johntorg

I was wondering if anyone with with experience with 944 Turbo S/928S4 Brakes can tell me the following:

1. How do they compare to Big Reds/Blacks?

2. I know that adapters are required, but are larger rotors required?

3. Do I need to change the proportioning valve and which one to use?

4. Is it worth the trouble ... Improvement over Stock 951 brakes with track pads?

Thanks for your help

StyleLab

1. How do they compare to Big Reds/Blacks?

Same or similar pad/piston size I beleive

2. I know that adapters are required, but are larger rotors required?

yes you need the turbo S/S4 rotors

3. Do I need to change the proportioning valve and which one to use?

You don't have to but many say you should

4. Is it worth the trouble ... Improvement over Stock 951 brakes with track pads?

I don't beleive the improvement is much better if any better than 951 calipers and good pads. If you use the car on the track, the brakes will hold up longer since calipers, pads and rotors are bigger and can absorb/dissipate more heat before become innefective and getting crazy fade.

944Fest (aka Dan P)

Regarding #4. My 89 has NEVER had brake issues in 20+ hard track events. I run in A group with hawk blue pads. My associates running similar lap times with normal 951 brakes are constantly bleeding and fighting other braking issues, quite regularly. The TS stock brakes are fabulous. If you held one brake pad of each in your hand, you would see the TS pads look 50% larger, if not more. IMHO, It makes a BIG difference, especially on track. Depending on what year Turbo you want to put them on, you will at least need the desirable TS hubs, spindles and rotors. If you are an 86 with the early offset, you will need even more.

Thom

As 951 S calipers are bigger than 951 calipers they are filled with more brake fluid, hence the longer brake pedal travel required to brake down a 951 S compared to a 951. This allows for heel & toeing, as 951 S brakes begin to be effective when the brake pedal is basically at the same level as the throttle pedal (at least this is true when using stock pads). It is impossible to heel & toe with the 951 as the brake pedal travel is much shorter.

So apart from outright efficiency the bigger brakes also bring a driving advantage.

Ski

Here is a good description of brakes from a trusted source on here:

M030 front calipers, which are 928S4 calipers, which are 993 front calipers
Radial mount, these have Big Red sized pistons in a 993 frame, meaning 36/44mm pistons, for use with a 304mm rotor. Each piston has a pressure seal and a dust boot, readily available. 48mm tall pad. This upgrade is easiest, as 993 fronts are easy to find, are relatively new, and you can use off-the-shelf Turbo S/1989 brake rotors. 928S4/M030 calipers? I'd say forget it - no reason to pay more for an older caliper. Used values sit at $300-400 a pair for any of them, so buy the newer 993 calipers.

993TT/928GTS front calipers
Radial mount, these are commonly known as the Big Red and the Big Black. They are identical in all ways except for their color. 36/44mm pistons paired with a 322mm rotor. Each piston has a pressure seal and dust boot, readily available. 58mm tall pad. A number of rotors available, some requiring custom hats, others a direct fit. 928GTS rotors are a direct fit and non-drilled. 911 C2 3.6 Turbo rotors are a direct fit and drilled. 993TT rotors require custom hats and are 2-piece and drilled. Used values sit over $500 a pair.

Either upgrade requires a master cylinder upgrade to match for 100% operation. This is the only way to maintain track-worthy pedal. There are bolt-in ATE 23 as well as 25mm master cylinders available from other cars. Look at early-90s BMW 7-series for the 25mm, and mid-90s 911s for the 23mm.

evil 944t

Shameless plug.. I have one 968 mo30 front right caliper for sale. It has about 200mi's on it. $200? Its the same as the "turbo S"

944Fest (aka Dan P)

I've been told by a Porsche parts counter guy the 993 and TS/928 calipers are not directly interchangeable, they are different part #s. IIRC, It was something about the position of the crossover tube that needed to be swapped over. Easy enough to do, I suppose. Does anyone have first hand experience?

Van

I believe it's the distance between the mounting holes and the centerline of the pad squeezing area -- in other words, the 993 (non TT) uses the same size pad and same diameter rotor, but the hubs are different. If you lay a 993 rotor on the floor next to a turbo S one, the hat sections are at different heights.

Matt Sheppard

S4 brakes also add 7lbs of unsprung weight to each wheel over stock 951 brakes - most of it being the rotor.

Renn 951

Is your current setup inadequate on the track? Are you getting pad fade with the stock brakes?

If the answer is no, then stick with what you have. You'll spend less on pads because the stock ones are cheaper, and you can swap them front to back to even out the wear and make them last longer. And the unsprung weight is less as pointed out above. And if you aren't running with 17" wheels, you will likely need to upgrade them to accommodate the S4 brakes.

OTOH, if you are experiencing pad fade with heavy, repeated braking at the track, it is time to upgrade to the S4 brakes. The bigger brakes don't really give you shorter stopping distance, they are just more resistant to fade. If you use your brakes hard the S4's are worth it; but if you aren't feeling like you are running out of brake on a regular basis, you don't need to go to the expense of the upgrade just yet. (And you are better off changing the proportioning valve when you upgrade.)

RKD in OKC

What if I am experiencing super blue boiling at the track with the TS or S4 brakes?

Geneqco

I had this problem in another car. I put in braided s/s lines and changed to Motul RBF 600 which has a boiling point about 60F higher - I no longer had the problem.

johntorg

Thanks, I'm running stock 951 brakes with Performance friction 97 pads and ATE blue fluid. So far no fading but I'm new to track days and not going as fast as I hope to in the future. I was just checking for future use as I and the car get faster.

azmi951

if you are having fade on regular turbo brakes do not dismiss a good brake cooling kit like the ones that replace the dust shield and have a hose going to either the stock cooling duct or one that replaces the fog lights.

333pg333

If you were going to upgrade to the 'S' brakes you would just do the Big R/B's. The increase of pad area from the 'S' to the BR's is quite significant where the weight difference doesn't go up too much. Rotor weight goes up 4lbs per corner but the pad area goes up from 112 sq cm to 151 sq cm which is a massive increase. Once you go up from the BR's to GT3's or equivalent your unsprung weight goes up almost double! As others have said, change your pads to something better (PFC's are great!!) get s/s braided brake lines, race quality fluid, and ducting. There is a stock part that is used on the 968's which is the underbody air deflectors. These seem to help quite a lot for cooling.