Rear brake size? Really ford!

[Laztug]

Here I was upset because my rear brake rotors were so big!:lol: I couldn't fit my 15x10s back there.

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[Turbo Ghost]

Jesus tap dancing Christ.

:doh:

 

[Zerobar78]

This: http://wilwood.com/BrakeKits/BrakeK...R&year=2015&make=Ford&model=Mustang&option=GT

And of course their matching front kit. I had their SL6R kit on the front of my new edge, great quality stuff and excellent customer service and they're substantially lighter than stock.

 

[908ssp]

Sorry Tomo you are wrong no race car even rear engine race cars have equal braking front and rear. The laws of physics simply doesn't work that way. No matter where you put the weight the weight shifts to the front and all race cars including the ones in your pictures above have bigger more powerful brakes on the front. You can even see it if you look closely. The Aston you wrongly point out has the same size rotors in fact they don't the rears are a narrower band than the fronts and the calipers are smaller.

 

[G RUSH]

Sorry Tomo you are wrong no race car even rear engine race cars have equal braking front and rear. The laws of physics simply doesn't work that way. No matter where you put the weight the weight shifts to the front and all race cars including the ones in your pictures above have bigger more powerful brakes on the front. You can even see it if you look closely. The Aston you wrongly point out has the same size rotors in fact they don't the rears are a narrower band than the fronts and the calipers are smaller.

To add to this, front bias braking is inherently more stable. There is not a single racing driver out there who wishes to be in a rear brake lockup situation because it's incredibly difficult to control.

The reason I posted the Ferrari in the first place is because it's a cool (hot?) picture of the vast majority of braking setups, especially for 'daily' cars, and quickly sums up why the Mustang has the brakes it does.

Glow is accentuated by the carbon brakes, steel does not go that bright.

 

[Impulsed7]

Holy crap, throw some track pads front and rear and then tell me you don't have enough braking. Go out and do it before saying I NEED better stuff.

 

[Tomo]

Also

I really didn't have any intention of starting any sort of internet fight, but flat out saying I'm wrong is really aggressive. So, internet fight it is. Firstly, perhaps I wasn't clear enough when I said things like "more rear bite" and "60/40". To the prior, I meant it as a relative term, and to the latter with front being represented by 60. However, because you are so adamant, I'll defend the position that:
A. Symmetrical setups have merits and could be found in motorsport
B. Some of these cars would potentially have more rear bias than YOU are comfortable with
C. Despite the fact that my intention was never to attack Ford's decision or your new car (as you seem to believe I've offended it's potential lacking), I now will suggest why they could be better.

A. There are other exhibits of cars with symmetrical, or REAL damn near symmetrical setups.

Lets start with A.

Now there is more going on here in the front caliper. Seems a lot more cut-away for venting and cooling. But these rotors are within 10mm IF THAT and very well could be the same size, and those rears are 6 Pot calipers. I'd be a bit surprise that the fronts were what then... 8 Piston? I don't think so. (Why more pistons? I'll get to that later)

However, I can easily make the case that race teams would even want to have symmetrical set ups for the ease of carrying replacement parts. Carry 2 extra calipers to any race and now you can replace any corner even with 2 failures. Rotors? Pads? All easier to replace. And given these rotors are nearly the same size, there isn't much weight advantage to slimming down the rears. You can adjust the clamping force through the bias adjuster they already have.
To be sure the corvette is not wholly unique in its setup.
Can you find evidence supporting otherwise? Sure, but that was never my point. You were intent on saying "No One"...not me.

