Thinking Brake Upgrade

[VFR750]

Continuing the Brake Upgrade Discussion with my thoughts and info.

Starting Point: 911SC, 2,900 lbs wet, est 215 rwhp, R888R Tires, Stock SC brakes & Hawk HT-10 pads, Motul-600 brake fluid

Problem: brakes are toast after every track day. Long pedal after cool down, Spongy and need to be flushed.

Also: frequently, I see the front bearing caps leak grease onto the wheels. Must be getting pretty hot to liquefy HT grease.

Pads look toasted too: Note the heavily checked surface, crumbling edges, and paint burnt off the back sides. (This happens after the first runs) HT-10s are very high temp pads by Hawk, not many more options except DT-60/70.


I read almost all of the Brake Upgrade threads. A lot of good info. Unfortunately, 930 brakes are no longer a cost effective option. The calipers, if for sale, are just not affordable in 2018.

Used Bill Verburg's data to see what I am getting into.

Researched the Stop Tech path, and concluded Level 1 (ST-42 caliper Front Only) really doesn't get much except a much wider front rotor. You have to jump to the Level 2, front and rear to make a real difference.

I am now thinking the Rebel Racing Boxster S/996 upgrade might just be the affordable upgrade.

The Boxster S/996 upgrade (front and rear) seems to offer a lot for about $2,400 investment: Gain 40% more pad area, 28mm wide front and 24mm wide rear rotors for heat dissipation. Need 930 master cylinder. Bias shifts forward, but can be compensated with higher friction pads in the rear.

A Hybrid configuration with Carrera rear Wide-M caliper gets the 24mm wide rotor, better bias, but you are stuck with the tiny brake pads

I color coded the parts by configuration, My SC = Yellow, etc.... And the pad area percents in yellow are the Boxster S/996 increase from stock SC area.

[Bill Verburg]

Originally Posted by VFR750

Continuing the Brake Upgrade Discussion with my thoughts and info.

Starting Point: 911SC, 2,900 lbs wet, est 215 rwhp, R888R Tires, Stock SC brakes & Hawk HT-10 pads, Motul-600 brake fluid

Problem: brakes are toast after every track day. Long pedal after cool down, Spongy and need to be flushed.

Also: frequently, I see the front bearing caps leak grease onto the wheels. Must be getting pretty hot to liquefy HT grease.

Pads look toasted too: Note the heavily checked surface, crumbling edges, and paint burnt off the back sides. (This happens after the first runs) HT-10s are very high temp pads by Hawk, not many more options except DT-60/70.


I read almost all of the Brake Upgrade threads. A lot of good info. Unfortunately, 930 brakes are no longer a cost effective option. The calipers, if for sale, are just not affordable in 2018.

Used Bill Verberg's data to see what I am getting into.

Researched the Stop Tech path, and concluded Level 1 (ST-42 caliper Front Only) really doesn't get much except a much wider front rotor. You have to jump to the Level 2, front and rear to make a real difference.

I am now thinking the Rebel Racing Boxster S/996 upgrade might just be the affordable upgrade.

The Boxster S/996 upgrade (front and rear) seems to offer a lot for about $2,400 investment: Gain 40% more pad area, 28mm wide front and 24mm wide rear rotors for heat dissipation. Need 930 master cylinder. Bias shifts forward, but can be compensated with higher friction pads in the rear.

A Hybrid configuration with Carrera rear Wide-M caliper gets the 24mm wide rotor, better bias, but you are stuck with the tiny brake pads

I color coded the parts by configuration, My SC = Yellow, etc.... And the pad area percents in yellow are the Boxster S/996 increase from stock SC area.

Mike, while I like the 996 front a full 996 setup ios still more front biased than I like to see. The main issue w/ that is it puts more of a load on the front and lets the rears loaf.

