83 911 Brake Upgrade

[911TerryT]

Looking for some guidance on upgrading the brakes on an 83 911. I have 17 inch fuchs, stock flares with a 3.6 motor. There seems to be a Boxster, 930, Brembo and other options. Curious if anyone has some experience going down this road before. The 930 option seems to be over a 6K option which seems to be the most expensive. The others seem to be less but there are adapters, rotors, lines and master cylinder possible change to consider as well.
Thanks in advance,,,,

[darrin]

what brake characteristic do you find sub-par with your 911sc's current system? As I understand it, since stock 911 brakes are more than appropriate for our cars in stock/not-super-upgraded tune) as they will lock up the wheels when one slams down on the pedals (they have stopping power that exceeds the tires' adhesion), the only real "upgrade" one will realize from different brakes is increased fade resistance from the increased thermal efficiency of larger rotors (something that only really comes into play in track/track-type situations). Boxter calipers and/or other options that use stock rotors will not decrease fade (but do generally create other problems, such as sub-ideal front/rear bias). The 930 option is a great SYSTEM that Porsche designed to work with the increased demand of the 930's turbo engine, but is pricy. Suggest you read up on the posts that resident brake guru Bill Verburg has made regarding the plusses and minuses of the various brake "upgrade" options out there. One VERY straightforward upgrade to consider for your 911SC would be to upgrade to the wider front rotors introduced with the '84 911 Carrera -- these would provide additional thermal efficiency for a (relatively) minimal $$$ outlay.

[pocv0]

Lots of threads regarding this. As darrin pointed out, upgrading to Carrera brakes is the least expensive direction, 24mm thick rotors as opposed to SC's 20mm thickness, wide A calipers.
I recently upgraded the front brakes on my '82 IROC to 944 Turbo rotors ( 28mm thick) and 964 calipers. Hubs and rotors required machining , calipers required mounting hole modification.
You could go with early 930 calipers and rotors, custom hats , but that's going to be pricey.$$$

[911TerryT]

darrin,
Thank you for this and will definitely search out Bill's posts. As far as the sub-par characteristics, the car has not seen the road for many years and the brakes will all need gone through and was considering an upgrade at this point. I really cant comment on the performance of a healthy stock brake set up. thanks again

[911TerryT]

https://forums.pelicanparts.com/porsche-911-technical-forum/1162875-911sc-frotn-brake-upgrade-recommendations.html

[2.7RS]

Are you planning on.....

DE?
Time Trail?
Random Track?
Racing? Enduro? Sprints?


Or it's just your hotrod that you drive on public roads?

[911TerryT]

Originally Posted by 2.7RS

Are you planning on.....

DE?
Time Trail?
Random Track?
Racing? Enduro? Sprints?


Or it's just your hotrod that you drive on public roads?

Great question. My goal is to drive a fair amount(spirited driving/cruising on the Blue Ridge Parkway....) and track lightly in the near future.

[PeteKz]

Then your stock brakes are good enough. Changing them will just increase wallet fade.

[jac1976]

Originally Posted by PeteKz

Then your stock brakes are good enough. Changing them will just increase wallet fade.

This is gold.

[nickelplated5s]

https://www.early911sregistry.org/forums/showthread.php?171318-Alfa-Brembo-Calipers-what-hubs&highlight=alfa+brembo

PeteK's driven mine and it ... stops. For an 83 I'd just stay stock. If you want to go big get the 930 setup and add the GT-3 front. My Boxster setup added about 200lbs. GT-3 front will shave a bunch of that weight. Shift over to braided lines if you haven't.

[-Levi-]

I have a 911 sc with a hot 3.8 engine behind it.
The stock brakes were powerful with Hawk Blue racing pads and good fluid, but they were not consistent and would fade on track.
I went with Stoptechs kit, thicker rotors, better calipers. I have good power, better modulation and more consistent pedal feel. I like the 930 setup but the cost is prohibitively expensive.

[-Levi-]

[PeteKz]

Originally Posted by nickelplated5s

https://www.early911sregistry.org/forums/showthread.php?171318-Alfa-Brembo-Calipers-what-hubs&highlight=alfa+brembo

PeteK's driven mine and it ... stops. For an 83 I'd just stay stock. If you want to go big get the 930 setup and add the GT-3 front. My Boxster setup added about 200lbs. GT-3 front will shave a bunch of that weight. Shift over to braided lines if you haven't.

You are right. Your early car with Boxster brakes has really good brakes. Now you just need to take it to the Nurburgring where you can really use them!

[faverymi]

Originally Posted by PeteKz

Then your stock brakes are good enough. Changing them will just increase wallet fade.

