Brake Upgrade dribble

[Roy]

Talking to someone again the other day about brake upgrades...and how when i win lotto want 343mm front rotors with AP 6-pot brakes and 328mm rear rotors with AP 2 pot brakes:)

However....my pet ramble:) is how these sorts of brake setups are massive overkill for most of us, even ppl that do track work in cars.

Something i posted a while ago that came to mind again today whilst dribbling propoganda with another forum goer...

Car & Driver did a test a few years ago testing StopTechs brake kits against some more recognised names, showing similar results.

Test Car was a WRX (US Spec which only uses two piston sliding caliper, not as good as Nissan 4 spot or later Model WRX 4 pots)

So tested kits were, std car, std car with upgraded pads and fluid, Brembo F50 Kit, Brembo Lotus Kit (Similar to as fitted to GTRs, 44/38mm pistons), Stoptech it and Prodrive Kit (Alcon)

Stopping Distances 70mph - 0 , 3 Stop

Brembo F50;_____________ 185 / 183 (Average / Best)

Brembo Lotus; ______________ 200 / 196

Prodrive; __________________ 198 / 194

StopTech;__________________ 187 / 186

Stock; ____________________ 205 / 196

Stck with pads and fluid; ____187 / 184

The above figures are all in feet, one stop difference between pad and fluid upgrade to crappy sliding caliper brake setup and massive Brembos is 1 ft...lol 30cms:( And over 3 stops the average is 2 ft...lol 60cms:)

So you can see the one stop max of the upgraded pads and fluid is damn good when you consider the $$$ to % difference.

Stopping Distances 100mph - 0 , 25 Stop

Brembo F50; _____________ 299 / 288 (Average / Best)

Brembo Lotus; ______________305 / 294

Prodrive; __________________ 308 / 295

StopTech;__________________ 297 / 290

Stock;_____________________ 340/317

Stck with pads and fluid;_____316/299

Not the world of difference you would be led to believe by the "you need 6pot caliper 343mm rotor crowd."

Specs of the kits:

Rotor Weight (pounds) Size in inches (diam / thk)

Brembo F50;.................15.8......................... .13.1 / 1.3

Brembo Lotus;..............12.9.......................... 12.9 / 1.1

Prodrive;......................16.5...........................13.0 / 1.1

StopTech;...................13.9..........................12.9 / 1.1

Stock;.................. ......14.2..........................11.6 / 0.9

Caliper Weight , Piston Size, (mm)

Brembo F50;..........8.6 pounds...........40 / 44, Leading / Trailing

Brembo Lotus;.......6.8.......................36 / 40

Prodrive;...............9.1..................... 34.9 / 41.3

StopTech;.............9.3.....................36 / 40

Stock;.................10.8.................. .43 / 43

...and COST!!!

Brembo F50;.......................US$2,995

Brembo Lotus;.....................US$2,595

Prodrive;.............................US$1,999

StopTech;...........................US$1,695

Stock with pads & fluid;....... US$130

And remember thet US Spec cars dont get the same 4 pot calipers that WRX get in Aus. And the aftermarket setups have much bigger rotors then the std WRX setup.

So would expect better performance from OZ Spec WRX or Nissan 4pot calipers with pads and fluid.

It seems the main benefits of the big brake kits are reduced operating temperatures, and more feel and firmer pedal. The reduced temp means the rotors arent being knocked around near as much, and you can run a nicer pad which means there is likely to be less wear on the rotors. And of course less likely to boil and ruin the pricey brake fluid

There is no doubt that the big brake upgrades offer great improvements in feel and consistancy, but they dont reduce stopping distances like people imagine. Thats what a combination of good tyres, suspension and brakes do.

Food for thought when you are shopping for the 2nd hand GTR brake calipers:) They offer improved feel, but wont really do much regarding stopping distances and fade. But they do look hell cool and i still want a brake upgrade:thumbsup:

[(B1) MR_fanny]

very interesting. yeah i guess what you pay for is the consistancy and long term breaking performance if your planing to do 10+laps on the track?? so i take it stockies with upgraded pads and fluids will do just as good a job at stopping for the occasional track day..say for 5 consitant laps maybe?? ad another $100 bucks or so for a brake master cylinder stopper for better feel ontop of the $130 and your set:D:D

[Roy]

The 25 stop tests from 100mph is punishing brakes....and track work would be easier on brakes for a couple of reasons.

In the test the only time the car had to cool the brakes was on the acceleration from 0 to 100mph then it jumped on the anchors again. On the track you have straights where the brakes are getting cooling flow so the test would be harder on brake setups then track work.

Secondly on the track you wont be consistantly braking to wash off 100mph, typically you would be washing off 40-80km/h with one maybe 2 big 100km/h stops. So test is again harder on brake setups then track work.

With my existing brake setup i have done around 25-30 laps at Wakefiled in NSW with no problems. Its a matter of thermal control much like it is with engine temps. I think with the right fluid and pads, std brakes are no reason why you shoudlnt be regularly enjoying your car at a track:)

So basically im trying to encourage ppl to get to the track, even with essentially std brakes, just a pad and fluid upgrade:)

[Duncan]

good post Roy.

