[Bandini]

I always hear that our stock brakes are pretty good, and if that's the case I'm sure mine must be faulty. I'm looking for an improvement.



On road tires, I never noticed a problem, but since I put on track tires the problems are showing. My rotors are stock and old, but my mechanic assures me they look good. My front pads are PBR MetalMasters, which I got based on recommendations in this forum (but may not buy again).



First clue, I guess, was that the ABS just wouldn't engage on track. My initial though was that my new tires were so sticky they just couldn't lose traction, but really? I'm standing on the brakes here. The ABS isn't broken either, as confirmed recently on road tires on a very wet track.



Second clue, after the event, "low dust" MetalMaster dust was covering my front wheels, and a couple of track days later my "long life" pads were used up. There were also signs of excess heat, as the insulation to the sensor wires had melted.



Third clue; in a DE event last weekend, on brand new MetalMasters, I got a pit sign after my first heavy braking. They told me flames were coming out of my front brakes. Actual flames, pretty cool, huh? I checked the damage, and it appears that PBR paints their pads, and it was the paint that had caught fire. Apart from that everything looked OK, but there's a reason for me not to get MetalMasters again. Why paint?



Those are my clues that something isn't right, along with the most important fact that I don't think my stopping power is all that great.



I seem to have a cooling problem. One thing I have considered is that my track wheels may not let enough air through. They are old BBS RS split wheels, and compared to my stock Cup wheels they don't look very open. On the other hand, they were once top of the line, and disc brakes were in use at the time.



Now, to improve braking, what do you think I need to do?



Brake kit - do I need more substantial calipers and rotors, and in that case, do I need to go up in wheel size. Both my road and track wheels are 16", so moving up would mean 8 new wheels and tires. Not an ideal option. Are there smaller brake kits that are still much better than stock?



Cooling - do I need to route more cool air to my brakes, perhaps replacing my fog lights with brake ducts? Do I need to replace my old wheels with a more open design?



Rotors - do I need new rotors? Slotted rotors? Cross drilled? Does it matter?



Brake pads - Here's where you could make me euphoric; are MetalMasters really this bad? Would Brand X pads cure all my problems. Here's hoping...

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[bob blackwell]

Jon, you are obviously using the brakes beyond the PBR Metalmaster capacity. I recommend the M030 Brake option (same as 928S4 front brakes, rear remain the same.) This will increase the capacity of your brakes to the standard you are needing. I would change from the PBR Metalmaster pads to the Pagid Orange pads or some comparable racing pads. The Metalmaster pads are not really suited to prolonged racing use. No need to change the wheels with the M030 (928S4) brakes. I use both the optional 17 inch wheels and the 928 16 inch wheels with no problems. However, if you really want to optimize the traction of your 968 on the track, the 18 inch wheels make a decided improvement. You can find some good used 18 inch wheels if you search for them. (I have a set of OZ Racing wheels available for $600 plus shipping cost). Good luck, Bob Blackwell.

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[JWahlsten]

Are you certain your factory brakes are up to snuff? How many miles and have they ever been rebuilt?



Are you just braking too much? I stopped having brake problems when I stopped overbraking(I am a charter member of OBA, overbrakers anonymous). That being said a cool brake kit is a great idea. The 968 has factory pieces available for this.



I highly doubt you need upgraded brakes. Check your fire wall for cracks. Get your original brakes working perfectly, and try some track pads and you should be okay. I don't think Metalmasters are up to track work. I agree with Bob. Try some Pagid Oranges or Performance Friction PF 97s or whatever the latest is.



YMMV

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[Dave]

Gotta agree with the above. I ran the stock set-up in many DE's right up until I was forced to go with the M030 fronts for Club Racing (read 60-90 minute enduros).



Path should be:



1) Ensure everything in working order (too many items to cover here)

2) Run excellent brake fluid (Ate Blue or better) and flush each event

3) Step up in pads. Usual progression is stock -> Metalmasters -> KFP Magnum Gold or similar -> Pagid Orange/Black or similar

4) Replace stock rubber lines with braided steel (as you should now be cooking fluid enough to swell the rubber lines a bit)

5) Upgrade front calipers + proportioning valve



You DO need to break in new track pads. My break in procedure usually produces a lot of smoke from the wheel wells. This was prominent with the KFP Golds (painted color codes), but much less so with the Pagids (which I assume are not "painted").



The stock 968 cooling ducts are quite effective and really shouldn't need to be messed with other than ensuring all the parts are in place.



I agree with Joel that you may need to look at HOW you are using the brakes. Short hard use is the only way. It's maximum go and maximum stop on the track, no in between or long drawn-out braking zones.