Yup

New seals. Master cylinder
Good pads and rotors

Done

[Bill Verburg]

Originally Posted by 911TerryT

Looking for some guidance on upgrading the brakes on an 83 911. I have 17 inch fuchs, stock flares with a 3.6 motor. There seems to be a Boxster, 930, Brembo and other options. Curious if anyone has some experience going down this road before. The 930 option seems to be over a 6K option which seems to be the most expensive. The others seem to be less but there are adapters, rotors, lines and master cylinder possible change to consider as well.
Thanks in advance,,,,

Your stock brakes can easily generate enough braking torque to stop your car a few times. This process converts the cars inertial energy into heat. This heat raises the temperature of the components and must be dissipated by conduction, convection and radiation. If the rate of those 3 processes is inadequate then the temperature of the components rises w/o limit. This leads to boiled brake fluid, failed seals, glazed pads and thermal hot spots in the rotor that lead to cracking and friction variability. None of this is good.

so given that the goal is to increase the thermal envelope of the braking system and reduce the inertial input both are beneficial.

to reduce the inertial input
lighten the car
drive slower
use the brakes less, less frequently and w/ less input force

to increase the thermal envelope
use higher temp components, primarily pads and fluid
direct larger amounts of convective air to the components
increase the mass of the thermal sinks, primarily rotors
use rotors w/ better geometry that enhances flow of air over, through and away from the rotors.
use better technique to get the most from what you have

thermal weakness is magnified by track use and mountain use
you are going faster at least on a track
you are using the brakes harder and more frequently in both environments, the bigger the mountains the harder the use

thermal deficiencies show up most prominently at the front where the vast majority of the input inertial energy is transformed into heat, for a 911 w/ 40/60 weight distribution over 60% of the thermal and torque loads goes to the front but it's also important to utilize the rears as much as is possible, the more rear that you can effectively use the less the front has to do. That's where bias comes in.

To enhance the thermal envelope w/ components

look for more massive rotors w/ better internal geometry

for a 911 a small an inexpensive step is to use Carrera 3.2 front rotors and matching calipers which are 4mm thicker than pre '84 front rotors,

I dislike using Boxster calipers on 911 rotors, they do potentially generate more, unnecessary, brake torque but this torque transforms into more heat in an already burdened system exacerbating the thermal issues.

Boxster S calipers on Boxster S rotors is an ok set up thermally and torque wise but has poor bias, in that it moves more of the load to the front wasting the utility of the rear.

after that a the inexpensive pad, cooling and fluid steps are taken it gets very expensive

Levis' Stoptech set up looks promising but w/o detailed specs it's impossible to evaluate

There are other kits out there using Brembo and other calipers again w/o details it's impossible to evaluate

I general anything using 930 rotors will provide adequate thermal performance
930s rotors are a bolt on for a 911
specs
front: 32 x3054mm
rear: 28 x309mm

rotors up to 322 fit inmost 17s maybe even 330 though I haven't tried that but you really don't need more than the 930 sized rotors


here's some comparison graphics

[911TerryT]

Bill,
Thank you for the information. Learning on this end for sure. One thing I find that everyone is consistent on is the 930 components. The rotors and calipers seem to be the best bolt on option but again the most $$.

Curious is anyone has experience with the Brembo Granturismo set up.

[nickelplated5s]

BillV, my numbers guy! Pete is coming over later today and we'll drive mine. I did add the 22.5 dual MC with the brakes. I did a 'panic' stop when a bicyclist wobbled into my lane with oncoming traffic. The front certainly grabbed but wasn't thinking about the rear at the time. Real world seat of the pants results this afternoon.

[3rd_gear_Ted]

Cheapest route forward but disdained by some:
Decent bias, not perfect.
951 turbo front calipers, mounting mod for front caliper required
Carrera rear calipers
Carrera front & rear rotors
930 M/C
Raybestos ST-43 pads
Brake duct cooling from front nose

[Kraftwerk]

Something to consider in budget as well, is the cost of new wheels, you might need bigger space to allow for the bigger brakes.

[Bill Verburg]

Originally Posted by 3rd_gear_Ted

Cheapest route forward but disdained by some:
Decent bias, not perfect.
951 turbo front calipers, mounting mod for front caliper required
Carrera rear calipers
Carrera front & rear rotors
930 M/C
Raybestos ST-43 pads
Brake duct cooling from front nose

951T front caliper are the same as 964 front calipers, it wants a 28x 298mm rotor, the 24 x292 Carrera rotor is at the minimal wear limit for the caliper w/ new pads when the rotor is also new

other than that bias is fair to good @ 1.554, compared to very good stock pre '84 911 1.491

pedal is excellent @ 32.91

again putting bigger calipers on the same smallish rotors doesn't really help, you would have a better setup w/ Carrera front calipers on the front w/ the Carrera rotors

the bigger pads used by the bigger calipers do last longer

both 964 and 993 Calipers can be used w/ 930 rotors as a fairly easy do it yourself project, the improvement in thermal envelope is massive

to take advantage of more brake torque you need to use bigger stickier tires

to take advantage of more rear bias you need a lower stiffer car w/ an effective LSD