LS 4-piston Brake setup for my SC4
07-16-09, 07:29 PM
#226
Driver
Join Date: Mar 2009
Location: wa
Posts: 140
Likes: 0
Received 0 Likes
on
0 Posts
so your cheep, well that explains why you dont want to upgrade your brakes.
your on a highway, the guy infront of you slams on the brakes. With those higher capacity brakes you avoid rear ending him. With your oem brakes, well you know the story, your at fault and you pay money to his insurance company.
Just because you dont see a use for better brakes on the street doesnt mean it doesnt exist.
your on a highway, the guy infront of you slams on the brakes. With those higher capacity brakes you avoid rear ending him. With your oem brakes, well you know the story, your at fault and you pay money to his insurance company.
Just because you dont see a use for better brakes on the street doesnt mean it doesnt exist.
2nd thing, if you slam the brakes and the ABS kicks on........OH NEVERMIND.
rjp
Last edited by RANDY P; 07-16-09 at 07:58 PM.
07-16-09, 07:45 PM
#227
Driver
Join Date: Mar 2009
Location: wa
Posts: 140
Likes: 0
Received 0 Likes
on
0 Posts
Cuz I own an SC400. Basically the same car you do (but mine has only 60K miles). If mine hits someone in a rearend collision, yours will too.
Regardless of whatever you bolt up front.
rjp
Regardless of whatever you bolt up front.
rjp
07-16-09, 07:58 PM
#228
Driver
Join Date: Mar 2009
Location: wa
Posts: 140
Likes: 0
Received 0 Likes
on
0 Posts
Actually Reyno, on 2nd thought I apologize for the comments above. You're probably in a different point in your life than I am, and frankly I don 't know you or your car.
My apologies, was uncalled for and untrue.
rjp
My apologies, was uncalled for and untrue.
rjp
07-16-09, 08:57 PM
#229
your on a highway, the guy infront of you slams on the brakes. With those higher capacity brakes you avoid rear ending him. With your oem brakes, well you know the story, your at fault and you pay money to his insurance company.
Just because you dont see a use for better brakes on the street doesnt mean it doesnt exist.
No need to call each other names like cheap...Lets just keep this what it is..a discussion.
07-16-09, 11:56 PM
#230
If the guy in front of you is going 80mph and you are going 80mph with 20 ft in front of you, how are you going too slow? Your distance should be consistent. Just because there is a 20 ft gap from the car in front of you does not mean you are driving slow. The freeway is not meant for catching up to the car in front of you. Unfortunately, I understand what you are saying and this false perception may be true. I do not let others dictate my driving actions. Anyways, I think this thread is heading towards the Clubhouse so I'll stop here.
07-17-09, 12:07 AM
#231
I'd like to share my experience based on the performance that I have. I had rebuilt my stock SC4 brake calipers, bled completely, threw in Brembo rotors with Akibono pads, then changed to Beck/Anley pads. I then swapped to LS400 4 piston calipers, bled completely, threw in China drilled/slotted rotors with Monroe pads.
The result is complete different after swapping to LS calipers. The tires/suspensions are the same. The car stops so much quicker with LS calipers, which means within a shorter distance. If I don't gradually press on the brake, and instead slam on the brake, the car will nose-dive. My buddy with the same car and did the same brake swap just as I did also has a great improvement in the braking force. We didn't regret it at all.
We then moved on to the Supra TT 2 piston rear caliper swap and the braking just got better. I really do have confidence in bigger brake with more pistons. I respect the articles written about bigger brake doesn't mean it'll stop better, but in my case, it did.
The result is complete different after swapping to LS calipers. The tires/suspensions are the same. The car stops so much quicker with LS calipers, which means within a shorter distance. If I don't gradually press on the brake, and instead slam on the brake, the car will nose-dive. My buddy with the same car and did the same brake swap just as I did also has a great improvement in the braking force. We didn't regret it at all.
We then moved on to the Supra TT 2 piston rear caliper swap and the braking just got better. I really do have confidence in bigger brake with more pistons. I respect the articles written about bigger brake doesn't mean it'll stop better, but in my case, it did.