Even with stock brakes, street or DOT-R tires, and winky pads... I could always induce the ABS on the track. You should be able to up until the point of experience significant brake fade. THEN, it's time to correct for the brake fad.



Make sense?

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[Bandini]

Thanks for all your valuable input. I'm actually hoping my factory brakes aren't "up to snuff". I feel that braking should be better than this, even without expensive upgrades. The M030 option is interesting, though, for sometime in the future.



My brake fluid is good and new, and I have brand new steel braided lines. Pedal feels stiff and consistent.



I'm not easy on the brakes, but pretty much on/off. My closest track is rather short - about 1m30 laps - and includes one heavy braking from 200 km/h which takes about 100 m with the pedal to the floor. This is where the corner marshal reported flaming brakes. Maybe there's not enough time for the brakes to cool down on this track?



I have only replaced pads since I bought the car, so I don't know how old the rotors or calipers are. I notice that the front pads are touching the rotors slightly, but not so I can't easily turn the rotors by hand. Should there be a visible gap between pads and rotor?



It's quite possible that my calipers aren't moving smoothly enough. I suppose this could explain the pads touching, and therefore overheating and wearing. But when I am standing on the pedal - I find it hard to believe my calipers are so resistant I can't even push the pads with full force. Could that really be the case?



By the way, I just had my car safety tested (Swedish DOT equivalent, I guess), and one test is braking capacity. The fronts were showing between 2.5 and 2.6 on the gauge, which said someting about Newton. Tells me absolutely nothing, but perhaps it means something... My car didn't fail the test, but that doesn't mean the numbers were any good.



Finally, the rationale behind running 16" wheels is, besides cost, that larger wheels would give me taller gearing, and if anything, I would like it shorter. So I'm trading better grip for slightly better acceleration. Probably doesn't help my lap times, but it's just for fun anyway.

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[Jim Child]

Metal Masters are simply not up to track duty. Switch to a full race pad and you'll notice a huge difference. Pagid Orange or Black as mentioned above would be a good choice.

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[Bandini]

[quote name='Bandini' post='34758' date='Apr 29 2007, 05:07 PM']The fronts were showing between 2.5 and 2.6 on the gauge[/quote]

Hang on, I found the record. It says; left front 2.4, right front 2.6, left rear 1.6, right rear 1.6. No unit is mentioned, though.

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[rustech]

Metalmasters are simply recommended by some because they are cheap. They really are basic pads that can't hold up to track applications. If you find some Carbon/Kevlar/Ceramic compounds, you will notice a world of difference. I have rebuilt calipers, carbon/kevlar pads, ss brake lines, bias valve, and absolutely love my braking ability on the track all with stock calipers. I have not found the limit to the stock brakes though I'm sure it exists.

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[msamuels]

Jon:



I am a Porsche Club driver's ed instructor, and I track my 968 regularly in South Florida at tracks that combine very high temperatures and use lots of braking (like Sebring).



My '92 track car was upgraded from the standard suspension to the M030 setup several years ago for track use. However, the brakes were not upgraded, and I have been using the standard calipers and rotors for 10 years of track use. I have never overheated the fluid or experienced any brake fade during that time, even with air temperatures of over 90 degrees F and track temperatures much higher. And that is running in the instructor group.



The only modification I have made to my brakes is to use Performance Friction 97 racing pads, and to bleed the brakes before each event with Ate Super Blue brake fluid. The 968 includes built-in brake air scoops that do a very good job of cooling the calipers. There is absolutely no need to go to bigger brakes.



Years ago, when I ran street pads and sticky street tires, I noticed that it was difficult to lock up the wheels (invoking ABS) on the street in dry conditions. I also noticed that there seemed to be limited braking available at the track. When I went to racing pads and got some heat into them, I noticed dramatically stronger braking. In fact, as my pads heat up during a 30 minute session, the amount of pedal pressure that I need drops. The pads grip better, and the tires (Hoosiers) get a little more slippery in hot weather, so I push on the pedal less hard to stay out of ABS.



Some caveats: The pads I mentioned are my favorite, but they are pretty marginal for street use. They would not work in any sort of cold weather, needing to warm up somewhat. So I would switch them out after a track session if my car were driven on the street. Also, they are particularly good at preventing the transfer of heat from the rotor to the caliper, preventing the brake fluid from heating up. But that tends to leave heat in the rotor, which eventually causes the rotor to crack. These pads are much easier on rotors than some other track pads in terms of mechanical rotor wear, but the heat build-up in the rotor is greater. The 968 brake scoops tend to cool the caliper more than the rotor. For that reason, after years of using this setup, I added additional brake ducting recently to cool the rotors directly.



