Lets Talk Brakes
2nd Gear Member
Joined: Dec 2006
Posts: 452
From: Tri Cities, TN
Are you into the ABS at all? The brake bias and ABS settings are pretty carefully calculated with these cars based on their stock proportions. Adding big front brakes can actually cause premature and erratic ABS function, increasing stopping distances and reducing braking effectiveness. Just something to consider.
Colin what rear pads are you running? Some folks have suggested to me that both "too mild" and "too aggressive" rear pads can cause the problem I'm experiencing - which is just frustrating...thus the tests to see for myself what helps. By "aggressive" I mean mostly initial bite and then overall friction.
I'm currently running XP12s on front Stoptech brakes w/14" rotors and XP10s in the OEM rear calipers w/stock rotors. That's the common sort of "split" many folks advocate, but then I get different stories on what combination works with a larger rotor up front.
Camp 1: Larger rotors yield a longer torque arm, so the fronts are acting just a bit more aggressively than before. So going to an "even" compound front and rear yields a similar "split" as is often recommended.
Camp 2: Absent stiffer springs, the rears are just getting so unloaded that the higher initial bite compound in back is only going to lock up the rears. A pad w/less initial bite will give the rears tires a chance to work rather than snapping into lock up. So an even larger split is required (like XP12 front and XP8 in back).
Me, I'm not in either camp; I don't understand jack about what the heck is going on with my car now, I just don't like it. I'm not driving anywhere near the limit with the current set up.
When I first went on track with the Stoptech system I did have street pads in the rear (didn't get my order in on time for the rear pads). I had the Bobcat pads in. They did get loose in the back, but I was able to compensate for it with shock settings in a way I haven't with the XP10s in back. That seems to favor Camp 2's view, but that was also on a track with very different characteristics than the one I ran the XP10s. To add to the mess, there are other issues going on that I need to sort out first before I declare the current XP12/XP10 combo a failure. So the tests I spoke of are to first sort that stuff out. Then re-test the current combo, then swap back to the Bobcats and test those. If things move in a positive direction with the Bobcats, I'll likely switch to XP8s for track use. If they move negative I may order a set of XP12s and test those.
At this point, I'm so frustrated with the braking that I'm willing to shell out the money just to do the damn test. I want to drive! I can't drive if I'm second guessing my braking (call it a character flaw). I need it to be there in that "the sun will rise tomorrow" sort of way. Ironically, my old OEM fronts never gave me such angst. They were never super confidence inspiring for late braking shenanigans, but they were as consistent as the sun rising. And I even bucked convention and ran XP10s on all four corners (but never with R-comps, just damn fine summer streets: Toyo R1Rs).
Anyway, I'll keep you posted on the results.
Best,
-j
p.s. - I just realized that some of what I just said might give folks the impression I think the switch to the BBK has been all bad. It hasn't. Under most conditions they feel far better than the modified OEM set up. I'm just having a bad situation right now, but I feel confident that once things have been sorted out they'll be outstanding. I do think they'll be "super confidence inspiring" and "super consistent" at the same time.
I'm currently running XP12s on front Stoptech brakes w/14" rotors and XP10s in the OEM rear calipers w/stock rotors. That's the common sort of "split" many folks advocate, but then I get different stories on what combination works with a larger rotor up front.
Camp 1: Larger rotors yield a longer torque arm, so the fronts are acting just a bit more aggressively than before. So going to an "even" compound front and rear yields a similar "split" as is often recommended.
Camp 2: Absent stiffer springs, the rears are just getting so unloaded that the higher initial bite compound in back is only going to lock up the rears. A pad w/less initial bite will give the rears tires a chance to work rather than snapping into lock up. So an even larger split is required (like XP12 front and XP8 in back).
Me, I'm not in either camp; I don't understand jack about what the heck is going on with my car now, I just don't like it. I'm not driving anywhere near the limit with the current set up.
