911SC brake upgrade

[ardenlalla]

Which is the easiest and cheapest brake upgrade for a 1983 Porsche 911SC.

[RWebb]

new pads, fluid & hoses

add a wing underneath to funnel in air

[ardenlalla]

Thanks. I don’t mind spending some money but not a whole bunch. Thinking if I can upgrade to boxster calipers? Would like to know options?

[darrin]

What do you find lacking about your current setup? Brake upgrades are generally performed to reduce fade at the track. Bigger (boater) calipers won’t help with that.

[tirwin]

I’m sure the brakemeister, Mr Verberg, will chime in.

You can upgrade the front calipers/rotors to the Wide A caliper with 24mm front rotors from the 84-89 Carreras.

If you do the Boxster it will upset the brake bias. Do a search... Bill has about a squillion posts on this subject.

[Jeffreypang911]

I looked into the Boxster route heavily but decided to go with the Wide A calipers instead. My car is an earlier G body without booster and it stops great, highly recommended. I decided to go against the Boxster route exactly for the same reasons as Tirwin says - messes with the break feel and brake bias. Can be done but will take a bit more tweaking and setup.

[75 911s]

You also can’t run 15” wheels on Boxster brakes- if that matters. Edit - I was so wrong! Sorry guys! you can fit them under ---

[PhillIB]

I have Boxster calipers over 3.2 discs on my 78 SC and have done for many years.
No issues with brake bias and I run 15" cookies.
Steering is noticeably lighter and the brakes feel better, go for it.

[Bill Verburg]

Std brake bias through '83 was 1.491 w/ Boxster front on 3.2C rotors thuis goes to 1.669, ie a step to the worse side. Is it dangerous? no, You are just throwing away a bunch of thermal potential, for around town DAs macht nichts, for track use it makes a marginal situation much worse.

pedal ratio through '76 was 41.311 from '77 through '83 it was 35.328, from '84 through '89 it was 38.345, w/ Boxster fronts and '83 M rears it's 43.17. The closer to 30 the better the pedal feel and modulation, so again a negative.

The #1 issue wrt to 911 brakes is and always has been thermal endurance in track use, the later(heavier & more powerful motors) the less thermal margin and the sooner the brakes overheat and go away w/o careful management of marginal resources. When bias ges more front(higher numerical metric) the less thermal margin you have. You certainly don't want too much rear(lower numerical metric)~1.4 is as low as most 911s will be able to use unless specifically set up for it, RSR's w/ adjustable bias can go from ~1.2 to ~2.0.

The best thing for the op to do is use fresh performance fluid, performance pads w/ at least 50% material left and add some cooling deflectors. Of course normal maintenance of lines, pistons, seals etc must continue so that the operating environment is nominal

[Sebscst]

Originally Posted by 75 911s

You also can’t run 15” wheels on Boxster brakes- if that matters.

I have boxster brakes front and back on my sc with 15” 7”& 8” Fuchs no issues with fittment

[Rodsrsr]

I have the Boxster setup as well and its great. I think the issue is when people only install the Boxster fronts with stock rear calipers and also don't upgrade the master cylinder.

[Flojo]

step 1 = refurb stock (fluid, pads, discs, hoses, pistons)

step 2 = keep stock disc (20/282) and get the BMW e23 4-piston caliper (front) and assorted BMW pads

step 2.1 = go step 1 and add Carrera brake at rear (caliper and 24/290 disc)

step 3 = upgrade to Carrera calipers overall with 24/282 (f) and 24/290 (r) discs

step 4 = any of the above and add clever weight saving! remove junk from frunk, install lighter battery, install lighter carpet, etc.

all steps above can keep the SC master cylinder.


the rest (i've learned from Bill) is costly and brings periphere issues (bias, adaptation, changing MC, etc).

I just a 964 caliper upgrade.
it was fun, works well, but it was far from plug-and-play, time consuming and costly.

[ardenlalla]

How ease is the Boxster calipers to install?
Is it a direct bolt on?
New to this.

Thanks for all the responses.

