DTC-70 Pad Coloration with AP T-1 Caliper Kit
05-31-2011, 11:04 PM
#1
Drifting
Thread Starter
DTC-70 Pad Coloration with AP T-1 Caliper Kit
I had my first track day with my new AP T1 caliper kit this weekend. It's on a C5 Z06 and I'm using the NAPA type rotors. The pads are DTC-70 in front and DTC-60 in the rear (stock calipers in back) and I use Prestone DOT4 brake fluid. It was in the 90's for the first timetrials event of the MCSCC season at Blackhawk Farms
I was checking the pads for wear & taper tonight and noticed that the outside pads have a polished band on the surface. The other thing is that the outside pads look like they ran hotter than the inside.
Performance wise, I have no complaints. Any explanation for differences?
I was checking the pads for wear & taper tonight and noticed that the outside pads have a polished band on the surface. The other thing is that the outside pads look like they ran hotter than the inside.
Performance wise, I have no complaints. Any explanation for differences?
06-01-2011, 04:10 PM
#2
Supporting Vendor
Hi,
First, I'm glad you're enjoying the brakes. Thanks for purchasing them (we supply Hardbar with the AP components).
It is normal for outside pads to run hotter than the inside. They are often tucked up inside the wheel and don't get as much cooling air...heat gets trapped in that area, etc. If you look at the discs that come with the complete T1 kit, they have scallops in the hat that allow air to flow from inside the disc across the outer disc face. The NAPA type discs you are running would not have that provision.
I would double check a couple of things:
1) Make sure the caliper bracket is installed securely/flush on the upright, and make sure the caliper is sitting flush against the bracket. If these components are out of alignment that would prevent the caliper from running true on the disc.
2) Also make sure the pads are sitting down all the way in the caliper, and that the top edge of the pad isn't higher than the outer edge of the disc. Again, this would be indicative that something is a bit out of whack as in point 1 above.
Another possibility is that you had some inclusions or gaps in the outer region of the pad material. Sometimes these gaps fill in or smear when the pad gets heated up to track temps. Were both outer pads showing the same banding at the top?
All of that said, it's also not abnormal for pads to bed-in on only a portion of the disc to begin with. After they get some more time on them they sometimes settle into the disc, and show a more complete transfer layer across the face of the disc. If you watch my video on bed-in, you'll see that my transfer layer starts on the outside edge (that video was shot with OEM calipers, napa discs, and hawk blue race pads). I actually had to go back out and work the discs over a bit more to get them to transfer across the entire disc face.
First, I'm glad you're enjoying the brakes. Thanks for purchasing them (we supply Hardbar with the AP components).
The other thing is that the outside pads look like they ran hotter than the inside.
I would double check a couple of things:
1) Make sure the caliper bracket is installed securely/flush on the upright, and make sure the caliper is sitting flush against the bracket. If these components are out of alignment that would prevent the caliper from running true on the disc.
2) Also make sure the pads are sitting down all the way in the caliper, and that the top edge of the pad isn't higher than the outer edge of the disc. Again, this would be indicative that something is a bit out of whack as in point 1 above.
Another possibility is that you had some inclusions or gaps in the outer region of the pad material. Sometimes these gaps fill in or smear when the pad gets heated up to track temps. Were both outer pads showing the same banding at the top?
All of that said, it's also not abnormal for pads to bed-in on only a portion of the disc to begin with. After they get some more time on them they sometimes settle into the disc, and show a more complete transfer layer across the face of the disc. If you watch my video on bed-in, you'll see that my transfer layer starts on the outside edge (that video was shot with OEM calipers, napa discs, and hawk blue race pads). I actually had to go back out and work the discs over a bit more to get them to transfer across the entire disc face.
06-01-2011, 10:54 PM
#5
Drifting
Thread Starter
Hi,
First, I'm glad you're enjoying the brakes. Thanks for purchasing them (we supply Hardbar with the AP components).
It is normal for outside pads to run hotter than the inside. They are often tucked up inside the wheel and don't get as much cooling air...heat gets trapped in that area, etc. If you look at the discs that come with the complete T1 kit, they have scallops in the hat that allow air to flow from inside the disc across the outer disc face. The NAPA type discs you are running would not have that provision.
I would double check a couple of things:
1) Make sure the caliper bracket is installed securely/flush on the upright, and make sure the caliper is sitting flush against the bracket. If these components are out of alignment that would prevent the caliper from running true on the disc.
2) Also make sure the pads are sitting down all the way in the caliper, and that the top edge of the pad isn't higher than the outer edge of the disc. Again, this would be indicative that something is a bit out of whack as in point 1 above.
Another possibility is that you had some inclusions or gaps in the outer region of the pad material. Sometimes these gaps fill in or smear when the pad gets heated up to track temps. Were both outer pads showing the same banding at the top?