When I first went on track with the Stoptech system I did have street pads in the rear (didn't get my order in on time for the rear pads). I had the Bobcat pads in. They did get loose in the back, but I was able to compensate for it with shock settings in a way I haven't with the XP10s in back. That seems to favor Camp 2's view, but that was also on a track with very different characteristics than the one I ran the XP10s. To add to the mess, there are other issues going on that I need to sort out first before I declare the current XP12/XP10 combo a failure. So the tests I spoke of are to first sort that stuff out. Then re-test the current combo, then swap back to the Bobcats and test those. If things move in a positive direction with the Bobcats, I'll likely switch to XP8s for track use. If they move negative I may order a set of XP12s and test those.
At this point, I'm so frustrated with the braking that I'm willing to shell out the money just to do the damn test. I want to drive! I can't drive if I'm second guessing my braking (call it a character flaw). I need it to be there in that "the sun will rise tomorrow" sort of way. Ironically, my old OEM fronts never gave me such angst. They were never super confidence inspiring for late braking shenanigans, but they were as consistent as the sun rising. And I even bucked convention and ran XP10s on all four corners (but never with R-comps, just damn fine summer streets: Toyo R1Rs).
Anyway, I'll keep you posted on the results.
Best,
-j
p.s. - I just realized that some of what I just said might give folks the impression I think the switch to the BBK has been all bad. It hasn't. Under most conditions they feel far better than the modified OEM set up. I'm just having a bad situation right now, but I feel confident that once things have been sorted out they'll be outstanding. I do think they'll be "super confidence inspiring" and "super consistent" at the same time.
4th Gear Member
Joined: Dec 2007
Posts: 1,692
From: Ontario, Canada
Philostang
Right now I'm running XP10 front on GT500 calipers and rotors and XP8 rear on stock OEM calipers and rotors. As they have a few more track days in them I don't need to decide yet whether to continue with them or go to XP10/XP10 per your Camp 1.
We may get some further input in the other forum from SoundGuyDave as if my memory is correct he is also switching to the GT500 setup around now.
The other factor I've wondered about is how different the GT500 master cylinder/brake booster is from the GTs.
You may also be braking at higher G forces than I. I'm going to go through my data to see what levels i was at this past weekend and my brother was at last month.
Good luck with your tests.
Right now I'm running XP10 front on GT500 calipers and rotors and XP8 rear on stock OEM calipers and rotors. As they have a few more track days in them I don't need to decide yet whether to continue with them or go to XP10/XP10 per your Camp 1.
We may get some further input in the other forum from SoundGuyDave as if my memory is correct he is also switching to the GT500 setup around now.
The other factor I've wondered about is how different the GT500 master cylinder/brake booster is from the GTs.
You may also be braking at higher G forces than I. I'm going to go through my data to see what levels i was at this past weekend and my brother was at last month.
Good luck with your tests.
3rd Gear Member
Joined: Jan 2006
Posts: 757
From: Chicago
I wouldn't be so frustrated if the problem was under super-severe braking. I'm not into the ABS when I get the troubles - which are actually twofold:
1. Rear end wiggle (as described before)
2. Odd sort of swaying (like a fish-swimming motion, think of a shark swimming and that's how it feels)
What's odd is that I get the shark motion under moderate braking. It happens before any real lightness in the rear happens (that's why I think of it as a shark-like motion; the car hasn't yet gotten into a real strong front pitch, she's more or less level, but there's a side-to-side motion). When I'm braking harder I get a distinct loose feel in the back that seems to only aggravate the swim (sometimes she settles straight and then it's just the loose rear). I've gotten some crazy out of proportion straight-line braking going from just 90-100 mph to 60-70 mph. I don't think that's extreme braking by any means, yet I'm getting a seriously unsettled car.
Dave is a buddy of mine, and yes he's already got the Brembo swap in. He's also running way stiffer front springs and has little nose dive. I'm sure that's helping things. At any rate, he loving his brakes. He also runs Hawk pads, so I'm reluctant to try swapping his for a test. If I remember correctly, he is using the same pad compound on all four wheels. BUT (lest we forget steelcomp's insight) keep in mind that he's also running AST coil overs with much heavier springs than most folks (at least those who still pretend to drive their cars on the street).
