Carrera brakes: 19 or 23 mm master cylinder? Options

[fasthonda]

I am installing 87 carrera brakes on my track car front and rear.

Is the 23mm master cylinder offered by Automotion a better choice than an ATE 19 mm unit?

Thanks in Advance

Will be posting my track car build shortly to share with the club.

Michael

[SirAndy]

I am installing 87 carrera brakes on my track car front and rear.
Is the 23mm master cylinder offered by Automotion a better choice than an ATE 19 mm unit?

I run 85 carrera calipers and rotors on all 4 corners on my 914 using a 19mm MC.
I also replaced the rear proportioning valve with a "T".

The brakes work great and the pedal feel is just about perfect. Just make sure you get enough air to the front brakes, good sized ducting is a must for a track car.
If you don't mind replacing rotors more often, get the crossdrilled or at least slotted ones.
You'll have to check them for cracks on a regular bases anyways.

I just replaced a set of vented rotors on the 911 track car in the pits at PIR. The metal had been baked into oblivion. The rotors had small cracks in the hundreds. Too much heat. But then again, the 911 is about 500 pounds heavier than the 914.

(IMG:style_emoticons/default/driving.gif) Andy

[Racer]

23mm will make the pedal feel hard and therefore harder to modulate. 19mm would feel softer in comparison, but would be easier to modulate braking pressure. Not sure of your "build", but my '70 was a street car with 2056 and 84-89 carrera brakes all around and I never worried about fade at street or track and I ran with no brake cooling.

[SirAndy]

my '70 was a street car with 2056 and 84-89 carrera brakes all around and I never worried about fade at street or track and I ran with no brake cooling.

That just means you weren't running it hard enough! (IMG:style_emoticons/default/biggrin.gif)

Without the cooling ducts, i can get the front brakes to go away after 10 minutes of hard driving.
(IMG:style_emoticons/default/popcorn[1].gif) Andy

[Racer]

my '70 was a street car with 2056 and 84-89 carrera brakes all around and I never worried about fade at street or track and I ran with no brake cooling.

That just means you weren't running it hard enough! (IMG:style_emoticons/default/biggrin.gif)

Without the cooling ducts, i can get the front brakes to go away after 10 minutes of hard driving.
(IMG:style_emoticons/default/popcorn[1].gif) Andy

To be fast, you must brake less (IMG:style_emoticons/default/biggrin.gif) Or east coast tracks are just better (IMG:style_emoticons/default/driving.gif)

[Gunther]

I agree with Racer. (IMG:style_emoticons/default/agree.gif)
Brakes? We don't need no stinking.... Brakes just slow you down. (IMG:style_emoticons/default/biggrin.gif)

No seriously, SirAndy if your brakes are going away after 10 minutes something is wrong. You may want to change or experiment with different brake compounds. Or change your driving style.
I don't use ducts and have driven some of the most famous tracks in the country, east and west coast without any problems. Shure I dive into the corners and late brake hard and fast. I don't ride the brakes, thats a no no. Thats were most people make their mistake.
I also crew for a couple of HSR teams that race 914s and half of them don't use ducts. And these are front running and championship cars.
Don't get me wrong, I've seen my fair share of cracked rotors, but I haven't heard our drivers complain about brake fade.

fasthonda, 19 or 23? It depends on yor driving style. Some people like a real hard peddle feel and some not as hard. Both will work well for your application.
Good luck and best wishes,
Gunther

[SirAndy]

Well, i've got some HP, so yes, my driving style is a bit different.
Gone are the days of momentum.

Coming up the main straight at Thunderhill at 135mph trying to slow down for turn one, trust me, you WANT to brake hard ...
(IMG:style_emoticons/default/shades.gif) Andy

[jt914-6]

I agree with Andy..... Maybe the guys who don't need to brake so much aren't going as fast as we are!!!!!

I'm using C2 front calipers W/24mm Carrera rotors and in the rear C2 Turbo calipers W/24mm Carrera rotors..... Rotors were "frozen" and they are slotted.

