Why is everyone looking for a rear brake kit?
12-29-2002, 06:02 PM
#31
Registered User
Join Date: Dec 2002
Location: columbia,md
Posts: 134
Car Info: 03 wrx,944 turbo racecar, Lexus is300
Originally posted by Kobayashi
Bro you need to settle down. I dont think anyone here has "challenged" what Gary has to say. Most of the statements you are making are more about blowing your own horn rather than addressing the topic at hand. I seriously doubt Gary needs any backup from you. My questions were not inteneded to "challenge" Gary, they were simply that, questions. As a matter of discussion Gary and I agree on almost any braking issue. Gary and I shared platform on a number of issues on the old i-club regarding the need or lack thereof of upgrades. I find it humorous, your vain attempt to ride Gary's coattails into some sort of online celebrity.
Back on topic, I can't speak for other peoples vehicles but let me explain a bit about my own. Lets eliminate calipers from the discussion, beacuse you, 944 guy, as an experienced track aficionado, should know the performance is largely a rotor issue. My Subaru came stock with 277x24mm front and 266x10mm rear rotors. I upgraded both the front AND rear rotors to 294x24mm and 290x18mm respectively. This equates to an almost identical to stock front to rear brake bias and a significant increase in the cooling capacity of the system in general. And it looks better than stock as well.
Do I have any remorse or concerns about the effects this will have on my braking? No. Is the system superior to the stock system? IMO, yes it is in every important way. As long as the bias is maintained, any upgrade in the cooling capacity of the system is a good thing.
k.
Bro you need to settle down. I dont think anyone here has "challenged" what Gary has to say. Most of the statements you are making are more about blowing your own horn rather than addressing the topic at hand. I seriously doubt Gary needs any backup from you. My questions were not inteneded to "challenge" Gary, they were simply that, questions. As a matter of discussion Gary and I agree on almost any braking issue. Gary and I shared platform on a number of issues on the old i-club regarding the need or lack thereof of upgrades. I find it humorous, your vain attempt to ride Gary's coattails into some sort of online celebrity.
Back on topic, I can't speak for other peoples vehicles but let me explain a bit about my own. Lets eliminate calipers from the discussion, beacuse you, 944 guy, as an experienced track aficionado, should know the performance is largely a rotor issue. My Subaru came stock with 277x24mm front and 266x10mm rear rotors. I upgraded both the front AND rear rotors to 294x24mm and 290x18mm respectively. This equates to an almost identical to stock front to rear brake bias and a significant increase in the cooling capacity of the system in general. And it looks better than stock as well.
Do I have any remorse or concerns about the effects this will have on my braking? No. Is the system superior to the stock system? IMO, yes it is in every important way. As long as the bias is maintained, any upgrade in the cooling capacity of the system is a good thing.
k.
12-29-2002, 06:12 PM
#32
Registered User
Join Date: Dec 2002
Location: columbia,md
Posts: 134
Car Info: 03 wrx,944 turbo racecar, Lexus is300
I started out by saying I was worked up,..and you never said what you use your car for anyway...
I will say very little other than this.......
let's see what happens with all that rear brake "bias" you guys talk about as you try to carry some brake into a corner, on the track or on the street. Most racers get every little amount of speed from carrying some brake into the corner, which you cant do with alot of rear "bias".
And I seriously dont need to toot my own horn, not is that what I was doing, let alone swingin' on Gary's nuts,..my purpose of telling you the things about me was to support what I was saying with what I do,...NOT WHAT I TALK ABOUT DOING. And the fact still remains that alot of people on here ( I-club ) only talk,..and are limited with what they have done, and its frustating to sit and read alot of BS. As for you,..if you live in the D.C area I invite you to the track and I 'll take you for a ride and show you what I am talking about.
944 turbo guy
I will say very little other than this.......
let's see what happens with all that rear brake "bias" you guys talk about as you try to carry some brake into a corner, on the track or on the street. Most racers get every little amount of speed from carrying some brake into the corner, which you cant do with alot of rear "bias".
And I seriously dont need to toot my own horn, not is that what I was doing, let alone swingin' on Gary's nuts,..my purpose of telling you the things about me was to support what I was saying with what I do,...NOT WHAT I TALK ABOUT DOING. And the fact still remains that alot of people on here ( I-club ) only talk,..and are limited with what they have done, and its frustating to sit and read alot of BS. As for you,..if you live in the D.C area I invite you to the track and I 'll take you for a ride and show you what I am talking about.
