[ZR1] ZR1 rotor life with track use: my data
10-11-2012, 12:35 AM
#1
Drifting
Thread Starter
Member Since: Jan 2005
Location: Deerfield, Illinois Turn On, Turn In, Track Out
Posts: 1,282
Likes: 0
Received 2 Likes
on
2 Posts
ZR1 rotor life with track use: my data
This is info from my recent thread re: caliper removal but I thought the title may give others some helpful info as it answers some questions I had in the past...
I weighed the rotors at my friendly neighborhood post office, which has a scale in the lobby open 24 hours. It weighs in lbs and ounces to 2 decimal places, then I converted the weight with an iPhone app (but clearly the ol' 2.2 lbs=1kg is not too tough to work with...) I also stopped at a FedEx Office that has a similar scale that I thought would weigh directly in kg but it was in lbs/ounces as well. The scales agreed to .01 kg converted from lb/oz. I looked into buying a scale from Office Depot and Staples but they only measured to 0.1 oz so I saved the $100+ by not buying a less accurate scale that I'd need only once/season.
Rotor weight info after 73 track sessions, 20-30 min each: left front 5905g, discard at 5901g; right front 5813g discard at 5839g. The left rear was 7336 g discard at 7245 g; I did not bother removing/weighing the right rear as the left has much more to go before it is spent. As noted above, the thickness looked good but the weight shows I got every last track session out of this set, and JVP is correct that the weight is clearly the more important factor. The right front rotor was under weight but did not crack or show much obvious outward wear; the sign I noted was that the pads simply don't hold up when the rotors have lost volume. Pads often last 18-20 sessions when new (as I recall), and maybe 8 sessions or less when the rotors have lost volume.
Most sessions were on pilot sport cup tires and PTM 4, some were PTM 3. Most sessions were at autobahn country club, with many turns and little time to cool the brakes; about 16 sessions were at Road America with much faster straights and more time for cooling. I have installed cooling ducts but they were on only for the last 13 sessions. I am headed to Road America for the last run of the season for 12 sessions, 20 min each, with new pads and rotors installed. Hopefully the weather will hold up!
I weighed the new rotors before installing them: one was 5966g (didn't record the discard weight) the other was 5926g discard at 5801.
I will weigh the next set at just under 70 sessions; this might take away some guess work in the future. Hope adding some data helps somebody out...
I weighed the rotors at my friendly neighborhood post office, which has a scale in the lobby open 24 hours. It weighs in lbs and ounces to 2 decimal places, then I converted the weight with an iPhone app (but clearly the ol' 2.2 lbs=1kg is not too tough to work with...) I also stopped at a FedEx Office that has a similar scale that I thought would weigh directly in kg but it was in lbs/ounces as well. The scales agreed to .01 kg converted from lb/oz. I looked into buying a scale from Office Depot and Staples but they only measured to 0.1 oz so I saved the $100+ by not buying a less accurate scale that I'd need only once/season.
Rotor weight info after 73 track sessions, 20-30 min each: left front 5905g, discard at 5901g; right front 5813g discard at 5839g. The left rear was 7336 g discard at 7245 g; I did not bother removing/weighing the right rear as the left has much more to go before it is spent. As noted above, the thickness looked good but the weight shows I got every last track session out of this set, and JVP is correct that the weight is clearly the more important factor. The right front rotor was under weight but did not crack or show much obvious outward wear; the sign I noted was that the pads simply don't hold up when the rotors have lost volume. Pads often last 18-20 sessions when new (as I recall), and maybe 8 sessions or less when the rotors have lost volume.
Most sessions were on pilot sport cup tires and PTM 4, some were PTM 3. Most sessions were at autobahn country club, with many turns and little time to cool the brakes; about 16 sessions were at Road America with much faster straights and more time for cooling. I have installed cooling ducts but they were on only for the last 13 sessions. I am headed to Road America for the last run of the season for 12 sessions, 20 min each, with new pads and rotors installed. Hopefully the weather will hold up!
I weighed the new rotors before installing them: one was 5966g (didn't record the discard weight) the other was 5926g discard at 5801.
I will weigh the next set at just under 70 sessions; this might take away some guess work in the future. Hope adding some data helps somebody out...
10-11-2012, 08:02 AM
#4
Tech Contributor
Member Since: Mar 1999
Location: Northern VA
Posts: 10,087
Received 3,835 Likes
on
1,156 Posts
"Ask Tadge" Producer
Prior to weighing them, did you scrub them down good with soap and water, and then let them dry completely?
and JVP is correct that the weight is clearly the more important factor.
jas
10-11-2012, 12:31 PM
#5
Le Mans Master
Thanks for the good info! I recall Spring Mountain saying a rough estimate for rotor life is two full sets of pads. So, every 2 pad swaps, you will probably have to swap the rotors. Considering the cost of pads and rotors, I may trade it in for a newer ZR1 when that time comes.
