Skewed front brake-pad wear on GTR Pro
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Skewed front brake-pad wear on GTR Pro
I track my GTR Pro and have the TiKT brake cooling ducts and the Pagid/TiKT brake pads. I flush the (MOTUL 660) brake fluid yearly and bleed after every few track days, depending upon conditions. I also gently tap the calipers with a rubber mallet when bleeding to help ensure that no small air bubbles remain.
What I'm seeing is that the front pads are wearing unevenly, from top to bottom. Currently, after 7 track days, I have:
Left Front: 9 MM bottom & 10 MM top
Right Front: 7 MM bottom & 9 MM top
I also have temp stickers on the top-back and bottom-back of the calipers, currently showing highest temps in degrees Celsius:
Left Front: upper between 166 and 187 and lower between 210 and 231
Right Front: upper between 188 and 209 and lower between 210 and 231
Question: is anyone else experiencing top-to-bottom skewed brake-pad wear on a GTR Pro or a GTR with carbon ceramic brake rotors?
Normally, this would indicate that the caliper-piston pressure is uneven between the top/middle/bottom pistons. Supposedly, equalizing the squeeze is why the 3 pistons are of different sizes.
Anyone care to share any wisdom/ideas related to this issue?
What I'm seeing is that the front pads are wearing unevenly, from top to bottom. Currently, after 7 track days, I have:
Left Front: 9 MM bottom & 10 MM top
Right Front: 7 MM bottom & 9 MM top
I also have temp stickers on the top-back and bottom-back of the calipers, currently showing highest temps in degrees Celsius:
Left Front: upper between 166 and 187 and lower between 210 and 231
Right Front: upper between 188 and 209 and lower between 210 and 231
Question: is anyone else experiencing top-to-bottom skewed brake-pad wear on a GTR Pro or a GTR with carbon ceramic brake rotors?
Normally, this would indicate that the caliper-piston pressure is uneven between the top/middle/bottom pistons. Supposedly, equalizing the squeeze is why the 3 pistons are of different sizes.
Anyone care to share any wisdom/ideas related to this issue?
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Thanks for responding ... makes me feel more comfortable.
Yes, that's what I meant. Does seem to be a bit of a design issue WRT caliper piston-pressure distribution.
I'd heard the inside-wear comment previously. One of the issues with the TiKT brake-cooling ducts is that you can't see/measure the inside pads (well, not without a fair amount of work).
Since you have a lot of track-day experience, would you care to guess at a "rule of thumb" difference in the wear ... i.e., 1 MM, 2 MM, ...? I'd not want to go too thin on these pads.
I also noticed that there's a slight run-out/wobble on my right-front rotor ... i.e., when on the hoist and turning the wheel by hand, there's a slight brake-pad binding at one position as the wheel rotates. This may also account for some of the extra wear on that side.
Since you have a lot of track-day experience, would you care to guess at a "rule of thumb" difference in the wear ... i.e., 1 MM, 2 MM, ...? I'd not want to go too thin on these pads.
I also noticed that there's a slight run-out/wobble on my right-front rotor ... i.e., when on the hoist and turning the wheel by hand, there's a slight brake-pad binding at one position as the wheel rotates. This may also account for some of the extra wear on that side.
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‘24 BMW iX M60
If you have the CCM rotors and want to be super cautious re: trying to minimize rotor oxidation from heat and hence having to replace them often, a good rule of thumb is to replace the pads when they have worn down to 1/3rd of the original thickness. You might be spending a little more in replacement pad costs in this fashion but I'm convinced that it will slow down degradation of those very expensive rotors. Always remember that the inner pads wear faster than the outer pads and they do taper.
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From: Edmonton, Alberta, Canada
Winnebago, Yugo
Thanks for responding ... makes me feel more comfortable.
Yes, that's what I meant. Does seem to be a bit of a design issue WRT caliper piston-pressure distribution.
I'd heard the inside-wear comment previously. One of the issues with the TiKT brake-cooling ducts is that you can't see/measure the inside pads (well, not without a fair amount of work).
Since you have a lot of track-day experience, would you care to guess at a "rule of thumb" difference in the wear ... i.e., 1 MM, 2 MM, ...? I'd not want to go too thin on these pads.
I also noticed that there's a slight run-out/wobble on my right-front rotor ... i.e., when on the hoist and turning the wheel by hand, there's a slight brake-pad binding at one position as the wheel rotates. This may also account for some of the extra wear on that side.
Yes, that's what I meant. Does seem to be a bit of a design issue WRT caliper piston-pressure distribution.
I'd heard the inside-wear comment previously. One of the issues with the TiKT brake-cooling ducts is that you can't see/measure the inside pads (well, not without a fair amount of work).
Since you have a lot of track-day experience, would you care to guess at a "rule of thumb" difference in the wear ... i.e., 1 MM, 2 MM, ...? I'd not want to go too thin on these pads.
I also noticed that there's a slight run-out/wobble on my right-front rotor ... i.e., when on the hoist and turning the wheel by hand, there's a slight brake-pad binding at one position as the wheel rotates. This may also account for some of the extra wear on that side.
I usually change mine out at ~4mm remaining.
Last year I was out at Area 27 which is about 1000km from home and I pushed the limit on the pads more than I usually would.
