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Old 10-25-2016, 10:29 AM   #1
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Spec Boxster brake pad questions

Hey Guys - school me please on brake pad options/combinations for my Spec Car build.

I thought I'd get some ideas a few weeks ago at Hallett with the Boxstoberfast Spec races, but after looking at 25 cars and talking to people, it seemed like I have about 30 options to choose from off of 25 cars...

Here's where I'm sitting with my braking system:

Zimmerman cross-drilled rotors, front and rear
Braided stainless steel brake hoses
GT-3 front cooling ducts
80mm wheel studs x all four corners

I've had recommendations of Pagid yellow/front and black/rear, and Hawk HP Plus on all four corners.

Any other recommendations/ideas for pads and overall brake system build?

Here's the mandatory pictures of the car on the trailer on the way home from Jon's (78F350) home, and sitting in my drive as I'm cleaning carpet and sound deadening glue out of the tub, stripping some more interior items and starting to clean up the wiring.

Now begins the build and the slippery slope into the abyss. All comments, help, and critiques as I move forward in the build process are gladly accepted, and I'll even listen to and incorporate some of them.

More on the cars background (1999) and the planned adventure in future posts.

Thanks!

Rick
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Old 10-25-2016, 12:33 PM   #2
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Hey! I'm in Oklahoma and was there for Oktoberfast. I volunteered Saturday and drove Sunday in the DE group in my Boxster GTS. I am having a spec Boxster built, they are using the Pagid yellow/black pads. Other than that, I got nothing but wanted to say Hi!
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Old 10-25-2016, 01:52 PM   #3
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I don't have a Spec Boxster - but for my Boxster track car I run the yellow/black combination. It has served me well.
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Old 10-25-2016, 02:20 PM   #4
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I've heard lots of folks using the yellow/black combo for the SPBs. Recently, talk on another forum suggested PFCs. It will eventually come down to how you like the car to behave under braking, but I think the yellow/black config is where I'll be starting.
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Old 10-25-2016, 05:03 PM   #5
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I ran a BSX Spec Box for 5 years. My 2c

Many of the SpecBox drivers are running 255 square tires. If that is you, the yellow/black combination works pretty well. This shifts brake bias aft and prevents standing the car on it's nose under heavy braking. I ran this way one year.

If you run 235/255 staggered, running the same pad F/R results in good F/R bias due to the smaller contact patch up front. I ran this way for 3 years, mostly with Raybestos ST-43 pads. I found them to offer better heat management and modulation than Pagids and also lasted longer.

In 5 years of testing and data analysis, my car nearly always turned faster laps staggered than running square. Higher speeds on long straights paid out and 3/4 BSX track records were set running staggered. It runs against current BoxSpec fashion but those were my results consistently.

Good luck and enjoy the car. I think the 2.5L Boxster is an excellent track ride with a very active class. I may have to jump back in some day.
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Old 10-25-2016, 06:51 PM   #6
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Pads: Lots of options and opinions available! Most of the people I've been around have used different combinations of Pagid yellow and black, and more recently I've been hearing people mention PFC pads. I used to use Pagid orange, then went to yellow mainly for longer life, and currently due to an incorrectly filled order am running yellow rear / black front, which is a common combination and seem fine to me. Honestly, I am not good enough to feel much difference in the compounds' behavior. The wear rate difference is noticeable, though! Cost per lap, maybe less so.

Rotors: Personally I like slotted, and think that drilled should be avoided because they will crack. I would go with inexpensive (but anti-rust coated) rotors because they all last a long time (as long as they don't crack at the drilled holes!).

The GT-3 ducts are supposed to be good.

