13" Viper brake upgrade
Former Sponsor
Joined: 10-03-2007
Posts: 45
From: tempe, az
Interesting... I have already said that I don't know a lot about brakes. But the guy who built these for me has been doing them for 25 years. He has successfully put these kits on thousands of cars, for both street and track. And at a fraction of the cost of Wilwoods. As has been stated, this is the entry level kit for people who want a small performance gain and a big bump in cosmetic appeal. We do realize this is not a race ready performance brake set. but I did put a couple of hundred miles on them on the Pacific Coast Highway last weekend and let me tell you, no matter what scientific stuff may be thrown out to confuse people, these are head and shoulders about stock HHR brakes and won't put you in the poor house.
Todd, I don't know you and don't have anything against you, but you do have a horse in this race. You want to sell your Wilwood kits. You even changed your signature to Wilwood brakes, which was the sway bars until this post. And that is fine, but lets not try to hide that fact. You do indeed have a horse in this race. And it is fairly obvious to me that the powers that be on this forum are trying to help you with that. That is why I can't get any information about my friend becoming a Supporting Vendor on this forum.
Wilwoods are nice brakes kits. They are not Brembos, but they are nice. Unless something has changed, Wilwoods are also not street legal. Brembos are. The ultimate kit that Chris will build will use Brembo calipers and two-part rotors, and will still be less than the Wilwoods AND it will be street legal.
The problem with all of these is that they are just too dang expensive for most people who just want a little extra performance bump for their street vehicle. What I contact Chris for was to put something together that gives just that but is still affordable. And I think we have that. No, it is not going to please everyone, just like the, in my opinion, crazy priced big name brakes aren't. But there is enough room around to have more than one supplier selling more than one kit.
And foolmoon, thank you. That is what I have been saying from the start. The larger rotor will shed heat better and give better braking when it is needed. And even though I don't know fancy science to try to impress and confuse people, after nearly 1000 miles on them I can tell you that they do improve braking immensely.. and they look cool as he... And those two things are what they are intended for. And for barely more than a normal brake job done at a shop, or buying normal size slotted and drilled rotors and doing them yourself. And this package will give far better braking than either of those options.
Todd, I don't know you and don't have anything against you, but you do have a horse in this race. You want to sell your Wilwood kits. You even changed your signature to Wilwood brakes, which was the sway bars until this post. And that is fine, but lets not try to hide that fact. You do indeed have a horse in this race. And it is fairly obvious to me that the powers that be on this forum are trying to help you with that. That is why I can't get any information about my friend becoming a Supporting Vendor on this forum.
Wilwoods are nice brakes kits. They are not Brembos, but they are nice. Unless something has changed, Wilwoods are also not street legal. Brembos are. The ultimate kit that Chris will build will use Brembo calipers and two-part rotors, and will still be less than the Wilwoods AND it will be street legal.
The problem with all of these is that they are just too dang expensive for most people who just want a little extra performance bump for their street vehicle. What I contact Chris for was to put something together that gives just that but is still affordable. And I think we have that. No, it is not going to please everyone, just like the, in my opinion, crazy priced big name brakes aren't. But there is enough room around to have more than one supplier selling more than one kit.
And foolmoon, thank you. That is what I have been saying from the start. The larger rotor will shed heat better and give better braking when it is needed. And even though I don't know fancy science to try to impress and confuse people, after nearly 1000 miles on them I can tell you that they do improve braking immensely.. and they look cool as he... And those two things are what they are intended for. And for barely more than a normal brake job done at a shop, or buying normal size slotted and drilled rotors and doing them yourself. And this package will give far better braking than either of those options.
The signature has not change since forever though. Granted I have not pursued the HHR for some time now so I'm not sure the "sway bar" comment meant.