All of that said, it's also not abnormal for pads to bed-in on only a portion of the disc to begin with. After they get some more time on them they sometimes settle into the disc, and show a more complete transfer layer across the face of the disc. If you watch my video on bed-in, you'll see that my transfer layer starts on the outside edge (that video was shot with OEM calipers, napa discs, and hawk blue race pads). I actually had to go back out and work the discs over a bit more to get them to transfer across the entire disc face.
First, I'm glad you're enjoying the brakes. Thanks for purchasing them (we supply Hardbar with the AP components).
It is normal for outside pads to run hotter than the inside. They are often tucked up inside the wheel and don't get as much cooling air...heat gets trapped in that area, etc. If you look at the discs that come with the complete T1 kit, they have scallops in the hat that allow air to flow from inside the disc across the outer disc face. The NAPA type discs you are running would not have that provision.
I would double check a couple of things:
1) Make sure the caliper bracket is installed securely/flush on the upright, and make sure the caliper is sitting flush against the bracket. If these components are out of alignment that would prevent the caliper from running true on the disc.
2) Also make sure the pads are sitting down all the way in the caliper, and that the top edge of the pad isn't higher than the outer edge of the disc. Again, this would be indicative that something is a bit out of whack as in point 1 above.
Another possibility is that you had some inclusions or gaps in the outer region of the pad material. Sometimes these gaps fill in or smear when the pad gets heated up to track temps. Were both outer pads showing the same banding at the top?
All of that said, it's also not abnormal for pads to bed-in on only a portion of the disc to begin with. After they get some more time on them they sometimes settle into the disc, and show a more complete transfer layer across the face of the disc. If you watch my video on bed-in, you'll see that my transfer layer starts on the outside edge (that video was shot with OEM calipers, napa discs, and hawk blue race pads). I actually had to go back out and work the discs over a bit more to get them to transfer across the entire disc face.
I had to file off some of the upright ears to make the adapter brackets fit flush with the mounting surfaces. This was flashing on the aluminum forging and I don't expect that this affects strength. I talked to Gary about this. After removing about 1.5 mm at a 45 degree angle to vertical, the brackets bolted on nicely. I'm pretty sure everything is square with the world.
I also had to put 1 mm thick shim washers between the adapter and the upright to center the caliper on the rotor. I missed this at first and that was why the rotors were rubbing on the calipers on the outboard sides. The shims are stainless, 14 mm x 22 mm x 1 mm. I bought them from McMaster-Carr.
Finally I was able to push the pistons back until they were flush with the inside of the body. After I did this, the pads slipped in with plenty of clearance even though they were almost 21 mm thick over the paint/powdercoat. I tried screwdrivers, putty knives and feeler gauges but nothing will push the pad/pistons back. BUT, if you pull the pad out and stick the handle of a Craftsman 1/2" drive ratchet between the rotor and piston, it easy to rotate the handle and push the pistons back flush. The handle profile is a rounded rectangle. I got the UPS shipping label last week, but I can't see a reason to return the calipers at this point. Thank you for offering to look at them.
The top radius of the pad friction material matches the OD of the rotor perfectly. The rotor surface has a nice even finish with virtually no heat checking visible.
Both outer pads show the same banding at the top. I would agree with your assessment that the the rotor cooling is probably not even due to the geometry of the 1 piece rotor.
Unfortunately I can't comment on the pad material transfer to the rotor as it's probably gone now. I put a set of BP-10 pads in for the drive home and 100 miles of highway use probably removed everything.
I experienced green fade at the end of my first 3 lap practice session, so I assumed that the pads were fully bedded. We had 4 practice sessions like that and then 5 timed runs in the afternoon. It was hot and Blackhawk has a reputation for being hard on brakes.
I measured the DTC-70 front pads last night and the average thickness is about 19 mm with a tiny bit of taper top to bottom and inside to outside. I marked them so I can flip them next time.
I think I made the right decision to purchase the AP T1 kit and can't wait for Autobahn next week.
Erik Guldberg
06-01-2011, 10:59 PM
#6
Drifting
Thread Starter
06-02-2011, 09:37 AM
#7
Supporting Vendor
Thanks for all of the details Erik. It sounds like you have everything on and square. Only 1 mm of pad wear and no discernible disc wear for a complete event is a nice amount! If everything feels good as you say, I'd just run them next time and see how it goes. I don't think you mentioned too much about bedding your pads before your event, so I'd recommend spending a little more time before the start of the next event doing so. You can do it in your first practice session, or on a country road near the track (if there is one). Investing a little more time on bedding could give you more even wear out of the components, not to mention superior performance. Good luck at Autobahn! 