Wheel studs are a godsend for easy wheel swapping! Get HIGH QUALITY studs and nuts from Apex: Apex Competition Systems - Auto Racing Parts and Equipment

Brake lines: I don't have a good source for this because my current set are OK though not quite right, but make sure to find a source for flexy lines that can be PROPERLY MOUNTED. The fittings on the end not only need to be the right thread, but ideally should have the necessary outside shape/size to fit the brake line mounting bracket. At both ends of each flexy line there is a fixed mounting point (on the car and on the upright) that has a hole of a certain size that the head of the fitting should slot into, held secure with a little clip. I suspect many cars that have had the flexy lines replaced or enough caliper r&r cycles may be missing these little clips -- several of mine must have disappeared onto the floor of some shop years ago.... The reality is that as long as you can secure the 4 outer ends to the caliper brackets, things won't vibrate, but it's best to have all 8 locations properly mounted.

Last edited by trygve; 10-25-2016 at 07:00 PM.
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Old 10-26-2016, 11:20 AM   #7
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I have run various combinations of Pagids for the past few years but made the switch to Hawk this year since they have NASA contingencies. Have been running DTC60s all around with great success. Tried DTC70 fronts and found I was overbraking in many instances. I run staggered 235/255 RR or NT01 and 245/275 A/R7s.

Second the good call on Apex wheel studs. They make wheel changes a breeze.
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Old 10-26-2016, 12:31 PM   #8
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Hello,

the problem with the drilled Zimmermann discs is that the drilling was done after the casting. That means they can get cracks when they get too hot. So i wouldn't recommend to aggressive brake pads in that case. The GT3 ducts will help, but if you combine these brake discs with too aggressive pads you'll run into problems.

If you have high quality discs where the wholes were done with the cast and afterwards drilled there are less problems with very high temperatures. But these discs cost a lot more.

Braided stainless steel brake hoses: there is a manufacturer over here in Germany who hold the patent for braided braided stainless steel brake hoses with an inner teflon sleeve. They also have an ebay shop: http://stores.ebay.de/Fabian-Spiegler-Bremsencenter-UG?_dmd=1&_nkw=porsche+986

Shure there are other companies in the US that do good stuff.

I would recommend DOT 5.1 brake fluid instead of DOT 4 brake fluid. It's compatible withe the 986 brake system.

Regards, Markus
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Old 10-26-2016, 03:37 PM   #9
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Use plain rotors, not cross drilled. They will crack very quickly.

Pagids are good pads, but start to crumble and need replaced when they have 50% material left and you will be throwing a lot of good pad out.

I run Raybestos ST43 on the front, PFC 01 on the rear. Square setup for tire management.

I also use the 997 GTS brake ducts, they are larger than the GT3 and fit round the control arm, so are less likely to get lost in an off.

PN's 99734148403 and 99734148303

Castrol SRF brake fluid is my go to, but I have some endless RF650 to try soon. The endless is double the price of the Castrol, (which is already crazy expensive) so it had better be good.
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Old 10-27-2016, 10:02 AM   #10
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I prefer pfc pads over pagids. I have used both and the pfc's are far more consistent and last longer than the pagids which seem to crumble and lose performance once they are about 50% worn. I was running pfc 08 front 06 rear on my spec boxster.
Rotors, I recommend to go with a slotted rotor. Not drilled as others have said they will crack too easily. For slotted there are a few choices. To name a few: ATE Premium one, sebro, or contact Chris at LC Motorsports. He makes custom coated/slotted rotors for spec boxsters that are a little mroe expensive, but worth the extra money in my opinion. sales@merlinmfgusa.com is his email.
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Old 10-27-2016, 11:23 AM   #11
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Thanks guys for all your responses to my questions. As you can see even from this small sample, there are a lot of different ways to skin a cat, or in this case, to brake a Boxster.

I know from other threads I have read that slotted rotors are considered (by many) the way to go, and I agree with the evidence of drilled rotors cracking. When I was at Hallett several weeks ago for Boxtoberfast, I figured I'd see 25 cars with slotted rotors. Nope. I saw cars with slotted rotors on all four, drilled rotors on all four, solid rotors on all four, and even mixed drilled and solid.

After this discussion, I do think I'll save the drilled rotors I have at the ready to put on one of my other Boxsters and find a set of slotted to use on the Spec car.

I do have Apex studs and nuts, so I'm good there.

Marcus and Trygve - I'll check into your brake lines suggestions compared to what I have.

