Size does matter. (my SC to Carrera brake upgrade)

[Bill Verburg]

Was the pedal soft?

Why run softer pads in the back?

[jhynesrockmtn]

The pedal was soft with the 964 calipers and stock SC MC.

When I first put the carrera calipers on I didn't have the PV so I ran it with PF97 pads up front and stock rear pads to make up for the fact that I was missing the PV.

Once I got the front pads bedded a bit it was actually not bad. Should have seen the rears lock up when I first took it out after putting on the calipers with new pads, that was a bit scary. I spent one day at the track with that configuration. Still felt a bit "twitchy" in the rear if that even makes sense. Just wasn't real confidence inspiring but the day went fine.

Now I've got carrera calipers all around with the stock carrera PV installed and 97's on all 4 wheels.

The pedal still feels a bit softer than my other SC with stock brakes after mucho bleeding but it still feels solid and after a bit of break in seems to stop well and straight.

I'm going to the track on Thursday and will be able to bed the pads better on the way to the track. I think once they are warmed up I should be in good shape.

[PorscheGuy79]

Jerry, did you cut the lines to install that or use the factory line with PV already installed?

[azasadny]

Matthew,
Good job!!

[PorscheGuy79]

Originally Posted by jhynesrockmtn

How has your setup performed over the last year. Any issues with heat build up, etc.? I do have cooling ducts to the fronts.

Well, honestly. Good but not great. And I must first admit there are other culprets to be considered, as I am attributing some of this to the fact that my brakes lines are not in good condition (I have been having trouble with them because the PO seemed to have swapped the size of the line attachment points because all of the lines I have order, 3 sets, have been a tad to large)

At first they ran great, giving me much better heat control even without the addition of any kind of ducks, but I was at Road America last weekend and turn 6 found my pedal to the floor after some very hard braking into 5. It wasnt too bad, and I was able to drive the car through it despite not being able to shed enough speed.

On smaller, tighter courses (the ones I prefer) I found them to be a great addition and have held up nicely through the season.

Question: Can worn lines cause brakes to overheat?

[jhynesrockmtn]

I bought the PV and the line from the MC to it and then line from the PV to the rear distribution block under the car from a fellow Pelican who was parting out an 84 Carrera. Those pieces are a direct replacement for the line that runs from the MC to that distribution point.

[Bill Verburg]

Originally Posted by jhynesrockmtn

The pedal was soft with the 964 calipers and stock SC MC.

When I first put the carrera calipers on I didn't have the PV so I ran it with PF97 pads up front and stock rear pads to make up for the fact that I was missing the PV.

Once I got the front pads bedded a bit it was actually not bad. Should have seen the rears lock up when I first took it out after putting on the calipers with new pads, that was a bit scary. I spent one day at the track with that configuration. Still felt a bit "twitchy" in the rear if that even makes sense. Just wasn't real confidence inspiring but the day went fine.

Now I've got carrera calipers all around with the stock carrera PV installed and 97's on all 4 wheels.

The pedal still feels a bit softer than my other SC with stock brakes after mucho bleeding but it still feels solid and after a bit of break in seems to stop well and straight.

All of that is to be expected, w/ stock 20.64mm m/c the 964 front/Carrera rear will have ~24.3% longer stroke than a stock SC the pedal will feel soft.

The full Carrera set will have ~8.5% longer stroke than stock SC

the 964front/Carrera rear will have ~14.6% longer stroke than the full Carrera.

If you want the Carrera to feel like the SC, put SC rotors and calipers on the back & remove the p/v. This gives you better bias, a better pedal and you don't need the thermal capacity of the 24mm rotors in the back.

The stock Carrera is very heavily biased to the back. The 33 bar p/v is very aggressive. It has 33 bar knee though so when ever line pressure is below 33bar the full effect of the rear bias makes itself known. Only above that knee does the line pressure to the back become limited to 46% of the front

[PorscheGuy79]

Originally Posted by Bill Verburg

I spent one day at the track with that configuration. Still felt a bit "twitchy" in the rear if that even makes sense. Just wasn't real confidence inspiring but the day went fine.

We all know Bill is the best when it comes to this stuff and so it comes as no surprise that he is right on with this quote. When I used mixed pads, same as the set up you did, I had exactly the same experience.

Better but still not confidence inspiring.

[PorscheGuy79]

Originally Posted by azasadny

Matthew,
Good job!!

Thanks! It's been a bit since I posted this so it was a little nostalgic to have it pop up again.

[jhynesrockmtn]

I had this latest set up at the track last Thursday. Much improved. Pedal feel was very good, more solid and no fade at all during the day. The car felt much more secure and balanced under heavier braking. I love the PF97 pads so far.

[Northy]

I am doing the same conversion as this - does anyone know which outlet from the M/C is for the rear?

[jhynesrockmtn]

Check this picture.

[Northy]

Yeah, looking at that picture though I can't decide if the lines crossover behind the servo or if they stay as they are?

[jhynesrockmtn]

You just need to follow that line to the back of the MC. It's not hard to get at. You can verify it's the correct line by following it to the distribution point below the car where you can see the lines going to the front and rear of the car. That's how I did it from a similar picture that's in this same thread on the 1.

[David Borden]

Does the Carrera brake upgrade also work with a 74 911S with manual brakes?

Any difference from the SC conversion in this thread?

David

[Bill Verburg]

Originally Posted by David Borden

Does the Carrera brake upgrade also work with a 74 911S with manual brakes?

Any difference from the SC conversion in this thread?

David

Yes, just do the fronts as long as you have 3.5" brake mounts on your struts

the only other difference is that '74 doesn't have power brakes. But that's not even relevent to using the Carrera calipers and rotors on the front only.

[David Borden]

Thanks Bill!

The brakes are fairly pathetic on the car now, and figure if I am going to re-do them I should consider an upgrade.

Is this a recommended upgrade if the car is an 911S? If so, can I assume direct bolt on with my stock struts and will these fit under my stock 15x6 fuchs?

appreciate the assitance...

David

[Bill Verburg]

Originally Posted by David Borden

Thanks Bill!

The brakes are fairly pathetic on the car now, and figure if I am going to re-do them I should consider an upgrade.

Is this a recommended upgrade if the car is an 911S? If so, can I assume direct bolt on with my stock struts and will these fit under my stock 15x6 fuchs?

appreciate the assitance...

David

the only difference is that the 3.2 Carrera rotors are 4mm thicker than the rotors used from '69 -83 on all other 911s.

for tracked cars the little bit of extra mass in the rotors is enough to keep the trotor temps under control. For faster cars you would still want to go to 930 brakes.

But for many that little bit extra is enough

the calipers are identical except that the 24mm Carrera rotor needs an A caliper w/ a 4 mm wider throat, so you need the Carrera calipers and rotors as a set.

You only do the front because the Carrera rears have bigger pistons that mes up the bias and all the hard work is done by the fronts anyway.