Will bigger brakes make an older car perform like ...

To Begin, We Can’t Cease

The brakes discovered on the second-generation MR2–notably early automobiles like ours–are, in a phrase, awful. Even on the high-performance Turbo fashions, the unique brakes barely measure 10 inches in diameter. Then add single-piston calipers and pads across the measurement of a saltine cracker.

Earlier than making any modifications, we ran our MR2 on the Florida Worldwide Rally & Motorsport Park for some baseline laps. And people laps have been fairly sketchy when it got here to braking. Preliminary software felt obscure, and fade appeared nearly immediately as terrible fluid compressed previous pads. 

We might handle an aggressive lap–like, only one–however we actually needed to decide and select our braking alternatives since each arduous pedal software was primarily a roll of the cube.

We knew we might do higher. 

Our MR2’s efficiency via only one nook reveals how a lot the previous brakes have been hurting us. The swollen hint of the previous brakes (blue) reveals imprecise preliminary deceleration. The EBC hint (crimson) reveals rather more aggressive and linear deceleration, with forces that shortly surpass the inventory brakes.

Whereas we received’t go too deep into the physics equations right here–we’ve bought loads of earlier editorial that exhaustively covers the science of how brakes work–suffice it to say that with regards to brakes, measurement issues. On condition that their main features are to show kinetic power into warmth, then by some means shed that warmth to allow them to take up extra, properties like mass and floor space are key. Further measurement additionally means extra leverage for the brake rotors to behave upon.

So, backside line, tiny brakes are at a giant drawback with regards to severe–and even informal–high-performance work. Bigger brakes would imply extra laps at pace earlier than having to again off. 

Hitting Refresh

However as an alternative of instantly throwing large brakes on our traditional sports activities automotive, we first needed to maximise our present setup. These tiny 10-inch rotors appeared comical inside our 17-inch König wheels, however might contemporary pads, rotors and fluid make a distinction? We began the method with a set of pads and cryogenically handled rotors from EBC.

Our pad alternative was EBC’s Yellowstuff 3068 compound, which is the model’s hottest choice worldwide. Whereas no brake pad can do all the things, the 3068 is a high-performance compound that’s observe succesful for the weekend warrior who doesn’t wish to change pads for an occasion.

However there’s a tradeoff: You may’t simply pop in these pads and go, as they wish to be correctly bedded in. However as soon as they’re, they’re mentioned to supply good really feel on the road and good fade resistance on observe.

Our unique brakes appeared like they got here off an deserted mine cart. Contemporary fluid–a tester solely prices a couple of bucks–plus new pads and rotors from EBC gave our Toyota MR2’s brakes a brand new lease on life whereas retaining inventory dimensions.

To provide our pads a preventing probability of beating the warmth, we paired them with a set of EBC’s cryogenically handled rotors. Cryo remedies are standard in brake functions as a result of, when carried out correctly, they will enhance the hardness of the rotor, which decreases put on and extends life. 

Consider cryo remedy like high-delta warmth remedy. In typical warmth remedy, steel is heated to a particular temperature–depending on the kind of steel and the precise nature of the warmth remedy being carried out–at which level the atomic lattice construction of the fabric modifications and turns into extra ordered than “uncooked” steel. The temperature is then diminished to ambient at a particular fee to lock in that stronger construction. 

Now, that’s a grossly oversimplified clarification, and warmth treating is a broad science that may have an effect on metallic construction in extremely particular methods, however that’s the final course of at work. 

Improper warmth treating can produce steel that’s extraordinarily arduous however very brittle, like glass. Or it might ship extraordinarily mushy steel that’s tough to fracture. Neither is nice for brake rotors, so we’re glad there are of us smarter than us who know what they’re doing.

With cryo treating, the method is analogous, however as an alternative of lowering the temperature to ambient throughout the quenching part, the temperature is diminished to nicely under zero, normally with a medium like liquid nitrogen. This additional hardens the fabric and will increase total sturdiness, one thing these rotors are going to want to cease a 2800-pound, 250-horsepower automotive.

We additionally gave our calipers a radical cleansing and made certain the pistons might transfer freely within the bores. Calipers for these early SW20-chassis automobiles have gotten uncommon, so merely changing them might have been time-consuming and costly. Regardless of wanting like they’ve spent a while on the backside of a harbor, fortuitously ours nonetheless appear to work nicely. 

Lastly, we changed our aged brake fluid, which had the consistency of Dr Pepper left in a automotive whereas it sat on the airport for every week. Our brake fluid tester–a easy, extraordinarily useful system that measures the moisture content material of brake fluid–gave an audible warning once we inserted it into our brake fluid reservoir. (To that time, we didn’t even notice that our tester had an audible warning operate.)