Best,
-j
1. Rear end wiggle (as described before)
2. Odd sort of swaying (like a fish-swimming motion, think of a shark swimming and that's how it feels)
What's odd is that I get the shark motion under moderate braking. It happens before any real lightness in the rear happens (that's why I think of it as a shark-like motion; the car hasn't yet gotten into a real strong front pitch, she's more or less level, but there's a side-to-side motion). When I'm braking harder I get a distinct loose feel in the back that seems to only aggravate the swim (sometimes she settles straight and then it's just the loose rear). I've gotten some crazy out of proportion straight-line braking going from just 90-100 mph to 60-70 mph. I don't think that's extreme braking by any means, yet I'm getting a seriously unsettled car.
Dave is a buddy of mine, and yes he's already got the Brembo swap in. He's also running way stiffer front springs and has little nose dive. I'm sure that's helping things. At any rate, he loving his brakes. He also runs Hawk pads, so I'm reluctant to try swapping his for a test. If I remember correctly, he is using the same pad compound on all four wheels. BUT (lest we forget steelcomp's insight) keep in mind that he's also running AST coil overs with much heavier springs than most folks (at least those who still pretend to drive their cars on the street).
Best,
-j
2nd Gear Member
Joined: Dec 2006
Posts: 452
From: Tri Cities, TN
I wouldn't be so frustrated if the problem was under super-severe braking. I'm not into the ABS when I get the troubles - which are actually twofold:
1. Rear end wiggle (as described before)
2. Odd sort of swaying (like a fish-swimming motion, think of a shark swimming and that's how it feels)
What's odd is that I get the shark motion under moderate braking. It happens before any real lightness in the rear happens (that's why I think of it as a shark-like motion; the car hasn't yet gotten into a real strong front pitch, she's more or less level, but there's a side-to-side motion). When I'm braking harder I get a distinct loose feel in the back that seems to only aggravate the swim (sometimes she settles straight and then it's just the loose rear). I've gotten some crazy out of proportion straight-line braking going from just 90-100 mph to 60-70 mph. I don't think that's extreme braking by any means, yet I'm getting a seriously unsettled car.
Dave is a buddy of mine, and yes he's already got the Brembo swap in. He's also running way stiffer front springs and has little nose dive. I'm sure that's helping things. At any rate, he loving his brakes. He also runs Hawk pads, so I'm reluctant to try swapping his for a test. If I remember correctly, he is using the same pad compound on all four wheels. BUT (lest we forget steelcomp's insight) keep in mind that he's also running AST coil overs with much heavier springs than most folks (at least those who still pretend to drive their cars on the street).
Best,
-j
1. Rear end wiggle (as described before)
2. Odd sort of swaying (like a fish-swimming motion, think of a shark swimming and that's how it feels)
What's odd is that I get the shark motion under moderate braking. It happens before any real lightness in the rear happens (that's why I think of it as a shark-like motion; the car hasn't yet gotten into a real strong front pitch, she's more or less level, but there's a side-to-side motion). When I'm braking harder I get a distinct loose feel in the back that seems to only aggravate the swim (sometimes she settles straight and then it's just the loose rear). I've gotten some crazy out of proportion straight-line braking going from just 90-100 mph to 60-70 mph. I don't think that's extreme braking by any means, yet I'm getting a seriously unsettled car.
Dave is a buddy of mine, and yes he's already got the Brembo swap in. He's also running way stiffer front springs and has little nose dive. I'm sure that's helping things. At any rate, he loving his brakes. He also runs Hawk pads, so I'm reluctant to try swapping his for a test. If I remember correctly, he is using the same pad compound on all four wheels. BUT (lest we forget steelcomp's insight) keep in mind that he's also running AST coil overs with much heavier springs than most folks (at least those who still pretend to drive their cars on the street).
Best,
-j
Have you checked your bump steer?
Are you toe in or toe out?
How much camber?
How about rear LCA angles and rear end center?
Maybe F1Fan will chime in...he's a lot better at diagnosing these kinds of things and has a lot more hnds on experience at this than I do. I'd be all over trying to figure out what that problem was. That has to be terribly distracitng.
4th Gear Member
Joined: Dec 2007
Posts: 1,692
From: Ontario, Canada
Philostang
I just went through my data for my fastest session and at the end of the main straight my braking was in the .8 to .9 G range. What I have no way of figuring out is on which times it felt squirrelly.
