when are your brakes to big ?

[darkling]

so i asked the question on a different thread but not to many responses anyone know the true answer .

does weight of the car come into factor when choosing your brakes ?

does wheel and tire size also factor in other then the diameter you can fit inside the rim ?

[corvettekid1973]

I'm not a authority on this by any means but I do think that yes weight should be a factor in brakes. Also the bigger and wider the wheels the more rotating mass you have there for the more work on the brakes. All of that will cause a lot of heat in your brakes.

[darkling]

hmm having a hard time putting my total question into words . i have noticed most larger american cars have had alot of lock up in turns wondering if that is really caused by to much braking surface .
lets say like a 3000 lbs car with 17 inch rotors and 6 piston calipers might it be the fact that the 1500 or so lbs on the front rotors isn't enough to allow the brakes to get some slippage thus causing a total lockup .
not factoring in driver fat foot error .
hope that helps

[regal454]

lets say like a 3000 lbs car with 17 inch rotors and 6 piston calipers might it be the fact that the 1500 or so lbs on the front rotors isn't enough to allow the brakes to get some slippage thus causing a total lockup .
not factoring in driver fat foot error .
hope that helps

The friction between the tire and the road is what stops the car, not the brakes. In the case above, you would need a bigger tire or softer compound.

[CFster]

When you can't fit anything bigger!

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[badazz81z28]

I feel there is no such thing. Obviously you can go bigger than what's needed, but nothing negative about it. Go as big as the wheels will allow and call it a day

[Todd in Vancouver]

When you can't fit anything bigger!

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That looks AWESOME !

[SLO_Z28]

I feel there is no such thing. Obviously you can go bigger than what's needed, but nothing negative about it. Go as big as the wheels will allow and call it a day

The exact opposite is true. You have a large mass spinning at thousands of revolutions per minute on a larger axis than you originally had. It increases sprung weight, unsprung weight, and decreases steering responsiveness, and has negative effects on the tires traction. Big is heavy, heavy is bad.

[darkling]

but due to the clamping force of a huge brake kit on a light front end won't it be harder to find the sweet spot between tire traction and lockup . i know pedal feel has alot to do with that . and maybe using a adjustable proportioning moving more of that pressure to the rear might help ?

i just keep seeing lockup over that over i really just want to solve this before i drop 2k on brakes and find issues

[rustomatic]

Look at what they use on a new car that stops in a very short distance. Look at an economy car, then drive one, if you haven't recently. My 2012 Honda stops like hell, and has single-piston calipers on not-very-large rotors in front; it has (small) drums in back (they only give you rear discs with the cosmetic options package that includes alloy wheels--you can see the discs through them). The science of effective application is not found in bolting on the biggest and blingiest things you can find.

By the way, the Honda (Civic) weighs more than my 1963 Falcon; I surely do not need 14-inch rotors to stop as well in the old car...

[TLWiltman]

You only need a rotor large enough to get rid of the heat produced by the brakes during heavy use. Anything larger is extra weight and generally cosmetic. Keep in mind the ubiquitous NASCAR stock car. 15" wheels and just shy of 13" rotors (actually, I think they have a short track setup with 13" rotors nowadays).

[corvettekid1973]

He could go with 10'' rotors and single piston calipers on all four corners and it could stop great, but those breaks would fail if he ever decided to track his car with those brakes and larger wheels. It depends on his intended use of his car. Do bigger brakes add weight? Yes but that's what's needed for heat dissipation, which helps with reliable consistent braking. Its works the hell out of brakes when people put those 20" wheels on brakes that was meant for a 15" Wheel

[darkling]

i'm actually looking at the 12.88 wilwoods 6 piston on my nova in the front with 18's but not to sure how to set up the back i'm going to be using a strange 9 inch was thinking that just the 2 piston would even be overkill

[Paul Huryk]

Like others have said, the important thing is the tire friction to the ground that matters - and that 65% of the braking friction is generated through the front tires and brakes. One of the best things you can to in terms of stopping power is put a wider and/or stickier tire on the front of a car.

Don't get me wrong, if your ride is 20+ years old (and still has OEM brakes), it would be better off with better brake systems. As an example, I'm in the process of putting on a 13" Wilwood FSL system on my 1989 Trans Am (10.5" front brakes stock) - rears are the 12" (and are more than enough). I already moved up to 275-40-17 tires from 245-50-16 and that made a difference with stock brakes. My Baer 13" 2 piston kit stops my Camaro from 60 in 105ft - you don't need a 15" 6 piston race system to stop anything short of a 6000lb SUV.