B. Race cars run REALLY BIG Tires, and nearly universally (new Nissan being an exception) rear tires being run are bigger than fronts. One could, in fact, reasonably say that there is more rear grip available in a strict tire-to-tire comparison. IF it were me designing a brake system I'd want to make as much utilization of brakes as possible, this means that I don't want to over-work my fronts compared to rear brakes. End up with issues like...needing to frequently replace front pads while rears are fine (a common mention in this very thread). Obviously full utilization of as much braking force as you can get is the positive of moving more braking force rear-ward. What are the negatives? Rear lock-up, and potentially snap-rotation. OH! Rear lock up! Yeah that's bad, no doubt. But then..so is front lock up. Which is worse? Conventionally, particularly by manufacturer standards rear. However, the most ideal brake set up is closer to 4 at once. This is THE MOST Efficient/utilized, having all 4 tires lock up at once (though if trail-braking likely will cause spin)

But Tomo! Didn't you say the rear tires have more grip than the fronts? Well...yes I did. In a tire-to-tire comparison in a strait line those rear tires can likely suffer more braking force than the fronts. Things get a little messy because we end up with a shift in weight going forward, even with all the anti-dive teams try to build into the suspension. So, the rear tires end up not having as much weight over them and being able to do less than they'd otherwise be able. Is it less than the front? Probably, but I'd say its a real squishy area that might require constant adjustment..with some kind of knob they might put in the cabin for the driver...I wonder what we'd call this kind of knob?

Now, not all racing is so strait forward as "brake in a strait line" It's certainly advisable, because even if you don't have issues with your rear locking before the front, well...that might mean your front locks before your rear. If that's what's going on expect to go off track. Can't turn and brake with no grip. So, maybe you need a bit of reaction time, to realize you need to pull off the brakes. OK, maybe you would like your car to rotate a little more at corner entry...well rear bias might be your friend, since that's what happens when you turn in and pull off the brakes with rear bias. yes OFF of brakes with some rearward bias rotates. Which IS FASTER, drivers want it, and teams want it. Plenty of articles out there about getting more rotation.

I think maybe that is sufficient for B?
Off to the C we go! (are we pirates? sailors?)

C. Ford used a single sliding rear piston in the back of all performance levels of their Mustang. Why? Hmm, good question, they seemed to believe the fronts could be improved, and if we are improving the entire brake system, should we not also improve the rear?

A valid question I think. I wouldn't fault anyone for thinking as much. Maybe you only care about the aesthetics, I don't think you are wrong there either. A lot of other performance cars match front Brembos with some line of better rear Brembos.

Here's the bottom line, the rear caliper is capable of locking up the rear tire. So, it's got sufficient clamping force. Maybe this changes with some REAL sticky tires.
Do the fronts do more work than the rears on the Mustang? Sure do. Do they have more clamping force with the 4 Piston or 6 Piston Brembos? Nope.

Unless ford installs a new proportioning valve or a different master cyl into PP Mustangs, the fronts do just as much of the grabby and squeezy as the non performance. Locking up tires is locking up tires. Which, is never the best way to stop, but certainly shows your brakes are up to muster. (slight difference withstanding on larger rotors because of the leverage being further from the hub center which means more of it)

What bigger brakes, and even bigger rotor do is allow for more consistent braking for longer. They are larger heat sinks and dissipate heat that much better. Also the Brembos are made of aluminum, its no secret that aluminum is lighter than iron. And finally, having multiple pistons allows for the brakes to have the clamping force more evenly distributed across the pad and rotor. Preventing any one particular part of either getting too hot. Some brake manufacturers even get fancy and change the size of the pistons with the "Front" pistons being smaller than the "Rear" (front to back in the direction of rotor rotation) to even out the pad wear.

However, again without a change in the hydraulic forces you will not get more clamping FORCE from a multi-piston caliper.

Here's where things can improve though. 1. Iron, we know is heavy the rear single piston sliding caliper on the Mustang is iron, weight gains could be as much as 10lbs . 2. Sliding calipers actually are a bit slower to respond as compared to a like-sized two caliper piston, worth replacing for that fact slower? Eh? Not likely. 3. More even clamping force achieved with multi-piston for a more even pad wear. 4. Sliding Calipers SUCK to change brakes on. (though I'll admit I've not changed my new, not even built yet brakes) 5. Well...it just looks better!


Phew. Pretty sure I lost some people in there. Lots of TL;DR.

