GT Performance Mods 2005+ Mustang GT Performance and Technical Information

Upgrading Stock Calipers

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Old Jul 13, 2008 | 05:34 PM
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Jon_Purdy's Avatar
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Upgrading Stock Calipers

Is there anything to gain by upgrading the stock calipers on a daily driver that only sees "spirited" street driving? If I had a spare car, I might be tempted to race the car but that is not possible. Any thoughts?

Jon
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Old Jul 13, 2008 | 08:30 PM
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The stock calipers are actually pretty good... Your best bet, if you're looking for better braking durability, is to go to a more aggressive compound, like Carbotech or Hawk performance street pads, better fluid (Motul RBF600, Castrol, ATE) and maybe stainless flex-lines. The uprated pads will give you more initial bite, and are more fade resistant than the stockers. Please note that NO brake kit will change your minimum stopping distance, since that is tire-limited, at least for the first stop. Ten in a row, however is a different story.
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Old Jul 14, 2008 | 09:47 AM
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Thanks for the info Dave. The plan is to upgrade the brakes at the same time I have 275/40ZR18's put on the car. With that in mind, what should I be looking at caliper-wise?

Jon
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Old Jul 14, 2008 | 02:05 PM
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Well, if you want to step up your caliper game, then it's time for a "big brake kit," and all the usual suspects have offerings. FRPP's GT500 kit is (obviously) good, and there are also kits from StopTech, Brembo, Baer, Stillen, and the rest, but you're into mega-buck pricing.

I still think, that if you're doing "spirited street driving," that a better set of pads would do the trick. I'm going to guess that you're experiencing fade, either where the brakes just get hard and don't stop the car (overheated the pads) or where the pedal gets spongy and heads towards the floor (boiled brake fluid). If either is the case, then changing pads and fluids will do the trick for you.

If you're looking for shorter stopping distances, then upgrade your tires to something a lot stickier! Even with stock brake pads, you can slam on the brakes (panic stop), and put the car into ABS, which tells you that you have exceeded the maximum amount of grip from the tires. In other words, the brakes (stock, remember!) can slow the tires down faster than the tires can slow the car... If you do that a few times, then you'll overheat the pads, and they lose their ability to grip the rotor. More aggressive pads will withstand higher heat (generated from repeated high-rate braking), and thus can brake more often before failing. At that point, you may overheat the fluid before you overheat the pads. Swap fluid (I use Motul RBF600) and pads, and you will have a lot more durable braking package, that doesn't alter the front-rear braking balance, or play games with the ABS computer.

The primary advantage (in terms of performance) to a BBK is that the larger rotor area equates to lower temps with a given amount of braking force. Also, the larger rotor diameter means that less brake torque is required to slow the rotor down by a given amount. The primary downsides are cost and increased unsprung and rotational mass. If the kit isn't properly engineered, with the proper pad balance (front and rear), it can actually cause the ABS to false-trigger, and the car will actually take LONGER distances to stop! The GT500 kit comes with new rear pads to maintain balance, and the StopTech kit is pressure-neutral though the use of a larger quantity of smaller pistons.

There's a really good white paper on brake kit design up on StopTech's website, and I think it's a must-read if you're starting to get into brake mods.

FWIW, I open-track my car with stock calipers and rotors on all four corners. I did swap pads to Carbotech XP-10 up front and XP-8 in the rear, I'm running Steeda brake hoses, Motul fluid, and have cooling ducts for the front rotors, and I can run hard for lap after lap, with repeated 120+ to 35 heavy braking zones (hitting the brakes 400-500 feet from the turn-in point) without brake fade. I bleed the brakes after about 60 minutes of run time, and the pads and rotors last me about 3 weekends.

I'm not trying to talk you out of a BBK, but make sure that your goals are achievable with that parts combination before you drop the coin. When it all comes down to brass tacks, the tires are what really stop the car. You said you're upgrading, what are you going to? THAT will make a huge difference in what would be the "proper" brake package to run. Nitto NT555's are a LOT different in terms of grip than NT-01, Toyo R888, or Hoosier A6/R6 in the same size.
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Old Jul 14, 2008 | 02:56 PM
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From: New Carlisle, Ohio (20 miles north of Dayton)
I agree with Dave's first post. Since you wouldn't be racing the car save yourself tons of money with just a stock brake upgrade. I did Rotorpro rotors with Centric pads and Earl's SS brake lines and a good synthethic brake fluid. Did it all for under $500 shipped. If I had to guess it made about a 25% improvement over stock at least in the way they feel. And I also agree with Dave that big brake kit only help when you are trying to stop the car 10 times in a row from 100 mph. You don't need big brake kits for a street driven car. Just a waste of money that can be spent on other mods.
Scott

Last edited by 70MACH1OWNER; Jul 14, 2008 at 02:57 PM.
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Old Jul 14, 2008 | 10:48 PM
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Given the way I drive the car, upgrading the rotors, pads, lines, and fluid sounds like the way to go. Now I just have to decide on what products to go with. Thanks for the info.

Jon
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Old Jul 15, 2008 | 12:13 AM
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Originally Posted by SoundGuyDave
Please note that NO brake kit will change your minimum stopping distance, since that is tire-limited, at least for the first stop. Ten in a row, however is a different story.
sort of true....from 60 or 70 mph most brakes will apply enough pressure to achieve threshold braking... the point just before lockup. Over 100mph, though, bigger brakes may be required. But back to topic, spirited street driving, an upgrade in pads and maybe rotors should be adequate.
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Old Jul 15, 2008 | 07:11 PM
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Originally Posted by nonsensez9
sort of true....from 60 or 70 mph most brakes will apply enough pressure to achieve threshold braking... the point just before lockup. Over 100mph, though, bigger brakes may be required.
Or a more aggressive pad.
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