S front brakes - Worthwhile upgrade?

[kyle h]

Well as luck would have it, rebuilt all 4 calipers and when I went to replace the bleeder on the last caliper (front) it snapped clean off. Havent had much luck in getting it out so as Im starting to shop for a replacement it looks like $350 or so is what its going to cost me. This has me wondering if I head down the "might as well" slippery slope of just doing an upgrade to the S struts and calipers. Obviously this is closer to $2000 to do the swap so Im curious to hear if people who have done the swap were pleased with the return or if its a minor upgrade and money is better spent elsewhere. Car is a 1972 911T with the motor rebuilt to 2.7RS spec. Car is not a concourse car but is a very clean driver that's mostly original with just mods for driver satisfaction (aside from the motor) which include Wevo PSJ and shifter, SSI headers, and M&K exhaust.

[jpnovak]

Not worth it. No extra thermal capacity. Some slight pad torque increase but doubt you would notice it. Keep the stock M calipers. route cool air ducts if you are overheating.

I only ran out of thermal capacity on M calipers at the track. In summer. In TX. cooling ducts solved all these problems even with 105F air temps.

[kent olsen]

For what its worth i installed SC calipers on the front. Gives me about 25% more pad area and they were bolt on.

[spuggy]

Originally Posted by kyle h

Well as luck would have it, rebuilt all 4 calipers and when I went to replace the bleeder on the last caliper (front) it snapped clean off.

D'oh! Bad luck.

Originally Posted by kyle h

Im curious to hear if people who have done the swap were pleased with the return or if its a minor upgrade and money is better spent elsewhere

Unless you track the car, IMHO you'd be better off getting the caliper fixed (think machine shop or caliper refurb/exachange) or simply replaced. Much better ROI.

It's been years, but pretty sure the consensus will be that while the S calipers are a little lighter & look nice (alloy), they don't deal well with heat when pushed hard as well as the iron ones - so ironically aren't the performance upgrade you might think (very early turbos mostly got S calipers - and the description "chocolate brakes"). Under very hard (track) use, S calipers apparently also flex more than iron ones.

The main advantage of going to the later 3.5" caliper mounts is bolt-on interchangeability, giving you a wider range of options. SC calipers/rotors would be a significant upgrade over early brakes (and get you wider, vented vs solid rotors IIRC), and should be all you'd need on a light car.

For a mostly-original driver with little/no intended track use, if the stock brakes felt good/up to the job, I'd be very inclined to just fix the one that broke...

Lots of good info in this thread (and many others):
Simple brake upgrade?
Brake upgrades for early 911 help please

[juanbenae]

if what kent says is in fact the case with the SC caliper spacing working on a 72 strut consider a set of later Carrera calipers with the wider 24mm rotor. best bang for the buck brake upgrade you can do for M caliper brakes. I suppose kent would have noted if the master cylinder was upgraded for the SC M caliper application. since there is no greater piston size between the Carrera and SC M's if the 72 is like the SC the wider Carrera calipers should bolt on. you will need the Carrera rotors for the upgrade though. wait until mr. bill verburg chimes in for master cylinder capability to be sure.

I moved from SC calipers to the carreras on both my old SC spec911 racecar and my current 75S that I ditched the late S calipers with the 20mm rotors for the 24mm. with cooling on the racecar I never had any braking issues in a
#2400 car & driver weight combo.

[seafeye]

Boxster brakes are cheap.

[kent olsen]

I had previously upgraded to after market drilled/slotted brake discs. Then at the recommendation of Rothsport I picked up two Calipers from an SC and just bolted them on. No other changes. Many track days since and I've never had any issues in my 72 911 with a twin plug 3.0L.

[spuggy]

Originally Posted by juanbenae

if what kent says is in fact the case with the SC caliper spacing working on a 72 strut

Depends on the struts. If S brakes are fitted, then it already has 3.5" caliper mounts. Otherwise it could have either 3.0" or 3.5" on a changeover car, my understanding.

[mepstein]

If you have 3” struts, you could use Alfa aluminum calipers. They bolt right in to your current struts, cost less than restored S calipers, weigh 1/2 as much as stock calipers and have almost as much pad area as S calipers. Check PMB Performance for stock.

