What big front brakes to go for?

I have a UK Spec Supra so I still have UK Spec's on the front now but due to me having to downgrade the rear brakes to J Spec (to fit my 15 inch wheels over) im looking to upgrade the front brakes to compensate....

Looking to spend about the £1k mark give or take and have been looking at K Sports but also wanting to check dimensions as I dont really want to change my wheels and the wheels I am using have no daylight between the caliper and the spoke so would need to not stick out as far as UK spec calipers

You're just going to end up unbalancing the braking on the car even more if you fit bigger brakes to front than

you already have.

Ksports definitely offer more clearance than UK calipers so if your current wheels fit with UKs you'll have no issues

Whifbitz actually keep them in stock too, the only place that does and saves the 15+ week wait

I love mine [emoji3]

From a journal

The first thing that will improve your vehicle’s braking capabilities will be a set of performance tires.

And brake balance is influential on performance.

You're just going to end up un balancing the braking on the car even more if you fit bigger brakes to front than

you already have.

This!!!!! I would stick with the UK's myself

I've got ksport fronts with jspec rears. Can't fault them tbh. Never had a problem with balance on the road and seeing as the fronts do most the work anyway I don't see how it'll make much difference. I'll be doing rear ksports soon anyway but for the last year they've been a great addition. Will be doing a trackday soon so I'll let you know how I get on if you haven't already decided mate

You're just going to end up unbalancing the braking on the car even more if you fit bigger brakes to front than

you already have.

Exactly what I was going to put! I've seen this happen on a friends car, the rears now come in harder than the fronts as they offer the least path of resistance due to a big set of brakes on the front.

Uk's ftw buddy

hmm alot of interesting points.... was just thinking for my type of driving (straight line speed line and not track) that it would still benefit me... would it unbalance them enough to notice alot as like BoGIe says most of the braking is on the front and wouldn't be seeing track use...

Can't believe no one has shamefully asked for your UK front brakes off you Shawn [emoji51] (yes please)

hmm alot of interesting points.... was just thinking for my type of driving (straight line speed line and not track) that it would still benefit me... would it unbalance them enough to notice alot as like BoGIe says most of the braking is on the front and wouldn't be seeing track use...

No offence mate, but for your style of driving you're not going to out brake a well set up pair of UK front brakes. Good pads, good fluid, braided brake hoses, and good tyres and you are sorted, save the money for the fuel bill

Loads of info here

http://www.mkivsupra.net/vbb/showthread.php?137208-stoping-distance-on-quot-big-brake-kits-quot&highlight=braking+imbalance"]http://www.mkivsupra.net/vbb/showthread.php?137208-stoping-distance-on-quot-big-brake-kits-quot&highlight=braking+imbalance[/url]

What pads do you have in the uk's at the moment?

Ksports definitely offer more clearance than UK calipers so if your current wheels fit with UKs you'll have no issues

Thankyou mate thats what I was hoping

Can't believe no one has shamefully asked for your UK front brakes off you Shawn [emoji51] (yes please)

haha sorry mate but they will be going on the green one as the green one only has j spec's on atm

No offence mate, but for your style of driving you're not going to out brake a well set up pair of UK front brakes. Good pads, good fluid, braided brake hoses, and good tyres and you are sorted, save the money for the fuel bill

haha nah that is a valid point to be honest it is more of a show queen than driven properly

What pads do you have in the uk's at the moment?

Just OEM atm that was another thought of mine was trying different pads, cheers for the info il have a little read

Just OEM atm that was another thought of mine was trying different pads, cheers for the info il have a little read

Put some Porterfield Race pads in, and Motul RBF600 or 660 brake fluid, and they will easily cope with anything you will throw at them, trust me

You'll absolutely ruin your car, the read below from Chris Wilson

Brake upgrades can set out to try to achieve several objectives. The commonest are to increase resistance to fade and or increase braking effort for a given pedal effort. IE, the pads are pushed against the discs harder for a given pedal effort than before the upgrade, or the brakes will stop the car from 100 MPH, hard, for more times before fade sets in, than previously. The feel from the pedal, that almost intangible quality, can also be addressed and sometimes improved upon by brake size, or pad material changes, or brake flexi hose upgrades to something less squashy than rubber. It's easy to get carried away by the thought of brake upgrades. The limitation in most cars as to how short a distance they can stop in is tyre friction. Leaving aside pedal feedback, and fade, it is almost certain that a Supra on stock Jap spec brakes will stop in just as short a distance as one with an AP six pot kit on it, a Brembo kit, Pauls KAD kit, or whatever. It may not feel to the driver that it does, but usually such is the case if you just nail the pedal as hard as you can. The fancy kits may *FEEL* to stop the car faster, due to less pedal effort, and a better bite, but in reality, if you hit the pedal as hard as you can with stock Jap spec brakes, UK spec brakes, AP kit, KAD, whatever, the car will stop in the same distance. Repeat this test 10 times and stock Jap brakes may be on fire and long since faded, or the fluid boiled, UK ones may be very hot and bothered, but the upgraded ones will probably still be working within pad, disc and brake fluid temp limits. Add in the intangible "feel" factor, and a desire to brake as hard as possible, using as little skill as possible, but WITHOUT relying on the ABS to take over, and for sure a well set up brake upgrade may well allow more finesse.

 

Herein though lies the rub.

 

Upgrade only the fronts and the brake balance of the stock car may well be compromised. Let's take stock brakes. You press smoothly on the brake pedal with (say) 50 pounds force. The car stops fine. 70 pounds, the fronts are just beginning to lock (car makers ALWAYS aim for the fronts to lock first, as rear wheel lock makes the car very unstable and liable to swap ends). The rears are doing as much work as the brake engineers deemed safe to prevent premature rear lock up. The ABS cuts in, and maximum retardation has been reached. Now, take a car with big front discs and calipers. Only 40 pounds pressure now gives a smooth, lock free and powerful retardation. 50 pounds and the new, more powerful, (for the same pedal pressure), fronts are locking. The ABS cuts in. BUT, and this is the crux, those original rear calipers and discs are still well below the caliper pressure where they are able to achieve maximum retardation without fear of the rears locking.

In other words the FRONT brakes are doing TOO MUCH work, albeit without breaking into a sweat, and the rears are, to exaggerate a bit, just along for the ride. The BEST scenario is to upgrade front AND rear brakes, carefully ensuring the original balance of effort at any given brake pedal pressure remains as designed, but that the more efficient front AND rear brakes stay cooler for more hard stops, and that old intangible "feel" from the brake pedal is improved, at lower rates of driver effort on the pedal. The latter may or may not be good or desirable, and can be engineered out by changing BOTH front and rear caliper piston sizes, or pad areas. In a race car the balance would be adjustable via 2 brake master cylinders, with a driver selectable change in mechanical leverage effort between front and rear brake circuits, one cylinder operating the front brake calipers, the other the rear. This can also be achieved on road cars, but to do so is usually complex and expensive, especially if ABS and brake circuit failure safeguards are to be maintained. It is far easier to calculate the caliper and disc sizes, along with pad area and compound to achieve this, as near as available off the shelf equipment will allow.

 

Caveat. I said before makers engineer more effort on the front brakes to encourage straight line stopping if the tyres are locked up . They err on the excessive side, as, in the wet, the rear tyres can take a lot more braking effort than in the dry, due to less weight transfer onto the front tyres, as they will lock before as much weight is transferred when the grip of the road surface is reduced. So adding yet more front brake effort worsens this existing imbalance, especially in the wet. If it were not for the ABS the front wheels would be locking up very early. On the Supra a relatively sophisticated ABS allows some effort to be taken off JUST the fronts, and an artificial and very inefficient balance is returned. On cars with lesser (1 or 2 channel) ABS, or no ABS at all, a brake upgrade on just one end of the car can be lethal.

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Get the best pads you can on the rears, beef those up and get some good stuff on the front. You're only doing 1-2 stops so you'll be within the parameters of the setup.

Bear in mind how much power the car will be running though.

I still think you should beef up the rears

Another interesting video from motive dvd, it didn't upset that gtr atall. If you are doing it mainly for show shawn you will be fine. Its worth pointing out the amount of US Supra with large front/small rear brake setup for drag is high and has been done for years.

If I was upgrading id be looking at fronts and rears leaning towards a set that was designed for the car, some like AP racing or Brembo but obviously that is ££££!