07-17-09, 07:58 AM
#232
Originally Posted by Ryeno
Why would you want your front brakes cooled? Less heat = less friction = less stopping power. Not to mention your tubbing isnt even going to work because the spinning wheels will just move the air out of the way.
So if you actually do have tubing running to your brakes i would remove it. Besides looking stupid, it wont work and you'll get laughed at by any real car enthusiast.
So if you actually do have tubing running to your brakes i would remove it. Besides looking stupid, it wont work and you'll get laughed at by any real car enthusiast.
07-17-09, 03:48 PM
#233
Wow, there is a lot of misleading information and misconceptions in this thread. Kohinoor is completely right to the point with his post.
I found a excellent tech article in a recent issue of Modified Magazine for those who are "confused". Some of you guy(s) should check it out.
http://www.modified.com/tech/modp-09...kes/index.html
Here are few highlighted quotes that is related to this discussion.
I found a excellent tech article in a recent issue of Modified Magazine for those who are "confused". Some of you guy(s) should check it out.
http://www.modified.com/tech/modp-09...kes/index.html
Here are few highlighted quotes that is related to this discussion.
Obviously, the role of brakes is to slow down the car. More appropriately, a braking system takes away the kinetic energy of your moving car by converting it into heat energy through friction. The ability to maintain friction and dissipate heat is what brakes are all about. Brakes can be broken down into three basic components: the rotating assembly like a rotor or drum; the fixed portion with the calipers, and pads/shoes; and the controls that involve the hydraulics, master cylinder, biasing circuit and traction controls and ABS. We'll ignore the control components because few people modify this and it's a big can of worms except to say that the size of the brakes has to be designed to work with the master cylinder size, the ABS and the active handling control system.
Fixed Calipers
Most aftermarket big brake systems, some high-end sports car's brakes and most race applications use a fixed caliper design. Fixed calipers are rigidly mounted to the hub and use opposing pistons on each side of the rotor to clamp down onto the pad. Oftentimes, higher-quality calipers with two or more pistons on each side use a staggered piston layout where the leading piston (in the direction of rotor rotation) is smaller than the pistons behind it. This decreases the force on the leading edge of the brake pad, creating more even pad wear.
Most aftermarket big brake systems, some high-end sports car's brakes and most race applications use a fixed caliper design. Fixed calipers are rigidly mounted to the hub and use opposing pistons on each side of the rotor to clamp down onto the pad. Oftentimes, higher-quality calipers with two or more pistons on each side use a staggered piston layout where the leading piston (in the direction of rotor rotation) is smaller than the pistons behind it. This decreases the force on the leading edge of the brake pad, creating more even pad wear.
Rotors
Rotors are the spinning part of the brakes that the calipers and brake pads clamp onto. In addition to providing a friction surface, the rotor's main role is to pump away heat generated through braking because it experiences the highest temperatures. Most rotors are sand-cast from gray iron of various qualities and have an air gap between the two rotor faces. The air gap (commonly referred to as a vented rotor) allows air to move through the rotor and pull away heat. Solid rotors also exist, typically on the rear brakes of non-performance platforms. Several designs exist for the vents, but most can be broken down to directional or non-directional categories. As the name suggests, non-directional (aka straight vane) rotors can rotate in either direction and still provide venting, although not as effectively. Stock factory brakes and lower-end replacement rotors use this design because the same part can be used on both sides of the car. A take-off of the straight vane design is the pillar vane design that is better at maintaining a smooth, consistent friction surface.
Directional or curved vane rotors only cool effectively when rotating in the right direction but are far more efficient at moving cooling air through the rotor. Most high-performance applications and race rotors (with the exception of carbon/carbon rotors) use curved vane rotors. A directional vane rotor upgrade on cars like the EVO, Z or STi are a simple but hugely effective choice. Our StopTech rotors use a patented variation of the curved vane design called Aerorotor with alternating differential curved vane lengths to further increase cooling effectiveness. To maintain rotor strength, slots and drills in curved vane rotors are typically machined in the opposite sweeping direction than the vanes so that a slot doesn't occur directly on top of a vane or a hole drilled through it.