Moisture in brake fluid is dangerous. Despite the fact that water is incompressible, it might simply boil underneath the warmth load of even delicate braking. And when that absorbed water boils, it produces fuel bubbles which can be extraordinarily compressible, resulting in a situation referred to as fluid fade. 

Fluid fade is identifiable by a mushy pedal and little braking drive. This isn’t the identical as pad fade, nonetheless. Pad fade usually ends in a more durable pedal however no braking drive. 

Any moisture contamination in your brake fluid is undesirable–by no means thoughts the truth that water causes rust–so specialists suggest flushing the fluid when the measurable quantity exceeds 1%.

A Higher Baseline

Armed with our contemporary braking system, we carried out a radical pad bedding. EBC recommends bedding in pads towards new rotors by progressively heating them via repeated functions. 

Don’t carry out full stops, the corporate notes, however somewhat speed up briskly after which brake from about 50 mph to twenty mph. Then repeat. 

A number of gradual decelerations are preferable to fewer arduous braking functions. The pads and the rotors warmth at completely different charges, and by extending this break-in interval, you distribute the warmth extra evenly by way of conduction all through the system.

Proceed this cycle till you get some telltale indicators of pad fade–once more, a agency pedal with diminished braking effectiveness. Then permit the brakes to chill to ambient over an prolonged interval by driving for a bit with minimal brake software. Don’t instantly park and permit hotspots to kind. 

As soon as the brakes have been totally bedded, we headed to The FIRM for some baseline laps. Significantly better. We might really use the brake pedal to steadiness the chassis a bit throughout path braking, and preliminary software chew felt extra optimistic. The information traces mirrored all of this as nicely.

The lap instances improved, too, as we dropped a little bit greater than half a second on a 90-second course. This was largely as a result of our potential to carry throttle longer in two key straights since we knew we had the braking capability as soon as it got here time to erase that pace.

However the braking elements’ sheer lack of floor space and mass was nonetheless working towards them. Whereas the pads produced good friction towards the rotors, these tiny discs nonetheless had a tough time coping with all that warmth. Consequently, fade crept in inside a pair laps. 

With a sizzling lap/cool lap alternating cycle, we might keep out for longer periods, however back-to-back sizzling laps shortly overwhelmed the small brakes’ capability. For a enjoyable road automotive, autocrosser and really occasional observe automotive, this might need been a suitable compromise, however for a automotive we wish to actually run on observe, we wanted extra. 

Our Massive Brake

Look, it might sound trite to say that merely bolting on huge brakes made all the things higher on observe, however few upgrades could make such an enchancment–assuming, after all, you’re overheating your inventory rotors. There’s simply an invincible feeling that accompanies a agency pedal with nice chew and simply modulating braking drive that stops a automotive on a dime lap after lap. 

The catch: There hasn’t precisely been an off-the-shelf answer for bolting huge brakes onto the SW20-chassis MR2.

Nonetheless, some elements from different automobiles may be tailored. Maxda RX-8 and fourth-generation Toyota Supra rotors and calipers may be made to work, however whereas they’re massive, they’re additionally fairly heavy. Plus, as these automobiles age out, costs for the elements are going up as nicely.

So we turned to a boutique producer, Wilhelm Raceworks. Proprietor Alex Wilhelm produces a slew of hand-built go-fast goodies for the second-generation MR2. One among his hottest hop-ups is a brake equipment that pairs multi-piston calipers with customized two-piece rotors. 

He provides a number of big-brake choices that change in value and weight, and we went with the mid-priced equipment that makes use of the Wilwood Solid Superlite calipers. This $2500 equipment would give us four-piston calipers entrance and rear, together with 12.19-inch-diameter rotors at every nook of the automotive. The bolt-on equipment additionally contains customized strains, rotor hats and mounting adapters. 

Time to get severe with a contemporary big-brake equipment from Wilhelm Raceworks: larger rotors for extra warmth administration, swept space and leverage, plus lighter, multi-piston calipers. The Wilhelm equipment contains all the things wanted, together with the customized brackets, making this a bolt-on operation. Then we completed it off with a very good, high-temp fluid. To fine-tune the steadiness, we changed the inventory proportioning valve with an adjustable Wilwood piece.

Wilwood, whose elements we efficiently used on our C5 Corvette project, is a giant supporter of kits like Wilhelm’s that use its calipers and {hardware}. “For us to inventory adapter kits for cool however area of interest automobiles wouldn’t be a very good enterprise resolution for us,” Wilwood’s Michael Hamrick tells us. “However we’re large followers of small-volume producers who can service their clients by adapting our off-the-shelf merchandise to work for his or her functions. We do no matter we will to make it simple for specialists to combine our merchandise in as many functions as doable.”

