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-   -   Brake Fade (https://www.rx7club.com/race-car-tech-103/brake-fade-214298/)

DigDug 08-13-03 05:09 PM

Brake Fade
 
Not to say anything bad about the stock brakes on 3rd gens, but...

The fronts (at least) are WAY undersized. I don't have much experience driving stock FD's, especially threshold braking, but my track car (93 R1 with stock calipers and rotors) quite easily cooks the brakes at any of the local tracks (Summit, VIR, Beaverun) in a matter of a few laps, in the end-of-the-straight braking zones. Once already, I had to replace pads/rotors after a single weekend at the track. It takes significant care to keep them working for an entire session/race, else they quickly fade and don't seem to be able to cool back down in any reasonable amount of time (i.e., must do a *full* cool-down lap or pull off and cool down in the paddock for a while). I run Hawk Blacks currently.

Anybody else have similar problems with their FDs w/ stock calipers and rotors? Anybody else using/used Hawk Blacks? Anybody get significant improvement going to Hawk Blues? Or am I stuck needing to go to bigger rotors? (which is really what I have assumed from square one)

If that is the case, the question becomes, what is generally agreed upon to be the overall best (front) brake setup that fits within the stock wheels? I know there is a lot of opinion when it comes to this kind of question, but I figure maybe somebody has some useful input here...

Taz 08-13-03 06:10 PM

Hawk Blues are awesome, but murder on the rotors. I'd try Carbotech's XP's before moving on to the blues. Also, are you running brake ducts? If you can get the hose to the eye of the rotor it'll be like running a different brake setup.

bros0000 08-13-03 06:37 PM

I use Blues in the front (never tried Blacks), EBC greens in the back, and ATE Super Blue fluid, and don't have any brake problems on sticky tires. I have never noticed any fade with my setup. I'm probably using them at about 95% capacity. (Someone who was pushing the car to 100% may have a different experience.)

After something like 8 1-day events I have finally noticed some minor surface cracking in the (cryo-frozen www.frozenrotors.com) rotors, so they need to be replaced, but they are still well above the rotor thickness tolerance. Pads have lasted 6 events now, and I imagine I'll get 1-2 more out of them. I am probably going to look at brake ducting merely to get even more life out of the system.

PaulyDee 08-13-03 11:28 PM

Brake ducting would definately help the "cooking" situation. The black compound you are using is probably not the best. Blues (in Hawk anyway) or HT-9s might be a better option. I am unfamiliar with other brands so I won't offer any opinions there.

As for brake upgrades, there are a host of kits out there for the FD.

You should check with shops like N-Tech or Pettit and ask them what would be best for your application.

The PFS Firehawk car probably had to run stock brakes per the regs, but you obviously don't have that restriction.

DigDug 08-14-03 03:38 PM

Unfortunately, I'm not running brake ducts, because I simply cannot fit them into the wheelwells - I am running 245/45-16 Hoosiers on stock FD wheels - if I turn the wheel in one direction more than about 60 degrees, the tires are rubbing away at the wheelwell liners. Fortunately, I never really have to turn the wheel that much on the track. But the effect is that brake ducts are, as far as I can tell, impossible to fit in the wheelwells...

I am running Motul 600 fluid, so there really isn't any room for improvement there - except to use SRF, which I tried previously, with no difference in results.

I have read about the cryo-treated rotors, but never tried them. My stock (front) rotors seem to develop minor surface cracks after only a few events. Honestly, I have not been able to perceive a difference in braking with or without the surface cracks, so I had been operating under the assumption that they were not hurting me any.

And yes, the stock brakes are a legacy problem with my car. But I do not have this restriction, so I was thinking it might be time to go to a bigger front setup. I will definitely check with Pettit to see what kind of insight they can offer, and maybe I'll go bother Peter some more...

Thanks for the input, guys. I appreciate it! Sometimes I find some clarity simply by getting some extra eyes on the issue...

Fritz Flynn 08-14-03 06:22 PM


Originally posted by DigDug
Unfortunately, I'm not running brake ducts, because I simply cannot fit them into the wheelwells - I am running 245/45-16 Hoosiers on stock FD wheels - if I turn the wheel in one direction more than about 60 degrees, the tires are rubbing away at the wheelwell liners. Fortunately, I never really have to turn the wheel that much on the track. But the effect is that brake ducts are, as far as I can tell, impossible to fit in the wheelwells...

I am running Motul 600 fluid, so there really isn't any room for improvement there - except to use SRF, which I tried previously, with no difference in results.

I have read about the cryo-treated rotors, but never tried them. My stock (front) rotors seem to develop minor surface cracks after only a few events. Honestly, I have not been able to perceive a difference in braking with or without the surface cracks, so I had been operating under the assumption that they were not hurting me any.

And yes, the stock brakes are a legacy problem with my car. But I do not have this restriction, so I was thinking it might be time to go to a bigger front setup. I will definitely check with Pettit to see what kind of insight they can offer, and maybe I'll go bother Peter some more...

