79 sc brake upgrade
02-21-2006, 02:39 PM
#16
Originally Posted by bc911sc
Thank you for your responses. The problem with my brakes is that they are getting worn (about 20% remaining) and I will have to replace them sooner or later. I find that the pedal feel is solid, but I drove a friends '96 993 coupe and was impressed with the more sensitive feel and stopping power with less pedal effort. Spend 500 dollars for stock pads and rotors or spend 1500-2000 for 930 brakes that will last and not need upgrading in the future is my dilemma.
IF economics are an issue,
First, I'd bet $1,500-2,000 is not enough to do a full 930 conversion... but some others can weigh in here...
Second, ongoing cost of maintaining the 930 brakes is higher.... pads more expensive, rotors more expensive... so added costs continue...
Two things bigger brakes give you... they can dissapate more energy and can create more "clamping" power or torque on the wheels...
Energy dissapation is really a function of speed and weight.... stopping from 180 to zero generates more kenetic energy than going from 80-zero... and stopping a 3300lb car from 80-zero generates more kenetic energy than stopping a 2700lb car from 80-zero.
Your SC brakes are optimized for the weight and power and tires of the car...
Third, "pedal feel" is subjective... the brakes may "feel" better, but won't really stop the car any faster.... the tires are really the limiting factor here... more "clamping power" doesn't necessarily translate into more performance... its using 80% of the SC brakes vs using 50% of the 930 brakes...
Also, "pedal feel" is related to the master cylinder design...braking power is generated by displacing a set amount of hydrolic fluid from the MC to the brake cylinders in the caliper...
You can move the same volume of fluid by moving a small diameter MC piston over a long path or a wide diameter piston over a short path... the choice is related to mechanical leverage...
Unassisted brake system will tend to use the narrow-diameter approach to reduce overall pedal effort... at the expense of more pedal travel...
A boosted brake system can use a wider-diameter MC piston to reduct pedal travel without the driver's pedal effort being too high... so they "feel" firmer, because pedal travel is shorter....
But if properly designed, both will deliver exactly the same stopping performance from the car itself....
02-21-2006, 03:16 PM
#17
Cruisin'
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"I have no problem clearing the 993 calipers at the rear with Bill V. method with 8" 911 Fuchs"
HMD
The rear 993 calipers as supplied by Dave at Probraking were drilled to suit 930 rotors rather than the 993 24mm rear rotors supplied with the kit.
After seeing a thread on pelican which showed the 993 'throat' mods I suggested to Dave that I could procure some 930 rotors and undertake the mods locally in the UK.
Dave would not support this modification and subsequently insisted that I return the 993 rear calipers to exchange for a replacement set of 993 calipers re-drilled to accomodate the 24mm rotors he supplied. Calipers were promptly fedexed in December and yes, nothing heard from Mr Walsh since?
Anyway following Bill V's advice on Pelican, I have now decided to be patient and source some second hand 965 rear calipers which already have the necessary throat width for 930 rotors and should provide a nice balance with the 993 front calipers.
Thx
Martin Gibson
911SC 3.6
HMD
The rear 993 calipers as supplied by Dave at Probraking were drilled to suit 930 rotors rather than the 993 24mm rear rotors supplied with the kit.
After seeing a thread on pelican which showed the 993 'throat' mods I suggested to Dave that I could procure some 930 rotors and undertake the mods locally in the UK.
Dave would not support this modification and subsequently insisted that I return the 993 rear calipers to exchange for a replacement set of 993 calipers re-drilled to accomodate the 24mm rotors he supplied. Calipers were promptly fedexed in December and yes, nothing heard from Mr Walsh since?
Anyway following Bill V's advice on Pelican, I have now decided to be patient and source some second hand 965 rear calipers which already have the necessary throat width for 930 rotors and should provide a nice balance with the 993 front calipers.
Thx
Martin Gibson
911SC 3.6
02-21-2006, 05:21 PM
#18
Racer
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Originally Posted by mrg3.6
Anyway following Bill V's advice on Pelican, I have now decided to be patient and source some second hand 965 rear calipers which already have the necessary throat width for 930 rotors and should provide a nice balance with the 993 front calipers.
Thx
Martin Gibson
911SC 3.6
Thx
Martin Gibson
911SC 3.6
The 993 calipers is the same as 965 but has narrower throat. The bulk of the work to get either one of these on the SC is modifying the ears, to widen the 993 calipers throat is the easier bit of the work required. Granted that with the 993 caliper you will need to slightly shave your pads. This is an alternative if you can't find 965 rear calipers.
