|TT Brake FAQ
Q: What does the TT kit change?
A: It gives you bigger rotors (11" --> 12.3"). It also gives you carrier adapter brackets to fit your stock caliper over the new, bigger rotor. You will also get pads.
Q: Where do I get the TT kit?
A: Check out Potterman's. They offer the kit with various rotor brands, as well as pad brands. In my experience, their price is the best.
Q: If I get the TT kit, can I put my front rotors on the back?
A: No. Your rear rotors also serve as hubs. The bearings for the rear wheel are in there and the rear and front rotors are therefore very different (see pic below of rear rotors). If you want bigger rear brakes, check out Bahn Brenner
Q: Is the TT kit better than Wilwood?
A: There is hardly any way to categorize this. The TT kit increases swept area which will increase stopping power, whereas the Wilwood kit increases the stopping force (applied by the upgraded 4-piston calipers), which also increases stopping power. The only way to know is to compare the force applied by the stock caliper and the Wilwood caliper and compare the two. Here's why:
The factors that stop your car are outlined as such (if you can't mulitply, please skip):
Work Done by brakes per "a" degrees of swept area -->
W = f*d = f*r*a = m*P*A*r*a
Where, W = work, m = coefficient of friction, P = pressure applied, A = area under brake pad, r = radius of rotor, a= angle swept
Stopping power = work/time. So see how long it takes to stop your car from some pre-set speed and you can calculate the "stopping power", assuming you know some of the variables above.
I posted this once before and some pencilneck got mad because I used pressure instead of force. Well, you won't measure the force directly, you would have to measure pressure. Notice, however, that pressure is P=F/A (force divided by area). P is multiplied by A, so in the end the quantity P*A =F. By measuring pressure, you get the force. Nobody is going to conduct this experiment anyway, but if you did, you'd calculate pressures (or "stress" as the MSE and ME guys call it).
Pros for TT kit
1. OEM parts = easy to find/replace.
2. Affordability (about $485)
3. Uses stock calipers, so you don't have to bleed your brakes
Cons for TT Kit
1. uses OEM parts!
2. if you have older calipers, you might need to replace them, and then you are getting into the price range of a total brake rebuild
Pros for Wilwood
1. 4 piston calipers are neat
2. This is affordable for a total brake re-do
3. the aluminum Wilwood calipers are feather light
4. Changing pads is a snap (literally) with the nifty Wilwood design. They come right out of the top (see pic below)
Cons for Wilwood
1. Technically, these brakes are for race applications only.
2. Since the parts are not OEM, if something needs replaced it is more expensive
Q: Why do I have to worry about stopping power?
Almost all of the work done by your brakes is devoted to sucking kinetic energy from your moving car and converting it to dissipated heat (which is why slotted rotors is such a good idea). What this tells you is the following. If you want to increase the stopping power of your car (the work done per unit time) you:
1) Increase the coefficient of friciton between rotor and pad (the factor "m" from above), i.e., try different materials (both kits do this)
2) Increase the pressure (P) between rotor and pad, i.e., get yourself some beefy calipers (i.e. Wilwood Kit)
3) Increase the area of your pads (A).
4) Increase the radius (r), and therefore the diameter, of your rotors (i.e., TT Kit)
In this case, using the TT kit, we go from a 280mm disc to a 312 mm disc, increasing our radius by a factor of 1.114. So we increase the work by a factor of 1.114. (Since you use the stock caliper, pressure remains the same).
This equates to an ~11% increase in stopping power, given a fixed amount of time for stopping measurement, the same pressure P exerted by the piston, the same area A of the pad, the same coefficient of friction m, and a fixed rotation of the rotor angle a. This is all theoretical, of course.
In realistic situations, I would guess that the net increase in stopping power would be on the order of ~5% (I don't care if you think I'm being subjective. This is an internet forum ). This is far less than what you would gain with a brand new 1900$ Brembo kit, but it's a nice alternative.
Now it all comes down to price. MMP sells the Wilwood kit for about $650, which isn't much more than the TT kit. You basically get a nice brake rebuild without using any stock parts. After debating over this for months, I chose the Wilwood kit. The Wilwood kit will give you kick ass braking, and it will fit in 15" wheels or larger. That's what I eventually went with: