2nd rain free track day
02-29-2012, 01:08 PM
#1
Thread Starter
Join Date: Jan 2012
Location: Florida
Posts: 19
2nd rain free track day
Just did my 2nd track day at Homestead with Chin,
I had a question on brakes maybe someone could confirm.
After about 4 laps in after warm up session, braking on corner approach produces some steering shimmy; I don't feel a significant pulse in the
brake pedal though.
After talking with my buddies, we thought it could be uneven deposits on the rotors. Its a 2010 GT w/stock brakes and Ate brake fluid.
I do notice on the street now when you crawl along with slight brake pressure
you can feel the car lope along like the pads are skipping across the rotors, but at normal braking speeds, the brakes feel smooth.
Is there any proceedure to clean off the deposits if it turns out that is what it is, if not I'm looking at new rotors/pads then.
By the way, I had a blast driving, building speed, learning the line, put over 100 miles on the track in one day!
I had a question on brakes maybe someone could confirm.
After about 4 laps in after warm up session, braking on corner approach produces some steering shimmy; I don't feel a significant pulse in the
brake pedal though.
After talking with my buddies, we thought it could be uneven deposits on the rotors. Its a 2010 GT w/stock brakes and Ate brake fluid.
I do notice on the street now when you crawl along with slight brake pressure
you can feel the car lope along like the pads are skipping across the rotors, but at normal braking speeds, the brakes feel smooth.
Is there any proceedure to clean off the deposits if it turns out that is what it is, if not I'm looking at new rotors/pads then.
By the way, I had a blast driving, building speed, learning the line, put over 100 miles on the track in one day!
02-29-2012, 02:26 PM
#2
Join Date: Feb 2012
Location: CA
Posts: 8
Wow, sounds like it was a good day. As far as brake deposits go, brake cleaner will do if that is it. if you can see a color pattern or anything like that on the rotor, that could be localized heat treatment, not good. It all makes a good case for a front brake upgrade. I don't have any plans now to track, but AX keeps my brakes from getting heavier use. Keep us informed.
02-29-2012, 03:47 PM
#3
3rd Gear Member
Join Date: Jan 2010
Location: Louisiana
Posts: 738
Warped rotors. Unfortunately any decent aggressiveness on the stock rotors without some extra cooling, especially prolonged exposure (several laps) those type of conditions will easily warp our stock rotors.
The shimmy should get worse the harder you brake (the harder the pads are riding the warp).
Go get your rotors turned and get a brake cooling kit if you plan on aggressive braking for track usage.
The shimmy should get worse the harder you brake (the harder the pads are riding the warp).
Go get your rotors turned and get a brake cooling kit if you plan on aggressive braking for track usage.
02-29-2012, 05:05 PM
#4
1st Gear Member
Join Date: Jan 2012
Location: CA
Posts: 79
Do you have brake cooling ducts?
Were the brakes ever bedded in?
It might be time for new rotors and pads and a bed in process.
I assume you have stainless steel lines as you're running ATE' hi temp fluid?
I track my car once a month and usually do a quick brake bleed before each event.
Were the brakes ever bedded in?
It might be time for new rotors and pads and a bed in process.
I assume you have stainless steel lines as you're running ATE' hi temp fluid?
I track my car once a month and usually do a quick brake bleed before each event.
03-01-2012, 05:44 AM
#5
Thread Starter
Join Date: Jan 2012
Location: Florida
Posts: 19
I think I'll try that, followed by a correct bedding of the pads.
I also thought about block sanding the glaze off the pads before rebedding.
Good idea?
I guess turning the rotors would be a good idea too, a little less $$ than new rotors for now, with a little sacrifice in heat disipation.
I did shop for new rotors, still can't decide on which ones, many choices, the slotted power slots look like a good candidate, what do you think?
I took off the dust shields, thinking better air flow would help, but no change. Ducts are next on my list, either fab my own or a kit ($$)
[/QUOTE]Were the brakes ever bedded in?[/QUOTE]
No I never did that, but as per above response, I hope to have some succes with this.
[/QUOTE]I assume you have stainless steel lines as you're running ATE' hi temp fluid?[/QUOTE]
No stainless lines yet, on my list too. (Using ATE blue)
[/QUOTE]I track my car once a month and usually do a quick brake bleed before each event.[/QUOTE]
Yes we actually flush through about 1 liter prior to track day. My buddy has a bunch of brake fluid so I'm good there
Thanks a lot for the responses, I'll continue to post as events allow, will try to get some pictures up too.
My next track day is ar 17 at Homestead, and the Mar 24 at Sebring.
see ya!
I also thought about block sanding the glaze off the pads before rebedding.
Good idea?
I did shop for new rotors, still can't decide on which ones, many choices, the slotted power slots look like a good candidate, what do you think?
