Autobahn Brake Performance Post - RB/DTC60
10-01-08, 03:05 PM
#1
Autobahn Brake Performance Post - RB/DTC60
Ok, this is the big summary post that I have promised for a while.
First I want to thank a couple people for helping me out with this setup.
1) Warren at Racing Brake for getting me the custom DTC60's in the front for the Porsche Big Reds (and DTC60s for the RB rear kit)
2) Chad/Ben for helping me out with the collection of temp data.
3) Chad for letting me use his Traqmate to collect GPS/accelerometer data.
4) Damian for helping me out at the shop.
Ok, lets start by looking at the track map from the GPS data:
As you can see this is a fairly busy track. There's 3 solid braking zones (into 1, 8, 11) and 5 other medium braking zones (into 4, 5, 6, 9, 13) per lap. There isn't really a long time for the brakes to cool at any point on the track, really 10-11 is the best break for them and that's only about 15 seconds.
Here's the data from the accelerometers on the braking/acceleration:
You can see based on this my braking style. In 1/8/11 I get on them hard to start, but I have a hard time maintaining that high level while I heel-toe. Generally you can see the spikes when I let go of the clutch as well and get the additional engine braking. Realistically I'm too tall for the car, and with the stock setup I have a hard time getting my feet in the right place. With more practice I will get better here. Also you can see that in turns like 4/6/8 I use a fair amount of trail on the way in to get the car to rotate. On some of the sharper turns like 9 or 11 there's very little trail. Depending on weather/track surface etc. I can generally get to 1.2g's of decel. I lean on the ABS as well especially if I'm trying to go fast. Mine has always worked pretty well.
Here's the lateral numbers from that same lap:
As you can see, I normally get about 1.2g's laterally from these tires as well.
Ok, now on to the brake data. Before this event I put caliper paint on every pad and every rotor face so i could collect some peak numbers.
Based on the heat, the paint changes color, giving you an ideal of the peak temps. With some of my older setups (stock brakes etc) I was able to melt the paint right off the parts.
Thankfully with the new setup that isn't a problem. Here's the chart with the numbers from the AB weekend:
First, lets talk about pad wear. I have generally had good pad wear with the new TT calipers up front, and I have always had good pad wear in the rear. With HT-10's I can get usually 16-24 20 min sessions (4-6 days depending on the track) out of a set of fronts and 40-48 sessions (10-12 days) out of a set of rears. Usually the pad feels very good for the first 2-3 days, and then the last couple days as the pad thins out I start to get a squishy pedal as there is some boiling of the fluid due to the additional heat transfer. Usually this is remedied by bleeding the brakes more often near the end of the pad's life.
With the new DTC 60's, it looks like I can expect an additional day or two out of each set as long as I rotate the pads around to even out the wear. These pads were motorsport thickness, so I started out with .06" more pad than I have before. (.710" or 18.03mm) In addition the as you can see from the numbers, I only used a maximum of 2.3mm of pad and that was only on the outside front left. I did get a little bit of inside to outside taper on that pad as well. The rest of the pads are relatively similar in thickness and taper.
For the rear pads, again the outside left had the highest wear, with 1.3mm out of a .515" (13.08mm) starting value. This is bascially in line with what I have seen before for wear with HT-10s or Carbotech pads.
With respect to pad temps there are a couple different things that are interesting:
Also of note is that we can see the effect of the Racing Brake rotor design. In the right rear I had paint both next to, and opposite of the tabs that hold the rotor to the hat. The difference shows up very obviously in the paint as a 200 degree difference in temp. Here's the pictures that also show the temp difference:
For Road America I put alot more paint on the rotors so we could see how far that temp gradient extended into the rotor face as well as if we could see it on the outside edge. Stay tuned for that data later.
As you can see on the front rotors, there is no temp difference on those by the time they get to the outside edge.
Finally lets talk about braking feel. I have always liked the feel of the HT-10s better than any other pad I've tried. So for me, the main goals with the DTCs were to get additional brake torque so that I could get the same decel with less pedal input (or more decel if I got better tires for the same input) and longer life. The pedal input was definitely reduced as compared to the HT-10s. In addition they brake better while cool than the HT10s, however my tires still take quite a while to come up so I wasn't able to use that capability. The pedal was high and firm the entire weekend and I didn't bleed them at all. (Actually I didn't bleed them for the next weekend either but I'll discuss that in the next installment) In fact they were so good that I would consider going back to the stock master cylinder to lower the pedal input pressure a bit.
OK. Lots of words there, so lets summarize:
First I want to thank a couple people for helping me out with this setup.
1) Warren at Racing Brake for getting me the custom DTC60's in the front for the Porsche Big Reds (and DTC60s for the RB rear kit)
2) Chad/Ben for helping me out with the collection of temp data.
3) Chad for letting me use his Traqmate to collect GPS/accelerometer data.
4) Damian for helping me out at the shop.
Ok, lets start by looking at the track map from the GPS data:
As you can see this is a fairly busy track. There's 3 solid braking zones (into 1, 8, 11) and 5 other medium braking zones (into 4, 5, 6, 9, 13) per lap. There isn't really a long time for the brakes to cool at any point on the track, really 10-11 is the best break for them and that's only about 15 seconds.
Here's the data from the accelerometers on the braking/acceleration:
You can see based on this my braking style. In 1/8/11 I get on them hard to start, but I have a hard time maintaining that high level while I heel-toe. Generally you can see the spikes when I let go of the clutch as well and get the additional engine braking. Realistically I'm too tall for the car, and with the stock setup I have a hard time getting my feet in the right place. With more practice I will get better here. Also you can see that in turns like 4/6/8 I use a fair amount of trail on the way in to get the car to rotate. On some of the sharper turns like 9 or 11 there's very little trail. Depending on weather/track surface etc. I can generally get to 1.2g's of decel. I lean on the ABS as well especially if I'm trying to go fast. Mine has always worked pretty well.