944 turbo guy
12-30-2002, 06:43 AM
#34
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Posts: n/a
Originally posted by toasteRS
If people are going to upgrade their brakes, why don't they just upgrade the front and then place the removed fronts onto the back? Simple, cheap and effective. Six spot fronts and four spot backs (read: overkill for anything other than competition
If people are going to upgrade their brakes, why don't they just upgrade the front and then place the removed fronts onto the back? Simple, cheap and effective. Six spot fronts and four spot backs (read: overkill for anything other than competition
Youre not the first to have thought of it tho.
And I dont know where you were going with the 4pots rear in your above reference(meaning after moving the front to the rear,) none of the USDM Subarus come equipped with 4pot front calipers. The WRX et al have 2 piston sliding(non-opposed) calipers in the front.
k.
12-30-2002, 02:09 PM
#37
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Posts: n/a
Wow, you guys *really* get ripped off, even more than we do down under (when compared with the Japanese specs)!
We get on the WRX:
4-spot ventilated, vacuum assisted, disk brakes - front
2-spot ventilated, vacuum assisted, disk brakes - back.
The only difference appart from the number of calipers is that the disks are smaller on the back.
You'd be supprised at the number of competition spec Rexes that use 6-spot fronts and 4-spot backs
Apparently there is a new STi coming up which will never be sold in Australia. This is most likely because it is too powerful, doh! The government has to protect the local GMH Holden and Ford (read: pushrod puss) market somehow, I guess.
)
We get on the WRX:
4-spot ventilated, vacuum assisted, disk brakes - front
2-spot ventilated, vacuum assisted, disk brakes - back.
The only difference appart from the number of calipers is that the disks are smaller on the back.
You'd be supprised at the number of competition spec Rexes that use 6-spot fronts and 4-spot backs
Apparently there is a new STi coming up which will never be sold in Australia. This is most likely because it is too powerful, doh! The government has to protect the local GMH Holden and Ford (read: pushrod puss) market somehow, I guess.
)
12-30-2002, 09:35 PM
#38
Registered User
iTrader: (1)
Join Date: Nov 2002
Location: Mid-Atlantic somewhere
Posts: 820
Car Info: '97 Legacy 2.5GT sedan
Originally posted by Zahnster
Here's a thought. Isn't Gary's car noticably lighter than the stock WRX? Wouldn't that make his need for a larger (than Stoptech...?) front kit or a larger (than stock) rear kit lessened?
Here's a thought. Isn't Gary's car noticably lighter than the stock WRX? Wouldn't that make his need for a larger (than Stoptech...?) front kit or a larger (than stock) rear kit lessened?
There is a press release on the USTCC site that talks briefly about this. We will have to carry a lot of weight. The rules of the series call for 13lbs per 1hp (stock engine output). With 227hp, we have to run at 2,951lbs. With the AWD we have to add 150lbs. Total weight is 3101lbs - heavier than stock.
So, the curb weight of the car is pretty close to a stock WRX sedan, but of course the weight distribution is way better because they stripped out all the excess crap and then added ballast where needed. That actually adds more weight (pun intended
) to Gary's argument - their race car has even more weight on the rear than a "normal" car does, yet it doesn't use up the rear brakes.Pat
12-31-2002, 10:15 AM
#40
AaronC,
I think you hit the nail on the head. You need to maintain the balance front to rear. As you pointed out, we use Stoptech brakes on our car (are sponsored by them as well). This are the only upgrade brake kit we've used on our racecar. Since they are already sized (both rotor diameter and piston diameters) to work optimally with the stock rear set-up, I wanted to know why so many people wanted to upgrade the already properly sized rears.
So you're right. If you don't use a front brake caliper and rotor that is specifically engineered to be used effectively with the stock rears, you will also have to upgrade the rear brakes to maintain proper brake bias.
Kobayashi,
You got the rotor diameter fairly close (1.04 f/r stock compared to 1.01 f/r upgraded), but did you match the cylinder volumes of the calipers to the same ratio as stock? If not, you may have changed your bias dramatically.
This is what 944 Turbo Guy is talking about. Your brake system may feel great to you in straight line braking, even if the bias is too far to the rear. Have you had the opportunity to try your setup using threshold trailbraking into a fast corner on the track? If not, you may be in for a big unpleasant surprise.
