat envelope and moving that envelope to match your application. That being said how do more pistons modify your heat range? Is my understanding inaccurate? The only thing I can think of is you could potentially have a larger pad surface area, so they heat/cool faster... What gives? :icon_scra

[Jeffvette]

I'll tackle this question in the morning.

[Patton]

Thanks much Jeff!

[Jeffvette]

Yeah, they are just way to expensive. Baer says they reduce 13Lbs of unsprung weight per wheel. That is significant.

What about the whole multi-piston calipers deal. I figure if you have enough pressure to cause the wheel to stop turning and break traction than you should divert your attention to heat management,... Brodening your heat envelope and moving that envelope to match your application. That being said how do more pistons modify your heat range? Is my understanding inaccurate? The only thing I can think of is you could potentially have a larger pad surface area, so they heat/cool faster... What gives? :icon_scra

13 lbs is significant, but you will not notice it at all. It's like adding 5 hp and saying you can feel the difference.

Multi pistons, what you are trying to accomplish is much more even pad force over the whole caliper. Something a sliding caliper can't give you. Multi pistons are usually in a much better caliper (stronger) and will flex less than a slider and that will eliminate pad taper.

Going to a larger caliper also give you much more heat absorbtion and diispation. Which is critical in high performance driving. Even having fresh air coming onto the stock J55 calipers they will boil the fluid and still be hotter than hell.

[Aurora40]

The real issue with what happened is the fluid boiled due to not being changed frequent enough. it should be on your list to do every year, and more if you track your car (every event)
I hope this isn't hi-jacking, but I am interested in the annual fluid change. The drop in boiling point is from water entering, right? Not from the fluid getting hot or being used?

It seems to me, that for street use, as long as the fluid is clear and not ancient, wouldn't that be an indication it is good? For example, mine was all gross brown when I bought the car. I pulled it through the calipers until it was clear, putting in that Valvoline Syn-whatever stuff (seemed like the nicest store-bought stuff). I'm rarely doing high-speeds, or serious braking, though I certainly want the brakes to perform properly. But if a year from now, the fluid is still clear and not cloudy, how much worse could it be?

The system is fairly well sealed, there's a rubber moisture seal on the cap, and hydraulic fluid generally turns cloudy when moisture is mixed in. So if it's clear and old, and I don't do track events, is the annual change really necessary?

I hate brake fluid and hate dealing with it. I'll change it if it needs to be, but I wonder if it does. One thing I do though, is to always bleed the fluid out when changing pads, by which I mean as I'm resetting the caliper, the fluid being displaced is being sucked out the bleed screw instead of going back into the master cylinder. In this way the fluid gets refreshed gradually. And if it was ever cloudy or getting dark I'd definitely flush it out.

Is this improper thinking? Would it be bad if I, say, tried to stop just one time from high speed?

I can totally see why you'd want to flush it if you tracked the car and such. I'm just wondering if it's overkill for mostly street driving. Sorry if this is long or off the topic. :)

[Aurora40]

As an aside it would be on my wish list to one day get Wilwoods or something for the fronts. I don't know if it's the calipers or just the way the master cylinder/system works but the brakes always feel like crap on my car (they did on my previous Corvette too). They work fine once you push the pedal enough, but it's like the first bit of pushing doesn't do jack. The Aurora's brakes feel one heck of a lot better, more linear and firmer. The Aurora also has a much thicker caliper and caliper bracket, even though it's a single piston on a 12" rotor, which I think might contribute to this.

[Patton]

No no, right on topic. Good question. My thoughts exactly actually.


Jeff,
Thanks for the info, very very helpful!

[Jeffvette]

As an aside it would be on my wish list to one day get Wilwoods or something for the fronts. I don't know if it's the calipers or just the way the master cylinder/system works but the brakes always feel like crap on my car (they did on my previous Corvette too). They work fine once you push the pedal enough, but it's like the first bit of pushing doesn't do jack. The Aurora's brakes feel one heck of a lot better, more linear and firmer. The Aurora also has a much thicker caliper and caliper bracket, even though it's a single piston on a 12" rotor, which I think might contribute to this.

You can swap out the MC for a 93-02 Camaro and use it, it will firm the pedal up. I'm using one currently with my Brembos.

[Jeffvette]

I can totally see why you'd want to flush it if you tracked the car and such. I'm just wondering if it's overkill for mostly street driving. Sorry if this is long or off the topic. :)

Theoretically the system is sealed. It has rubber surrounding it which does go bad and has plastic as well, which is porous as well. As pieces age, it will leak more air/moisture.

Do check your fluid, if it seems clear you should be good, but doing a system flsuh is just good maintenence.

[Mika73]

http://www.ebcbrakes.com/

Has anyone tryed EBC brakepads?

I did order red ones. Havent pick them up from partstore yet.

:cheers: :thumbsup:

[Patton]

Never heard of them.

Thanks for the Hawk tip Jeff, my buddy daily drives and autoX's his Miata and SWEARs by the HAWK HP Plus.

[Jeffvette]

Hawk HP+ will eat your rotors quicker, dust a lot more, and I mean A LOT.

They need to be warmer to work effectively. They will squeel more as well.

[Patton]

Sounds like you know your stuff, Who'da thunk it?
His sentiments exactly. I can bare testiment to that fact as well, for my application It seems the Hawk HPS's are the perfect choice! Im slappin em on this weekend. Wish me luck that I dont oops something. :mrgreen:

[Jeffvette]

Sounds like you know your stuff, Who'da thunk it?
His sentiments exactly. I can bare testiment to that fact as well, for my application It seems the Hawk HPS's are the perfect choice! Im slappin em on this weekend. Wish me luck that I dont oops something. :mrgreen:

I thnk you'll be happy with the HPS pads.

Mika, never tried the EBC.

[Patton]

Well, mission accomplished,... almost. I misplaced my chilton service manual so I winged it,... Never doing a brake job before made it even more unnerving. On the first wheel I actually took the caliper brace off of the wheel instead of just removing the cotter pin!! HAAA! I felt like a moron when I undid the bolts (they were put on with some SERIOUS torque) only to find the cotter pin right after. So the first wheel took me extra long. But the experience was well worth it as the second wheel was a breeze. No problems except for one of the rubber boot looking coverings that the pistons have was a little torn up. Nothing was leaking from it at all, but should I consider repairing/replacing the caliper?

I ran out of daylight before I could do the rears,... will complete tomorrow.

For anybody wondering how long a do it yourself brake job takes, It took me two hours to do the first wheel, and one to do the second. But I'm somewhat of a perfectionist and I take extreme caution and care, especially when I am in uncharted territory. The vast majority was just studying it because I didn’t have a book to tell me what to do next.
Tomorrow I suspect It will take me somewhere in the ballpark of 30 minutes for each wheel.

Thanks for all your help guys!