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Thread: Brake upgrades

  1. #1

    Brake upgrades

    Would anybody care to list the various brake upgrades for the early 911? Please be brief but succinct.

  2. #2
    I will take a shot at this, since I have been investigating this subject for quite some time, while considering what to do with the brakes on my race cars over the last 3 years. I do have a problem with being brief, though, so bear with me.

    I would begin by saying that if you are not going to track the car, do not even worry about upgrading the brakes. The factory discs and calipers supplied on any 911 are sufficient for any street driving you will ever do, as long as they are well maintained. There is really no reason to upgrade as long as you are not racing (except that Big Reds are very cool looking, which is not really a very good reason). It is a commonly misunderstood fact that bigger brakes will not stop your car any faster, given the same tire size. If you can lock up the tires with your brakes, you have reached the friction limit of your system and more clamping power ain't going to stop you any faster, although it may give you more "feel" in modulating the brakes and preventing lockup. The real advantage of larger calipers and rotors is in heat dissipation, which only becomes necessary with repeated, heavy usage, as in racing.

    As soon as you start to stress the brake system with 20-minute run sessions with repeated braking from high speed, such as in time trialing, you may begin to reach the heat dissipation limits of the smaller early brakes. This can be mitigated somewhat by using race brake pads and fluid, and ducting cooling air to the brake calipers and discs, but if you are still having problems with fade, the only solution may be bigger brakes, although I have had experienced racers tell me to just use the brakes less! They only slow you down, after all.... d:-)

    For autox and slalom type events, with only 1 lap at a time, I have never had a problem with overheating my stock brakes and pads in either my 1967 911S or my 1973 911E. I did experience very scary brake fade in the '67S at a time trial, however. There is nothing worse than getting into the brake zone after a long straight and having the brake pedal go to the floor. Quite the sinking feeling in the gut.

    Once you have determined that it is necessary to upgrade, your choices are limited by what struts, trailing arms and wheels you have, and how far you are willing to go in modifying your car. The early SWB 911S ('67-6 with 3" caliper bolt spacing and 15" wheels are a real problem. With adapters, a later "S" or "A" caliper and rotor can be fitted to the front, but many people will opt for just changing out the struts to the later type. A very good upgrade is to just transplant the entire front suspension from the '84-'89 Carrera into the early cars, which gives the added benefit of the lighter aluminum crossmember as well as the bigger Carrera brakes. I can hear all the purists screaming right now- "Don't do that to an early S, you will be committing sacrilege!" OK, I have to admit, I couldn't do it to my stock, original, one-owner, '67S, and I couldn't recommend it to anyone else. But if you are going to seriously track one of these cars, the choices are limited.

    There is one BMW 3-series caliper which I have heard will fit the 3" bolt spacing, with some small shims behind the bolts to center the rotor, but the choice of pads is limited, especially in racing compounds.. There is also a Girling 4-piston caliper upgrade using Coleman rotors that is very trick and effective for about $700. A 914 guy in Texas is putting together these kits with a Coleman rotor, and they are purported to be very effective. They have almost the same pad size (swept area) of the early turbo brakes. You could probably also fit one of the Wilwood light calipers on the front, too, but I haven't heard really good things about them. The bad rap is they are too flexible, and uneven pad wear results.

    The rears on the '67-68S are very problematic, as there is no really effective upgrade that I know of that will preserve the Emergency brake setup. The rotor hats for '67-68 911S were unique, and they are horribly expensive (a "dealer-only" item that list for $320/ea.!) Grafting on later brakes will not allow the use of the stock E-brake. If you are willing to do without an E-brake, then upgrading is possible to the later S, SC or Carrera setup, or even swapping out the "L" calipers from the front (which have a bigger piston and pad) with the right adapters. Remember that when upgrading, brake proportioning must be taken into account, and a proportioning valve fitted if the F/R brake power ratio changes too much.

    For the '69-73 cars with the later 3.5" caliper bolt spacing of the "S" struts, your options are limited mostly by wheel size and cost. The best upgrade for these cars if you want to retain your 15" wheels is the 917 brakes from the '78-79 911 Turbo. These are getting very rare and pricey, however. Expect to pay about $3500 for a complete setup, including calipers, floating rotors, custom hats and adapters (installation extra). You will need the later aluminum trailing arms for the rear as well. Of course you could try to scrounge used parts, put it in yourself, and save about 50%, maybe. There is also a very trick Alcon 4-piston monobloc brake setup that will work with 15" wheels, but it is $1000 more expensive.

    If you are willing to fit 16" wheels, then you can go with the S4 brake upgrade, which will set you back about $3800, plus installation. You will need flares for the rear and 9" wheels, plus the 944T 8" wheel with the 23mm offset in the front, which serves to add about $2-4K to the total cost of the upgrade.

    If you can go with 17" wheels, then a Big Red Brembo upgrade is a no-brainer, and will cost a bit more than the S4 kit.

    If money is no object, then the ultimate solution is the new Porsche Ceramic brake system. I hear it will run about $15K. You would probably go with a custom coilover suspension at that point, too, plus 18" wheels, which will require bigger flares, and the cubic dollars will fly out of your wallet.