My brother's braking was a little higher G on average but still did not exceed 1 G.
I just went through my data for my fastest session and at the end of the main straight my braking was in the .8 to .9 G range. What I have no way of figuring out is on which times it felt squirrelly.
My brother's braking was a little higher G on average but still did not exceed 1 G.
5th Gear Member
Joined: Sep 2007
Posts: 2,059
From: Nor Cali
What do you guys think of the Cragar 13" brake kit? I'm thinking of getting them sometime in the future. The price can't be beat since you're getting front and rear kits.
http://www.stage3motorsports.com/pro...ront-Rear.html
http://www.stage3motorsports.com/pro...ront-Rear.html
3rd Gear Member
Joined: Jan 2006
Posts: 757
From: Chicago
What do you guys think of the Cragar 13" brake kit? ...The price can't be beat since you're getting front and rear kits.
http://www.stage3motorsports.com/pro...ront-Rear.html
http://www.stage3motorsports.com/pro...ront-Rear.html
I don't see the value in this kit. About all that is special here is the model - if you're into blondes.
Take my comments lightly, as I don't know much about this kit. Mine is a first reaction. You're looking at floating calipers in front (like the OEMs) and the same/similar single piston calipers in back. There are obviously some "touches" added (stainless pistons are a nice touch), but beyond that I doubt they'll do more than make your car look different (better? your call).
I'm reasonably sure Cragar isn't manufacturing these, which means they're farmed out to someone else. Find out who that is and what's really in this kit. If you're looking for a street upgrade (read: bling) go for it. If you're looking for inexpensive performance upgrades, read the earlier posts in this thread.
-j
3rd Gear Member
Joined: Jan 2006
Posts: 757
From: Chicago
Steelcomp, thanks for that; I needed the reminder. Just feel free to smack me anytime. 
Maybe F1Fan can wait until I bring information that would be more helpful. It's been some time since my last alignment, and I cannot rule out changes or wear...esp. since my steering wheel looks a bit clocked lately. (Ok, you can hit me harder...
) Well, I suppose this is one of the benefits of a forum...
I do know I had some nasty brake piston knock-back, and the new front hubs took care of that. If the hubs were going, it's entirely possible that other key components aren't happy.
My previous suspension settings were as follows:
Camber: -1.95 deg
Caster: 7 deg
Toe: 1/16" total IN
Rear CA angle: 3 deg tail down
Rear end: centered to w/in 1/8"
Never bothered with checking bump steer, as I never felt any ill effect from my modest lowering in the front (approx. 1"). I'll look into it more (now).
Best,
-j
Maybe F1Fan can wait until I bring information that would be more helpful. It's been some time since my last alignment, and I cannot rule out changes or wear...esp. since my steering wheel looks a bit clocked lately. (Ok, you can hit me harder...
) Well, I suppose this is one of the benefits of a forum...I do know I had some nasty brake piston knock-back, and the new front hubs took care of that. If the hubs were going, it's entirely possible that other key components aren't happy.
My previous suspension settings were as follows:
Camber: -1.95 deg
Caster: 7 deg
Toe: 1/16" total IN
Rear CA angle: 3 deg tail down
Rear end: centered to w/in 1/8"
Never bothered with checking bump steer, as I never felt any ill effect from my modest lowering in the front (approx. 1"). I'll look into it more (now).
Best,
-j
4th Gear Member
Joined: Oct 2007
Posts: 1,778
From: Harrisburg PA
John - when I was tracking my Stang with stock brakes +standard upgrades, Hawk HT-10 and NT01s I did get some of the 'wiggle' you describe. I remember distinctly the car doing this. In fact, I remember at VIR, heading into Oak Tree, hitting the brakes hard and the wiggle was enough for my instructor to comment on it. It was his opinion that its a common trait of stick axle cars. Another data point - just recently on another forum a guy who traked his stick axle F-body was complaining of the same thing. For me it was never all that bad though so I'm guessing yours is much worse.
Ever hear of Jay Andrews? He is a former NASA Nat Champ in American Iron, drives an older stang or at least he did last time I followed that series). He is also a Hawk dealer and brake expert - he frequently is sought after to give clinics on brake tech. Really nice guy, you may want to call him and discuss it. http://www.andrew-racing.com/
Regarding rear pads - the biggest reason 'common wisdom' says to use less pad in the rear is not due to the agressiveness or friction but rather due to the temperatures. Rear brakes have lower temps and therefore need pads whose sweet spot occurs at a lower temp than the fronts. At least for normal brake systems thats the way it works. For the S197 system....not sure, I've heard so many confusing things about the brakes on this car its hard to tell what true and whats not.
Which StopTechs do you have - ST40? Is it the kit made specifically for the S197 Mustang? I'm sure you know this but for those folks who don't - vendors like ST make the same caliper with different bore sizes for different cars. Its not a one size fits all kind of deal. When swapping fronts from a 2 piston, 13" brake to a 4 or 6 piston, 14" brake and keeping the OEM rears its very important to keep the front and rear brake bias the same or nearly the same. A high quality vendor like StopTech does this by sizing the pistons. So...the ST40 caliper for say a STI will not work properly on a Mustang. Some vendors don't do this and a lot guys don't know this and then they end up wondering why the sexy red BBK they bought on flea bay doesn't stop as well as their old OEM setup.
Ever hear of Jay Andrews? He is a former NASA Nat Champ in American Iron, drives an older stang or at least he did last time I followed that series). He is also a Hawk dealer and brake expert - he frequently is sought after to give clinics on brake tech. Really nice guy, you may want to call him and discuss it. http://www.andrew-racing.com/
Regarding rear pads - the biggest reason 'common wisdom' says to use less pad in the rear is not due to the agressiveness or friction but rather due to the temperatures. Rear brakes have lower temps and therefore need pads whose sweet spot occurs at a lower temp than the fronts. At least for normal brake systems thats the way it works. For the S197 system....not sure, I've heard so many confusing things about the brakes on this car its hard to tell what true and whats not.
Which StopTechs do you have - ST40? Is it the kit made specifically for the S197 Mustang? I'm sure you know this but for those folks who don't - vendors like ST make the same caliper with different bore sizes for different cars. Its not a one size fits all kind of deal. When swapping fronts from a 2 piston, 13" brake to a 4 or 6 piston, 14" brake and keeping the OEM rears its very important to keep the front and rear brake bias the same or nearly the same. A high quality vendor like StopTech does this by sizing the pistons. So...the ST40 caliper for say a STI will not work properly on a Mustang. Some vendors don't do this and a lot guys don't know this and then they end up wondering why the sexy red BBK they bought on flea bay doesn't stop as well as their old OEM setup.
Last edited by Argonaut; Jun 19, 2010 at 10:23 PM.
3rd Gear Member
Joined: Jan 2006
Posts: 757
From: Chicago
Thanks Argo! At least I don't feel like I'm going crazy, and I'll likely see what help I can get from Andrews.
As far as the stick axle goes, that's the first time I've heard of that. I do run rod ends on everything out back except for the pumpkin bushing. They're all relatively new, so I doubt it would be a compliance issue. Anyway, something else to keep a thought on. If it is a common trait, I'm guessing I have other issues that are just exacerbating the situation to a truly uncomfortable level.
Yes, I'm running the ST40 calipers from the kit they put together for the S197 cars. That's part of the reason I wasn't thinking much about throwing the front to rear bias out of whack with their BBK; I know Stoptech doesn't slap kits together haphazardly.
Thanks again for the Andrews tip.
Best,
-j
As far as the stick axle goes, that's the first time I've heard of that. I do run rod ends on everything out back except for the pumpkin bushing. They're all relatively new, so I doubt it would be a compliance issue. Anyway, something else to keep a thought on. If it is a common trait, I'm guessing I have other issues that are just exacerbating the situation to a truly uncomfortable level.
Yes, I'm running the ST40 calipers from the kit they put together for the S197 cars. That's part of the reason I wasn't thinking much about throwing the front to rear bias out of whack with their BBK; I know Stoptech doesn't slap kits together haphazardly.
Thanks again for the Andrews tip.
Best,
-j