Rotors are the spinning part of the brakes that the calipers and brake pads clamp onto. In addition to providing a friction surface, the rotor's main role is to pump away heat generated through braking because it experiences the highest temperatures. Most rotors are sand-cast from gray iron of various qualities and have an air gap between the two rotor faces. The air gap (commonly referred to as a vented rotor) allows air to move through the rotor and pull away heat. Solid rotors also exist, typically on the rear brakes of non-performance platforms. Several designs exist for the vents, but most can be broken down to directional or non-directional categories. As the name suggests, non-directional (aka straight vane) rotors can rotate in either direction and still provide venting, although not as effectively. Stock factory brakes and lower-end replacement rotors use this design because the same part can be used on both sides of the car. A take-off of the straight vane design is the pillar vane design that is better at maintaining a smooth, consistent friction surface.
Directional or curved vane rotors only cool effectively when rotating in the right direction but are far more efficient at moving cooling air through the rotor. Most high-performance applications and race rotors (with the exception of carbon/carbon rotors) use curved vane rotors. A directional vane rotor upgrade on cars like the EVO, Z or STi are a simple but hugely effective choice. Our StopTech rotors use a patented variation of the curved vane design called Aerorotor with alternating differential curved vane lengths to further increase cooling effectiveness. To maintain rotor strength, slots and drills in curved vane rotors are typically machined in the opposite sweeping direction than the vanes so that a slot doesn't occur directly on top of a vane or a hole drilled through it.
Last edited by One HoT; 07-17-09 at 03:59 PM.
09-05-09, 11:42 PM
#234
Driver
Join Date: Jun 2007
Location: Uranus
Posts: 112
Likes: 0
Received 0 Likes
on
0 Posts
If they aren't stuck then there's no reason to rebuild. Can't see how that will eliminate mushiess unless you got them burned up to begin with.
It sounds like these calipers bolt up, but the MC in the our cars isn't big enough to supply fluid to this caliper- piston area for the MC is probably too small. Henceforth the mushy pedal -
Tell me, is it a longer stroke to engage the calipers? You may stop when you mash the pedal, but it's a long, mushy feel and your brake feel (modulation) is probably for schit now..
Frankly it sounds like a different MC is required for this to work properly..If this is the case why would anyone want to do this? It's unsafe.
I'm honestly curious, not a flame - it sounds like more times than not this winds up with mushy pedal, and some of you have gone to some extreme measures to make sure there's no air in the system.
Has ANYONE done this mod without creating a weird pedal? Meaning, if you were not trying to panic stop does it feel like stock?
It sounds like these calipers bolt up, but the MC in the our cars isn't big enough to supply fluid to this caliper- piston area for the MC is probably too small. Henceforth the mushy pedal -
Tell me, is it a longer stroke to engage the calipers? You may stop when you mash the pedal, but it's a long, mushy feel and your brake feel (modulation) is probably for schit now..
Frankly it sounds like a different MC is required for this to work properly..If this is the case why would anyone want to do this? It's unsafe.
I'm honestly curious, not a flame - it sounds like more times than not this winds up with mushy pedal, and some of you have gone to some extreme measures to make sure there's no air in the system.
Has ANYONE done this mod without creating a weird pedal? Meaning, if you were not trying to panic stop does it feel like stock?
Mechanically, the larger rotor is a more efficient primary heat sink with the larger calipers being an arguably better secondary heat sink. Caliper design does not matter as much as assumed as well. Two pot sliders that compete in piston surface area equitable are a wash when figured against a four pot. I'd like to do the math on this mod before taking seat of the pants impressions. Anyone who has the specs requested, please post. Thanks.
If anyone wants to do the clamping force math themselves, then this is a shortcut equation. First, calculate the surface area of the caliper piston. You can do this by multiplying the diameter of the caliper piston times itself, and then multiply by 0.785 to get the total surface area. Once you have the piston area, multiply that by the line pressure generated by master cylinder needed to lock up the brakes. My bet is that braking engineers at Lexus opted for a MC with greater psi output potential for the heavier LS.
