legacycentral bbs

so i have 2 brake upgrade choices, subaru 4 pot kit (calipers, rotors, backing plates, and pads with half-life) for $450, but i'm trying to talk him down. or i can go with perrin/willwood 4pots (calipers, brackets, 2 sets of pads - one of the pad sets new, and some rotors) for 375 shipped to my door. i've heard about the perrin setup having some flexing problems due to their aluminum bracket, but i've yet to hear anything bad about the subaru 4pots. i dont know which one i should go towards. the perrin fits under stock WRX wheels, the subaru 4pots dont, and would require me getting larger wheels. so, help me decide please

both setups are probably overkill. WRX stockers are plenty strong, spend the money elsewhere.

206er wrote:both setups are probably overkill. WRX stockers are plenty strong, spend the money elsewhere.

I whole heartedly agree with this statement. Unless you are tracking the car regularly, just get WRX front brakes and H6 rears.....or just keep your stock rears.

Have you ever overheated your stock brakes?

Have you tried a good set of pads?

I would agree with everyone else, both setups are probably a bit much unless you plan on running really wide tires. Just keep your stock back and put some good pads on. Then upgrade your front to the WRX and save your money for other things. However, if you do want to go with the 4-pots, I'd say Subaru just because my friend's STi just plain stops when you want it to.

id take either. i hate and emphasize hate my brakes. 2 days after i got new rotors and pads under spirted driving in a canyon they started to shake and fade like mad. like they had warped again.

if you decide on the perrins, point me to the seller of the 4 pots.

Do NOT get Wilwood calipers unless they are the brand new Dynapro caliper's. They don't have dust boots, so the pistons are VERY easily contaminated, and require rebuilding every 5 to 10 thousand miles.

4-pots are really heavy.

I'd recomend getting these if you HAVE to go 4-pots....



Racing Brake's new 4-pots. 1/2 the weight of stock Subaru 4-pots, they feel lighter than stock WRX brakes even. I can't wait to get them on!

I would either get street legal race rubber or flare the fenders for wide tires for anything bigger than WRX. WRX brakes can easily lock decent 205 tires up. Anything more would be more harm than good - you'd be much better off getting nice pads and cryo-treated rotors for the stock brakes than that.

Steve

No such thing as brake overkill, IMO.

I agree about the Wilwoods being crap. They flex, and create uneven pad wear, no rubber sheilding, gaurendeed to have problems in the future. Theres a reason why there so much cheaper than Brembos.

I do like the Subaru calipers. Very strong, bolt right in, and reliable, but heavy.

I wanna set myself.

i guess i just want them for they better stopping distance, plus they look cool. my dad has the full subaru 4 pot/2 pot setup on his car and it has save his butt a couple times (mine too) and my older brother has the front 4pots for his 95 Legacy. upgrading the stock stuff just wouldnt work for me, and WRX stuff is not that much better. so basically its out of these two brake setups, which one would you prefer? i think if the guy will take 350 for the subaru stuff i'll get them. but if he wont i'll probably get the perrin/willwood calipers. i would get those racing brake calipers if i had $1000 lying around.

well, looks like i'm getting the perrins. i offered the guy selling the 4pots $350 for everything, he says $350 for just the calipers, but i can get those new at the dealership for $209 a caliper, and his are used. he basically said get lost. oh well. and thawa you have a pm, good luck

evolutionmovement wrote:I would either get street legal race rubber or flare the fenders for wide tires for anything bigger than WRX. WRX brakes can easily lock decent 205 tires up. Anything more would be more harm than good - you'd be much better off getting nice pads and cryo-treated rotors for the stock brakes than that.

Steve

Steve - Remember, brakes aren't just about locking up the wheels. Stock brakes can lock up the wheels. It's all about the area under the curve.

Do you want turbo-Civic brake ability, or do you want AMG CL600 brake ability (very peaky, i.e. locked or unlocked, or super smooth shit load of modulation and control and feel?)

The brakes on the STi aren't overkill, are they? Not in my book. Those brakes are fantastic. You can do a LOT with a good set of brakes.

Hmm.

Rare is the vehicle that can't lock up its brakes at any speed, or cooks its brakes in normal driving. Larger brakes don't make for more braking force, that's pressure exerted. Larger brakes have more thermal capacity and more surface area- it takes more heat to heat them up and they dispel heat faster. More pistons means better feel and minutely better pad distribution.

Excess heat is bad, your brake pads only work within a certain heat range. Heavy duty pads are more effecient at a higher heat range. At low temps they require more pedal pressure to provide the same braking force as normal light duty pads.

So, if you cook your brakes, you need to get pads that can handle the heat you expose them to or brakes that can shed the heat quickly enough. Seeing that pads are way cheaper and don't add unsprung weight or extra centripetal force to the wheel, they're the obvious first choice. If you've never overheated your brakes, leave the buggers alone, as a normal pad is ideal in a normal panic stop.

If you want to lower your braking distance, alter your weight distribution and suspension. Since the weight shifts forward on braking, more weight distributed to the rear will make for shorter stopping distances. This weight distro change will have numerous other effects to the cars handling. Stiffer suspension will reduce the forward weight transfer, so the rear wheels can grip more and the front are less overworked. Ideally, since you've now reduced the weight distribution/transfer, you can now tip your brake bias a bit more to the back. This isn't advisable if you dont know exactly what you're doing.