Alex,
Towards the end of the season, our car had to weigh 3,320 pounds, which is significantly more than stock. And our car uses the stock motor and turbo, which is no where near as powerful as a lot of the street WRXs out there. Our race car is more than 200 pounds heavier and has much less power than many streetcars, including yours. You're right, it's not fair to compare street to race. I guess that's why we run a street brake kit on our racecar and you run a full front and rear race kit on your streetcar. Right?
Back to AaronC,
Yes, we are sponsored by Stoptech. Correct, we don't run a rear brake kit. But Stoptech doesn't make a rear kit because it's not needed with the way they have engineered their front brakes. I have to say that we agree with them. Not because they are a sponsor, but because of what we see in performance on the track and the heat that we see at the rears. I wish you could see them sometime after a race. We've got 4 race weekends on the rear rotors and I believe 3 race weekends on the rear pads. Maybe 4. No rear heat issues at all and great brake balance.
azscoobie,
Your example is solved simply by upgrading brake pads. The brakes should never catch fire. A few of you may remember when we ran out of front brakes at Road America in 2001 while using the stock calipers and rotors. After the 3rd lap, I was on the backing plates in the front (due to our error in forgetting to replace pads before the race). So for the rest of that 40 minute race, I had the bias to full rear trying to get as much rear brake as possible. When we finished, our front brakes looked like this:
Our rear brakes wore out in that race, but they never caught fire. And, to top it all off, we managed to finish in second place.
I'm guessing you were using the stock pads when yours caught fire, right? That's a big no-no with these cars.
Gary
Sheehan Motor Racing
www.teamSMR.com
I think you hit the nail on the head. You need to maintain the balance front to rear. As you pointed out, we use Stoptech brakes on our car (are sponsored by them as well). This are the only upgrade brake kit we've used on our racecar. Since they are already sized (both rotor diameter and piston diameters) to work optimally with the stock rear set-up, I wanted to know why so many people wanted to upgrade the already properly sized rears.
So you're right. If you don't use a front brake caliper and rotor that is specifically engineered to be used effectively with the stock rears, you will also have to upgrade the rear brakes to maintain proper brake bias.
Kobayashi,
You got the rotor diameter fairly close (1.04 f/r stock compared to 1.01 f/r upgraded), but did you match the cylinder volumes of the calipers to the same ratio as stock? If not, you may have changed your bias dramatically.
This is what 944 Turbo Guy is talking about. Your brake system may feel great to you in straight line braking, even if the bias is too far to the rear. Have you had the opportunity to try your setup using threshold trailbraking into a fast corner on the track? If not, you may be in for a big unpleasant surprise.
Alex,
Towards the end of the season, our car had to weigh 3,320 pounds, which is significantly more than stock. And our car uses the stock motor and turbo, which is no where near as powerful as a lot of the street WRXs out there. Our race car is more than 200 pounds heavier and has much less power than many streetcars, including yours. You're right, it's not fair to compare street to race. I guess that's why we run a street brake kit on our racecar and you run a full front and rear race kit on your streetcar. Right?
Back to AaronC,
Yes, we are sponsored by Stoptech. Correct, we don't run a rear brake kit. But Stoptech doesn't make a rear kit because it's not needed with the way they have engineered their front brakes. I have to say that we agree with them. Not because they are a sponsor, but because of what we see in performance on the track and the heat that we see at the rears. I wish you could see them sometime after a race. We've got 4 race weekends on the rear rotors and I believe 3 race weekends on the rear pads. Maybe 4. No rear heat issues at all and great brake balance.
azscoobie,
Your example is solved simply by upgrading brake pads. The brakes should never catch fire. A few of you may remember when we ran out of front brakes at Road America in 2001 while using the stock calipers and rotors. After the 3rd lap, I was on the backing plates in the front (due to our error in forgetting to replace pads before the race). So for the rest of that 40 minute race, I had the bias to full rear trying to get as much rear brake as possible. When we finished, our front brakes looked like this:
Our rear brakes wore out in that race, but they never caught fire. And, to top it all off, we managed to finish in second place.
I'm guessing you were using the stock pads when yours caught fire, right? That's a big no-no with these cars.
Gary
Sheehan Motor Racing
www.teamSMR.com
Last edited by GarySheehan; 12-31-2002 at 10:21 AM.
