AX brakes vs. Racing brakes..., what setup or both???? Options

[BKLA]

The narrow body AX/race car I purchased last October has Boxster brakes up front and "m" front calipers mounted at the rear. I just ordered Rich Johnson's rear boxster kit for the 914 and will install it before the first AX this season up here... seems like a good idea to have a matched set of brakes that are engineered to work with each other. (I believe that the car is in E mod for the PCA AX, but honestly, I have no idea.) This is all well and good for AX, but places me in all kinds of weird and uncompetative classes in PCA, SCCA and is not legal for histerical classes.

I am not planning to race the car this season, but would like to go thru a few DE days and an SCCA drivers school in order to re-activate a 15 year lapsed license... Next year though, I would like to do a few historicals as well as an SCCA race or two.

Anyway, now I have a good set of "M" fronts, a set of "M" rear (smaller piston size) calipers (rebuilt) and I was thinking...Hmmmm

I could put together a complete set of front struts and rear trailing arms with these brakes and have a legal historical, SCCA and PCA system that I could just bolt on. Of course, I need shocks to match, but I have a set of front struts as well as trailing arms with elephant racing bearings installed - so this seems like a no brainer.

Am I over thinking this? - I'm not out to win, been there done that...I'm out to have a really good time - so running in the other classes in an uncompetative car shouldn't really matter.

Any advise from the peanut gallery?

[Crazyhippy]

if the M calipers are enough for the big track, why would you want or need more for AX??

I'd build the car to be leagal for the historics the 1st time, and swap brake pads if needed as opposed to struts.

BJH

[Aaron Cox]

i have M's up front with porterfield r4s pads....

plenty of braking for me...

boxsters are for the cool factor (IMG:style_emoticons/default/smile.gif)

[BKLA]

if the M calipers are enough for the big track, why would you want or need more for AX??

I'd build the car to be leagal for the historics the 1st time, and swap brake pads if needed as opposed to struts.

BJH

One of the local SCCA techs (name withheld to protect the guilty) suggested that I just leave the boxster stuff on and wait to get protested. He felt that because the car is a narrow body running a TIV, most other EP drivers wouldn't care. Remember, this is just going to be a local car - maybe to seattle once in a while...and it already had boxster brakes on the front.

I just happen to have all the parts in boxes lying around to do this - maybe a project for next winter?

Aaron - Why did you want the boxster brakes when I first bought it from thomas? Wow factor only? (IMG:style_emoticons/default/biggrin.gif)

[Crazyhippy]

Another good idea... And 99% of people wont protest until you beat them. Would really suck to go have a great (or lucky) race and win, only to have it taken away by a protest. Especially if you already have the parts.

Kinda depends on if you are trying to be competitive, or just having fun.

[Joe Ricard]

You need 2 sets of pads.
There is a major difference between AX pads and road race pads.
AX Porterfield R4s pads have very high grip when cold. But when subjected to track work they will get too hot and start to fade ( you may not have that problem with the big ones you got)
However track pads Porterfield R4 do not grip worth a hoot when cold and you must get them warm to be effective. Once up to temp beginning at 250 degrees minimum they are fantastic.

[drgchapman]

BKLA,

Looking forward to meeting you at the first a/x in March. My wife and I have become quite involved in the PCA scene. You and I can chase JP and Brit in their monster tired, ginthered, super light 914. Several 914's in the Mod class here, tons of fun!

See a at PIR.

Gary

[914forme]

Boxsters are over kill in auto-x and with a narrow car, can be hard to modulate on and off on a track. Lockups happen more than not, and tire choices will have to be well perfect. Narrow cars don't have a huge foot print to use, got to keep tire friction working for you, and a locked wheel does little more for you that flat spot a tire. Don't get me wrong locking a wheel has its advantages, or at least dragging a wheel or two can. But it is not usually associated with auto-x or DE. But there are still ways I use it to my advantage.

I run Carrera brakes on my front and rear, I like matched items also, have an adjustable prop valve out back, fronts will just barely lock before rears in most instances. I run stock OEM pads or a DS11 pad in these. Point being over kill over kill over kill. I can lock all 4 up at will. On an auto-x Only time I use them to their full potential is coming off the course. Even though they like to toss a gate or two before the finish line, in a 914 it is a minor diversion and you can usually cook it at 60-90, then I need the brakes to get down to safe speeds for the paddock. But note, a single time the -4 brakes would pull this off with out issue. They would cool before my next run and not be an issue.

My original setup was a set of M fronts, on stock 914-4 rotors, and 914-6 rears with a 19mm master. I had to remove the spacers out of the M, for my none vented rotors. But with pad technologies the way they are and experience on the track, with PCA J class race cars, you can do really well, with stock -4 parts, better than you think. Biggest problem is heat soaking and some ample use of coatings can really reduce this issue to almost nil. For auto-x you don't need to add cooling, but on a track, we ran them on the front rotors, built a set of ducts, over the rotor, that on the outside looked like a beer can, inside had a few baffles to help direct the air over the rotors, trying to reduce, lopsided cooling issues. I should have gotten a set of Bud stickers and slapped on the cans. (IMG:style_emoticons/default/beer.gif)

Auto-x and racing are controlled environments. But I am a believer in huge brakes, on the street, you can never have enough brakes, or acceleration, both are needed for accident avoidance.

