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Quote:
Originally Posted by Bill Verburg View Post
It's a fairly complicated procedure to add a vacuum booster to a non boosted 911
But wouldn't that still be less complicated than grafting in a complete 930 brake setup (including a boosted 930 brake-compatible M/C)?

Old 01-14-2020, 02:32 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #21 (permalink)
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Quote:
Originally Posted by Bill Verburg View Post
It's a fairly complicated procedure to add a vacuum booster to a non boosted 911
but would the 930 setup stop better when cold vs 3.2 calipers?

cause they are both 4 pot correct? is the piston diameter bigger?

thanks
Old 01-14-2020, 02:33 PM
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Originally Posted by Chassis87 View Post
but would the 930 setup stop better when cold vs 3.2 calipers?

cause they are both 4 pot correct? is the piston diameter bigger?

thanks
Chassis87, 930 are 4 pot but Carrera are only 2 pot -- I'm interpreting Bill's info as indicating that you'd have more stopping power cold with an unboosted 930 caliper/disk combo than you would with a Carrera setup, but still not understanding what's required to add vacuum boost to your SWB, and suspect that a 930 setup's going to run somewhere north of $4k in parts for the calipers/disks/mc (and some machine work). That said, Bill V is THE expert on these issues, so it's great that your issue has his (and this forum's) attention
Old 01-14-2020, 02:45 PM
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Quote:
Originally Posted by darrin View Post
But wouldn't that still be less complicated than grafting in a complete 930 brake setup (including a boosted 930 brake-compatible M/C)?
Probably, one of the big issues is the front deck needs some hefty reinforcement to maintain rigidity and keep flex out of the brake process. Later cars('77 up) have this done from the factory.

The machining of the rear calipers is relatively easily done and us very straight forward, the fronts are a straight bolt on

other issues like the stop light actuation are also easily addressed
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Old 01-14-2020, 02:56 PM
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Quote:
Originally Posted by Chassis87 View Post
but would the 930 setup stop better when cold vs 3.2 calipers?

cause they are both 4 pot correct? is the piston diameter bigger?

thanks
cold stops are as much an issue of pad compounds as anything else, for the best cold stops you want to use a soft street pad, oe Textars or even Pagid Blue, you don't want a track pad which really like a lot of heat.

brake torque is a function of piston sizing and effective rotor diameter

930s have more torque because there is more piston area and larger effective rotor radius, larger piston area requires a bigger m/c there is a window for the m/c sizing you want the ratio of slave/master to be in the range of ~30-45 non boosted adjust that downward if boosted.

for non boosted the most initial bite will come from a ratio closer t 45 but as the ratio goes up feel and control go down. As the m/c size goes down the ratio goes up,The smallest m/c that i'd feel comfortable w/ for 930 brakes is a 22.6mm, I believe that VW Corrado might work but I haven't used one so can't say w/ certainty.
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Old 01-14-2020, 03:04 PM
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Quote:
Originally Posted by darrin View Post
Chassis87, 930 are 4 pot but Carrera are only 2 pot -- I'm interpreting Bill's info as indicating that you'd have more stopping power cold with an unboosted 930 caliper/disk combo than you would with a Carrera setup, but still not understanding what's required to add vacuum boost to your SWB, and suspect that a 930 setup's going to run somewhere north of $4k in parts for the calipers/disks/mc (and some machine work). That said, Bill V is THE expert on these issues, so it's great that your issue has his (and this forum's) attention
hehehe yes I think Bill is the king on the subject.

yes u are right the 3.2's are 2pot my mistake.
Old 01-14-2020, 03:22 PM
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Quote:
Originally Posted by Bill Verburg View Post
cold stops are as much an issue of pad compounds as anything else, for the best cold stops you want to use a soft street pad, oe Textars or even Pagid Blue, you don't want a track pad which really like a lot of heat.

brake torque is a function of piston sizing and effective rotor diameter

930s have more torque because there is more piston area and larger effective rotor radius, larger piston area requires a bigger m/c there is a window for the m/c sizing you want the ratio of slave/master to be in the range of ~30-45 non boosted adjust that downward if boosted.

for non boosted the most initial bite will come from a ratio closer t 45 but as the ratio goes up feel and control go down. As the m/c size goes down the ratio goes up,The smallest m/c that i'd feel comfortable w/ for 930 brakes is a 22.6mm, I believe that VW Corrado might work but I haven't used one so can't say w/ certainty.
wow very very interesting. I use DS2500 ferrodo, what do you think bill?

pricing is in 7k range for 930 kits!
Old 01-14-2020, 03:27 PM
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Originally Posted by Chassis87 View Post
wow very very interesting. I use DS2500 ferrodo, what do you think bill?

pricing is in 7k range for 930 kits!
Never used them but when I switched from pagid 29 to PFC08 I noticed much improved initial bite hot or cold. It's for sure that different pads have different friction curves.
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Old 01-15-2020, 10:04 AM
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Never used them but when I switched from pagid 29 to PFC08 I noticed much improved initial bite hot or cold. It's for sure that different pads have different friction curves.

yes Bill indeed, but the ferrods are the one variable I do not want to change, since on other classics and modern cars I know exactly how it behaves as a pad. So I would be willing to change them only after the big upgrade to understand how it works.

Old 01-16-2020, 01:14 AM
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