10-11-2012, 04:22 PM
#8
Drifting
Thread Starter
Member Since: Jan 2005
Location: Deerfield, Illinois Turn On, Turn In, Track Out
Posts: 1,282
Likes: 0
Received 2 Likes
on
2 Posts
Hard to pin down street vs track miles. The car is a daily driver except in snow; I have just under 21K miles and picked it up end of March 2011 new. This is the second set of rotors; the first set was replaced due to vibration in 8/11.
10-11-2012, 04:25 PM
#9
Drifting
Thread Starter
Member Since: Jan 2005
Location: Deerfield, Illinois Turn On, Turn In, Track Out
Posts: 1,282
Likes: 0
Received 2 Likes
on
2 Posts
I'm glad you were able to weigh the rotors, but, for what little it may be worth, I think it makes sense to pony up the cash for a good scale. Specially given the cost of the rotors. This scale is what GM dealers who are ZR1-certified have on hand to weigh the rotors. I have one of them in my garage at home. The keys with it are A)it can display down the the gram, and B)it has a 5kg calibration block.
Prior to weighing them, did you scrub them down good with soap and water, and then let them dry completely?
I have an impeccable source for my information.
jas
Prior to weighing them, did you scrub them down good with soap and water, and then let them dry completely?
I have an impeccable source for my information.
jas
10-11-2012, 04:28 PM
#10
Safety Car
...and about the vibration, as you went through those track events, did you notice any of it (vibration) coming back on? or were they dead smooth all the way to the end? I'm curious, mostly for the physics aspect, thinking as the rotor looses mass it would become imbalanced...
10-11-2012, 04:32 PM
#11
Drifting
Thread Starter
Member Since: Jan 2005
Location: Deerfield, Illinois Turn On, Turn In, Track Out
Posts: 1,282
Likes: 0
Received 2 Likes
on
2 Posts
It may well end up to be about 5 sets of pads; the trouble is that I don't want to have to burnish new pads in the middle of a track day and it's silly to buy a new set for every track day also. I ended up with some half-used pads that I would bring as spares so that if I was running low (4 mm is about the limit, when I removed pads with only 3 mm left on them they were crumbling) I would put the half-used, pre-burnished pads on to finish the day. I can go through my records to try to get an accurate count on the pads... The other problem as mentioned is that the pads last through fewer and fewer sessions as the rotors lose their volume.
10-11-2012, 04:52 PM
#12
Drifting
Thread Starter
Member Since: Jan 2005
Location: Deerfield, Illinois Turn On, Turn In, Track Out
Posts: 1,282
Likes: 0
Received 2 Likes
on
2 Posts
...and about the vibration, as you went through those track events, did you notice any of it (vibration) coming back on? or were they dead smooth all the way to the end? I'm curious, mostly for the physics aspect, thinking as the rotor looses mass it would become imbalanced...
Some of the vibration after a track day can easily be from tire pickup on the tires themselves or from lots of rubber pickup on the inside of the wheels; it still happened on my street tires, but less after road force balancing. I am a little pessimistic the problem can be 100% solved; it is a bummer in an otherwise great car.
10-11-2012, 04:58 PM
#13
Safety Car
You are correct; the second set of rotors were balanced when new, then would vibrate sometimes after an event, before an event, on certain roads but not others... I do think that as they lose mass there can be imbalance... I am told these are the same rotors used by Ferrari, and that the other holes in the rotors that are not being used to connect to the hat is for the Ferrari hat. I wonder if Ferraris have the same problem? I wonder if jas/Mr. Inside Brake Info Guy has any information on this? I know a solution has come from Aston Martin re: balancing.
Some of the vibration after a track day can easily be from tire pickup on the tires themselves or from lots of rubber pickup on the inside of the wheels; it still happened on my street tires, but less after road force balancing. I am a little pessimistic the problem can be 100% solved; it is a bummer in an otherwise great car.
Some of the vibration after a track day can easily be from tire pickup on the tires themselves or from lots of rubber pickup on the inside of the wheels; it still happened on my street tires, but less after road force balancing. I am a little pessimistic the problem can be 100% solved; it is a bummer in an otherwise great car.
Do the new rotors have any provision to balance them directly? I know one member was told this and I'm curious...seems like it would be almost worth it having your owner wheel balancer ! lol
10-11-2012, 05:15 PM
#14
Tech Contributor
Member Since: Mar 1999
Location: Northern VA
Posts: 10,087
Received 3,835 Likes
on
1,156 Posts
"Ask Tadge" Producer
10-15-2012, 12:43 PM
#15
Racer
I do not know if we should make a separate thread for this subject. I just measured mine.
Basically with 80 twenty minute sessions 2000 track miles 14000 total miles in 1.5 years, 2 sets of pads for all corners, the rotors have about 100g extra on the rears and about 85g extra on the fronts. I got scared with this post, as it seemed to me very fast to be needing new rotors...