12-31-2002, 11:46 AM
#43
Guest
Posts: n/a
Originally posted by GarySheehan
Kobayashi,
You got the rotor diameter fairly close (1.04 f/r stock compared to 1.01 f/r upgraded), but did you match the cylinder volumes of the calipers to the same ratio as stock? If not, you may have changed your bias dramatically.
This is what 944 Turbo Guy is talking about. Your brake system may feel great to you in straight line braking, even if the bias is too far to the rear. Have you had the opportunity to try your setup using threshold trailbraking into a fast corner on the track? If not, you may be in for a big unpleasant surprise.
www.teamSMR.com
Kobayashi,
You got the rotor diameter fairly close (1.04 f/r stock compared to 1.01 f/r upgraded), but did you match the cylinder volumes of the calipers to the same ratio as stock? If not, you may have changed your bias dramatically.
This is what 944 Turbo Guy is talking about. Your brake system may feel great to you in straight line braking, even if the bias is too far to the rear. Have you had the opportunity to try your setup using threshold trailbraking into a fast corner on the track? If not, you may be in for a big unpleasant surprise.
www.teamSMR.com
You know those are good questions. I can answer a couple of those immediately and speculate about one.
The front and rear calipers on my car(Legacy GT wagon) are from 2002 GT-B(TT Legacy Wagon.)
Fronts: The front calipers/brackets are identical to the 02 USDM WRX calipers and brackets. The caliper portion of the system is also identical to the calipers found stock on my car. So without reservation I can say the only change to the front system was rotor diameter/torque increase.
Rears: The rear calipers are gonna be the source of the speculation. As this caliper is unique to the B4s and GT-Bs, I am not certain the caliper piston size it has. I dont even know if the piston size is different on the B4 vs the GT-B. I would speculate it is near the same as the one in the USDM WRX. I will try to measure this this evening to verify and compare with the piston size that came stock on my wagon.
After upgrading the fronts and rears, I did disconnect the ABS and try multiple high speed straight line stopping tests. The consensus of my observers was that the fronts repetitively locked before the rears. The time difference between the fronts and rears locking depended on my speed and pedal pressure. I unfortunately have no high speed turning/braking info.
Misc: Stock front and rear GT-B pads, ATE Type 200 fluid, Cobb (Stoptech) SS lines and Kumho 712 tires.
This brings up some intersting other questions as well.
I have had so many Subaru brakes on hand at one time(5 complete front and rear sets about 2 months ago) that I have been amazed at how Subaru interchanges components on vehicles with widely different weights, weight distributions, and tires. It makes me wonder a couple of things: 1. How sensitive is the braking system to interchanging? I mean does Stoptech make a different front brake setup for the GDA vs the GGA WRXs? RS vs WRX? 2. If this a highly sensitive system where do the manufacturers fine tune out the differences? The proportioning valve? For instance, the GC series of Imprezas came with front brakes ranging from 1pot 260mm to 4pot 294mm and rear brakes ranging from drums to 290mm 2pots.
I would postulate, while I know there is some variation is piston diameter in an apples to apples comparison of Subaru brakes (ie 2pot fronts vs 2pot fronts) there is not enough of that to account for the wide variety of models upon which the same brakes are placed. This leads me to believe that one of the following things is true:
1. Subaru custom designs proportioning valves for each seperate front to rear to vehicle brake setup.
2. Small changes in weight, weight distribution, equipment dont upset the apple cart enough to be a problem.
I would genuinely like to know what the truth actually is. Has anyone compared for example proportioning valves on a pair of Subaru vehicles that only differed in front or rear brakes(all else being equal)?
Good discussion.
k.
12-31-2002, 02:07 PM
#44
I have wondered why as well Gary..its primarily a look thing, followed by a :I ahve more mods than you do" thing
Adam
Z-1 Performance
www.z1auto.com
Adam
Z-1 Performance
www.z1auto.com
12-31-2002, 08:26 PM
#45
Registered User
Join Date: Nov 2002
Posts: 48
Originally posted by Kobayashi
I would genuinely like to know what the truth actually is. Has anyone compared for example proportioning valves on a pair of Subaru vehicles that only differed in front or rear brakes(all else being equal)?
Good discussion.
k.
I would genuinely like to know what the truth actually is. Has anyone compared for example proportioning valves on a pair of Subaru vehicles that only differed in front or rear brakes(all else being equal)?
Good discussion.
k.
Last edited by AaronC; 01-01-2003 at 08:18 AM.