Brake Question after VIR track weekend.

SVTmojo

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First off, sorry this is long, but I figured this is the group of people that might be able to help, with some of my background first as well.

So I ran VIR north and Full course this weekend for the first time. I have a autocrossed for a few years now, 3-5 events a year, and this was my 3rd open track weekend. So I am pretty green to everything, and soaking up as much possible, and loving every second of it! This was my first open track event in my new to me cobra, and I have only done one auto-x in it, so I am still learning the car as well.

The car ran great, no issues what so ever. The car has a Kenny Brown suspension package, along with 00R brembo front brakes. During all my 2 previous open track weekend, I really didn't shift at all, my 03 had enough torque to pull my out of most of the turns, and I spent my time learning lines and working on being smooth the the steering, throttle, and brake inputs. So this weekend I started playing with shifting, and my instructor was teaching me double clutching downshifts and heel/toe braking, which I have never done before.

First, I was having trouble with heel/toe, getting the side of my foot over far enough to touch the throttle under braking with the stock petals ....any suggestions for that?

Secondly and more importantly, Muscle Mustangs was there with Kenny Brown, and the editor of the magazine wanted a ride in a non-race prepped car with aftermarket Kenny Brown suspension parts. I had been spending some time with kenny Brown over the weekend, and he asked if he could use my car. So the one of the instructors that I know rather well, took my car out with the editor. When they got back, my buddy who previously owned a sn-95 cobra with a 00r cobra brake upgrage as well, said that my brake pedal felt funny. He said that he was struggling with his heel/toes shift because of my brake pedal. He said the first 3/4 to 1 inch of travel was real soft every time. From there on the pedal felt perfect and consistant with absolutly no fade. But due to the inch of travel before the pedal felt right, he almost had to lift his foot to get to the gas, as opposed to just rolling it to the side. I bleed the brakes the day prior to the event. And like I said the pedal felt great and consistant all weekend, just don't know why there is about an inch of soft travel before the pedal feels right. Any ideas????
 

SVTmojo

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What kind of pads are you using and how much of them is left?


Sorry, wrote this at work, and knew that I was going to forget something.

Currently I am running the stock Galpher pads. They are a little over 2 years old, but only have 3500 street miles on them, and look just at thick as the other set of galphers I have.
 

1993R

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Bleed your brakes,stainless lines, better pads...moves your accelerator pedal or buy some pedal covers and offset the accelerator one. I have small feet so I used Saleen pedal covers offset about 1/4 in.......
 

TroyV

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The pedal position on the Mustang really stinks for proper heel-toe shifting.. I could never get it right in either my 99GT or my 03 Cobra...with or without the gas pedal mod. I never used it going forward.

In addition to a thorough bleed of your brake system (including the two fittings on the MC), I would look at pad knock back as the next item up for bids.. Even with fresh front hubs, I had some knock back with the Cobra. I got into the habit of tapping the pedal just prior to the primary application of the brakes in the major brake zones. This would "take up the slack" and the pedal would be right at the top.

I'm not sure if this is your problem or not, but it is another thing to check on.
 

David Hester

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uM...
I've seen this mod before.
As I said, I've been racing 30+ years and don't even think about blipping the throttle, but I've never had problems with the Cobra or the Roush. In the old Fox bodies, you can bend the pedal toward the brake pedal. Mine are about 1" apart.
IMHO I'm thinking you really don't want the throttle any higher. The only time you blip is when your foot is on the brake pushed down, so the play works pretty well. It really doesn't matter how you blip.
I had been doing it for years, but my comp driving instructor, John Baucom,
John Baucom Home , said he just rotated his knee in his TransAm car to blip.
Side of foot to side of pedal, side of foot to top of pedal, works fine.
I've even blipped the pedal with my shoe laces before...and yes it was a hell-bent-for-leather pass that worked. And it is just a blip, not a stomp.
 

ac427cobra

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First off, sorry this is long, but I figured this is the group of people that might be able to help, with some of my background first as well.

