Quick brake question: fitting 3.2 Carrera brakes to my 74

[Ho Hum 74]

Hi folks,

I'm interested in upgrading my brakes to the Carrera 3.2 brakes. I've read a lot from Bill Verburg about the various upgrades and don't really want to go to the expense and hassle of the 944T or 930 brakes. I really only need a little more fade resistance.

I have the S calipers on my 74 combined with a cooling kit and Pagid Orange pads. At Road America into Turns 5 and 8 and Canada I'm getting a soft pedal. Of course I could just be a sissy and not brake so hard, but that wouldn't be fun would it? There are times where you really need some severe stopping and late braking ability.

Currently I have the yellow Bilstein dampers. Would I have to change my spindals etc? Or is this just a bolt on mod (of course the rotors change as well).

I guess the other option would be to but Castrol SRF fluid at about $75 a litre.

Thanks for the help
Tristan

[Eugene at Pelican Parts]

Carrera "wide-A" calipers have the same bolt spacing as your aluminum S calipers and will bolt right onto your struts. Have fun!

[IROC]

Originally posted by Ho Hum 74
Of course I could just be a sissy and not brake so hard, but that wouldn't be fun would it? There are times where you really need some severe stopping and late braking ability.

Actually, braking harder (and therefore, for shorter period of time) is easier on your brakes.

I ran the stock brakes on my '76 for years on the track. Initially, everything was fine as I wasn't going fast enough to really tax the brakes. Then, as I started going faster, I noticed that I was ending up with a soft pedal at the end of every session. I started looking into brake upgrades, etc, until a much more experienced track friend of mine told I was braking incorrectly.

He told me to brake as hard as possible (thresh hold braking) for as short a time as possible. I tried it and the soft pedal problem went away.

I have since upgraded to Carrera brakes because my driving skills and the car's capabilities (lots of other mods) finally exceeded what the stock braking system could really handle.

Just a suggestion. Might save you some money.

Mike

[Ho Hum 74]

Mike,

I know exactly what you're saying and I used to brake like that with my M3. I could just jump on that car really hard and it was fine. What I have been trying to do is to be smoother on the brakes but still remain firm. Since I don't have a lot of seat time in my 911 I was worried about too high corner entry speed since this is where 911s can get into trouble. I've come close to spinning once because of this. So I've been slowing the car down more and trying to be really smooth with the application and then also with getting off them. The reason being that I'm not sure how much I can disturb the car without causing bad behaviour. The nice thing is that my driving has really become much more smooth, I'm just treating the 911 with more respect and building up speed gradually.

I'll try and get on them harder for shorter periods of time but essentially you're requiring the same amount of work to get the car to the turn in speed. So do you apply more energy for less time or less energy for more time? Either way, the same amount of work needs to be done.

Tristan

[911pcars]

Ti Brake Shields. I don't push these too often since there are numerous solutions for increased braking efficiency, and their application might be a bit narrow - those who track their car (DE, time trials and racing). Those solutions include braking technique, fluid type, fluid change interval, airflow to brakes, pad type and rotor type - even choice of race track. If you've exhausted those optons and/or tire of bleeding brakes at the end of each run session, then you might want to try these before jumping to the next level. It's a fairly large jump as many of you know. The brake shields interpose a low thermal transfer material between the pads and caliper pistons; in this case, Grade 5 titanium.

Many owners find these brake shields cure a soft or long pedal due to air bubbles formed by boiling the brake fluid (one form of brake fade). In addition, many club racing regs (POC, PCA, HSR, VARA, etc.) may bump you a class if upgrading calipers and/or rotors, so these offer a legal method to perhaps maintain some distance from a wall, to avoid someone's bumper or hit the apex as planned.

They're not visible to passers-by and the "wow" factor is pretty low (wow is 930 or big red calipers), but for some they do the job.




My attempt at low-key commerce,
Sherwood
www.seinesystems.com
(soon to be offered by Pelican Parts)

[IROC]

Originally posted by Ho Hum 74
I'll try and get on them harder for shorter periods of time but essentially you're requiring the same amount of work to get the car to the turn in speed. So do you apply more energy for less time or less energy for more time? Either way, the same amount of work needs to be done.