Who told you Wilwood brakes are not street legal? They are no more or less legal than any other system. There are no DOT requirements for a brake caliper or kit to be deemed legal. This is the same argument others make of ss braided hoses that are DOT approved. There is not such thing- there are DOT compliance standards that are recommended for such parts and some may or may not pass those tests. But there is no requirement for any of these calipers, hoses or your parts to be tested and certified legal.
Cost wise....$1200-1500 for a front big brake kit is pretty much the lower end of the spectrum. But I fully understand that is not in everyone's budget. And I have zero, nothing, nadda, against this oe cross fit application you are working on. In fact I generally welcome them as they give the consumer a chance to analyze the pros and cons of both.
My main reason for posting was that another person has made comments that are simply not correct when dealing with brakes. Your comments earlier where more spot on than some of the others. It irks me when I read someone putting up posts asserting to be the final word that are not true. It spreads rumors and misinformation that can hurt any of us in the business. I prefer to educate and give folks the tools to make a smart decision.
Thread Starter
Senior Member
Joined: 06-16-2006
Posts: 830
From: Bakersfield, CA
Todd, I owe you an apology. It was another supporting vendor with the sway bars in the signature. I guess since being a Supporting Vendor turns the letters brown in your name I thought it was the same one.
Former Sponsor
Joined: 10-03-2007
Posts: 45
From: tempe, az
Some good reading... Looks like most agree that larger rotors are good for braking. And that is all this kit is about. You guys are talking about calipers and lots of other stuff that is not even involved with what we are doing here - yet. But it does appear that lots of big name companies think that larger pads, causing more friction, do help braking. Read the Audi page especially.
http://www.xtremeimportperformance.c...ed-rotors-myth
http://www.camarotech.com/brakes.html
http://www.audiworld.com/tech/wheel16.shtml
http://www.xtremeimportperformance.c...ed-rotors-myth
http://www.camarotech.com/brakes.html
http://www.audiworld.com/tech/wheel16.shtml
A larger effective radius is what is spoken of later in the text about a larger swept area. And moving to a four pot vs two or single can be right also. Just adding pistons is not going to change things. *What's missing in the Audi page is that they are referring to AUDI parts- meaning whatever parts are being used here someone has (hopefully) done some calcs on it to compare the info.
Keep in mind that if you move from a pad height of 1.5" to one of 2.5" that while your surface area and swept area is UP that the effective radius is actually DOWN on the same rotor and you've lost torque. That's the reason for race pads to be "tall and skinny" (viewed) rather than short and fat as most oe pads are to promote longevity.
The increase/decrease in function of the rear relative to the fronts in the Audi page are hard to quantify without more info. Why? Because they are referring to static line pressures. Yes the rears can go up or down and help/hurt the rear brake performance. But what's missing is that function is dynamic braking not static. The rear pressure is run through a proportioning valve and has preset knee point for reduction. If the front pistons are too large rear pressure is too low...if the front pistons are too small they require more effort and then the rear pressure goes up- but only for a moment as the prop valve cuts is by up to 50% negating what was a great plan in static pressure applications.
Former Sponsor
Joined: 10-03-2007
Posts: 45
From: tempe, az
For grins...and then I really do need to go out and cut the lawn!
Factoring a 12" rotor and those two pad heights above:
The 2.5" pad with more "swept area" generates 10% less torque than the 1.5" tall pad that's going to wear out sooner. Oh, and it will probably wear out the rotor sooner too!
Factoring a 12" rotor and those two pad heights above:
The 2.5" pad with more "swept area" generates 10% less torque than the 1.5" tall pad that's going to wear out sooner. Oh, and it will probably wear out the rotor sooner too!
Senior Member
Joined: 07-01-2010
Posts: 284
From: Denver, CO
Todd TCE, as to your rebuttal: if we follow your theory, any brake system that has the power to force the tires into lock is as good as any other system that can do the same, since the limiting factor is the coeficient of friction of the tires on the road surface. Therefore, I can see no reason anyone would ever buy your product - with most modern brake systems, you can continue to apply pressure to the pedal until the tires go into skid (the anti-lock kicks in) even on a dry surface. I know this is true of my HHR SS - it hass happened in commuting for me when the traffic compresses from highway speeds and I am forced to use the limits of traction.
