Upgrade to power-assisted brake
10-27-2003, 09:24 PM
#1
1st Gear
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Upgrade to power-assisted brake
I am considering upgrade my early 911's manual brake to power-assisted brake. What can I expect for spending $1500 for this? Shorter stopping distance? Safer driving?!
Thanks,
Jeff
Thanks,
Jeff
10-28-2003, 10:41 PM
#4
Race Car
I did it, but only after trying to manage 930 calipers/rotors with a 19mm master cylinder. My options were to go to the 23mm manual master cylinder, or the power unit (also) with a 23mm master cylinder.
The difference between the manual 19 and the assisted 23 was pretty dramatic, in terms of ability to very consistently predict braking behavior on the track. But I was starting out with a non-stock (and probably mismatched) system, so I don't know that my experience would translate very well to your situation.
For street driving, I can't see it making any real difference at all, other than requiring less pedal effort. As Steve points out, you'll stop a little quicker because your wallet will be lighter.
The difference between the manual 19 and the assisted 23 was pretty dramatic, in terms of ability to very consistently predict braking behavior on the track. But I was starting out with a non-stock (and probably mismatched) system, so I don't know that my experience would translate very well to your situation.
For street driving, I can't see it making any real difference at all, other than requiring less pedal effort. As Steve points out, you'll stop a little quicker because your wallet will be lighter.
10-28-2003, 11:11 PM
#5
When big brake kits are installed the master to slave ratio is altered. 
When a big m/c is added to properly service the big brake kit the master/slave ratio is again altered. If the m/c is a manual one, smaller individuals(often of the female persuasion) will "occasionally" complain that it's "too hard" to use the brakes. 
To regain some semblance of peace and quite an expensive mod(to boosted brakes) is sometimes desireable. 
I agree w/ Steve though. No gain for quite a bit of wallet pain
When a big m/c is added to properly service the big brake kit the master/slave ratio is again altered. If the m/c is a manual one, smaller individuals(often of the female persuasion) will "occasionally" complain that it's "too hard" to use the brakes. To regain some semblance of peace and quite an expensive mod(to boosted brakes) is sometimes desireable. I agree w/ Steve though. No gain for quite a bit of wallet pain
10-29-2003, 03:11 AM
#6
RL Technical Advisor
Jack,...Bill,......great input!
Just a followup/addendum to your comments and observations,.....Its true that the commonly used 23mm MC is a tad large for these applications, but its the only practical choice. I've never seen a 22mm MC that would fit on these cars.
In the cases when somebody complains about a pedal effort that is too hard, I use brake pads as a way to alter the amount of initial "bite" the brakes have and I've had good luck with that method.
Each and every brake pad differs in temperature range and braking torque and I consider this a tuning tool to achieve the brake pedal feel and modulation effort that one prefers.
Just a followup/addendum to your comments and observations,.....Its true that the commonly used 23mm MC is a tad large for these applications, but its the only practical choice. I've never seen a 22mm MC that would fit on these cars.
In the cases when somebody complains about a pedal effort that is too hard, I use brake pads as a way to alter the amount of initial "bite" the brakes have and I've had good luck with that method.
Each and every brake pad differs in temperature range and braking torque and I consider this a tuning tool to achieve the brake pedal feel and modulation effort that one prefers.