Bottom line: For track use, you do not need to go to bigger brakes. While the behavior you mention is normal with street pads, go to track pads and you will have all the brakes you need. Just switch them back out after the track day is over.



Michael

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[Bandini]

This is all sounding very good. My conclusion is I get rebuild kits and track pads for my front brakes, and I should be pretty OK.



Pagid Orange seems to be the concensus. How are they for street use? I would prefer pads that I don't have to switch between street and track. And reading Michael's interesting post, I suppose I would prefer pads that don't tend to leave heat in the rotors. Also, Pagid are pretty expensive. If that's what I need, that's what I'll get, but how do some of the race pads in the $100-$150 range compare? I don't need race winning performance, only a signinficant improvement. Dave mentioned KFP.

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[Eric_K]

Another vote with the above. Change the pads. I found the Pagid Blues RS4-2-1 a decent street/DE compromise. The Pagid Orange or PFC97 are also good but maybe more track oriented than what you want.

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[bibbetson]

I agree with everyone. Your sympoms are those of pads that are getting cooked on the track. If you want to know what really good pads feel like, then buy a set of Pagid Orange. After that you will have a good basis for comparison with other pads. The Pagid are expensive, but you get what you pay for. I wouldn't do anything to your brakes other than change pads (and standard fluid changes).



As stated previously, be careful with racing pads on the street. Daily use on the street will give very poor performance and will eat your rotors due to a lack of pad material transer (that's what bedding is all about).

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[sguy]

I agree that you need track duty pads. Dedicated track pads have poor street performance (some might even characterize them as dangerous). There are some compromise pads that you might consider. The PFC Gold may be good for a compromise (I have tried the PFC silver and they were inadequate on the track). I have just finished off a set of Porterfield R4-1 pads. They are sold as a vintage racing compound that can take track use, but have a lower temperature requirement and will perform OK on the street. They hold up pretty well on the track, and I was unable to fade them on a brake-fade type track (stock brakes). I also autocross and they will run on the ABS cold. They cost about $110 a set, so they are also affordable.



Cheers, Stephen

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[333pg333]

I concur with much of the above. New pads will make a world of difference. I am a convert to the PFC's running 01's f and 97's rear. They are SO much better that the EBC Yellows that I had previously and I find them absolutely fine for the road as well although it may be warmer in Sydney than where you are. The underbody duct's seemed to help quite a lot too although I am also going to use some ducting to the rotors. While my car is different to yours, the balance and weight is very similar and I think you'll find the upgrades mentioned by all like chalk and cheese. Very different in a good way.

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[pickwick]

Yea, what they said. I'll cast my vote for Hawk Blues, but I've never used Pagids. With good pads and good fluid there's no need to upgrade the hardware.



I gave up trying to find a combined street/track pad. Resign yourself to swapping out at least the fronts when you go to the track.

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[flash]

i would step up to the stainless brake lines and change the bias valve, but that's the only hardware changes i would make



as for pads, i LOVE the porterfield 4S and have not yet been able to get them to fade, including on the track - they are a street compound, so i am sure i would eventually find their limitations, but my car is a street car that is occasionally taken on the track, so i think they are perfect - lower dust (that is also easier to clean off) and no cold stop issues or noises



if i can find them for my other cars, i will be removing the repcos and replacing them with the porterfields

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[bibbetson]

I've been using Porterfield pads for many years. I started with the 4S and they are great for AX and light duty track events, however they will burn up when used hard on the track for an extended period of time. I liked them too Bob, but I can't recommend them for track duty. I've got the warped backing plates to prove it. What happens to non-race pads is the material gets too hot and starts rapidly disintegrating. They will look great until suddenly the heat destroys them. I really like Porterfield. Call them and tell them what you are doing and they will set you up with a great pad. I'm currently using a Raybestos racing pad recommended by them that are working great at the hot southern California tracks.

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[flash]

i have no doubt that the race car will need better pads - i'll deal with that when i get started on that car - i still have a few more things to design first - i'm doing this one backwards, and working things out on the street car before i implement them on a race car - when i am done, it won't resemble a 968 much, and will be in an oddball class



this one is a street car, that will only see the track for testing purposes - i doubt i will ever have an issue - i have not yet been able to get them to fade or anything, even on the day when the track was 130 and 100 in the shade - even the instructor i had drive the car remarked on how well they were doing - i'm not sure why - i just know they have been fine so far

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