I did 2 more sessions after my low pad light came on. So I probably had 2-3 mm left on the inners when I got the warning.
I shut it down when the brakes started making an awful noise... backing plate rubbing on rotor.
Last edited by canucklehead; Sep 1, 2022 at 05:52 PM.
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If you have the CCM rotors and want to be super cautious re: trying to minimize rotor oxidation from heat and hence having to replace them often, a good rule of thumb is to replace the pads when they have worn down to 1/3rd of the original thickness. You might be spending a little more in replacement pad costs in this fashion but I'm convinced that it will slow down degradation of those very expensive rotors. Always remember that the inner pads wear faster than the outer pads and they do taper.
I actually ran my inner pads down to the backing plates while still showing about 3mm on the outer pads.
I usually change mine out at ~4mm remaining.
Last year I was out at Area 27 which is about 1000km from home and I pushed the limit on the pads more than I usually would.
I did 2 more sessions after my low pad light came on. So I probably had 2-3 mm left on the inners when I got the warning.
I shut it down when the brakes started making an awful noise... backing plate rubbing on rotor.
I usually change mine out at ~4mm remaining.
Last year I was out at Area 27 which is about 1000km from home and I pushed the limit on the pads more than I usually would.
I did 2 more sessions after my low pad light came on. So I probably had 2-3 mm left on the inners when I got the warning.
I shut it down when the brakes started making an awful noise... backing plate rubbing on rotor.
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From: Edmonton, Alberta, Canada
Winnebago, Yugo
I agree ... even expensive pads are really cheap compared to the CCB rotors!
Ouch. Did that with my C63 S iron rotors, once ... apocalyptic braking noise but surprisingly good braking! Curious, was the backing plate hard enough to score the CCB rotor surface? Just did 1st day at Area 27 in the GTR ... fav track (I'm still way too slow, but phenomenal track).
Ouch. Did that with my C63 S iron rotors, once ... apocalyptic braking noise but surprisingly good braking! Curious, was the backing plate hard enough to score the CCB rotor surface? Just did 1st day at Area 27 in the GTR ... fav track (I'm still way too slow, but phenomenal track).
Area 27 is a great track. Too bad non-members are limited to 3 days.
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Repeat Question: Can anyone guess at a "rule of thumb" for the difference in the wear between the outer pads and the inner pads ... i.e., should one assume the inner pads are 1 MM thinner, 2 MM thinner, ... (when they're about 2/3 worn)? I'd not want to go too thin on these pads (and can't see the inner pads due to the TiKT brake-cooling ducts ... hmmm, unless I use a borescope).
That doesn't surprise me as the CCB rotor surfaces are amazingly hard.
Agreed regarding Area 27. I'd only been there once, about 3 years ago, with the C63 S sedan (on summer tires) so I was still pretty slow, this time around ... but soooo much fun! Too bad it's so hot there in mid-summer.
When I went to VIMC about a month ago (for the first time ... also a hoot, but a very challenging track) they indicated that it's no longer a member track so it looks like there'll be more public events there.
Agreed regarding Area 27. I'd only been there once, about 3 years ago, with the C63 S sedan (on summer tires) so I was still pretty slow, this time around ... but soooo much fun! Too bad it's so hot there in mid-summer.
When I went to VIMC about a month ago (for the first time ... also a hoot, but a very challenging track) they indicated that it's no longer a member track so it looks like there'll be more public events there.
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Posts: 2,524
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From: Overland Park, KS
‘24 BMW iX M60
Repeat Question: Can anyone guess at a "rule of thumb" for the difference in the wear between the outer pads and the inner pads ... i.e., should one assume the inner pads are 1 MM thinner, 2 MM thinner, ... (when they're about 2/3 worn)? I'd not want to go too thin on these pads (and can't see the inner pads due to the TiKT brake-cooling ducts ... hmmm, unless I use a borescope).
That doesn't surprise me as the CCB rotor surfaces are amazingly hard.
Agreed regarding Area 27. I'd only been there once, about 3 years ago, with the C63 S sedan (on summer tires) so I was still pretty slow, this time around ... but soooo much fun! Too bad it's so hot there in mid-summer.
When I went to VIMC about a month ago (for the first time ... also a hoot, but a very challenging track) they indicated that it's no longer a member track so it looks like there'll be more public events there.
That doesn't surprise me as the CCB rotor surfaces are amazingly hard.
Agreed regarding Area 27. I'd only been there once, about 3 years ago, with the C63 S sedan (on summer tires) so I was still pretty slow, this time around ... but soooo much fun! Too bad it's so hot there in mid-summer.
When I went to VIMC about a month ago (for the first time ... also a hoot, but a very challenging track) they indicated that it's no longer a member track so it looks like there'll be more public events there.
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The TiKT/Pagid pads are somewhat expensive, but they really last, the end result being that they're the least expensive pads I've ever run (compared to the pads on my C63 S). It looks like they'll end up coming in at about $100 CAD per track day for the fronts and less for the rears. Given that our local track is truly brutal on brakes, this is "wonderful" at about 1/2 the cost for my next-best pads which were the EBC RP-X pads on the C63 S with my home-made brake-cooling ducts (C63 S pads are for sale, BTW).