Actually you can over brake a car - if you don't have ABS and can lock up the tires without being 90%+ on the pedal, you have too make brake for your tires. Sure some cars need more thermal capacity to not cook the brakes, but cooling and better rotors can solve that issue most of the time. A lot of the newest cars with huge brake systems use the ABS as a crutch in terms of modulation - not many can out stop the right systems on an retrofitted car without ABS in anything other than a wet turn.

[LowFast]

You only need a rotor large enough to get rid of the heat produced by the brakes during heavy use. Anything larger is extra weight and generally cosmetic. Keep in mind the ubiquitous NASCAR stock car. 15" wheels and just shy of 13" rotors (actually, I think they have a short track setup with 13" rotors nowadays).

This is true, however they use very thick vented disks to disapate the heat and monster calipers as well. I would actually like to see manufacturers provide NASCAR type brakes with thick disks and overall smaller diameter for those who do not want monster wheels.

[cornfedbill]

Big brakes are really most beneficial in the dissipation of heat. Small brakes overheat more rapidly than large brakes.

If they lock up too easily, the pressure can be reduced by changing to a larger master cylinder piston diameter or smaller brake caliper pistons. You can also change the pad compound.

It is true that small brakes can stop just as quickly - once. But repeated stops will cook the small brakes.

Is this for track use? Autocross? Cruising? An honest assessment of the goals may help you to decide how much brake (mass) is too much for you. I am sticking with 12" x 1.25" rotors. I am not planning on hard track use. They will be enough for some track use, autocross and more than enough for the street.

Remember that rotors are flywheels that suck power to accelerate and make it harder to stop. Rotating mass carries much more inertia than mass that is not rotating.

[Quickboat]

When you can't fit anything bigger!

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Bet those dont stop so well with that brake line and banjo bolt lying on the ground like that...LOL....

[TheJDMan]

When you can't fit anything bigger!

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Agreed!

73117

[SLO_Z28]

This is true, however they use very thick vented disks to disapate the heat and monster calipers as well. I would actually like to see manufacturers provide NASCAR type brakes with thick disks and overall smaller diameter for those who do not want monster wheels.

Everyone brings up NASCAR but that is not the series to get brakes from, the cup cars have absolutely terrible brakes. The biggest problem I see is that no one asks the right question here, which is what brake PAD you should run. Pad matters MUCH more than rotor diameter, and caliper piston count. Getting a pad that has the right feel to the drive, in the heat range the driver is used too, is more important than brake size.


Brian Hobaugh won every single event at Run To The Coast, smoked everyone on the road course, autocross, and speed stop, by a lot. Brian is on bone stock brakes.

[a67]

Everyone brings up NASCAR but that is not the series to get brakes from, the cup cars have absolutely terrible brakes. The biggest problem I see is that no one asks the right question here, which is what brake PAD you should run. Pad matters MUCH more than rotor diameter, and caliper piston count. Getting a pad that has the right feel to the drive, in the heat range the driver is used too, is more important than brake size.


Brian Hobaugh won every single event at Run To The Coast, smoked everyone on the road course, autocross, and speed stop, by a lot. Brian is on bone stock brakes.

OK, I'll bite, what pads was he running?

Bob

[Matt@BOS]

OK, I'll bite, what pads was he running?

Bob

I want to say the Wilwood Polymatrix "E" pads, which are more aggressive than the BP20s but still work pretty well without a ton of heat in them. Don't forget though that the big front tire on that car is also a factor to be considered.

[Rod]

Brian Hobaugh won every single event at Run To The Coast, smoked everyone on the road course, autocross, and speed stop, by a lot. Brian is on bone stock brakes.

yes on in a car that he has drove for more than 25 years, with more than 500Hp and 500Torque, sitting on an 18x12 rim on all four corners, the same wheel setup that Brett runs the Ridetech 33 on, a 12 wide rim helps alot when stopping, I noticed a huge difference switching from a 8" rim to a 9.5" rim, the braking stability was huge, along with turn in

[vette427-sbc]

Those stock corvette brakes are better than many stock brakes on newer cars though... 4 piston calipers all around on 12x1.25" rotors are in aftermarket territory (besides weight and seal design). If you can keep them cool, they are hard to beat :smoke:
Still says something for "smaller" rotors

[Quickboat]

Those stock corvette brakes are better than many stock brakes on newer cars though... 4 piston calipers all around on 12x1.25" rotors are in aftermarket territory (besides weight and seal design). If you can keep them cool, they are hard to beat :smoke:
Still says something for "smaller" rotors

They look more like 13 inchers to me, but I could be wrong.