Here's the lateral numbers from that same lap:
As you can see, I normally get about 1.2g's laterally from these tires as well.
Ok, now on to the brake data. Before this event I put caliper paint on every pad and every rotor face so i could collect some peak numbers.
Based on the heat, the paint changes color, giving you an ideal of the peak temps. With some of my older setups (stock brakes etc) I was able to melt the paint right off the parts.
Thankfully with the new setup that isn't a problem. Here's the chart with the numbers from the AB weekend:First, lets talk about pad wear. I have generally had good pad wear with the new TT calipers up front, and I have always had good pad wear in the rear. With HT-10's I can get usually 16-24 20 min sessions (4-6 days depending on the track) out of a set of fronts and 40-48 sessions (10-12 days) out of a set of rears. Usually the pad feels very good for the first 2-3 days, and then the last couple days as the pad thins out I start to get a squishy pedal as there is some boiling of the fluid due to the additional heat transfer. Usually this is remedied by bleeding the brakes more often near the end of the pad's life.
With the new DTC 60's, it looks like I can expect an additional day or two out of each set as long as I rotate the pads around to even out the wear. These pads were motorsport thickness, so I started out with .06" more pad than I have before. (.710" or 18.03mm) In addition the as you can see from the numbers, I only used a maximum of 2.3mm of pad and that was only on the outside front left. I did get a little bit of inside to outside taper on that pad as well. The rest of the pads are relatively similar in thickness and taper.
For the rear pads, again the outside left had the highest wear, with 1.3mm out of a .515" (13.08mm) starting value. This is bascially in line with what I have seen before for wear with HT-10s or Carbotech pads.
With respect to pad temps there are a couple different things that are interesting:
- You can see that the numbers from the wear correspond relatively directly. That is to say, the higher temps, showed higher wear. That makes sense, areas with higher temps are also wearing more.
- There is probably some sort of issue with the left rear caliper, since we can see that the temps and wear there are probably higher than they should be. It might be sticking somewhat.
- I need to check my front right brake duct to make sure everything is ok. The rotor temp there is substantially higher when it shouldn't be according to everything else. I may have a broken tube or a kink or it was plugged up with something.
Also of note is that we can see the effect of the Racing Brake rotor design. In the right rear I had paint both next to, and opposite of the tabs that hold the rotor to the hat. The difference shows up very obviously in the paint as a 200 degree difference in temp. Here's the pictures that also show the temp difference:
For Road America I put alot more paint on the rotors so we could see how far that temp gradient extended into the rotor face as well as if we could see it on the outside edge. Stay tuned for that data later.
As you can see on the front rotors, there is no temp difference on those by the time they get to the outside edge.
Finally lets talk about braking feel. I have always liked the feel of the HT-10s better than any other pad I've tried. So for me, the main goals with the DTCs were to get additional brake torque so that I could get the same decel with less pedal input (or more decel if I got better tires for the same input) and longer life. The pedal input was definitely reduced as compared to the HT-10s. In addition they brake better while cool than the HT10s, however my tires still take quite a while to come up so I wasn't able to use that capability. The pedal was high and firm the entire weekend and I didn't bleed them at all. (Actually I didn't bleed them for the next weekend either but I'll discuss that in the next installment) In fact they were so good that I would consider going back to the stock master cylinder to lower the pedal input pressure a bit.
OK. Lots of words there, so lets summarize:
- Brakes worked better than ever the whole weekend.
- DTC60 pads are new favorite pad, they felt better, and should last longer and I'd recommend them to all the track guys.
- More investigation to do, but temps seemed to be in check all around.
- More to come from my Road America weekend data.
10-01-08, 03:48 PM
#3
>>Can you share what year & model of the Porsche calipers you used up front, including piston sizes if known ?
He is running my old 993 'BIG RED' kit off my race car, pistons are 44mm and 36mm. However, I made them 'BIG YELLOWS' when I had them on my race car :-)
He is running my old 993 'BIG RED' kit off my race car, pistons are 44mm and 36mm. However, I made them 'BIG YELLOWS' when I had them on my race car :-)
10-01-08, 03:54 PM
#4
I have the Porsche 911 (993 - 1995-1998) TT "Big Red" calipers and they have 36mm leading and 44mm trailing pistons.
The front rotors are 12.677in (322mm) in diameter and 1.25in (31.75mm) thick.
I think I have the proper bias... Right now it's about 73%/27%, and under a consistent 1.2 decel I should be about 67%/33% and of course you want the fronts to lock first usually.
Practically speaking I lock the fronts and rears with regularity, and it doesn't seem to be consistently one or the other. Really just depends on the track surface. I would like to try the 70s in front and rear independently and test to see what it looks like under controlled circumstances.
The front rotors are 12.677in (322mm) in diameter and 1.25in (31.75mm) thick.
I think I have the proper bias... Right now it's about 73%/27%, and under a consistent 1.2 decel I should be about 67%/33% and of course you want the fronts to lock first usually.
Practically speaking I lock the fronts and rears with regularity, and it doesn't seem to be consistently one or the other. Really just depends on the track surface. I would like to try the 70s in front and rear independently and test to see what it looks like under controlled circumstances.
10-01-08, 06:23 PM
#5
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GooRoo,
Thank you for your excellent and detailed report. We are glad that our products have helped you improve your driving performance. We look forward to hearing about your continued success on the track.
Thank you for your excellent and detailed report. We are glad that our products have helped you improve your driving performance. We look forward to hearing about your continued success on the track.
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