Ryeno

iTrader: (3)

Its 50 dollars at a junkyard for each caliper (ls400) and 100 for each rotor new. Or you can get all that used off these forums for half the new cost.

A full supra tt set with used calipers + new rotors = 1000 and they out preform the 3g brembo brakes.

The MC is like what 300ish?

So ya its a worthwhile venture.

Irrelevent.

We all know the bigger brakes = less stopping distance. And If you are unhappy with the pedel feel then swap in a supra tt mc and get supra tt rear calipers (and possibly a new brake booster if you are a 92-94 sc)

Like i said, you are overthinking this.

Rex Ruthor

Check the table at the end of the Summary page

The overthought big brake kits that are designed by premier engineers to optimize all the variables I have been talking about produce shorter stopping distances. Big brake kits that use smaller pistons in the front calipers to match the OEM line pressure at lock achieve this through reverse engineering the system for balance. Confucius say too much is as bad as too little. If you are saying that people are getting mushy pedals with longer stopping distances, then I guess that answers the clamping force questions. Starting out with a mushy pedal before adding heat and brake fade seems questionable at best. Bolting on bigger parts because they fit and dismissing the physics and engineering questions as overthinking is okay by me. I prefer overthinking to underthinking like some prefer a PhD to a GED. I will agree to disagree with your position on this matter until the math proves otherwise.

Anyone else out there know line pressure at lock of the LS 400's MC vs. the SC's as well as piston surface area deltas?

It would be good to do the math on the rears as well because mismatching brake ratio bias with improper engineering at all four corners makes matters worst.

stevechumo

iTrader: (5)

This debate has been going on for decades with too many threads about it. Well, I'm not into that engineering perspective, but I know for a fact that my LS brake on my SC stops so good. If I slam on the brake, the car will nose-dive and it'll jerk my back forward. I've rebuilt the complete stock SC brake (front & rear) and used different rotors & pads setups but none of them can compare to the LS brake swap. I then swapped the rear brake to the Supra TT brake and it's much smoother than before. I guess that I've reduced brake bias as many have said by distributing the braking force more evenly. Either with just the front swap or front & rear swap, the braking is just so much better. It's good to learn about the engineering perspective, but I think none of us will want to spend the time to measure it like an engineer. Perhaps you can do that and brighten up our days.

Sometimes practice in reality proves it all. And that's how science is based on. It's "Knowledge, based on experience".

GSteg

iTrader: (15)

Negative.

LiCelsior

iTrader: (32)

^^^^^^^^.........................omg. so why is that all high end cars have huge calipers and rotors? for looks?

GSteg

iTrader: (15)

Looks certainly has something to do with it

There are performance reasoning behind it, but bigger brakes don't equal shorter stopping distances.

Ryeno

iTrader: (3)

if the braking force is greater then the added weight they do equal shorter stopping distance.

Sorry shouldnt have said bi"gg"er but be"tt"er but in this case they are interchangeable. Since the ls400 brakes are bigger and better.

GSteg

iTrader: (15)

Take out your ABS fuse and try to slam on the brakes. If the OEM brakes are strong enough to lock the wheels, why would more force reduce braking distance? Until you've upgraded tires that are so sticky that the OEM brakes cannot hold the rotors, all these BBKs won't net you any shorter stopping distance. ABS is there to stop the car as much as possible without locking up. Slap on some bigger brakes and the ABS will still function the same.

What BBKs do better is provide consistant stopping distances over time. With OEM brakes, you fade if you slam on it too often without sufficient cooling.

If your goal is to stop shorter than what OEM brakes provide initially, you're looking at the wrong 'upgrade'.

masagsxr

Great input GSteg.... Thanks for the pointers!!!

Ryeno

iTrader: (3)

GSteg just because you are activating ABS doesnt mean you are stopping well.

Take a supra na (comparible to a sc400) and a supra tt. Slam both cars and i guarantee you the abs system will activate but the supra tt will still stop in a shorter distance.

GSteg

iTrader: (15)

That's because the TT has wider tires and it comes with better rubber compound than the N/A variant.


ABS doesn't mean it'll stop better (of course). The point is that if the OEM brakes can lock up the wheels, then bigger brakes won't stop any better. Whether we like ABS or not, it'll always prevent wheel lockup. Even non-ABS will see the same effect unless you get stickier tires.

masagsxr

Ryeno: I dont mean to be part of a debate or anything but you can't compare apples vs oranges. First of all the supra TT setup is different. Brake booster/master cylinder handles more ft/pounds to optimize the grip it produces to push those pistons out. I'd have to agree with GSteg regarding ABS. ABS activates so that the car stops as much as possible without locking. If you are thinking just because the wheels lock, your car will stop on the dime. You could slide another 100ft or so when the wheels lock.

No argument here. Just an opinion... I like hearing it from everyone as I love feeding my brains to learn new things and perfect them

Rex Ruthor

Knowledge is power. It would be great to do the math on this. If anyone provides me with the requested data, I'd be glad to figure out if the math verifies experience. MC line pressure at lock (usually 800-1400 psi, depending on weight of vehicle usually); Piston number in given caliper and piston diameter on stock SC 400 vs. LS caliper; rotor diameter; and coefficient of friction of pads used. This will provide solid data related to clamping force and actual brake torque on the same tires at same heat via pyrometer. I am truly not trying to be antagonistic, just trying to verify impressions.

Most high performance vehicles have big brakes to get a system that is as impervious to fade ergo heat as possible; bigger rotor = bigger primary heat sink. More pistons and longer pad usually means more clamping force with less pad flex. Calipers that don't flex enhance the mechanical stability as well.

The reports of mushy pedals could be secondary to bad brake bleeding. It could very well be that the SC MC puts out enough line pressure to apply more clamping force with a greater piston surface area with the LS calipers even if it is less psi than a LS MC. Coupled with a bigger diameter rotor probably equates to more brake torque where pad coefficient of friction, equal fluid quality, and tire stiction is equal. I just want to prove on the bench what you guys seem to already know. Peace.

Ryeno

iTrader: (3)

so you are saying if i put tt tires(which are only 10mm wider) on an na supra it'll get the same braking as a tt?

So that extra ~655-750 brake hp doesnt matter, right

GSteg

iTrader: (15)

No. That's not necessarily the case. The brake bias is probably different on the NA vs TT.

If you want shorter stopping distance, you need stickier tires. It's one advantage the TT model has over the NA, not just wider tires.

Those high power Supras need bigger brakes because they demand higher heat capacity. At almost any given point on a closed course, the 650hp Supra is going to be quicker than a stock Supra. They need to be able to stop repeatedly at high speed without fading, which is something the stock brakes may not provide after slamming the pedal 10 times.