68' 911 hot rod brake upgrade

[racer9007]

I have a hot rodded 68 swb 911. It has the original master cylinder, but alloy s calipers and original rear calipers. What is the next best thing to improve the braking performance. It has good feel, but needs more bite... Thanks for input.

[Flieger]

More aggressive pads. If it's stopping power you are after, then get stickier tires since your stockers can lock the brakes you already have enough brake torque. Or you could look into a larger master cylinder, that will increase the pedal effort but make the stroke shorter. All depends on what you are after.

[gsjohnson]

Go to Porterfield pads and if you could find a set of L-wide S calipers for the rear, you'd be in for a minimal amount of work. Problem is the L-Wide calipers are rarer than hens teeth. Direct bolt on...no mods required.

[Neunelfer]

SWB cars are difficult to do major brake upgrades with. I'd tend to echo what Max has said and, the Porterfield recommendation.

You already have quite a bit of pad up front and, that's where about 70% of your braking is done. I would take the time to install a dual circuit MC at this time. Your front struts and calipers are already considered a modification so, push on to the next level and make the one modification that falls in the safety category.

Pad technology, like tire technology has changed over the years. I run Porterfields on everything from my wife's grocery getter to the 914-6/GT trib. car. They are Carbon/Kevlar pads that operate in the street temperature range. The R4-S compound (S=Street) is usually the best. I've been attracted to the R4-1 "Vintage Race" compound recently as the friction is much higher over the entire temp. spectrum. You might go through rotors a little faster but... who care$?

The rears are (obviously... or should be by now) the most difficult to do anything with because of their 2.25" mounting ear spacing. "All" of the replacements on the market use the same FMSI D30 pad sizes so, with a larger piston, you'll only increase the bias toward the rear and, only by a few points. You would be moving from a 1.88:1 ratio to a more common factory 1.6:1 ratio by installing the expensive Wide L-Calipers. Believe it or not, the 1.88:1 isn't a bad thing, it's when you dip below the 1.6:1 ratio that things can go scary in a big way. You do "not" want your rears locking up before your fronts and 1.6:1 seems to be the magic number in a mid or rear engined Porsche.

We offer a spacer kit for the standard L-Calipers in the rear. You would use a turned down 944 rotor back there vs. finding the two year only 911S or L rear rotors. That said, it really wouldn't help with braking.

Perhaps someone will be working on a caliper package with adapters that will fit all year cars...

[Mr9146]

Porterfields are really good pads. I run the R4 in my 1970 racecar, and I ran the R4-S in my 1974 street/race car (with turbo brakes).

[69911S]

Directing cooling air to the brakes will keep performance at its peak as well.

[Chris Pomares]

I have Eric's spacers on my rear calipers with 944 rotors turned down a few mm. I run a 3 inch bolt spaced Brembo up front with 48 mm pistons and use the pads he recommends. I converted my 67 to duel circuit master. The question I have is what happens when you go from 19 to a 23 mm master? I have the 19 now.
Chris

[gsjohnson]

All things equal, the larger bore master cylinder requires more pedal effort, but has less travel. The smaller master cylinder requires less pedal effort, but pedal travel is increased.