Brake Pad Thickness: When to replace?
02-12-2008, 04:03 PM
#1
Rennlist Member
Thread Starter
Brake Pad Thickness: When to replace?
After roughly 20 DE days in 2007, I am preparing for my first DE of 2008 in a few weeks. My GT3 is strictly a track car.
At what point are brake pads *done*? I am running RS19s up front, and RS14s in the rear. The RS14s look great, but the RS19s are definitely "thinner" than the 14s. I have read on various posts that the "50% of what they were new" rule applies, but am unsure what that equate to in millimeters.
What is your rule of thumb?
Thanks,
-Blake
At what point are brake pads *done*? I am running RS19s up front, and RS14s in the rear. The RS14s look great, but the RS19s are definitely "thinner" than the 14s. I have read on various posts that the "50% of what they were new" rule applies, but am unsure what that equate to in millimeters.
What is your rule of thumb?
Thanks,
-Blake
02-12-2008, 04:15 PM
#2
When the backing plate hits the rotor, they're toast.
Don't forget that they may not wear evenly and the part you see with the wheel on is the thicker section. That was my experience leading to the above.
Don't forget that they may not wear evenly and the part you see with the wheel on is the thicker section. That was my experience leading to the above.
02-12-2008, 04:39 PM
#3
Three Wheelin'
You should pull off the wheels to get a good look at the top and bottom and the outer and inner pad thickness. The rule of thumb is when the material is the same thickness as the backing plate it's time to change. Another thing to keep in mind is the thinner they get the faster they wear down.
02-12-2008, 05:18 PM
#4
Nordschleife Master
Blake, another variable to keep in mind is your specific use. If it is all tracking I would pull the fronts and take a look. If you are getting the pads very hot they can crack. It is not a big a deal for you as I am on PCCBs but the pad material can come off in chunks.
02-12-2008, 05:22 PM
#5
Still plays with cars.
Lifetime Rennlist
Member
New brake pads ae about 10mm thick. I replace them at 50 percent unless it is the last day of an event. I then replace them before the next one.
RS 14 in back help reduce front pad and rotor wear. I also found that the Cup brake ducts were useful. By going to 19/14 and the Cup ducts I was able to extend rotor life to 25 days. A big change from the 10 days I got previously on my 996GT3 in the Red run group.
Best,
RS 14 in back help reduce front pad and rotor wear. I also found that the Cup brake ducts were useful. By going to 19/14 and the Cup ducts I was able to extend rotor life to 25 days. A big change from the 10 days I got previously on my 996GT3 in the Red run group.
Best,
02-12-2008, 06:36 PM
#6
Nordschleife Master
As Bob said, at 50% thickness it's time to change. Brake wear is NOT linear, rather it's exponential. As you move past the 50% life, brake wear accelerates much faster than when at full strength. If I am near 50% I run and check after every session. And of course, I ALWAYS have a backup set up pads ready to go at all times. Don't forget to bleed with the brake change!
02-12-2008, 06:46 PM
#7
Rennlist Member
Thread Starter
Thanks guys!
Bob - I carefully researched all of your posts over the years when you had the 996 GT3. I run my current brake pads because of your recommendations, and have also added the cup ducts to benefit cooling in the front.
All - this is great advice. I will be down at the track on Friday to "play around" with the car... I'll take Roberga/Rob in VA/Holger B's recommendation and pull the front pads.
LVDell - next step for me is to try and catch up with your new garage!
You guys rock as usual.
-Blake
Bob - I carefully researched all of your posts over the years when you had the 996 GT3. I run my current brake pads because of your recommendations, and have also added the cup ducts to benefit cooling in the front.
All - this is great advice. I will be down at the track on Friday to "play around" with the car... I'll take Roberga/Rob in VA/Holger B's recommendation and pull the front pads.
LVDell - next step for me is to try and catch up with your new garage!
You guys rock as usual.
-Blake
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02-12-2008, 06:51 PM
#8
Pad Life
Someone much more knowledgeable than I told me that pads should be replaced no later than 50%. This is because at this point the carbon in the pad has depleted and its ability to absorb heat is greatly reduced. This means the heat is sent to the brake pistons and more importantly the piston seals. Temps approach 1200 degrees and rubber seals don't last long at these temps. So pay now or pay more later, its up to you.
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02-12-2008, 06:55 PM
#9
Three Wheelin'
02-12-2008, 07:01 PM
#10
Rennlist Member
Thread Starter
Good point Rob... This "internet thing" means that Dell is my virtual neighbor... When I need ANYTHING from his garage, I will be sure to borrow it from him... Dell, you've got a UPS Store near you, right?
-B
-B
02-12-2008, 07:16 PM
#11
Nordschleife Master
Virtual yes. Shipping? No!
02-12-2008, 07:24 PM
#12
Rennlist Member
Thread Starter
LOL. Post some pics of that new lift/garage, Dell. I have serious garage envy. Did you see that thread on the Racing forum? https://rennlist.com/forums/racing-and-drivers-education-forum/407802-who-has-a-lift-in-their-garage.html Damn!
Again, thanks guys for your feedback.
-Blake
Again, thanks guys for your feedback.
-Blake
02-13-2008, 04:37 PM
#14
Three Wheelin'
Craig at www.Renn store.com (he sells Pagids only) mentioned to me that the final 1/3 thickness is garbage time and also, as LVDell said:
"...at 50% thickness it's time to change. Brake wear is NOT linear, rather it's exponential. As you move past the 50% life, brake wear accelerates much faster than when at full strength. If I am near 50% I run and check after every session. And of course, I ALWAYS have a backup set up pads ready to go at all times. Don't forget to bleed with the brake change!"
Echoes what Craig said and has worked very well for me.
FWIW, I also went through the original equipment set of pads in 2.5 track days...........YIKES
"...at 50% thickness it's time to change. Brake wear is NOT linear, rather it's exponential. As you move past the 50% life, brake wear accelerates much faster than when at full strength. If I am near 50% I run and check after every session. And of course, I ALWAYS have a backup set up pads ready to go at all times. Don't forget to bleed with the brake change!"
Echoes what Craig said and has worked very well for me.
FWIW, I also went through the original equipment set of pads in 2.5 track days...........YIKES
02-14-2008, 07:54 PM
#15
Burning Brakes
Someone much more knowledgeable than I told me that pads should be replaced no later than 50%. This is because at this point the carbon in the pad has depleted and its ability to absorb heat is greatly reduced. This means the heat is sent to the brake pistons and more importantly the piston seals. Temps approach 1200 degrees and rubber seals don't last long at these temps. So pay now or pay more later, its up to you.
Not to mention overheating your brake fluid faster. The pad acts as an insulator as well just by virtue of it's thickness.... 50% for track use is a good reccomendation.