Never liked oem Supra brake peddle feel either.

p.s. you still got the UK rears?

 

Another interesting video from motive dvd, it didn't upset that gtr atall. If you are doing it mainly for show shawn you will be fine. Its worth pointing out the amount of US Supra with large front/small rear brake setup for drag is high and has been done for years.

 

If I was upgrading id be looking at fronts and rears leaning towards a set that was designed for the car, some like AP racing or Brembo but obviously that is ££££!

 

Never liked oem Supra brake peddle feel either.

Very different animal. The GTR ha 4WD and diffs that move power around. Works under acceleration and deceleration.

Bear in mind how much power the car will be running though.

 

I still think you should beef up the rears

Power of the car has nothing to do with it, you're still stopping the same car from whatever speed, whether it be an NA or a 1000bhp single, stopping is stopping. The brakes aren't fighting the power of the car, the are fighting the laws of physics.

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This is a good little app

https://www.blackartgraphics.com/pages/toyota-supra-brake-bias-app

What's this all about then?

 

Braking is a pretty simple concept, but is often misunderstood. In order for your brakes to be working effeciently, they need to be balanced, making the most of the available grip, and they need to be working at the correct temperature. Forget the massive discs and machined billet calipers with eleventy hundred pistons, if there is grip left on the table or the brakes are at the wrong temperature, then the system is crap.

 

This calculator is designed to be a quick check of those basic factors. Chuck you cars specs in the inputs, select your braking components and check the basic parameters of bias and temperature on the dial. You want to get all of them sitting in the green zones of the guages for your particular setup.

 

How does it work?

 

The calculator solves a complex algorithm which determines the point at which the front brake force overcomes the available traction, causing the tyres to lock up. Beyond this point, braking performance is reduced, so the point of front lock up (known as 'threshold braking') represents the maximum achievable braking performance available from a given set of parameters.

 

Why does this differ from other brake system calculators on the internet?

 

Although it's true that the tyres stop the car, the brakes are still a key point of optimisation and can affect the total braking performance by up to 50%.

 

Other brake calculators are open loop calculations, they will ask for a rate of acceleration or assume that 100% of the grip available is being used and take that as the acceleration, from which the load transfer and thus ideal bias ratio can be calculated. What they won't tell you is how much of that grip the brake setup is actually using, and thus what the actual rate of acceleration is, according to that particular set of parameters, meaning the actual bias can differ from the theoretical bias by a significant margin. The tool provided here is a closed loop system, it takes the tyre grip as an input and solves a circular problem where the front tyre traction is dependent on the load transfer, the load transfer is dependent on the amount of brake force, and the brake force depends on the amount of traction at the front tyre. Unlike other brake system calcliations this one will tell you how much of the brake force you can actually deploy. This calculator also hosts some other key benefits.

 

Drop down menus for common braking components, making entering your parameters a hassle free experience and requiring minimum specialist knowledge

Thermal simulation. Using a parameter for engine power, the calculator can simulate the amount of kinetic energy converted to heat by the brakes when lapping a simulated test circuit.

Easy to understand results. The guage system for dynamic bias and front/rear rotor temperature, presents a simple and intuitive glance at the most important aspects of the braking system.

What do the disc temperatures represent?

 

The vehicle is modelled to travel around an oval circuit made up of two 180 degree, 50m radius turns connected by two 400m straights. The car accelerates down the straights at a rate dependent on the power, weight and aerodynamic drag of the vehicle, and decelerates at a rate as calculated by the brake bias algorithm. Braking distances are calculated based on the speed of the vehicle and the calculated stopping distance, so the faster the car, the more the required braking distance increases. The test is designed to represent real life driving situations, where the amount of power, weight and grip of the car all affect the amount of kinetic energy being built up and dispersed as the car travels around a fixed test circuit.

Why does the braking distance get progressivly shorter if I keep adding rear brake force?

 

The algorithm is only set to solve for front lock up. You can continue to add rear bias past the point that the rear tyres would lock and it will continue to add to the overall brake force. I will sort this out, but for now make sure the guage stays out of the red area!

Is anyone running the full set of K-sports? I've been thinking about going front and rear in one go.

This is a good little app

 

https://www.blackartgraphics.com/pages/toyota-supra-brake-bias-app

Wow that is very trick! Thanks for posting!

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