Stock SC has a torque bias of 1.491 which is right where you want it.
full 996 is 1.811
996 front w/ C3.2 rear is 1.743
930 is 1.579

Of these you stock are best except for the heat issue
to address heat
are you using A-arm scoops? Ducts tend to be too small to do much good unless they are really big.
are you using Castrol SRF?
what pads? I'm assuming you have track pads
changing fronts to the Carrera 3.2 calipers and rotors helps a little

993 can be adapted w/ not too much effort, they would use 930 rotors f & r, front caliper adapters are available and some slightly tricky but doable mods to the rear calipers bias is 1.572, you would want 16s for this

[175K911]

Mike, a couple of questions first, then some thoughts. That's what my pads used to look like 35 years ago when I was first tracking my '83 SC. Back then I was still just an intermediate driver and there wasn't a lot of products available to upgrade the brakes.

Questions- Please don't take this the wrong way, but what level of driver are you? And have you done any brake cooling yet?

The reasons I ask this is because all the guys (and ladies) who race in PCA Club Racing E-stock race class are running stock brakes on both SC's and Carreras. They race hard all weekend and don't tend to have brake issues. I've raced a friend's '88 Carrera for 40 minutes and never lost faith in the brakes. And I've raced and tracked my own SC's and Carreras with stock brakes and never had issues once they were properly set up. Granted I now have 996TT brakes but also a lot more engine and suspension, but ran with stock Carrera brakes for 30+ years.

Also, the longer one is on the brakes going into a turn, that's less time for the rotors to cool between turns. I've always found that novice and especially intermediate students of mine tend to brake earlier and carry the brakes longer than the hard core advance drivers and experienced racers. It's a skill that has to be learned over time, but that's why so many of my intermediate students have more brake issues than the more advanced. Again, not to insult your skills, I don't know what level driver you are, just offering 30+ years of instructing observation.

Here's what I did, and many E-stock racers.
First on an SC, just change to '85+ Carrera brakes. This allows you to run 24mm rotors in the front which are wider and a better heat sink, and the rear calipers increase from 38 to 42mm to move some of the bias rearward and take some of the load off the fronts.

You need to move lots of air at the front brakes. If you can't put ducts in your front valance, you need to grab the air from somewhere, typically with the scoops that hang under the front control arms and duct up to the eye of the rotor. Helps a LOT.

Not a fan of the HT-10 pad, not a great hard trackwork pad. I've run either Hawk DTC-60 or 50, or the corresponding Pagid pads. True race pads.

I have always run Motul 600, never boiled the fluid over the course of a weekend.

Those are all relatively inexpensive things you can do to improve the performance of your brakes before going to conver$ion$. As an example before I went to the big brakes on my current '86 Carrera, I ran stock Carrera calipers and rotors, had Ruf style front and rear bumpers so I ducted air from the inlets in the lower front valance directly to the eye of the front rotors, ran DTC-60 pads, Motul 600. Granted I was 2650# and ran 23/34 torsion bars with revalved shocks, but back in 2010 I ran VIR 6 full days on the old R888 tires and never touched the brakes until the end of the 5th day when my pads were just plain worn out. No fade, no spongy pedal. Same thing that year, ran 3 days at Mid Ohio back to back with 3 days at Blackhawk Farms, no brake issues. All in the instructor group.

Sorry for the lengthy response, hope it helps before you jump off the deep end and into the world of expensive upgrades. I went to 996TT brakes because they were given to me so for just the price of some Instant-g hardware I was done. But only because I had the 3.6 in my garage to build up for the car.

[AG81]

This is excellent information. I considered a major brake upgrade this year and after all was said and done I opted for a complete over haul of my 88 factory setup with new rotors and pads. These cars are light and have excellent factory brakes.

[VFR750]

I forgot to add in the summary that have brake cooling ducts, a-arm mounted scoops and the block-off plates in the front hubs. So that part is done

First I heard of people not liking the HT-10 pads.

Maybe should try the DTC-60s next.

Also noted Pagid has a few endurance racing pad options for the older cars. Any recommendations?

I’ve been away from trackdays for a while due to college expenses. So I am relearning how not to over-brake.

Solid intermediate driver. Currently not enough days per year to move up. Somewhat on a plateau.

Trail braking into Big Bend at Lime Rock seems to be the worst for heat load. Pretty big speed change 120+ to ~60 mph and it is repeated once every minute or so. Trying to use the brakes harder, for less time to achieve same entry speed.

On hot summer days at Thompson speedway the brakes get soft too. Several braking zones close together.

[VFR750]

Bill,

What are your thoughts on running different pad compounds to offset the bias?

Pagid offers quite a few pad options for the 996, and it looks like I could run a pad with a higher cof in the rear to balance the bias.


Product Family RSL - PAGID Racing

[3rd_gear_Ted]

One other option to consider; 951 front brake calipers are a decent bias match with the stock Carrera rear calipers, both use the 24 mm Carrera rotors. I added a 930 M/C and use Raybestos ST-43 pads front & rear along with GS 610 brake fluid.
This combo allows me to run 35 minute sessions on the big track @ Fontana in the summertime on + 100 deg F days. Track temp, +160 deg F

[Bill Verburg]

Originally Posted by VFR750

Bill,

What are your thoughts on running different pad compounds to offset the bias?

Pagid offers quite a few pad options for the 996, and it looks like I could run a pad with a higher cof in the rear to balance the bias.


Product Family RSL - PAGID Racing

It can help if you can find the right pads but it's not a cure, Several guys were running Pagid yellow(29s) front and Black(14?s) rear

What fluid are you running? SRF id hands down the best

I'd talk to Dan J. about the hub block offs, seems to me he didn't like them much

Being able to carry more speed through the corner also helps, what tires are you running? Big bend is tough but you can carry an amazing amount of speed through it w/ the right tires and aero.

[Bill Verburg]

Originally Posted by 3rd_gear_Ted

One other option to consider; 951 front brake calipers are a decent bias match with the stock Carrera rear calipers, both use the 24 mm Carrera rotors. I added a 930 M/C and use Raybestos ST-43 pads front & rear along with GS 610 brake fluid.
This combo allows me to run 35 minute sessions on the big track @ Fontana in the summertime on + 100 deg F days. Track temp, +160 deg F

That's essentially the same as 996 front but w/ smaller rotors bais is ~1.5 to 1.7 depending on some specifics

The full 996 front w the 318x28mm rotor would be really nice if you could get something in back to get bias down to ~1.5 +/- unfortunately all the Brembo mono blocks that are good candidates are 28/30 unless you can scrounge up a set of 997RSR 28/36 rear or modify 993RS 30/36 rear, neither will be easy or cheap.

[VFR750]

The rebel racing kits essentially fit the 318-28 front rotor and the 996 rear caliper and 290-24 rear rotor.

Yes very few options to change the piston size in the rear.

I’m running Toyo R888R, 225/45 front and 245/45 rear.

[Bill Verburg]

Originally Posted by VFR750

The rebel racing kits essentially fit the 318-28 front rotor and the 996 rear caliper and 290-24 rear rotor.

Yes very few options to change the piston size in the rear.

I’m running Toyo R888R, 225/45 front and 245/45 rear.

If you use the 996 front w/ a 964 2 piston(44) rear on 3.2 rotors you get 1.588, if you use 930 rear rotors that goes to 1.544

As I said, nothing unsafe about a extra front. It's just not getting all that can be got from the back.

The heat issue is all at the front so anything that lightens the load whether its less mass to stop or more rear bias it all helps

[911 Rod]

Bill, is the SRF brake fluid than much better than the ATE brake fluid?

[chrisbalich]

I'm wildly outmatched in knowledge, but why not just 'upgrade' the brakes to early 964 C2 F&R?
Nearly identical to the f/r bias of SC, but aluminum calipers that will weigh less and shed heat more efficiently and larger rotors with more thermal capacity.