I think the main thing to remember is that it isn't really brakes that determine your stopping distance, it is tyres.

Pretty much any brake, right down to the crappy 1 caliper ones on the 350z have enough torque to lock the wheel, so it is the amount of grip the tyre has (resistance to locking) that makes the biggest difference

The main benefit of bigger calipers and discs is the larger thermal mass to let the heat out. Standard brakes tend to fade badly after repeated stops, and I'm really surprised that they went so well in the 25 stop test. They must have had great brake fluid to stop it boiling

[Roy]

cant remember the fluid, but Hawk pads were used...anyways off to the Motorpsort Show i go:)

[dangerous_daveo]

Thats cool! That would mean my pads, and slotted rotors would be heaps good. Then some good new fluid in, in the next few days. Then if I went braided lines too!!!

[predator]

Interesting comparison..

You would also in some ways have to take into account the force of mass.. so the heavier the car, the larger stopping force required. It is possible the differences between the different types may be more pronounced in differently weighted cars??

Also I notice that in the second comparison, the differences do become a bit larger - so faster speed = more difference between "std" setup, and the fancier stuff? At 200km/hr - 250km/hr would be interesting ...

Also 10-15 feet difference .. that is 4m .. that's roughly 1 1/2 car lengths. One car length built every corner just on braking.. etc

No mention of the time between runs though? 1 minute? 30 seconds, 10 minutes?

I remember when I took my old pov spec R31 on the track last year, with just 4 wheel discs, standard factory single pots, and cheapish Ferrodo pads, and only some (new) cheapish Castrol 5.1 fluid, it held well enough for braking not to be an issue. No brake fade, no massive problems, and by a few laps the fluid was still cool enough to touch. Although mind you it had trouble getting up to much past 150km/hr on the straight could have a bit to do with it.

I would really like to see a comparison.. from 100km/hr, take a WRX, Skyline, and say something like a big "standard issue" large Merc, and a few very average "family hacks" (like 1600kg commos with single pot brakes) and put them in a similar test.. 5km/hr over kills? depends what car you're driving doesn't it.. I think it could be quite controvercial, but make people seriously think about some things regarding the current "big topic" of road safety.

[Roy]

The same car was equipped with each kit, and after coming to a halt it was accelerated immeditaley back to 100mph where they jumped ont he anchors again to bring the car to a halt. So the brakes were being truly punished with plenty of heat and next to know chance for dissipating the heat.

The aftermarket kits did start to show the benifits after the 25 stops, but what i cant get out my head is that all these kits used much larger rotors over std, as well as larger calipers. So were always going to handle the thermal load better then the std WRX rotors.

And the std brakes used a truly horrible sliding caliper design, not near as good as id think the GTST and later model WRX calipers.

Heavier cars will always have more inertia, so to stop them will generate more heat in the braking assembly (all other things being equal). But for me in a GTST, i think my car is actually lighter then a MY01 WRX. So if you have a GTR/Commodore with plenty of mumbo to boot, then the heat you will be generating to slow the thing will be quite a bit more.

As for the stoping distances, well the top of the range 4 pot Brembo with 330 x 32mm thk rotors is only stopping 11ft shorter in one 100mph-0 stop then a 294 x 22mm thk rotor...well id be asking for my money back if i was told that "with these brakes you can outbrake every car out there"

What id be interested in doing is comparing the F50 Brembo setup with a WRX with 324mm rotors and the std Aus delivered 4 pot caliper. Id be very interested in looking at the results.

...and im not saying dont upgrade your calipers....im always on the hunt for a good buy...its just that from what i have read, and from what i have picked up when talking to ppl that know more then me, the differences in throwing on bigger braking systems wotn always result in great results. Scary to read, but if the system isnt balanced to master cylinder sizes etc then you can end up with a long pedal and less braking effeciency:(

[GTRgeoff]

Roy has the right of it, and unless you are seriously after track performance big brake upgrades on a street car are just another piece of expensive Rice. Especially the prices people are asking for the GTR Brembos. They are about the cheapest Brembo in the range and in my view are only worth around $500 for a front pair considering the cost of really nice AP Racing calipers.

The other issue is the larger pistons in BIG brakes will cause an imbalance between Master Cylinder and rear setup. On a non-ABS car you may find the rears locking easily, and having a long pedal to try to get the fronts to work to capacity as the rears still only need the same pedal travel to lock.

I also hear what Pred is saying and I'd suggest that the ABS is going to be the major difference. Snowies GTR34 has pretty aggressive ABS, and so do the top end AMG Mercs, apparently, but a Rex might have trouble matching them, especially with the constant AWD setup that may influence a bit too much with the extra inertia. That said, the others a fairly porky cars....

To be honest, if some are willing to spend $100 on a master cylinder stopper then I'll add it to my list of custom fabricated components. For $50 delivered!!! Just have to finish sorting specific dimensions for each car and they're on the market.