Have good cooling to fronts and using Hawk "blue 9012" racing compound on the track and Hawk "HPS" for the street.....

[fasthonda]

Thanks guys for the advice. I don't prefer a hard brake pedal so I will stay with the 19 mm MC I already have.

I race a Honda Civic so I have lots of track experience. I too am surprised to hear that Andy has brake fade after 10 min of hard driving with those brakes. I will probably add cooling ducks just because it is fairly easy on the Porsche and start out with a high performance street pad.

I will be running 205/50-15's R compound tires on 15x7 cookie cutters. Car will have about 250 hp.

Thanks again,

Michael

[Gunther]

I agree with Andy..... Maybe the guys who don't need to brake so much aren't going as fast as we are!!!!!

I'm using C2 front calipers W/24mm Carrera rotors and in the rear C2 Turbo calipers W/24mm Carrera rotors..... Rotors were "frozen" and they are slotted.

Have good cooling to fronts and using Hawk "blue 9012" racing compound on the track and Hawk "HPS" for the street.....

Of corse we are not going "as Fast".....We are going faster

[jt914-6]

"not as fast" means you're SLOWER!!!
I do agree with late, hard, and short braking.......

[pcar916]

Modulation is a key factor and how far the pedal depresses can be an issue for heel-and-toe action.

I have a 23mm cylinder, Wilwood front calipers, and Carrera calipers in the rear. It's just about perfect in both modulation and pedal travel. I'm thinking 23mm may be too big for stock calipers.

As mentioned above, braking effort changes between street and track compound pads.

I've never used ducted brake ventilation either. I use stock 993 air deflectors cable-tied to both lower suspension arms.

$15 each, easily replaced, and they weigh almost nothing.

Good Luck!

[Racer]

With 220+hp, I'd want something bigger than just (84-89) Carrera brakes.. Maybe 930 or 964 calipers and rotors. Carrera brakes with cooling might be ok.. just need to be mindful of them. All depends on the types of tracks you drive, tires, driving style etc.

[pcar916]

Now and then I'm tempted to go bigger than the Carrera rotors I use now, like the massive rotors on turbos and that come with big reds on 'em. But the Wilwood calipers I have now work great and replacing these rotors is cheap. Not so with the BIG ones... kinda like running 914 transmissions.

You can rebuild a bunch of them for what you can get a 915 or G50 for.

[andys]

Now and then I'm tempted to go bigger than the Carrera rotors I use now, like the massive rotors on turbos and that come with big reds on 'em. But the Wilwood calipers I have now work great and replacing these rotors is cheap. Not so with the BIG ones... kinda like running 914 transmissions.

You can rebuild a bunch of them for what you can get a 915 or G50 for.

Ron,

Which model Wilwood caliper (6 piston, right?) are you running, and what are the piston sizes you chose?

Thanks,
Andys

[pcar916]

They are 4-pot differential bores with the leading bores smaller than the trailing ones, and they're reasonably priced as well, compared to some of the others. The link to a page is below but the dimensions of the two bores are:

1.75/1.38" 44,5/35,1 mm

I installed these when they came out (circa 2000?) I've slept since then and am too lazy to look up the invoice!) because the differential caliper design fixed a problem I had with their older SuperLite II's with uneven pad wear. Here is the link to their page, they still make this caliper.

http://www.revolutionbrake.com/wilwood_billet_superlite.html

The Carrera rotor width is 24mm / ~.95in so the 1in version is the one to buy.

I like them... easy install and like I said before, the rotors are affordable, even vented ones.

[pcar916]

Here's what the installation looks like... took me a bit to find the pic.

[Justinp71]

Ron

Do you have the 3" caliper spacing struts or the 3.5" ones (later 911)?

[veltror]

Hmm, sorry to hijack this thread but has anybody fitted a 944 m/c is is a 19/23mm unit so I thought hook up the 23 to the front and the 19mm to the rear anybody have any comments

[pcar916]

Ron

Do you have the 3" caliper spacing struts or the 3.5" ones (later 911)?

My struts are from a '79.