[BKLA]

Thanks for all the info...

The rear boxster kit should be here by mid february so I have some time to mull this over. The car currently has Pagid orange pads on it. After replacing the rear calipers I was planning to use the same. (but new all around)
Once I get some time in the car - (haven't even driven the damn thing yet!) I may choose to change pads or the entire setup. Maybe I'll try the AX Porterfield R4s pads and buy a set of their roadrace pads as well.

I'm having the roll cage modified next weekend and the seat installed, so I can have an opportunity to finally drive it. I have a set of 16 x 6 front and 16 x 7 rear with street tires as well as a set of 16 x 6 all 'round with Hoosiers.

The first AX will be for fun and to work out the bugs... (IMG:style_emoticons/default/idea.gif)

The SCCA drivers school and novice race is early march, I think I'll postpone the roadrace stuff this year until I have some time in the car. That was my original plan anyway.

Again, thanks for all the info!

I'll post pics of the rich johnson rear boxster kit install here in this post when I get them.

[Eric_Shea]

Next year though, I would like to do a few historicals as well as an SCCA race or two.

S-Calipers up front.
M-Calipers in the rear. (or a 38mm equivalant such as the 914-6/GT caliper)

That's what "all" the HSR cars are running. They are almost all wide-bodied cars though.

For a narrow bodied car I would run:

M-Calipers up front.
Rear M-Calipers in the rear.

[BKLA]

Next year though, I would like to do a few historicals as well as an SCCA race or two.

S-Calipers up front.
M-Calipers in the rear. (or a 38mm equivalant such as the 914-6/GT caliper)

That's what "all" the HSR cars are running. They are almost all wide-bodied cars though.

For a narrow bodied car I would run:

M-Calipers up front.
Rear M-Calipers in the rear.

Would those be the "m" rears that you didn't want? (IMG:style_emoticons/default/poke.gif) (IMG:style_emoticons/default/biggrin.gif)

I have all the parts to put together what Eric suggests above, so after this AX season...

Were the 911 "M" rear brakes vented or solid? (just showing my lack of general porsche knowledge...scary Huh!?! Given the spacer in the caliper, I'd say vented!)

[Eric_Shea]

For that exorbitant amount of dead Presidents... yes, those would be the ones I didn't want. (IMG:style_emoticons/default/w00t.gif) (IMG:style_emoticons/default/tongue.gif)

The rear M's came in both configurations (early and late). You can put them together w/o the spacers and run solid. They bolt right on to a 914 at that point. Leave the 10mm spacer in and you can use the vented rotor but you'll have to either shim the caliper back 5mm or the rotor out 5mm. (IMG:style_emoticons/default/wink.gif)

[Eric_Shea]

Brett,

Keep in mind that some run groups insist on a solid rotor in the rear (SCCA G??). Again, this is why I like that caliper so much for the rear of a 914 (race car). They are the same as a 914-6 caliper but, literally a dime a dozen. They give you a much better balanced brake system over the 914 front to the rear trick.

If Marty ever gets the spot caliper to the market, these will be a killer caliper for the S-Caliper/A-Caliper crowd as well.

[jhadler]

Hmm, yet another thread on brakes...

Well, the first thing I would say is RTR. Read the Rules. If you're -really- only in it for the fun, then it doesn't matter. But how would you feel if you actually took a podium spot in a race, only to get the boot because of an illegality you could have easilly taken care of beforehand. PCA, Vintage, and SCCA can have very different rules depending on the series (W2W vs. AX), so pick the series that you're most interested in, and build to that.

The second this I would say is that in AX, weight is EVERYTHING. Run the smallest, lightest brakes you can. If you're overheating your brakes at an autox, then you've got a problem. If you can't lock up your wheels with stock 914-4 brakes in a narrow body car (even with super sticky tires), then the brakes are in need of work.

Then you've got the track. If you're running smaller race tracks, stock brakes can work just fine. If you're running bigger tracks, with a bigger motor, then maybe you need bigger brakes to handle the higher speed braking maneuvers. But even on smaller tracks, stock brakes with good cooling are pretty darn good.

That being said, do what you feel best doing. Just make sure that you don't overbias the rear and spin the car off the track the first time you really get on the binders.

-Josh2

[BKLA]

This first year, I am in it only for the fun. My original plan was to run it in AX's and do a DE day or two, them maybe an SCCA drivers school.

I am going to put off the drivers school stuff 'til next year go with my original plan. AX this year, slowly determine if the current setup - engine, gearbox, brakes, body configuration, performs well and is what I really want.

Based on everyone's comments, it appears that I have all the "stuff" to put together a braking system that will meet both the requirements of SCCA and Histerical racing. I just purchased the GCR so that will be my first read to understand the classifications and requiirements.

I am going to install the rear boxster kit as the monoblocks are significantly lighter than the "M" calipers. The first AX will be a "test" session to figure out brake bias and other settings. Other than maintenence items on the engine (oil change, tune up, valve adjust and carb adjust) and gear box, and the mods to the roll cage/seat area to get my fat a$$ in the car, I'll just show up as it is.

Thanks!