So I ran VIR north and Full course this weekend for the first time. I have a autocrossed for a few years now, 3-5 events a year, and this was my 3rd open track weekend. So I am pretty green to everything, and soaking up as much possible, and loving every second of it! This was my first open track event in my new to me cobra, and I have only done one auto-x in it, so I am still learning the car as well.

The car ran great, no issues what so ever. The car has a Kenny Brown suspension package, along with 00R brembo front brakes. During all my 2 previous open track weekend, I really didn't shift at all, my 03 had enough torque to pull my out of most of the turns, and I spent my time learning lines and working on being smooth the the steering, throttle, and brake inputs. So this weekend I started playing with shifting, and my instructor was teaching me double clutching downshifts and heel/toe braking, which I have never done before.

First, I was having trouble with heel/toe, getting the side of my foot over far enough to touch the throttle under braking with the stock petals ....any suggestions for that?

Secondly and more importantly, Muscle Mustangs was there with Kenny Brown, and the editor of the magazine wanted a ride in a non-race prepped car with aftermarket Kenny Brown suspension parts. I had been spending some time with kenny Brown over the weekend, and he asked if he could use my car. So the one of the instructors that I know rather well, took my car out with the editor. When they got back, my buddy who previously owned a sn-95 cobra with a 00r cobra brake upgrage as well, said that my brake pedal felt funny. He said that he was struggling with his heel/toes shift because of my brake pedal. He said the first 3/4 to 1 inch of travel was real soft every time. From there on the pedal felt perfect and consistant with absolutly no fade. But due to the inch of travel before the pedal felt right, he almost had to lift his foot to get to the gas, as opposed to just rolling it to the side. I bleed the brakes the day prior to the event. And like I said the pedal felt great and consistant all weekend, just don't know why there is about an inch of soft travel before the pedal feels right. Any ideas????

Mustangs have never been good for heel/toe work although the S-197 is decent. You need to adjust your gas pedal.

If this is the car in your sig, it has an SRA in it and they are notorious for pad knock-back. That is most likely what is causing your excessive pedal travel. Like Troy said, give that brake pedal a little tap just before you jump on it. Once you get a little more OT seat time you'll want to get into some more aggressive track inspired brake pads and that will also help as will braided caliper lines.

:thumbsup::coolman::beer:
 

SVTmojo

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Thanks for all the replies. I have been doing some reading about heel/toe. I am much more concerned with the brake petal feel. I have run Hawk hp+ on all my previous cars on track for botrh auto-x and open track, but had 2 sets of galpher, so I kept a set for street, and in the mind set of saving some money, ran the other set this past weekend at VIR, know that they were going to perform as good as the HP+'s. But with it being my first weekend in both the car and the track, I knew I wasn't going to be pushing her very hard, so I wasn't overly concerned. The car already has stainless lines, which I assume came with the 00r Brembos.

Is this "pad Knock back", something thatyou just have to live with. Troy mentioned changing the front hubs. That would help with knock-back? I have driven other sn-95 cars with the 00r brembo calipers and they didn't have this 1/2 inch of soft petal all the time. Do you think something as simple as changing the pads would resolve this issue?
 
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Ryan

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Mustangs have never been good for heel/toe work although the S-197 is decent. You need to adjust your gas pedal.
I'm not sure if the SN95 uses the same pedals as a Fox Body, but you could potentially look into the SVO pedal assembly...
 

wheelhopper

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What's up Mike. Doug here. I was the guy that had the white '03 Cobra.

I had to adjust my gas pedal to get a good heel/toe position. I simply grabbed the gas pedal assembly and slowly bent it up and over, just a little. It worked great for me. I did this after looking at my factory pedals and realizing they were plastic and appeared to be molded to the arm assembly.

It looks like you have all the brake info you need.
 

MFE

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I too suspect knock-back as a problem to be dealt with. It comes from flex in the axle/spindle assemblies and especially when front hub bearings and rear diff clutches are worn.

As good as they are, the Brembo calipers won't help the issue, and in fact being as they're a fixed design (as opposed to floating), they make the potential ramifications even worse, in the form of breaking the rotors off the hubs. And that only happens when you can least afford it...when you're on the brakes the hardest.

