Yes, I've seen many crude lookin' hoses and safety wire down there. Looks funky but it WORKS!

- Brent

 

I think I am explaining it quite clearly. Aside from the brake argument, brush up on basic physics. Rotational velocity is NOT the same throughout the radius of a disc. Thats ridiculous, go look at a record. Same physics applies to a CD-ROM, Constant Angular Velocity vs Constant Linear Velocity. CAV devices read at the same RPM, but the read speed increases as the disc reaches the edge. CLV devices read the same speed throughout the entire disc, but the disc slows in RPM towards the outer edge to maintain the same linear velocity.

That being said, some more properties of basic physics: mechanical advantage. The further away from the pivot (that would be the imaginary line drawn through the front wheel hub perpendicular to the rotor surface) you grip, the more your force is multiplied. This is the same way a longer wrench helps you exert more force on a pivot. This is the same way your brake pedal multiplies the force of your foot as you step on it. Pivot arms multiply force.

From Wilwoods site:
http://www.wilwood.com/products/rotors/rotors.asp

Its right there at the top. A key factor in rotor design is the diameter which either increases or decreases mechanical advantage. The more mechanical advantage you have in braking force, the more able you are to effectively control the maximal braking force before lockup, ie. ride the fringe of lockup so to speak. A smaller diameter rotor requires a lot of caliper force, and will tend to *suddenly* lock up. The amount of modulation available between rotation and lockup is very small, whereas a larger rotor, with more mechanical advantage will have a more linear and gradual progression to the point of locking. Both brakes will still lock if you stab the pedal, but larger brakes ARE superior due to the ability to apply braking force more evenly and linearly.

 

this all sounds a LOT different than what you were spewin before a lot more clear and concise.

Yeah you CAN get better pedal "feel" (used in a performance sense) with the caliper placed further from center-

I dont think it will help it stop any faster though- i may be mistaken on this.

I havn't really had time to think todays comments through-
i'm in the middle of moving 800lbs of crap into my truck and getting ready to drive 20 hrs in the next 28 hrs or so

so pardon my carelessness...

 

Thus far, we have been discussing braking at the limit of adhesion, ie. lockup. In that performance envelope, it will allow you to control braking more effectively. As far as braking from some ridiculous speed like 100mph, you better believe a larger (diameter) rotor will bring you down faster. Mechanical advantage is a wonderful thing.

 

Whew! I just stumbled onto this thread, and you guys really go at each other...umm I mean go at the topic.

I'm not a big supporter of treyZ28 in most of his posts, and he knows this well, BUT in this case, when he's talking about braking (not math or basic physics), he's in his own ballpark.

A few thoughts:

Dwoodaudio had a good post back on page 2 of 5. It's worth a re-read.

ZPaul2Fresh8 is not dispensing good advice. No flame intended, but I was struck by his naivete. Sorry, PF.

bryanz882 has a good handle on marketing things on page 4 of 5.

TheHeadFL is a little confusing. Multipiston calipers can more evenly distribute pad loading, especially with variable diameter(area) pistons, but if there's not enough disk mass to sink the heat, and dissipate it, the caliper is irrelevant. ABS can take a lot of "pedal finesse" out of maximum braking, as it was intended to do.

FWIW, max stopping is not necessarily just prior to lockup, but at some slight % of wheel sliding. A good ABS can approach that very closely.

Larger diameter rotors don't necessarily mean better control due to mechanical advantage. Rather, larger more massive rotors heat up less for the same amount of braking, and don't reach pad fade temps so soon. Hey the best braking cars in the world (F1) have 13 inch wheels and relatively small diameter diameter rotors. Of course they are carbon with carbon pads, and caliper stiffness is critical, but they are tiny. They also have normal tire loads (down onto the road) that vary from about 4 times the vehicle weight at 200 mph to just over the vehicle weight at 50mph, and no ABS. Watch them braking for the turn at the end of the oval portion of Indy. The whole braking system is working as a team, with all the mechanical advantage needed. The mechanical/hydraulic part is relatively easy to design/build.

Unless you are limited by rules (F1 and Winston/Nextel Cup) run the largest diameter rotors because they will probably be the most massive and stop you more times from high speed than smaller, lighter rotors.

Most SCCA autocross courses are not hard on brakes: If you never get out of first (or maybe second) gear, you don't have all that much kinetic energy, and 40-60 second runs are not braking enduros. I've watched a 63-37 distribution FWD car with stock brakes take PAX after PAX (factored fastest time) in Solo II. In those same races are slotted, drilled, zinc washed, racing pad brakes which barely got up to operating temp at the max stop at the end. Some even ran over the end cones.

trey has made some very good braking points (pun intended) here. Sure, he needs to review Physics I and has a little "deci-lexiphobia" --he misplaces decimal points regularly, but he's closer to the real world of brakes than most of us. I never thought I'd be saying this...but in this thread, you might want to listen to him.

Ok, AM?

End of rant.

My always highly-opinionated $.02

 

Just a little constructive criticism.... but I think if Trey'd spend a little less time on the internet and a little more time with his books.... ahem, and a dictionary, he might one day make a pimple on an engineer's butt.

Dedication is the key......

Good luck Trey.

-Mindgame

 

It's hard to disagree with you on this, 'Game.

 

geeze-
i even get ridiculed when i'm right

I'm going to find the closest cliff and or hanging tree

 

so i have something kinda off point but about braking.

i have a few cars right now and the worst brakes are on my TA. i can fill my old nissan truck with sand ( about 600 lbs ) and drive it at 80 and stop with no problems. if i hit my brakes once at 30 in my TA the are done vibrating all the rest of the day.

so i know these brakes are the worst things ever made. i have read so many posts about how bad they are and every one seems to end up saying the same thing. thier is nothing you can do to get brakes that dont warp on these cars. so why is it that every friggin single other car company can make brakes that work for thier cars? any why is it that every time someone mentions an aftermarked brake everyone here jumps down thier back saying they suck?

please someone tell me what works, what doesn't work, what lasts, and what i can get for the least amount of money