One other cool function: Despite the fact that the 12.19-inch Wilwood calipers function greater than 40% extra floor space than our inventory rotors, the setup weighs greater than 4 kilos much less as a result of intensive use of aluminum and fashionable manufacturing strategies. Extra space for friction manufacturing and warmth dissipation is an efficient combo.

Bolting on the equipment is a snap, and any issues might be as a result of age of the manufacturing facility {hardware}. The Wilhelm-built elements match each the Toyota and Wilwood elements like a glove, however be ready to your 30-year-old brake fittings to be mushy and rusty. Changing as a lot of the present {hardware} as you may is an efficient plan.

That is additionally a very good time to fine-tune the brake bias. Mid-engine automobiles can have tough brake bias since a lot of the load sits farther again within the chassis, however the backside line is that the unique MR2 Turbo brake bias valve isn’t dangerous–to a degree.

With inventory brakes and delicate pads, the bias is fairly favorable: the preliminary ratio is ready to ship about 58% entrance bias. At round 0.6g of decelerative drive, the valve kicks in to ship extra strain to the entrance brakes, which develop into more and more vital because the load will increase on the entrance axle. 

When working grippier pads, although, the elevated friction and stopping drive from lighter pedal pressures don’t permit sufficient strain enhance on the entrance wheels quickly sufficient; that’s as a result of brake bias valves are delicate to pedal strain and never g-loads. Consequently, the mid-engine automotive now has an excessive amount of rear brake drive. And which means path braking may be an thrilling proposition.

These tendencies are simply amplified with a big-brake equipment, which produces much more stopping drive and might alter the relative leverages produced at every wheel as a result of bigger rotors. With a big-brake equipment, the MR2–notably with the Turbo proportioning valve–is closely rear biased, even at reasonable stopping forces. 

The naturally aspirated MR2 prop valve is best, nonetheless, because it provides extra entrance bias, however the actually simple answer is to remove the OE piece altogether and set up an adjustable one. At $100, the Wilhelm Raceworks prop valve equipment–which features a Wilwood valve, correctly sized line, adapters and attachment {hardware}–offers a simple repair. 

With the 12.19-inch rotors and a set of delicate observe pads, the Wilwood valve’s knee level–the purpose the place it begins proscribing circulation to the rear brakes–initially equates to roughly 0.5g of decelerative drive. After which it begins to progressively bias extra drive to the entrance, staying within the perfect bias vary previous 1.1g of braking drive. This implies method much less dodginess on nook entry and much more linear “roll off” when releasing the brake throughout path braking.

As a crowning glory, we flushed the fluid once more–we now have to try this so much right here in Central Florida–and changed it with Wilwood 570 DOT4 fluid. With a dry boiling level of–you guessed it–570 levels Fahrenheit, this fluid provides us quite a lot of confidence that fluid fade might be off the desk for all however probably the most excessive circumstances. If we handle to boil this fluid, we’ve doubtless made another horrible mistake we have to deal with as nicely.

Slowdown Shakedown

To check our upgrades, we headed again to The FIRM, the place we once more dropped half a second from our quickest lap instances. However that doesn’t inform the entire the story. 

Whereas we have been in a position to run a reasonably good lap with our improved inventory setup, the important thing phrase there’s “a.” A couple of sizzling lap was an excessive amount of for that stock-based setup to comfortably handle. In distinction, the Wilhelm/Wilwood combo by no means felt prefer it was working notably arduous. With this setup, we’ll run out of fuel earlier than we run out of brakes.

Not solely does our big-brake equipment (blue hint) present more durable stopping forces, however we might expertise that efficiency lap after lap. 

Brake really feel was additionally markedly improved, and the information mirrored that. Peaks from acceleration to braking have been razor sharp, displaying immediate chew and simply controllable deceleration. Even sub-threshold braking functions painted good, straight strains, not the curved ones delivered by the less-than-precise modulation skills of the smaller brakes. 

Inventory MR2 Turbo

With big-brake equipment and inventory prop valve

With big-brake equipment and adjustable prop valve

The inventory MR2 Turbo proportioning valve works pretty nicely with the inventory brakes. However begin growing friction via pad upgrades, and you may see the bias begin to shift to the rear. A giant-brake equipment, due to its elevated leverage and stopping energy, simply magnifies these tendencies and sends much more brake bias to the rear axle. Putting in an adjustable proportioning valve permits exact balancing for perfect deceleration. 

Briefly, the improve made the braking system a correct high-performance device that aids the driving expertise somewhat than a limitation to be labored round.

Better of all, it gave new life to an older automotive with period-appropriate (learn: subpar) brakes. The Wilhelm/Wilwood bundle provides a really modern-feeling braking expertise to a beloved traditional, bringing one of many automotive’s few weak factors as much as fashionable requirements.

Pictures Credit score: Chris Tropea