Thanks for the input, guys. I appreciate it! Sometimes I find some clarity simply by getting some extra eyes on the issue...

If you have track tires and are braking late and hard over and over from 135 plus mph then the stock pads are not going to cut it for much more than a weekend event even with duct work.

I have a big brake kit for sale...hint hint :)

DigDug 08-15-03 10:20 AM

Well, I am using Hawk Black pads for the time being - but yeah, they don't seem to be all that fantastic by themselves.

But, ultimately, I am looking to go to bigger brakes. So what sort of setup are you selling? Will it fit within stock FD wheels? I have lots of stock FD wheels...

Silkworm 08-16-03 01:26 AM

I'd really look at pads and fluid before moving up brake sizes.. Granted, FDs with the power are going to need more help on the whoa, but i'm willing to bet the fade will significantly be reduced with a set of Panther XP1109s or the Blues, combined with Motul 600 or equivelant fluid.

DigDug 08-17-03 10:04 PM

Yeah, I guess I forgot to mention that I am running Motul 600 fluid. I still don't have a very good idea of how much better the Blues are over the Blacks, but I guess I should try the pads first.

PaulyDee 08-17-03 11:17 PM

Blues are a bit more grippy than the blacks. Most guys I know run blues in front and blacks in rear to dial in a little bias.

Blues take a bit more heat to get working but when they do, they have good grip quality. Give them a try. Don't forget blues and the street don't mix.

bradrx7 08-18-03 10:08 AM

DigDug,
It isn't just the fronts. You might want to look into upgrading the rears to 99 calipers and rotors. The increased diameter will take some of the strain off your fronts without increasing pedal stroke (calipers have the same capacity). Motul should carry the day and some ducting is important.
* Many folks think the issue is to increase the front brakes when they have braking problems. I remember vividly when I asked a NASCAR brake tech HOW they stopped those 3600 lb. cars at a track like Watkins Glen or MArtinsville which is very hard on brakes. Remember, they are restricted to 15" steel wheels. His answer? "We run really big rear brakes, too." On my track car (with manual brakes) using this knowledge solved my braking balance issues. try it.

DigDug 08-19-03 01:40 PM

I had considered upgrading the rears - I did this on a previous track car (Subaru Impreza), and it made an amazing difference. The Subaru had a tendency to dive under braking, even with a very stiff suspension. Upgrading the wimpy rear rotors on that Subaru to the factory rotors of the Subaru Outback H6 (went from 10.6" to 12.1" rotors, I believe it was) almost completely removed the tendency to dive, and instead the car squatted under braking. It was a very solid feeling I got threshold braking in that car, and I have to say, I enjoyed it thoroughly.

But I haven't really noticed any tendency to dive under braking in my FD. It seems to squat very much like my Subaru did with the bigger rear rotors (the FD actually seems to squat more). Of course, once I upgrade the fronts, the balance will change, and I may very well end up going to bigger rear rotors as well. But for now, without a whole lot of toe, my FD does have a tendency to get a bit squirrelly unless I set it up precisely into a braking zone. From my experience, alignment considerations aside (like I said, minimal toe), this indicates a bit too much brake bias towards the rear.

However, my car isn't a stock (or even close) FD. In fact, to be honest, I don't even know all of the modifications it has undergone. Of course, I know that it has completely stock calipers and rotors, front and rear. That was a restriction in the IMSA Firehawk Series, and then my car was later ran in GrandAm (GS), where they also have restrictions on brake modifications. That is why they are still stock, while the rest of the car is heavily modified. Go figure.

I am waiting to hear back from Pettit, who I contacted towards the end of last week. They are very busy, so I am expecting to wait at least a few days before I get a chance to talk to them. I want to see what kind of testing they have done with regards to the brakes on the FD - perhaps they will tell me, "well, we upgraded the fronts, and then the car was diving under braking, so we upgraded the rears too, and it made a big difference". Fortunately, I don't have any events scheduled for a couple of months, so I can take my time addressing this problem.

Meanwhile, the waiting game... :doughboy:

DigDug 08-19-03 01:44 PM

Actually, bradrx7, you mentioned "99 calipers and rotors". By "99", do you mean 1999? Are these like factory rotors/calipers from a 1999 Japanese model RX7 or something?

I do like the "factory" brake upgrades - like what I did with my Subaru - everything bolts together perfectly (usually) and looks as though it came that way from the factory. Plus, the components are almost always cheaper...

Fritz Flynn 08-19-03 03:15 PM


Originally posted by DigDug
Actually, bradrx7, you mentioned "99 calipers and rotors". By "99", do you mean 1999? Are these like factory rotors/calipers from a 1999 Japanese model RX7 or something?

I do like the "factory" brake upgrades - like what I did with my Subaru - everything bolts together perfectly (usually) and looks as though it came that way from the factory. Plus, the components are almost always cheaper...


I have the 99s on my car and they do help but you will see a huge difference with just duct work and BBK on the front vs the stock fronts. I was literally melting my front pads before upgrading.

I think the 99 and up are standard but it may be the rs model only.


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