However, there are other factors involved. Pedal "feel" (brake feedback through the pedal) and lack of fade with continued use are two big factors to contend with in performance driving. larger rotors can (and do) improve both.
As for larger pads having no effect, since the beginning of performance braking (sometime in the 1930's at least) there has been talk of something called "brake swept area." This is the total area that the brake surface "sweeps" on the stopping media (whether that's a rotor and pads or a drum with shoes). This figure is all-important in determining the total amount of braking force for a given pedal pressure, reducing fade due to excessive pad out-gassing, and again improving pedal "feel."
Don't take my word for any of this - my Masters is in Management Science, not Automotive Engineering. But there's an organization you might have heard of called the Society of Automotive Engineers (SAE). They're THE last word in automotive science and research. check out this slide presentation by one of their members - it supports all I have said (and some of what you said - I do agree with some of your post
):
http://www.sae.org/events/bce/tutorial-limberg.pdf
However, there are other factors involved. Pedal "feel" (brake feedback through the pedal) and lack of fade with continued use are two big factors to contend with in performance driving. larger rotors can (and do) improve both.
As for larger pads having no effect, since the beginning of performance braking (sometime in the 1930's at least) there has been talk of something called "brake swept area." This is the total area that the brake surface "sweeps" on the stopping media (whether that's a rotor and pads or a drum with shoes). This figure is all-important in determining the total amount of braking force for a given pedal pressure, reducing fade due to excessive pad out-gassing, and again improving pedal "feel."
Don't take my word for any of this - my Masters is in Management Science, not Automotive Engineering. But there's an organization you might have heard of called the Society of Automotive Engineers (SAE). They're THE last word in automotive science and research. check out this slide presentation by one of their members - it supports all I have said (and some of what you said - I do agree with some of your post
):http://www.sae.org/events/bce/tutorial-limberg.pdf
Former Sponsor
Joined: 10-03-2007
Posts: 45
From: tempe, az
if we follow your theory, any brake system that has the power to force the tires into lock is as good as any other system that can do the same, since the limiting factor is the coeficient of friction of the tires on the road surface.
Bingo! You hit it on the head. Tires are the primary limiting element of braking forces. At the risk of sending you to a competitor you might browse the Stoptech site a bit and read their lengthy story about such testing.
A brake kit is no guarantee of shorting stopping distances- I said this before. If it were true it would pan out on all surfaces no? Why wouldn't it be shorter in the wet or snow also? Because maximum adhesion remains at the road surface. You'll find also that oe suppliers use a larger swept area than race calipers do. Why? Because they last longer and are more stable- less prone to run out and don't shock the rotor as much with their heat build up. Race pads run a short pad and use only the outer edge of the rotor where temps are higher but pad wear is greater and stresses are more. While true that swept area is part of the story its simply not creating more torque all other factors being the same.
Why would anyone buy my (or anyone's) BBK? A couple of reasons;
1. Stopping problems for most if you really ask them is not about 'one time' stopping, it's repetitive stopping and fade. More durable parts and rotor mass (as you rightly point out) are key. Heat saturation can play hell with both pads and rotors.
2. Responsiveness is improved; moving to a fixed mount caliper ensures a faster reaction time to the clamping. Piston sizing is altered to give a firmer and more linear feel for modulation.
3. A change of tire; meaning a move from All Season tires to R compound means the brakes may be over taxed for the ability of the tire. More road grip means more brake torque can be applied. As the stock parts are pushed harder they lag and overheat.
4. More horsepower. Huh? Yes I say that too. But for some who add it and truly use it on a race track their speeds are higher. So what? Remember that Kenetic Energy thing? That's velocity squared. Meaning if the car runs 20mph faster.....I'll let you do the math, you get the idea.