*this is totally my plan for my car. but for unsprung weight loss as opposed to a racing application*

[Bill Verburg]

Originally Posted by 911 Rod

Bill, is the SRF brake fluid than much better than the ATE brake fluid?

Yes
listed w/ wet & dry boiling points
SRF = 518 604
Endless 650 =424 622 current factory fill for Cups/RSR
Motul RBF 600 = 401 594
Motul RBF 660 = 400 617
ATE 200 = 388 536

[Bill Verburg]

Originally Posted by chrisbalich

I'm wildly outmatched in knowledge, but why not just 'upgrade' the brakes to early 964 C2 F&R?
Nearly identical to the f/r bias of SC, but aluminum calipers that will weigh less and shed heat more efficiently and larger rotors with more thermal capacity.

*this is totally my plan for my car. but for unsprung weight loss as opposed to a racing application*

Here are most 911 setups


most 964 & 993 setups


some 9111 common setups


dual masters


964 4/4 or better 4/2 on all 930 rotors is good, I used the 4/4 on 930 for years very successfully till I went to 993RS on both my cars, this is overkill on a 911 unless you have a 3.6 or better but these are real hand of god brakes w/o any heat issues.

Again the typical SC/Carrera has no need of these. The standard solution is all 930 because they fit under 15s but the 964 on 930 is close enough but you need 16s

[VFR750]

Wouldn’t 964 4/4 bias be the same as 996 f/r at about 1.7?

Btw, I’m finding the carburetors paired with DC-40 cams are pushing the SC a little faster everywhere I go.

I’m only 16”. Phone Dials

[Bill Verburg]

Originally Posted by VFR750

Wouldn’t 964 4/4 bias be the same as 996 f/r at about 1.7?

Btw, I’m finding the carburetors paired with DC-40 cams are pushing the SC a little faster everywhere I go.

I’m only 16”. Phone Dials

while bias is important the real critical issue is thermal performance

using a stock 911 20mm front rotor as a base
3.2 has ~20% better thermal capacity
930 has ~86% better thermal capacity(actually more because of the better internal geometry but I can't quantify that)
996 has ~78% better thermal capacity(I need to look into the internal geometry)

Mike,

First of all, kudos for running an air cooler on track! Great to hear you are using it as intendd.

I second what has been said by Ed about technique. I instructed for 20 years and raced before (and during) that time. When I first started, I used to cook brakes all the time. As I continued to get better, I used the brakes less, to the point where they ceased to be an issue. I think what happens is that as we become more accustomed to high velocities, our adrenalin calms down a little, so we get better at controlling our muscle movements. That makes us sooth. This guy has a few thoughts on the subject.

For the 14 years I ran my pretty gnarly 944S2/968 track car, I had best luck with Performance Friction 08 compound (they renumbered them--I'm not sure what the equivalent is now). They were rotor friendly, worked cold, yet lasted well and tended not to boil fluid as fast. But the best thing was their nice, linear and progressive feel. I used ATE Super Blue and later Motul 600, and I bled the brakes every track day, no exceptions.

I also have never liked the way big brakes affect steering and handling. All through the time I ran my 944, I resisted the urge to move up to M030 front brakes, which were an option. I drove a lot of M030 cars, and I thought they lacked the nimble feel of the lesser brakes. I try to avoid super big (and heavy) wheels and tires for the same reason. the beauty of the 911 is its lightness.

[juanbenae]

after cooling my SC 20mm rotors in my spec car like you describe I found the biggest improvement was going to the 24mm Carrera set up front. it was later in the car's development so maybe I was getting better/easier on the brakes by then too while going faster.

it was pretty easy to do too..

[VFR750]

I will agree, I am not an expert. So my tendency to brake too much is hard to shake.

Interesting comment on the weight of the brakes. One thing I've noticed is the aluminum monoblocks are about the same weight as the small steel "A" caliper.