Take all this with a grain of salt.

If you want them because they look cool, you can always clean and paint your own calipers.

thats not the only reason i want the 4pots.

i would spend the money on suspension bu the suspension i'm hopefully buying is not available to me right now. the guy is waiting for coilovers and as soon as he gets those i buy his kyb agx's with tanabe springs (WRX stuff) i have some 01 RS suspension that i got for free which goes in as soon as i get some rear upper spring perches.

Phil - the STI also has ABS and wider tires. The WRX brakes are better than stock as far as fade resistance, response, and total stopping power, but any more power on 205 width reasonably well-rounded street tires (and on uneven, pot-holed, and sand-patched NE roads) would make them less useful due to too easy locking up. Cars don't stop as well on a melted puddle of rubber. You need some margin of safety, too - this is street driving where any idiot or kid can jump out of nowhere and brakes that can lock at the slightest provocation are not better than ones that allow you control without 100% concentration. This isn't a race track where you can anticipate and feel out the brakes. Sometimes you just have to stop without too much thinking. The stock WRX brakes on our cars I think are riding the line of perfect - any more would be a problem due to the inability to easily get proper rubber under the car. Tires ultimately brake the car. Same for acceleration, I don't care how much HP or torque an engine makes if the tires can't put it to the road when the lights come down the tree. I know I don't need to tell you this, but maybe I need to clarify my point on not recommending bigger brakes without a corresponding tire change (or maybe with ABS). I can already lock my tires at 65 and probably higher if I were so inclined to find out.

Steve

Steve, are you sure you're not confusing brake size and master cylinder bore?

scottzg wrote:Rare is the vehicle that can't lock up its brakes at any speed, or cooks its brakes in normal driving. Larger brakes don't make for more braking force, that's pressure exerted.

My previous post that came from was all my writing, i didn't clip it out of something. It's pertinent.

My folks have a 77 gmc van with single pot brakes behind 14" wheels (225 width) that can lock up at 80. I know this for a fact...

Yes. We are talking about THESE cars. Having more mechanical advantage will be a disadvantage. Would the master cylinder be too weak for them? I don't know, but the point I'm belaboring to make is about the distinct possibility of overpowering the tires too easily. A better, more extreme example would be braking in the snow - tires lock up easily. Need to be very careful.

Steve

I'm nearly certain that your premise is wrong- if you put X pounds of force into the brake line, that is how much force the brake has to turn into friction, regardless of how big the brake is. More pad area just means less force per square inch. Further away from the hub doesnt matter because the rotor has the same mechanical advantage that the caliper does, since they share the same fulcrum.

To lock up the brakes more easily would require more friction or more force. Big brakes provide neither.

I didn't mean MC bore, i meant brake boost, my bad.

interested in your thoughts

Then why do the WRX brakes make a difference? Pad area is more friction surface as well as larger rotor. Ignoring the merits of a larger brake in terms of heat sink capacity, there is still more contact area and more mechanical advantage. Putting a friction surface against the hub will have less affect than putting the same force and surface against a point further out. Larger brakes provide this advantage also. Now think of the unlikely idea of a friction rim on a bicycle that would contact the whole rim vs. the traditional small pad. Given the same clamping force the larger friction surface would bring the bike to a halt quicker. It's not like you're spreading out force ver a greater area like laying on a bed of nails unharmed vs. screaming like a B-movie queen laying on a single nail. The point is to turn kinetic energy into heat (and disple it efficiently). A greater surface area would need less force than a smaller one to perform the same amount of work.

Steve

Actually larger brakes do alter brake torque. They may or may not alter brake force which affects brake torque......it all depends on the size of the new caliper piston vs the old caliper piston.

Get some good pads. That's really all you need. Even when I had my 14" wheels....I had some carbon metallic pads on that thing, and to be quite honest, the car stops almost as well or better from high speeds then it does now. Things got much hotter, and I'm sure I overheated the brake system with the old setup, but pads alone can drastically alter how your car brakes.

Personally....BBK's are mostly eye candy IMO. They do offer benefits, but most people will never fully reap those benefits.

Legacy777 wrote:Actually larger brakes do alter brake torque. They may or may not alter brake force which affects brake torque......it all depends on the size of the new caliper piston vs the old caliper piston.

I was sure to miss some detail in my rebuttal. I assumed equal piston sizes.

Josh, as our resident brake guru, everything else i said is right though, right?

Given the same clamping force the larger friction surface would bring the bike to a halt quicker. It's not like you're spreading out force ver a greater area like laying on a bed of nails unharmed vs. screaming like a B-movie queen laying on a single nail. The point is to turn kinetic energy into heat (and disple it efficiently). A greater surface area would need less force than a smaller one to perform the same amount of work.

This is exactly what im disagreeing with you on. Yes, the larger pad will need less force per unit of area but the total force will be exactly the same. It's exactly like you're lying on a bed of nails vs a single nail, that's an excellent analogy. The total pressure on all those nails will be your weight, just as it would be on the single nail, assuming you dont get punctured.

So why are you guys saying the 4-pots are overkill and the wrx are just right?

I don't remember saying that...

Only reason that might be true is if the 4 pots tip the bias more to the front.