Tristan

You're exactly right. Since you're slowing the same mass through the same change in velocity, the energy is the same. The gain in braking for a shorter period of time is that you're giving the brakes longer to cool off for a given lap (since you're not on them as long). So, the net gain is greater heat dissipation capability for a given input of heat load.

Carrera brakes really help, though. I've enjoyed the increased rear bias that Carrera brakes give you in addition to the thicker rotors. Very nice, cost effective upgrade.

Mike

[MichiganMat]

Coleman Brakes

http://www.colemanracing.com/section/index.htp?id=416

http://www.colemanracing.com/prodex/cat.htp?cat=BRAKES

Saw a guy at AutoX this weekend, had these on his 914. They were insane, guy seemed to really like them. He said they bolted right up to his stock struts, pretty interesting upgrade.

[Ho Hum 74]

Matt,

Sounds to good to be true. I wonder if these have the nice Porsche feature of being able to remove the pads without removing the caliper from the strut. Also, you mention autox, I've never gotten fade at autox. Actually I think it's pretty much impossible - I lock mine before that happens.

What does that 914 weigh?

Tristan

[MichiganMat]

It was a full on tube-frame race-car with a fiberglass nose, a beautiful car. He had to take the nose off because of the bumps in the pavement, got to see some great shots of his setup. The rotors are super thick too, 1 1/4 inch. It would probably be a purely custom job to get them adapted, but the payoff would be amazing. I don't have any idea how big of a master cylinder you would need to run though, don't know if the stocker would be up to the challenge.

[Bill Verburg]

Tristan, I would give Sherwoods Ti insulators a try. You already have good cooling for the fronts , right?, you already have good track pads, right?, you are already using god fresh fluid as well, right?

If all the above are done then use the Carreras front only, it'll all bolt on.

[Bill Verburg]

If you are only getting a soft pedal in those 2 very hard braking zones it is possible that you are feeling flex in the calipers and or lines.

[Ho Hum 74]

Bill,

That's what I have heard from other S caliper users (flexing). I have done ALL the things you speak about in the above post. I did have a 180 lb instructor in the car (BMW events are mandatory) so that possibly added much to the heat equation. I was up at RA for the PCA DE but it was raining both days that I never got to really push the car without an instructor.

Bill, what is the cause of soft pedal AFTER the session? After the car has sat for a while and then started up again the pedal is immediately soft and then pumps back up again.

Tristan

[MotoSook]

Tristan, that happens to me all at the track too. I just pump it a couple of times on the way to the grid. It's also a good practice for checking that I have brakes before I go out. My guess (as it applies to me) is that the cool down lap and the drive to my paddack spot are sans braking! That leaves the pistons off the rotors. So when I go back to hit the brakes later, I have to move the pistons/pads out to the rotors. On the street, you always have your brakes applied when you park your car....on the track...I park and stop with the engine off and the clutch.

Bill?

[Bill Verburg]

Ok, if it goes soft and stays soft then the fluid boiled. Once it's boiled and cooled the air bubbles continue to be trapped in the lines and calipers. The fluid needs to be changed and bled between sessions.

For your brake ducting how large are the tubes, how are they routed bigger straighter and smoother bores are better, are you using the under A arm scoops and a rotor eye seal?

Definitely keep the weight as low as is feasible, but the thermal load is proportional to v&sup2, so when you start going fast that is the larger issue.

When all else fails bigger rotors are the way to go.

[Oldporsche]

Might try Ford "blue" brake fluid. It was developed by the SVT types at ford.

Good luck,
David Duffield

[A Quiet Boom]

Originally posted by old_porsche
Might try Ford "blue" brake fluid. It was developed by the SVT types at ford.

Good luck,
David Duffield

My brother is an engineer at Ford and he suggested that stuff. I don't know how it will perform on a track car but it worked great to pull a 3200lb Mustang down from 130 when drag racing and works reallly well in my Nissan truck with 31" Super Swamper TSLs and stock calipers when I hit the trail hard.

[Bill Verburg]

Sherwood put together a nice list of the various Brakes fluids available, as far as I can see he has kept it current
Brake Fluid