In the rear, pull a caliper off so it doesn't interfere with how much the axle can travel in and out of the housing, and check that endplay. If it's been a few years since you re-shimmed the clutch packs, or if it's never been done, I bet you'll find it's pretty excessive. Every bit of axle endplay turns into pad knockback during cornering, and the more endplay, the more knockback. if it's more than 1/8 of an inch, it's definitely time to consider re-shimming the trac-lok. If it's more than 3/16, it's time to stop considering it and get busy.

If it's virtually always been like that, and especially if you've ever changed the master cylinder or brake booster, then it's quite possible the booster rod needs to be adjusted longer.
 
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SVTmojo

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I too suspect knock-back as a problem to be dealt with. It comes from flex in the axle/spindle assemblies and especially when front hub bearings and rear diff clutches are worn.

As good as they are, the Brembo calipers won't help the issue, and in fact being as they're a fixed design (as opposed to floating), they make the potential ramifications even worse, in the form of breaking the rotors off the hubs. And that only happens when you can least afford it...when you're on the brakes the hardest.

In the rear, pull a caliper off so it doesn't interfere with how much the axle can travel in and out of the housing, and check that endplay. If it's been a few years since you re-shimmed the clutch packs, or if it's never been done, I bet you'll find it's pretty excessive. Every bit of axle endplay turns into pad knockback during cornering, and the more endplay, the more knockback. if it's more than 1/8 of an inch, it's definitely time to consider re-shimming the trac-lok. If it's more than 3/16, it's time to stop considering it and get busy.

If it's virtually always been like that, and especially if you've ever changed the master cylinder or brake booster, then it's quite possible the booster rod needs to be adjusted longer.

Wow, thanks for the great info. Looks like I need to get dirty and start checking some of these things. The cobra is a 97, and I am almost positive the master cylinder/brake booster are original, and the rear end had not been opened except for gears and a FRPP rear diff cover over 10 years ago.
 

TXPD

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The pedals in my 99 Cobra Bondurant car are very close together. I will try and get some photos of the pedals tomorrow.

The pedals in my Cobra R have a Steeda aluminum cover on it that is inverted and extended toward the throttle. Its still not as easily accessed as the Bondurant car.
 

brkntrxn

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I did the rubber hose mod to my accelerator pedal in our 99 that John posted above. Works great for me! So much so, that this past weekend I was in our 01 vert running the Dragon and kept screwing up shifts due to not being able to touch the accelerator pedal.

What you are describing with your brakes sounds like knock-back to me as well. A buddy with a 350Z feels that a lot in his car as well; describes it similar to what you posted. Check your wheel bearings as the others suggested.
 

TroyV

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Even with brandy new hubs I got a good amount of knock back, and so I just developed the habit of tapping the pedal..

You can also do it even earlier if you have someone on your ass as you come into a brake zone and want to "check up" on them before hauling your own machine down. Works like a charm......at least until the person behind learns your habits. :)
 

wheelhopper

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Not sure if my car has this "knock back". I got into the habit of taping my brakes just to make sure a little earlier than I was planning on using them, that they were still there. Unfortuneatley my sponsor, ME, is on a tight budget. So I have to lose a few seconds on my lap times to check brakes at the end of high speed straights.
 

brkntrxn

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My sponsor, spelled W-I-F-E, has an insurance policy on my persona. Therefore, I am not encouraged to check my brakes at the end of the straights.
 

SVTmojo

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My sponsor, spelled W-I-F-E, has an insurance policy on my persona. Therefore, I am not encouraged to check my brakes at the end of the straights.

haha:D

Looks like will start looking around at some new front hubs, and next time I am in the rear, I will have to take a look at the play in my rear axles.

I appreciate the help guys!
 

StacyStangz

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Hi Mike,

It was great meeting you last Saturday! I was hanging out at the Kenny Brown booth when you came up to get 'more' stuff for your cobra!

Hope to see you in Oct to do it again!
 

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