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[dipren443]

They look more like 13 inchers to me, but I could be wrong.

https://static1.pt-content.com/images/pt/2013/03/IMG_1481-1.jpg
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Wrong car. He was driving his dad's midyear Vette at RTTC. And yes, Delco Moraine Vette calipers can work VERY well.

73191

[cornfedbill]

Wrong car. He was driving his dad's midyear Vette at RTTC. And yes, Delco Moraine Vette calipers can work VERY well.

73191

So, if my calculations and numbers are correct, the Corvette with stock 4 piston calipers has 1 7/8" diameter pistons or 5.52 in^2 area. The C10 calipers I am using have single 2 15/16" diameter pistons or 6.78 in^2 area. Although the four piston design may be preferred over the floating single piston caliper, the C10 caliper has 22% more area and greater clamping potential.

My target weight is 3300 pounds. The Corvette, if at stock weight, is about 3100 pounds. Assuming that the tires and pads are equal, my Nova should THEORETICALLY stop as good or better that this 'Vette. That is good news for a guy on a budget like me.

Don't get me wrong, if I had no limits on spending, I would run ZR1 calipers and 15.5 inch carbon-ceramic rotors. They are so cool and will tolerate tremendous amounts of heat. :jump:

[Paul Huryk]

So, if my calculations and numbers are correct, the Corvette with stock 4 piston calipers has 1 7/8" diameter pistons or 5.52 in^2 area. The C10 calipers I am using have single 2 15/16" diameter pistons or 6.78 in^2 area. Although the four piston design may be preferred over the floating single piston caliper, the C10 caliper has 22% more area and greater clamping potential.

My target weight is 3300 pounds. The Corvette, if at stock weight, is about 3100 pounds. Assuming that the tires and pads are equal, my Nova should THEORETICALLY stop as good or better that this 'Vette. That is good news for a guy on a budget like me.

Don't get me wrong, if I had no limits on spending, I would run ZR1 calipers and 15.5 inch carbon-ceramic rotors. They are so cool and will tolerate tremendous amounts of heat. :jump:

Unfortunately you also have to consider the amount of tire patch on the ground (especially the fronts), amount of suspension anti-dive, and also the tire pattern and compound. But that is just to get the optimal braking number - real world results may be pretty darn close anyway.

[cornfedbill]

Unfortunately you also have to consider the amount of tire patch on the ground (especially the fronts), amount of suspension anti-dive, and also the tire pattern and compound. But that is just to get the optimal braking number - real world results may be pretty darn close anyway.

Paul,

You are absolutely correct. I doubt I will come close to the performance of this Corvette due to inherent differences in the chassis, suspension and tires, not to mention I have a loose nut behind the steering wheel. But it is good to know that the braking torque of the system I have is at least in the ballpark. Now I will just have to play around to see which pads work best for my setup and find a good way to get fresh air to the cooling fins in the rotors.

[Rod]

:getout:

[jpgolf14]

Paul,

You are absolutely correct. I doubt I will come close to the performance of this Corvette due to inherent differences in the chassis, suspension and tires, not to mention I have a loose nut behind the steering wheel. But it is good to know that the braking torque of the system I have is at least in the ballpark. Now I will just have to play around to see which pads work best for my setup and find a good way to get fresh air to the cooling fins in the rotors.

No, what you have talked about before is piston sizes. That will affect caliper force, but is not the only factor in the brake torque, the rotor radius also plays an equal part. It is a balance. Also, keep in mind, even OEM brakes have plenty of torque to lock up the wheels. What aftermarket brakes can do for you is:

- improve pedal feel, you can tune for a longer or shorter pedal, and a firmer or softer pedal, your choice. This is what nobody but me talks about. Brake are a huge FEEL item, if they don't feel good to you, you are going to think they are crap. Figure out what you like for brake feel and go from there. Bigger pistons not always better.

- improve heat dissipation from increased rotor size and improved vane geometry, larger thermal mass on the rotor and caliper. You only need it if you need it. If you aren't doing track days, you don't need it.