[Ronin 09]

i've got a cusco 32GTR stopper sitting in my garage waiting to go in if ya want to 'look' at it Geoff...

plus you can grab the pads off me too!

give me a buzz mate if you need em

[BHDave]

What i find interesting is the brembos are only fractionally heavier for the disk/caliper combo than the stockers, and the Lotus are significantly lighter for near enough to the same performance.

Any idea on the pad/fluid combo? Are we talking race pads or street/track compromise pads?

Interesting reading though. Makes me wonder why i upgraded now.....Just kidding, big slotted disks are cool.

[benm]

Yup it's all about heat dissipation and tyre grip more so than size/brand

If you want to stop better put in better quality fluid/pads.

If you want to stop better for longer upgrade your rotors/calipers.

I have the DBA4000 Slotted Rotors, overhauled calipers, braided lines, brand new master cylinder + cusco brace and good pads/fluids and I didn't have any issues when down at Wakefield last however... I noticed that when I backed off and did some cool down laps that my brake pedal went all mushy however soon as I got back up to pace the pedal came straight back... now that I find -extremely- weird.

[GTRgeoff]

Ben, maybe they weren't getting enough air over them.

Marcus

Thanks for hanging on to them. Other than tomorrow afternoon and around the middle of the day Weds I'm available. How about we catch up for an early lunch tomorrow? I have to come to the City briefly to pick up some piccies of my back. 0408 124 767

Another point I'd like to clarify is the tyre size issue. They will not in themselves generate more grip if they are wider, discounting distortion due to the weight and pressure. The same contact patch exists at the same pressure and overlying mass for each tyre of similar size. The advantage is in heat control and dissapation, so a wider tyre will handle more aggressive driving longer, and so until better technology comes along the onus for trackies is on getting the widest tyre possible, but on the road it's a recipe for aquaplaning........

[someonestolecc]

Great post good on ya guys.

[Abo Bob]

That doesn't make sense to me Geoff.

I just went from 225 40 18's to 265 35 18's same brand and kind of tyre just different sizes. I can definitely notice more rear end grip (front tyres stayed the same) and it seems to me the amount of rubber on the road would have to be greater.

[benm]

Ben, maybe they weren't getting enough air over them.

Yeah but what I find weird is...

On the street the pedal is fine

At the track whilst up to speed the pedal is just as good

At the track whilst backing off for 2-3 laps the pedal goes mushy.

I realise that the pads etc needs to be up to temperature in order to perform correctly however you would think that if the pedal is fine on the street and fine whilst zooming around the track that it would also be fine when backing off but still circulating the track.

I need more experience, only done 1 'full' trackday in my life

[Merli]

Another point I'd like to clarify is the tyre size issue. They will not in themselves generate more grip if they are wider, discounting distortion due to the weight and pressure.

Sorry, perhaps I'm not reading this right... But how can you discount those factors so willy nilly?

That's like calculating trajectory, "assuming no air resistance or friction"? These are integral parts of the calculation? :confused:

[Abo Bob]

Maybe he meant rim size?

[Roy]

There is theory around that says a wider tyre doesnt mean more available grip. LOL, i think its an instance where the theory gets lost on the way to application.

Want to slow an F1 car this season, give them a narrower tyre with grooves to reduce the contact patch with the ground. There are plenty of other examples...

As for the soft pedal while cruising around...i noticed it one a couple occasions at Wakefield myself. The best theory i can come up with is after thrashing your brakes silly you are cruising around trying to get some airflow thru them. But by not actuating the brakes and displacing fluid around, you are left with fluid sitting idle in a very hot caliper, and it perhaps boils to the point where you get a spongy pedal.

Once cool then they are fine...or of you keep actuating the pedal lightly forcing the pistons in and out and likewise the fluid, well perhaps that balances out the heat transfer to a larger volume of fluid?!?!?!?!?!? I dont know, thats a guess and i think its not a very good one:(

But yeh ive noticed the same problem at Winton, though i dont think its been since i upgraded my rotors and had my master cylinder re-co'd...too long ago

[Roy]

There is theory around that says a wider tyre doesnt mean more available grip. LOL, i think its an instance where the theory gets lost on the way to application.

Want to slow an F1 car this season, give them a narrower tyre with grooves to reduce the contact patch with the ground. There are plenty of other examples...

As for the soft pedal while cruising around...i noticed it on a couple occasions at Wakefield myself. The best theory i can come up with is after thrashing your brakes silly you are cruising around trying to get some airflow thru the rotors.

But by not actuating the brakes and displacing fluid around/thru the caliper, you are left with fluid sitting idle in a very hot caliper, and it perhaps boils to the point where you get a spongy pedal.

Once cool then they are fine...or of you keep actuating the pedal lightly forcing the pistons in and out and likewise the fluid, well perhaps that makes it a bit harder for the heat to boil that small volume of fluid bhind the pistons?!?!?!?!?!? I dont know, thats a guess and i think its not a very good one:(

But yeh ive noticed the same problem at Wakefield, though i dont think its been since i upgraded my rotors and had my master cylinder re-co'd...too long ago to be sure.