5. Appearances. Yes I said it. I'd wager 70% or more of BBK sales are sold mainly as an appearance enhancement more so than function. Who am I (or you) to tell them how to spend their money?
6. Shorter stopping distances. Huh? What?? You just said....! (left this one for last) But in some cases it IS true. How can it be, you just preached a page about it can't be etc. Yes but what I did not say (so not to confuse people more) is that shorter distances can be achieved; not by just fitting a bigger rotor for more leverage but other means. A proper designed front bbk can enhance rear brake performance and effectively force the rear brakes to work in a manner they did not before. This is done by comparing all the data including the pressure requirements and evaluating knee points and such as well to not over or under tax the fronts, thus making the rears perform at maximum efficiency.
The other issue is time. With a shorter pedal and more responsive caliper design having less travel you can achieve the maximum rotor torque sooner. A real reaching reply you say? Really? Suppose your are doing 85mph, you're moving nearly 125ft per second. So even .2 seconds (two tenths) of time nets nearly 25ft. Milliseconds is probably more like it actually but there are racers who'd give their right nut for a few feet deeper braking by waiting until the very last second to get it done.
Bingo! You hit it on the head. Tires are the primary limiting element of braking forces. At the risk of sending you to a competitor you might browse the Stoptech site a bit and read their lengthy story about such testing.
A brake kit is no guarantee of shorting stopping distances- I said this before. If it were true it would pan out on all surfaces no? Why wouldn't it be shorter in the wet or snow also? Because maximum adhesion remains at the road surface. You'll find also that oe suppliers use a larger swept area than race calipers do. Why? Because they last longer and are more stable- less prone to run out and don't shock the rotor as much with their heat build up. Race pads run a short pad and use only the outer edge of the rotor where temps are higher but pad wear is greater and stresses are more. While true that swept area is part of the story its simply not creating more torque all other factors being the same.
Why would anyone buy my (or anyone's) BBK? A couple of reasons;
1. Stopping problems for most if you really ask them is not about 'one time' stopping, it's repetitive stopping and fade. More durable parts and rotor mass (as you rightly point out) are key. Heat saturation can play hell with both pads and rotors.
2. Responsiveness is improved; moving to a fixed mount caliper ensures a faster reaction time to the clamping. Piston sizing is altered to give a firmer and more linear feel for modulation.
3. A change of tire; meaning a move from All Season tires to R compound means the brakes may be over taxed for the ability of the tire. More road grip means more brake torque can be applied. As the stock parts are pushed harder they lag and overheat.
4. More horsepower. Huh? Yes I say that too. But for some who add it and truly use it on a race track their speeds are higher. So what? Remember that Kenetic Energy thing? That's velocity squared. Meaning if the car runs 20mph faster.....I'll let you do the math, you get the idea.
5. Appearances. Yes I said it. I'd wager 70% or more of BBK sales are sold mainly as an appearance enhancement more so than function. Who am I (or you) to tell them how to spend their money?
6. Shorter stopping distances. Huh? What?? You just said....! (left this one for last) But in some cases it IS true. How can it be, you just preached a page about it can't be etc. Yes but what I did not say (so not to confuse people more) is that shorter distances can be achieved; not by just fitting a bigger rotor for more leverage but other means. A proper designed front bbk can enhance rear brake performance and effectively force the rear brakes to work in a manner they did not before. This is done by comparing all the data including the pressure requirements and evaluating knee points and such as well to not over or under tax the fronts, thus making the rears perform at maximum efficiency.
The other issue is time. With a shorter pedal and more responsive caliper design having less travel you can achieve the maximum rotor torque sooner. A real reaching reply you say? Really? Suppose your are doing 85mph, you're moving nearly 125ft per second. So even .2 seconds (two tenths) of time nets nearly 25ft. Milliseconds is probably more like it actually but there are racers who'd give their right nut for a few feet deeper braking by waiting until the very last second to get it done.