[juanbenae]

Originally Posted by seafeye

Boxster brakes are cheap.

plus they have the "cool" factor, I guess.. but they will also run a 24mm rotor like the Carrera units I suggest with no less performance. they also have greater piston area so a MC upgrade is more than likely required. I suggest mr verburg will chime in at some point and clear this all up.....


if the strut spacing is correct I have a set of SC fronts that need a rebuild that I will sell you for a song. PM me for photos and pricing discussion if interested.

toby

[cmcfaul]

Careful changing to bigger front calipers. It will change the braking bias of the car. Porsche knows what its doing.
M calipers and pads are fine under the most Sevier track conditions. M calipers are steel. S are aluminum. S are bigger, M are better heat syncs. (pretty much a wash performance wise). Just need the right pads.
Racing pads work well when red hot. Not so much so when cold. And vice versa. I use track pads on the track and change back to street pads before heading home. There are some good pads that are pretty good on both the street and track.

Chris
73 E

[Bill Verburg]

A '72 T would have 3" Boge struts w/ M front and rear calipers

While the change from M front to A or S isn't going to change braking performance the change to a Bilstein 3.5" is a nice upgrade. I'd want to do Bilstein at all 4 corners. I'd choose A over S for sure.

It all depends on what you want from the car though

[manbridge 74]

The 908 race car on which the S caliper debuted weighed 1,430 lbs. I’ve found no issues with mine even on the track but I’m pretty light at 2,200 lbs. The early 930 was like two 908s joined together but only having one set of brakes, hopeless. I’ve driven them all and not found any real difference but the S caliper is used on vintage racers in CA; with aluminum pistons from our host they are pretty light and a cool piece of hardware.

No ones ever hooked up a dial indicator to measure this flex business. I’m thinking it’s only possible on a real heavy car with super sticky hosier like tires. Most people struggle with getting all the air out on these and I think that the “flex” they are sensing is really a mushy vagueness.

[Trackrash]

FWIW, I changed from M to S calipers, along with upgrading to Koni struts. It is a big investment, but well worth it IMO.

You are correct that you will have to change struts to be able to use S calipers. Or any other Porsche brake upgrade for that matter.

It seems to me that the S calipers were a big improvement over the original M calipers. JMO

[kyle h]

Wow, lots of good advice in here. Maybe I’ll just try and get this caliper going and just spend time and effort piecing together a full Bilstein and Carrera setup for a future install. Never felt like I had issues with braking performance before but more of a “eh, while I’m here...” type upgrade. Thanks all!

[Bill Verburg]

There is absolutely no difference in brake torque or bias or pedal feel between M/M, A/M or S/M
The A & S pads do have ~50% larger area. The benefit of the larger area is longer pad life but no increase in brake torque or heat management capability.

Going to 3.2 Carrera front w/ stock M rear again no increase in pad area(from A or S) or brake torque or bias or pedal, but there is a small, but still nice, increase in heat management capability.

Going to full 3.2 Carrera is a mistake, again no change in brake torque. A small increase in heat management capability in back(where it's not needed) but bias is adversely affected as is pedal feel.

[juanbenae]

bill, pursuant to the comment above regarding boxster brakes and my recollection of you suggesting they would likely require a MC change due to the great piston area. am I recalling your suggestion correctly even say with an SC OE MC?

[Trackrash]

Originally Posted by Bill Verburg

There is absolutely no difference in brake torque or bias or pedal feel between M/M, A/M or S/M
The A & S pads do have ~50% larger area. The benefit of the larger area is longer pad life but no increase in brake torque or heat management capability.

Going to 3.2 Carrera front w/ stock M rear again no increase in pad area(from A or S) or brake torque or bias or pedal, but there is a small, but still nice, increase in heat management capability.

Going to full 3.2 Carrera is a mistake, again no change in brake torque. A small increase in heat management capability in back(where it's not needed) but bias is adversely affected as is pedal feel.

I would think that the S brake calipers would have better heat dissipation compared to the M calipers. Doesn't aluminum dissipate heat faster than iron?

[manbridge 74]

The S pad is made endurance race thick. It could be said that a small measure of additional heat capacity is present as thicker pad material keeps marginally more heat away from caliper.

[Trackrash]

My last set of pads were not thick. Probably the same as what the what the Carrera used, but that is a another story.

My point is the S caliper may be less prone to boiling the brake fluid, due to the aluminum's property of heat conduction, plus the larger surface area. Just a thought, probably splitting hairs....