Feel free to have a different opinion. I'm merely stating mine.

(Edit: replace : for ; to avoid ( : D)

 

[Todd15Fastback]

 

[Zerobar78]

All of you are wrong, brakes are for sissies.

 

[Tomo]

All of you are wrong, brakes are for sissies.

As Bugatti Said.

I make cars to go. Not to stop.

 

[Norm Peterson]

But Tomo! Didn't you say the rear tires have more grip than the fronts? Well...yes I did. In a tire-to-tire comparison in a strait line those rear tires can likely suffer more braking force than the fronts. Things get a little messy because we end up with a shift in weight going forward, even with all the anti-dive teams try to build into the suspension. So, the rear tires end up not having as much weight over them and being able to do less than they'd otherwise be able.

It's late so I just scanned through this. I think you're getting cause and effect mixed up a bit.

Suspension anti properties do not affect the amount of weight shift. That is solely a function of deceleration, sprung mass (weight), CG height, and wheelbase.

What the antis do affect is how rapidly the forward (in this case) load transfer occurs, and how much of it results in visible evidence (in the form of nose dive/tail rise). The boldfaced point means that if you make all of the forward load transfer occur geometrically, there will be no suspension movement. None. Not even if you had replaced the race-stiff springs with base V6 stock springs.

But at x amount of deceleration g's there still will be that same forward load transfer (and it will occur almost instantaneously, since it won't have to wait for the suspensions to compress and extend into their equilibrium positions under that braking).

Don't feel bad or offended. Lots of people confuse car body movement as causing the load transfer when it's really the other way around.


Norm

 

[Norm Peterson]

So got to flipping through my ford booklet for my gt with the performance pack and it says I have 13" Rotors with a SINGLE PISTON rear brake caliper! Like wtf was ford thinking putting a monster 6 piston up front with that useless ass thing in the back? Is there anyone making just a brake caliper upgrade without changing out rotors too?

13" rotors and single-piston calipers are already more than your car actually needs, at least until you get pretty serious and pretty fast out there on a road course near you. Even the 11.8" rear rotors and 1-piston calipers on my car are more than you'll ever actually need on the street, and they're better than the OE pads and DOT 3 fluid that I don't think anybody has mentioned yet.


Norm

 

[Tomo]

Don't feel bad or offended. Lots of people confuse car body movement as causing the load transfer when it's really the other way around.


Norm

The thought is certainly appreciated, I do know that the cause-effect is in that direction you indicated. However, the dive characterized by the loading of the front suspension does *I think* contribute to a secondary lift in the back end of the car. If you can use the geometry to try to flatten the car out, you don't get rid of the initial transfer of the weight, but you do I think end up preventing I guess the "Elastic Weight Transfer". I could be completely wrong, bit the vehicle motion in conjuncture with the initial transfer I think causes a further weight movement that Anti-dive would alleviate,

 

[ktapia]

Lol at some of these comments:lol::lol:

 

[Norm Peterson]

. . . vehicle motion in conjuncture with the initial transfer I think causes a further weight movement that Anti-dive would alleviate,

Not wrong at all, but I think I'd categorize it as a secondary effect because it needs that movement to have happened.

Certainly the geometric component [of load transfer] also varies with body movement, and if there's a net upward movement of the sprung mass then there will be more load transfer resulting directly from that. Plus a tiny amount of actual weight transfer due to the pitch angle, maybe half a percent or so.

Anti-dive and anti-lift (rear) geometries must change according to the suspension movement. Whether you end up with anti geometries that increase or decrease . . . depends. Conceivably they can even start out decreasing, level out, and then increase (as illustration only, anti-squat for a stock S197 does exactly this as the rear goes from OE static down into squat, and its sometimes evil twin anti-lift could do the same thing in a substantially lowered car under braking). Or the variations could be made to work the other way.

I suspect that anti-lift decreases slightly as the rear of the S550 rises under braking, which is probably a good thing.


Norm

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