I took off the dust shields, thinking better air flow would help, but no change. Ducts are next on my list, either fab my own or a kit ($$)
[/QUOTE]Were the brakes ever bedded in?[/QUOTE]
No I never did that, but as per above response, I hope to have some succes with this.
[/QUOTE]I assume you have stainless steel lines as you're running ATE' hi temp fluid?[/QUOTE]
No stainless lines yet, on my list too. (Using ATE blue)
[/QUOTE]I track my car once a month and usually do a quick brake bleed before each event.[/QUOTE]
Yes we actually flush through about 1 liter prior to track day. My buddy has a bunch of brake fluid so I'm good there
Thanks a lot for the responses, I'll continue to post as events allow, will try to get some pictures up too.
My next track day is ar 17 at Homestead, and the Mar 24 at Sebring.
see ya!
03-01-2012, 08:00 AM
#6
4th Gear Member
Join Date: Oct 2007
Location: Harrisburg PA
Posts: 1,778
A small amount of brake judder is nothing to worry about and it is probably due to pad deposits. What pads are you using? Most folks claim you can clean off old deposits with a scotch brite pad and orbital sander but I do it the easy way, throw in a set of track pads and go do a bedding process - cleans them up every time, track pads are seriously abrasive when cold and scrap any deposits right off. Here is a link to a good video on bedding and such: Preparing Brake Pads and Rotors
After doing this sport for several years I've learned a few things about brake cooling. The typical advice is throw on a set of cooling ducts and be done with it. But I'm begining to question that line of thought as the be all, end all. I think its a fine line between needing cooling air and having too much. Rotors need heat in them to work properly and they don't like severe temperature changes, it causes them to crack prematurely. So at a track like VIR, with its very long starights (long periods between braking), brake cooling kills the rotors. They get really hot going thru turn 1 thru 5 and then cool way down until going into the oak tree area, then a hard brake heats them up and then you hit the back straight, cool down, etc. Over a 30 min session you have a lot of intense heat followed by lots of cooling. Next time I go there I'm plugging the brake ducts. IMO, don't take the brake duct thing as gospel, it really depends on the track(s) you are running. If the track it tight w/ lots of braking points and few long straights then you need them. But on a wide open track...not so much and they may even do more harm than good.
After doing this sport for several years I've learned a few things about brake cooling. The typical advice is throw on a set of cooling ducts and be done with it. But I'm begining to question that line of thought as the be all, end all. I think its a fine line between needing cooling air and having too much. Rotors need heat in them to work properly and they don't like severe temperature changes, it causes them to crack prematurely. So at a track like VIR, with its very long starights (long periods between braking), brake cooling kills the rotors. They get really hot going thru turn 1 thru 5 and then cool way down until going into the oak tree area, then a hard brake heats them up and then you hit the back straight, cool down, etc. Over a 30 min session you have a lot of intense heat followed by lots of cooling. Next time I go there I'm plugging the brake ducts. IMO, don't take the brake duct thing as gospel, it really depends on the track(s) you are running. If the track it tight w/ lots of braking points and few long straights then you need them. But on a wide open track...not so much and they may even do more harm than good.
Last edited by Argonaut; 03-01-2012 at 08:18 AM.
03-05-2012, 03:12 AM
#7
1st Gear Member
Join Date: Sep 2009
Location: CA
Posts: 117
Shawn, I am surprised you got more than a track day on the stock pads. I fully consumed the first set of stock pads during the first track day. Ditto for Yellow EBC's the second track day. Since then, I've done about 8 track days on a set of DTC60 pads and they are down to the last few millimeters now.
Argonaut, Curiously, the DTC60's seem to have worn much faster since I installed brake ducts on the car but I wasn't measuring them each time. In saying that, I have never had a case of lost/soft brakes with any of the setups.
Argonaut, Curiously, the DTC60's seem to have worn much faster since I installed brake ducts on the car but I wasn't measuring them each time. In saying that, I have never had a case of lost/soft brakes with any of the setups.
03-05-2012, 12:04 PM
#9
Thread Starter
Join Date: Jan 2012
Location: Florida
Posts: 19
Actually, I disassembled the brakes prior to the second day to remove the dust shields thinking they were shrouding the inside face of the rotors, causing uneven temps from the outside face. (I'm no engineer) There was plenty of meat left on the pads (Stock)
I didn't see anything mentioning the yellow EBC pads in the post, I will consider aftermarket replacements when I have worn out the stockers.
I reviewed the brake bedding video (Thanks for that) and think I will try that before I go back to HMS on 3/17.
By the way I've been practicing Heel toe upshifts a lot per my instructors suggestion, and I think I have it figured out so I will try that too.
I didn't see anything mentioning the yellow EBC pads in the post, I will consider aftermarket replacements when I have worn out the stockers.
I reviewed the brake bedding video (Thanks for that) and think I will try that before I go back to HMS on 3/17.
By the way I've been practicing Heel toe upshifts a lot per my instructors suggestion, and I think I have it figured out so I will try that too.
