17mm vs 19mm Brake Master Cylinder, again! Options

[87m491]

With the prospect of incoming rotten tomatoes forefront, I wade in here looking for a little BTDT.
Background, just got the 74, 2.0 back on the road after a 7 year hiatus. Over the years,, I did fuel system, brake system (19mm master(ATE) /calipers (PMB rebuilt fronts, stock rears) /rotors/hoses) engine mechanicals and cosmetics.

I haven't driven the car during that time and I only had about 150 miles on it before it came off the road and memory ain't what it used to be.

I did the 19mm MC many years back because it was way less expensive than the 17 and the forum feedback seemed fine. I also have a mid 80's Carrera (with turbo brakes) against which many folks relate the 19mm MC pedal feel. I like a firm pedal and the 911 is pretty easily modulated, heavy but responsive.

Fast forward to this past week and some short shakedown runs. The 914 pedal is "right there" and noticeably firmer than the 911. But while being firmer, the braking is far from commensurate with pedal input. Yes, the 911 pedal is firm, but with the right effort, the car will slow/stop NOW. Been on the track with it no problem. On the 'teener, I feel like I am about to bend/break the pedal and the car seems to barely slow. No way I can lock up these brakes at any road speed, nor do I feel I could lose momentum in a hurried stop situation, even at in town speeds.

I'm wondering if I have missed something or is this type of pedal feel/action is "typical" of the swap? Shamefully, I honestly can't recall if I did pads, but the rotors are spotless and look like they're getting good pad contact but would love any pad advice as well.

[MM1]

Re: Porterfield R4-S brake pad OFFICIAL break-in procedure.

I recently installed Porterfield R4-S pads on my 914 V-8 (along with a new 19mm master cylinder). Please note it has the BMW 320 caliper conversion on the front. Yes, the 19mm master feels good to me (subjective preference) and the brakes improve with nearly every stop as I am nowhere near the 100 mile (apparently correct "no-hard-brake") break-in procedure. For reference, the very old and leaky 19mm master cylinder would easily lock up the BMW 320 front calipers with only a bit more than moderate-to-firm pressure.

My research showed that a "standard" break-in procedure is incorrect.

As hearsay from the "interwebs" is useless, I just contacted Porterfied directly after reading this thread. I requested the official break-in procedure for R4-S pads. Below is the text from said .pdf as well as a screen shot of the .pdf Porterfield just sent me:

" Porterfield Bedding procedures recommendations

Street pads (R4-S) are pre-bedded. Just install and drive normally and they will bed themselves in within
about 100 miles. Please avoid the 60+-0 absolute stops upon first installation to see how well they stop.
(Obviously if it is required for safety do so.) This can lead to glazing of the parts. Please allow the 100 or
so miles to pass before being more aggressive with them."

The text above is included so you can copy and paste it to all of your friends (since you don't have the time to call Porterfield), who have already glazed their "parts" with the "standard" break-in procedure. (IMG:style_emoticons/default/blink.gif)

[87m491]

Sweet! That'll up my 20 mile per year, the last 7 years, average! Honey, the Mr Porterfield says I have to drive the car, awesome!

Re: Porterfield R4-S brake pad OFFICIAL break-in procedure.

I recently installed Porterfield R4-S pads on my 914 V-8 (along with a new 19mm master cylinder). Please note it has the BMW 320 caliper conversion on the front. Yes, the 19mm master feels good to me (subjective preference) and the brakes improve with nearly every stop as I am nowhere near the 100 mile (apparently correct "no-hard-brake") break-in procedure. For reference, the very old and leaky 19mm master cylinder would easily lock up the BMW 320 front calipers with only a bit more than moderate-to-firm pressure.

My research showed that a "standard" break-in procedure is incorrect.

As hearsay from the "interwebs" is useless, I just contacted Porterfied directly after reading this thread. I requested the official break-in procedure for R4-S pads. Below is the text from said .pdf as well as a screen shot of the .pdf Porterfield just sent me:

" Porterfield Bedding procedures recommendations

Street pads (R4-S) are pre-bedded. Just install and drive normally and they will bed themselves in within
about 100 miles. Please avoid the 60+-0 absolute stops upon first installation to see how well they stop.
(Obviously if it is required for safety do so.) This can lead to glazing of the parts. Please allow the 100 or
so miles to pass before being more aggressive with them."

The text above is included so you can copy and paste it to all of your friends (since you don't have the time to call Porterfield), who have already glazed their "parts" with the "standard" break-in procedure. (IMG:style_emoticons/default/blink.gif)