    So what did I do? My '67S is only used for autox, and runs stock brakes and pads. My '73E had the alum. "S" calipers, and I sold them when they needed to be rebuilt and installed brand new SC "A" steel calipers with the money. Then I put a Coolbrake kit on them, ducted air from the front spoiler, installed Pagid Orange pads and gas-slotted rotors all around, and flushed the system with Ate Blue racing fluid. So far, I have never had the least bit of fade while time-trialing the car, but I am still running a 205 HP motor and 205/50 tires on 7" rims.

    When and if I go to a 300 HP race motor and do the RS flares and run Kumho 245/45-16s in the front and 265/45-16s in the rear, I am going to shell out the $$$ for the S4 upgrade. You gotta have the "Whoa" before you have the "Go"!


  3. #3
    Great information, TT. In addition to the modifications mentioned by Mr. Tweed, here are some more choices:

    Although no longer available, Bremtek had a 4-piston caliper which was sold in versions for both the early 3" mounting pattern and the 3.5" pattern for A or S struts. You can find these around every so often.

    Another upgrade for the front are the rear calipers from a Turbo 944. These use the thicker Carrera rotors (24mm). The caliper must be modified by plugging one of the holes (heliarc) then redrilling. The difference is just a few millimeters. A thin shim also centers the caliper over the rotor.

    Various suppliers have a kit to adapt Boxster calipers to the A or S strut. These are supposedly 1-piece "Monoblock" units which increases rigidity.

    The above modifications should all fit within the confines of factory 16" Fuchs. Not sure about 15" Fuchs.

    For 16/17" modular wheels, you can, with adapter brackets, fit the aforementioned 930 Big Reds, the 928 calipers and calipers off of various 993 models.

    There was an article in European Car mag a few years ago where the aluminum "S" caliper was modified so a 24 mm rotor would fit in place of the factory 20mm. I wouldn't recommend it since it involved removing metal from the structural part of the caliper.

    The rap on Wilwoods (a few years ago anyway) was that they were racing calipers and as such, the pistons were not equipped with dust covers. On the street, brake dust and environmental crud made short life of the caliper bores. In addition the early calipers used symmetrical (same size) pistons which resulted in uneven pad wear. I understand the current models are asymmetrical (differential piston size) for more even wear. Still, if they're weak, as TT reports, don't use them.

    I understand there is a 4-piston caliper that BMW used on a few models that will work on an A or S strut. Anyone know about this?

    Using 4-piston calipers may require a 23mm master cylinder for increased fluid volume.

    To see a list of high performance brake fluid, go to:

    I recommend Motul or the Ford Hi-Perf. stuff for the best bang for the buck.


  4. #4
    Thanks for covering everything I forgot, and more, Sherwood. I definitely left out the Bremteks, and I had even considered them, but they are getting increasingly hard to find. I saw a set on Ebay go for almost $1000 the other week.

    You're spot on about the 944 Turbo calipers, and the 23mm M/C upgrade. I didn't think about the other ways of getting a 4-piston caliper on the early cars because I had eliminated a lot of them from consideration for my personal use, and they slipped my mind while writing.

    I would have to advocate for a bigger rotor and more swept area than either the Carrera, Bremtek or 944 Turbo upgrade will give you, though, if you're going to race. It is all about more area, more mass and better heat sink properties with bigger brakes, and the carrera rotor is still too small. I think the Turbo and S4 rotors are a minimum, and that's why I'm upgrading to 8" & 9" x 16" Fuchs, so I can fit the S4 brakes.

    As I said before, if you aren't going to race, why are you even thinking of upgrading your brakes, anyway? There is a penalty associated with bigger brakes, and that is the added unsprung weight and rotational inertia. It is a considerable disadvantage to hang them on your car if you don't really need them. And unless you are getting brake fade from heavy usage, why take that hit on performance? Your stock brakes are good enough, in most cases, even for autox and an occasional DE event, especially with good pads, slotted rotors and cooling.

    A couple of good sources I have found on the net for upgrades:


  5. #5

    The latest on Wilwood

    After reading the the Registry's post about Wilwoods being flexable and having just bought a set of the new 6 piston Wilwoods for my 73S, I was concerened.
    After talking with the tech responable for their Winston Cup program, I'm feeling better.
    Yeah they are race calipers (its stamped all over them), but Wilwood manufactures several models that fit the early cars. Weight and stiffness are goverened by intended use. Ultra light calipers weighing from 1.5 to 2.5 pounds are primarly for low line presure rear wheel dirt applications, while 5 pound models like mine can handle the stresses of boosted, front wheel, asphalt use. The nice part about varity is that if I don't like these big brakes I can change back to 4 piston models lose about 1.5 pounds of unsprung weight per wheel and be legal for vintage racing.
    Hope this helps

  6. #6

    Re: The latest on Wilwood

    I'd like to hear more about the 6-pot Wilwoods- what rotor and pads do they use? Are they a bolt-on for the '73 struts?

  7. #7


    I found some slotted 87 carrera roters, and the willwood span is the correct 3.5 inches. The motor and transmission are out of the car, so I've been distracted and haven't attempted to bolt the brakes on yet. I'll let you know how it works out as I'm trying to make the Las Vegas soirée.

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