- improve component life, pads with larger volume will last longer, rotors with more material will last longer

John

[cornfedbill]

No, what you have talked about before is piston sizes. That will affect caliper force, but is not the only factor in the brake torque, the rotor radius also plays an equal part. It is a balance. Also, keep in mind, even OEM brakes have plenty of torque to lock up the wheels. What aftermarket brakes can do for you is:

- improve pedal feel, you can tune for a longer or shorter pedal, and a firmer or softer pedal, your choice. This is what nobody but me talks about. Brake are a huge FEEL item, if they don't feel good to you, you are going to think they are crap. Figure out what you like for brake feel and go from there. Bigger pistons not always better.

- improve heat dissipation from increased rotor size and improved vane geometry, larger thermal mass on the rotor and caliper. You only need it if you need it. If you aren't doing track days, you don't need it.

- improve component life, pads with larger volume will last longer, rotors with more material will last longer

John

John,

Thanks for the input. Unfortunately I do not have enough experience to know what the brakes will feel like. I am running C3 production rotors. This also gives me a proven product and the option to move to aftermarket curved vane 11.75X1.75 rotors with a bolt on hat that will dissipate more heat.

It is my hope that the large pistons will give me an acceptable pedal force without power assist. I worry that I will be experimenting with master cylinder piston diameter and pedal leverage for some time before I like it.

Anyway, thanks for the guidance.

[cornfedbill]

Duplicate

[72blackbird]

If big 6 piston calipers and 14" rotors aren't a requirement, why do alot of people seem to use them? I don't have alot of track time on my car, but used to race it on the local canyon roads and I definitely felt I was at the limit of my factory brake system (stock front discs w/ a disc brake rear from a 79 T/A) with a 400 hp 406. I'm upgrading to a 530-540 hp 455 and my thinking is that the current brake system is inadequate to handle such a power increase and the speeds generated will be too much for it.

If a 6p caliper/14" rotor front and 6p/13" rotor rear isn't really necessary, what brake system would do the job? I do plan to go the typical PT route (upgrade to 18 x 9's w/ 275/40R18's, GW a-arms, etc.).

[Henesian]

I agree that Pads are more important than rotor size diameter, but stickier pads heat the rotors up more than more stock level of pads. If you get more heat in smaller rotors faster, won't you just cook the rotors into oblivion? I think you need enough rotor so that you can keep the heat range in the optimal range of whatever race pad you're running, but not big enough that you get too much cooling.

[Paul Huryk]

If big 6 piston calipers and 14" rotors aren't a requirement, why do alot of people seem to use them? I don't have alot of track time on my car, but used to race it on the local canyon roads and I definitely felt I was at the limit of my factory brake system (stock front discs w/ a disc brake rear from a 79 T/A) with a 400 hp 406. I'm upgrading to a 530-540 hp 455 and my thinking is that the current brake system is inadequate to handle such a power increase and the speeds generated will be too much for it.

If a 6p caliper/14" rotor front and 6p/13" rotor rear isn't really necessary, what brake system would do the job? I do plan to go the typical PT route (upgrade to 18 x 9's w/ 275/40R18's, GW a-arms, etc.).

I think a lot of that has to do with need (as in I "need this" on my ride) and also the look of a large brake kit behind an 18" or larger wheel. Plus today these kits are availabile from a multitude of sources, including some OEM parts to retrofit.

Let me put it this way - it is very hard to stop from 60 in 100 feet or less on street rubber in a car - even with exotic rotor materials and a perfectly setup OEM ABS system - the tires just can't handle much more deceleration. Sure you might more thermal capacity, maybe you need a larger pad to get through a race - making a larger caliper necessary. But you can buy a 2 piston 13" brake setup and it will stop your car in 105 to 110 feet from 60 without ABS all day - super car territory even in 2013 - I should know as the Baer track kit on my Camaro from 1997 will do that - verified in fact. I might be able to knock of another 5 feet on race tires - but the brakes will still be under utilized, more so as the rotors get larger and piston counts climb.

Here's the kicker - I have a set of CTW Motorsports wheels on my Trans Am (I own the company) - which can easily fit 14" 6 piston brakes, yet I went with John's 13" Wilwood FSL kit that honestly makes the brake look tiny. Not a money issue, nor space - I didn't want to have to over brake the car by a rediculous amount where it would make driving it fast less fun (the spectre of being able to lock up the brake anywhere at any time). The only thing I would have done if the car would be road raced a lot would be a change to a 2 piece rotor and hat assembly - to minimize rotor warping.