Last edited by Todd TCE; Nov 1, 2010 at 05:08 PM.
Thread Starter
Senior Member
Joined: 06-16-2006
Posts: 830
From: Bakersfield, CA
So... we can all agree that larger rotors do indeed help braking, if only by helping shed heat. So this is a nice kit my buddy had put together. Can we find 10 interested parties for a group buy?
Senior Member
Joined: 07-01-2010
Posts: 284
From: Denver, CO
I'm down for a group buy. Todd TCE, we're all on the same page here, it seems. 
Do you like the floating rotor/fixed caliper system better? I don't believe I've ever had a car with that setup (in 65 cars) but have had motorcycles with them.
Do you like the floating rotor/fixed caliper system better? I don't believe I've ever had a car with that setup (in 65 cars) but have had motorcycles with them.
Former Sponsor
Joined: 10-03-2007
Posts: 45
From: tempe, az
I'll have to pass on the GB myself...lol Good luck on it though. My comments were never intended to steer anyone away from the kit and I don't know enough about it to evaluate it even if I wanted too. The only time I'd weigh in is if asked the pros and cons of it vs the other option. And we've covered some of that already. We know I can't match the price point so me thinks there's a market to be had for you as well!
Me, I have agreed all along that bigger rotors are a help. I live it. My main point was that it's not correct to assume that simply moving from 12" to 14" rotors is going to stop you better.
The issues always comes down to this thing "stops better". It's kind of a bogus two words that say a lot but nothing at all. I'm pretty certain I know what most consumers take it to mean.....like buying the "performance" rotor: somehow you will magically stop shorter. On the other hand "performance" can mean longer life, lower temps, less prone to hot spotting or simply looking better. We see this on nearly every aftermarket rotor-"Improved Stopping" or such. Really? How? It's the same diameter and Lewis was all over that aspect so he knows it can't be.
As for the other parts; fixed vs floating, my world revolves around fixed mounted calipers and fixed rotors. For "performance" floating or sliding calipers are not the norm. But there are a lot of them out there so they are certainly a proven part. The fixed mount caliper (4 pot example) allows quicker reaction time and more linear pressure as it's not a push/pull thing nor relies on how well lubed the slides are.
Floating rotors are nice in that they allow the two metals (alum/iron) to expand at different rates. They (like the floating caliper) are more tolerant of run out as both wiggle some under use. Too much though and they rattle and require excess pedal travel to pull straight. Again; better? Not something you're going to exploit as a daily driver that's for certain. And far more costly to buy and service as fixed.
Me, I have agreed all along that bigger rotors are a help. I live it. My main point was that it's not correct to assume that simply moving from 12" to 14" rotors is going to stop you better.
The issues always comes down to this thing "stops better". It's kind of a bogus two words that say a lot but nothing at all. I'm pretty certain I know what most consumers take it to mean.....like buying the "performance" rotor: somehow you will magically stop shorter. On the other hand "performance" can mean longer life, lower temps, less prone to hot spotting or simply looking better. We see this on nearly every aftermarket rotor-"Improved Stopping" or such. Really? How? It's the same diameter and Lewis was all over that aspect so he knows it can't be.
As for the other parts; fixed vs floating, my world revolves around fixed mounted calipers and fixed rotors. For "performance" floating or sliding calipers are not the norm. But there are a lot of them out there so they are certainly a proven part. The fixed mount caliper (4 pot example) allows quicker reaction time and more linear pressure as it's not a push/pull thing nor relies on how well lubed the slides are.
Floating rotors are nice in that they allow the two metals (alum/iron) to expand at different rates. They (like the floating caliper) are more tolerant of run out as both wiggle some under use. Too much though and they rattle and require excess pedal travel to pull straight. Again; better? Not something you're going to exploit as a daily driver that's for certain. And far more costly to buy and service as fixed.
Senior Member
Joined: 07-15-2009
Posts: 2,070
From: Waterbury CT