Here's a link to some solid white paper stuff authored by one of the best in the business.
The Physics of Braking Systems
09-05-09, 11:51 PM
#235
Driver
Join Date: Jun 2007
Location: Uranus
Posts: 112
Likes: 0
Received 0 Likes
on
0 Posts
After thought: The single best mechanical advantage to a higher piston caliper as well as having more pistons acting as clamping force multipliers to enhance clamping force is that more pistons lead to less pad flex. With the backing plate of the pad having more uniform pressure applied across the pad area, there is better transmission of clamping force from the pad to the rotor. On a short pad, a big single piston across the pad backing plate will probably suffice. I'd like to see stopping force tests after rear upgrade only changes with equal tires taking the friction to the street. Got to wonder if doing the rears is worthwhile, particularly with less line pressure in an inferior MC. Generally, fronts do most of the work depending on circuit bias.
09-06-09, 12:05 AM
#236
Driver
Join Date: Jun 2007
Location: Uranus
Posts: 112
Likes: 0
Received 0 Likes
on
0 Posts
Also, if line pressure variances are out of spec for the original design secondary to an inadequate MC, safety and liability issues become paramount. System valving design is very specific for each circuit mechanically and electronically (Via ABS ECU) for the ABS system; not to mention interface with Traction Control. Changing calipers all the way around without enough line pressure for system designs to modulate the ABS design is illogical, IMHO.
09-06-09, 12:31 AM
#237
Banned
iTrader: (3)
Join Date: Sep 2008
Location: NA
Posts: 1,262
Likes: 0
Received 0 Likes
on
0 Posts
Rex Ruthor long post short, you are over thinking this.
In short if you upgrade front brakes only then you will have a "dead zone" well more like the rears will lock during this dead zone and then the fronts.
If you upgrade fronts and rear then you will still have a dead zone but the rears will no longer lock up first.
If you upgrade fronts and rear and get a supra tt mc then everything will be perfect.
In short if you upgrade front brakes only then you will have a "dead zone" well more like the rears will lock during this dead zone and then the fronts.
If you upgrade fronts and rear then you will still have a dead zone but the rears will no longer lock up first.
If you upgrade fronts and rear and get a supra tt mc then everything will be perfect.
Last edited by Ryeno; 09-06-09 at 12:51 AM.
09-06-09, 05:19 PM
#239
Banned
iTrader: (3)
Join Date: Sep 2008
Location: NA
Posts: 1,262
Likes: 0
Received 0 Likes
on
0 Posts
2nd) the tt mc is proportioned for 4 pistion fronts, 2 piston rears, if you swapped it over with na rears, the rears would lock too fast.
If you wanted to upgrade the fronts and keep the rears then see if you could swap over a ls400 mc altho i personally think that would be a mistake.
09-06-09, 05:38 PM
#240
Driver
Join Date: Jun 2007
Location: Uranus
Posts: 112
Likes: 0
Received 0 Likes
on
0 Posts
Rex Ruthor long post short, you are over thinking this.
In short if you upgrade front brakes only then you will have a "dead zone" well more like the rears will lock during this dead zone and then the fronts.
If you upgrade fronts and rear then you will still have a dead zone but the rears will no longer lock up first.
If you upgrade fronts and rear and get a supra tt mc then everything will be perfect.
In short if you upgrade front brakes only then you will have a "dead zone" well more like the rears will lock during this dead zone and then the fronts.
If you upgrade fronts and rear then you will still have a dead zone but the rears will no longer lock up first.
If you upgrade fronts and rear and get a supra tt mc then everything will be perfect.
If overthinking the process leads to addressing line pressure deficiencies and upgrading MCs, then it may be a worthy discussion. It sure would be nice if we could figure the psi output at lock threshold of a MK IV Supra TT vs. an SC 300 vs. SC 400 vs. LS 400 just for *****s and giggles.
SC 400 Front only Stoptech Kit