02-21-2006, 07:42 PM
#19
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bc911sc,
I too was dissatisfied with the braking performance of my '83SC. Spirited drives into the mountains and a bad experience on track convinced me that they were sub par and I started looking into upgrades such as the 930 kit. However by taking the advice of forum members and simply optimising the stock brakes and I am now very happy.
In my case 'optimising' simply meant bleeding all four calipers with good quality fluid (not even high temp stuff). I could not believe the difference this made. It seems my old fluid had not been replaced by the PO in the 6 years he owned the car. It contained a lot of moisture and air bubbles which were causing it to boil very quickly under repeated hard braking.
So like others have said here try taking the time to make sure your current stock brakes are working at 100% and I think you will be pleasantly surprised.
Simon.
I too was dissatisfied with the braking performance of my '83SC. Spirited drives into the mountains and a bad experience on track convinced me that they were sub par and I started looking into upgrades such as the 930 kit. However by taking the advice of forum members and simply optimising the stock brakes and I am now very happy.
In my case 'optimising' simply meant bleeding all four calipers with good quality fluid (not even high temp stuff). I could not believe the difference this made. It seems my old fluid had not been replaced by the PO in the 6 years he owned the car. It contained a lot of moisture and air bubbles which were causing it to boil very quickly under repeated hard braking.
So like others have said here try taking the time to make sure your current stock brakes are working at 100% and I think you will be pleasantly surprised.
Simon.
02-22-2006, 10:37 AM
#20
Rennlist Member
If you ever intend to track your car, an upgrade to Carrera (84-89) front rotors (24mm vs 20mm thick) and calipers can be done very cheaply, especially if you were going to replace those parts anyway. They are a direct fit repacement. BTW, you will also need new Pad pins and springs.
02-23-2006, 03:02 AM
#21
Track Day
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Thanks a lot everybody for the responses. I am still weighing my options. Obviously the more prudent choice would be to replace with stock and flush with ATE. But a set of 930 brakes would put a bigger smile on my face and that is what Porsche ownership is all about right? I dont' think anybody answered my question about whether 930's fit under 16x6 and 16x7 fuchs and if they don't what spacers do I need?
02-23-2006, 08:17 AM
#22
Rennlist Member
I know they fit over 7s and 8s, not sure about 6s and 7s. IMO, if you are going to pay >$3,000 for a brake upgrade you might as well get Big Reds, as the cost of replacement parts are MUCH cheaper. IE I think the replacement front rotors for the 930 kits for our cars is close to ~$500 and if you plan to track this car, then that will be an annual expense.
02-23-2006, 08:20 AM
#23
Rennlist Member
Actually, now that I think about, if all you are after is looks (and don't plan to track the car), have you considered "Upgrading" to Boxster calipers in the front? You will need to get Carrera rotors but those rotors are only $120 for a pair. You can also use your stock mastercylinder with that setup too. If you do plan to track this car, then that set up is not recommended.
02-23-2006, 08:56 AM
#24
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read this it has all the info you required from Bill V.
http://home.nycap.rr.com/wmv/generalbrmd.htm
http://home.nycap.rr.com/wmv/generalbrmd.htm
03-17-2006, 06:13 PM
#25
Cruisin'
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Update
Dave Walsh at Probraking has recently done the decent thing and we have come to an amicable resolution regarding the problems associated with my 911SC brake upgrade kit. I wish him well with his future business.
I hope to have the Probraking 993 fronts (+ 7" 951 Fuchs) and VCI modified 965 rears (+ 8" 911 Fuchs) installed on my SC within the next two weeks.
Martin Gibson
911SC 3.6
Dave Walsh at Probraking has recently done the decent thing and we have come to an amicable resolution regarding the problems associated with my 911SC brake upgrade kit. I wish him well with his future business.
I hope to have the Probraking 993 fronts (+ 7" 951 Fuchs) and VCI modified 965 rears (+ 8" 911 Fuchs) installed on my SC within the next two weeks.
Martin Gibson
911SC 3.6
03-19-2006, 08:55 PM
#26
Track Day
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I went with the Boxster calipers front and rear with Zimerman rotors. Works awesome on the autocross track, only down side is I can't get rid of the squeeling problem when coming to a stop. I originally had Pagid pads and since then have changed to the stock Porsche brake pad. The noise is not as bad but is still there. See pics