[72blackbird]

Paul,
Thanks for the informative response. If I'm understanding what you said, then a 14" rotor isn't totally necessary for aggressive street driving combined with an occasional trip to the track and a few autocross events- a 13" rotor should be a good choice. I already knew a sticky race slick and race spec pads make the difference on the track, but didn't realize how much impact they have on overall braking, and it's a balance of tire, pad and caliper/rotor that determine a vehicle's braking performance.

As overkill as a FNSL6R caliper on a 12.88" rotor might be, I think it would be a good choice while I figure out which tire and brake pad combo work out best for each type of driving I'll do. I doubt my car will see a road course or autocross until it's completely sorted out, but in the meantime it will definitely see plenty of shakedown runs on my favorite twisty roads while I tune the suspension and get it the way I like it. I think I will be fine with the 1-piece rotor too- for $1120 that Wilwood kit is an excellent value and should work for me even if Idecide later to upgrade to the 2-piece rotor and hub.

Any recommendations for a sticky street tire that will be a good balance between grip and treadwear?

Thanks,
Geno

[Paul Huryk]

Paul,
Thanks for the informative response. If I'm understanding what you said, then a 14" rotor isn't totally necessary for aggressive street driving combined with an occasional trip to the track and a few autocross events- a 13" rotor should be a good choice. I already knew a sticky race slick and race spec pads make the difference on the track, but didn't realize how much impact they have on overall braking, and it's a balance of tire, pad and caliper/rotor that determine a vehicle's braking performance.

As overkill as a FNSL6R caliper on a 12.88" rotor might be, I think it would be a good choice while I figure out which tire and brake pad combo work out best for each type of driving I'll do. I doubt my car will see a road course or autocross until it's completely sorted out, but in the meantime it will definitely see plenty of shakedown runs on my favorite twisty roads while I tune the suspension and get it the way I like it. I think I will be fine with the 1-piece rotor too- for $1120 that Wilwood kit is an excellent value and should work for me even if Idecide later to upgrade to the 2-piece rotor and hub.

Any recommendations for a sticky street tire that will be a good balance between grip and treadwear?

Thanks,
Geno

No problem!

The kit you have should work beautifully - as long as you get the right pad and tire combo.

The advice I give to our front engined, RWD friends - regardless of make or model is to put as much tire in the front as possible. This helps the handling and also the braking more than most give credit to. So if you can fit a 255 width tire in front without issues - go for it over a 225 or 235 option. Keep in mind that there is a strong correlation between tire patch size and handling/braking capacity. If you cannot go wider, go taller - a 1" taller tire can give a 4% larger contact patch than a 1" smaller option; obviously tire clearance is the most important item in a street car.

Rotors are relatively easy to replace with 2 piece ones if needed - obviously the cost is much higher, but they hold up to much more abuse.

[Skip Fix]

"Brake are a huge FEEL item, if they don't feel good to you, you are going to think they are crap. Figure out what you like for brake feel and go from there"

I agree -when I swapped on the factory 79-81 TA 4WD rear and dual diaphragm booster but kept the single booster pedal the car stopped great but no feel-the factory dropped the pedal ratio with teh better dual booster. Luckily I did it when the pedal was till available.

I used to see road race slicks on B/P Corvettes autocrossing routinely be able to lock up the brakes with factory calipers and rotors.Not a bad system, now Wilwood backs an aluminum bolt on replcament caliper.

[MonzaRacer]

After having got burnt on one car by using Wilwood(not my car either) and finding leaking calipers two years later and they were "discontinued" and no parts available to even repair them. Wilwood rep got all snotty as I was "young kid" Ill never go back. NEVER. Besides when talking brakes Todd from Baer(may he race in peace) sold me on a different company.
NOW as a low buck builder, never having enough to build as I dream, so I build as I have funds for. My Monza will get ZQ8 spindles from 2wd S10, adapters and 325 mm Corvette rotors and calipers,,and I think I have good source for replacement rotors at better prices, may even be able to sell few sets. Also have company that says they can source a decent DD/Street pad with good feel and stopping capabilities and decent wear. Figure people could get higher dollar race style rotors and pads for track days, then use regular pads/rotors for street use.
At least thats my plan on Monza.
With tall GM spindles my Caprice will most likely have 18 Vette wheel copys and 14 in 6 piston Vette brakes.
biggest thin g hurting any system is balancing total mass versus performance. This is one reason I love Tobins work and using Corvette parts,, usually available lot quicker than an "aftermarket" part.
But this is me.