Also - thanks for the comments on brake fluids.

I'll have to ponder brake pads for awhile still - lots of suggestions from you guys and they all make sense.

Regarding running square vs staggered... this is another dilemma I'll have to work through. Topless - I've read a lot of comments such as yours about running faster laps staggered, and I remember Tom Stone's comments as he transitioned from staggered to square. My newb brain sees advantages each way, and I'm thinking the real answer is almost track dependent, with staggered having the advantage on tracks with more and longer straights vs square having the advantage on tracks with more and tighter turns and corners.

I do want to thank all you guys, as I have no doubt I'll be asking many questions over the coming months as I get the car put together. I have several complete build sheets from different cars, and I'm familiar enough with the rules that I know most of what I need to do - it's the little things and individual preferences that I'll have the most questions about.

I also want to give a big shout out to Tom Stone, as he took the time a while back offline to answer a lot of my questions on home building vs buying a built car vs buying a used car and the advantages and disadvantages of each. His thread on his build, racing adventures and advice on other threads has really helped me a lot as I move forward.

Topless and Marcus - you guys are two that I always file away your advice and comments for future use - thanks.

And thanks to the rest of you too for any advice small and large - I live in a very Porsche-less part of SW Oklahoma and other than my internet buddies, I don't have anyone local I can go stand in their shop, look at what they've done to their car and seek advice.

I think I'm going to act as the "general contractor" on my build. Some I can do, other things I can't, and I'll farm out what I can't or don't want to do.

Thanks again everyone for your advice - I'll be asking for a lot more of it as I progress.

Rick
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Old 10-27-2016, 04:12 PM   #12
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Brake pads are like motor oil - everyone has their favorites. The one thing that I will say though - is if you are changing compounds - the best time is to do it when you change rotors. There is always a possibility of incompatible compounds which usually result in brake shudder. Sometimes you can get the old compounds off - other times it just gets worse.

I've used the ST-43 compound on other track cars and liked it. Stuck with Pagid because it was on my car when I got it and I liked how they worked. When I go to new rotors - I might try something else - but then again - if it ain't broke.........
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Old 10-27-2016, 08:18 PM   #13
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Hey Rick, as you can see, lots of different inputs.

The good news is that this means there are a lot of ways to skin a cat and most of them will work out fine, so don't stress too much on getting it exactly right from the start. You will have to ultimately find what you like and what works best for you and that might not be what feels right or works best for me or someone else. Plus, you'll be replacing brakes fairly often so there will be many opportunities in the future to try something different if you don't love your first selection. Just find a good starting point and then go.

We're all here to help and, as always, feel free to reach out to me anytime to talk or get some feedback.
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Last edited by thstone; 10-27-2016 at 08:22 PM.
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Old 10-27-2016, 11:50 PM   #14
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Hello Rick,

some things i would like to add:

1.) If you can get vented discs without drilled holes or slots – these are the best from a brake POV if you don't race in wet conditions. Maximum friction surface, minimum / no risk to crack. You only need drilled or slotted brake discs to improve response of the brake in rainy / wet conditions.

2.) If some say their brake pads start to brittle after a while, than in general these brake pads got too hot.

3.) Best way to get a "cheap good" brake is to reduce the weight of the car and improve the cooling of the brake. Also it's important to learn where the limits of the brake system is. Because a brake in race condition is always only as good as the driver treats it. If you need more brake power you need a bigger brake surface. In general this means bigger brakes (diameter and thickness). But this also means more weight (if you use conventional steel brake discs). And to much weight is always bad, because a car drives better when the unsprung masses are minimal.

4.) Some sport / race brake pad manufacturers offer diagrams, so you can see where are the pros and cons of the brake pads. Because brake pads are always a compromise.

Example Brembo diagrams for HP 1000 and HP 2000 brake pads:



5.) Only buy from trusted suppliers. There is many fake stuff out there. Personally i don't buy brake stuff from ebay.

Happy racing
Markus

Last edited by Smallblock454; 10-27-2016 at 11:53 PM.
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