Measured with a 35lbs postal scale rated +/-0.5g accuracy and tested with test weights. cost of the scale about 32+shipping from:
http://www.oldwillknottscales.com/my...traship35.html
Basically with 80 twenty minute sessions 2000 track miles 14000 total miles in 1.5 years, 2 sets of pads for all corners, the rotors have about 100g extra on the rears and about 85g extra on the fronts. I got scared with this post, as it seemed to me very fast to be needing new rotors...
Measured with a 35lbs postal scale rated +/-0.5g accuracy and tested with test weights. cost of the scale about 32+shipping from:
http://www.oldwillknottscales.com/my...traship35.html
10-15-2012, 03:09 PM
#16
I just want to chime in here on replacing the pads. I am installing my 5th set of front pads and 3rd set of rear pads this weekend and there is absolutely no reason to replace the pads before you are rubbing the plastic sensors. Yeah they get a little crumbly looking but that's normal. Yeah the brass rivets freaked me out at first too, but that's normal too. As expensive as these are, you need to use all of them. I have had no problem burnishing just the fronts either, you'll notice when you burnish all four corners it is much harder to get the rears up to temperature. I have also burnished front and rears and put the old rears back on and kept the new rears ready. If you are driving the car correctly and not using stability control, the front pads should wear twice as fast vs. the rear pads.
Also the other thing I have learned is you can brake longer and lighter including trail braking into the corner and run just as fast of lap time, and I am getting better pad wear that way too.
Ian
Also the other thing I have learned is you can brake longer and lighter including trail braking into the corner and run just as fast of lap time, and I am getting better pad wear that way too.
Ian
Last edited by isnider; 10-15-2012 at 03:12 PM.
10-15-2012, 03:17 PM
#17
Racer
I just want to chime in here on replacing the pads. I am installing my 5th set of front pads and 3rd set of rear pads this weekend and there is absolutely no reason to replace the pads before you are rubbing the plastic sensors. Yeah they get a little crumbly looking but that's normal. Yeah the brass rivets freaked me out at first too, but that's normal too. As expensive as these are, you need to use all of them. I have had no problem burnishing just the fronts either, you'll notice when you burnish all four corners it is much harder to get the rears up to temperature. I have also burnished front and rears and put the old rears back on and kept the new rears ready. If you are driving the car correctly and not using stability control, the front pads should wear twice as fast vs. the rear pads.
Also the other thing I have learned is you can brake longer and lighter including trail braking into the corner and run just as fast of lap time, and I am getting better pad wear that way too.
Ian
Also the other thing I have learned is you can brake longer and lighter including trail braking into the corner and run just as fast of lap time, and I am getting better pad wear that way too.
Ian
10-15-2012, 09:53 PM
#18
Drifting
Thread Starter
Member Since: Jan 2005
Location: Deerfield, Illinois Turn On, Turn In, Track Out
Posts: 1,282
Likes: 0
Received 2 Likes
on
2 Posts
So you have gotten the "change brake pad" (or similar) warning? My warning has never gone off... I have worn sets down to the plastic of the sensor wire, which is 4 mm tall. Lately I have tired flipping to put the thinner side of the wire towards the pad and the thicker side towards the backing to get another mm out of them, but it causes the backing to bulge out a little bit and thought it would cause unwanted separation.
10-15-2012, 09:56 PM
#19
Drifting
Thread Starter
Member Since: Jan 2005
Location: Deerfield, Illinois Turn On, Turn In, Track Out
Posts: 1,282
Likes: 0
Received 2 Likes
on
2 Posts
I just want to chime in here on replacing the pads. I am installing my 5th set of front pads and 3rd set of rear pads this weekend and there is absolutely no reason to replace the pads before you are rubbing the plastic sensors. Yeah they get a little crumbly looking but that's normal. Yeah the brass rivets freaked me out at first too, but that's normal too. As expensive as these are, you need to use all of them. I have had no problem burnishing just the fronts either, you'll notice when you burnish all four corners it is much harder to get the rears up to temperature. I have also burnished front and rears and put the old rears back on and kept the new rears ready. If you are driving the car correctly and not using stability control, the front pads should wear twice as fast vs. the rear pads.
Also the other thing I have learned is you can brake longer and lighter including trail braking into the corner and run just as fast of lap time, and I am getting better pad wear that way too.
Ian
Also the other thing I have learned is you can brake longer and lighter including trail braking into the corner and run just as fast of lap time, and I am getting better pad wear that way too.
Ian
10-16-2012, 12:36 PM
#20
Racer
So you have gotten the "change brake pad" (or similar) warning? My warning has never gone off... I have worn sets down to the plastic of the sensor wire, which is 4 mm tall. Lately I have tired flipping to put the thinner side of the wire towards the pad and the thicker side towards the backing to get another mm out of them, but it causes the backing to bulge out a little bit and thought it would cause unwanted separation.