[Ayles]

Easy install. Bolts right up with an adapter. Will require lines and rotors as well.

[3rd_gear_Ted]

944 Turbo front calipers
Carrera rear calipers
All with slotted/drilled Zimmerman Carrera rotors, 930 master cylinder
& Raybestos ST43 pads
Front Rotor backing plate air induction set up for cooling is the most important part.

Of course 930 style is the best mod, BUT, this is a much lower cost option with a improved overall thermal capability.

[Bill Verburg]

Originally Posted by 3rd_gear_Ted

944 Turbo front calipers
Carrera rear calipers
All with slotted/drilled Zimmerman Carrera rotors, 930 master cylinder
& Raybestos ST43 pads
Front Rotor backing plate air induction set up for cooling is the most important part.

Of course 930 style is the best mod, BUT, this is a much lower cost option with a improved overall thermal capability.

Similar issues to the Boxster cludge

The main issue that needs to be addressed is thermal capacity up front, followed by bias and pedal.

944t and 964 front are the same caliper, I've used them w/ 930 rotors and matching 964 or 993 rear calipers also on 930 rotors, this is a worthwhile upgrade w/ a 23.8mm m/c. There is a huge increase in thermal capacity from the 930 rotors, bias isn't optimal though w/ too much front when 964 rears are used(though better w/ 964 2 piston than 4 piston rears) and too much rear for comfort w/ 993 rear. pedal is outstanding w' 23.8mm m/c

if you use the 964 front w/ any other rotor you loose a % of the thermal upgrade, depending on which rotor is used. worst is when a 3.2 Carrera front rotor is used where the rotor starts beneath the minimum for that caliper

If you must go w/ a Boxster front on 3.2 C front rotors then use 3.2 rear calipers and rotors and a 23.8 mm m/c

[darrin]

Originally Posted by ardenlalla

How ease is the Boxster calipers to install?
Is it a direct bolt on?
New to this.

Thanks for all the responses.

Suggest you re-read Bill Verburg's post above (post #9) -- bill's primary point is that a boxter brake "upgrade" is really a downgrade in brake bias (shifts too high a percentage of braking to the rear) and brake feel. While adding thicker Carrera rotors to the mix will help with thermal efficiency (i.e. reduce fade), the same can be accomplished much more easly by converting to Carrera calipers and rotors (which will maintain proper front to rear brake bias and brake feel).

One thing that boxter calipers should NOT do is make you "stop faster" == your stock calipers should lock up all 4 wheels whenever you stomp hard on the brakes. If you can't currently lock up your brakes, you should consider rebuilding your calipers/replacing swollen brake lines to get your brake system back in spec --

[tirwin]

Originally Posted by darrin

One thing that boxter calipers should NOT do is make you "stop faster"

Am I right in also thinking that tire choice is also very important if the goal is to stop faster? Is it fair to say that stickier tires would be more important that a bigger caliper?

Still I think this comment raises another important point. What is the goal of a brake "upgrade"? Is it to address brake fade on track days? Stop faster? Those are potentially different solutions.

[RWebb]

yes x2

an upgrade gets you better thermal mgmt. to reduce fade after multiple braking events

a downgrade gets you bling

if we ever get PCCB an upgrade will get you lower wt. and better thermal immunity to fade

[Trackrash]

Originally Posted by tirwin

Am I right in also thinking that tire choice is also very important if the goal is to stop faster? Is it fair to say that stickier tires would be more important that a bigger caliper?

Still I think this comment raises another important point. What is the goal of a brake "upgrade"? Is it to address brake fade on track days? Stop faster? Those are potentially different solutions.

I will defer to others on your first question. But you may be able to stop quicker with sticky tires, so less time on the brakes with a harder application?

The thing that occurs to me is there may be a misconception about braking performance and initial bite of the brakes on a street driven car.

With "street" pads my brakes "seem" to work much better after a few applications. When cold the first application feels like my brakes don't work very well.

I think there are a number of guys who see giant brakes on newer performance cars at a cars and coffee and think they need a brake upgrade.