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      02-12-2012, 10:43 AM   #1
paradocs98
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StopTech rotor wear allowances

Tried my best searching for this--extensive Google searches and an email to StopTech which was not answered:

What is the minimum rotor thickness for StopTech rotors? My ST60/ST40 BBK comes with 380x35mm front rotors and 355x32mm rear rotors. I'm on my third set of Street Performance pads in just under a year with the BBK setup, and I'm wondering when I need to consider replacing the rotors, or "friction rings" as StopTech calls them (thanks for pointing this out, Richard).

Richard at M-World did a recent DIY for replacing the friction ring component of the rotor assembly (rotor assembly consists of aluminum rotor hat secured to iron friction rings). I thought I may have seen somewhere that 2mm is the allowed wear for the rotor thickness before they should be replaced, but I can't find this reference. I believe Richard indicated he was replacing them after three pad changes.

It's not an insignificant concern because replacing the friction rings alone (and leaving the rotor hat as is) is upwards of $600 per axle. I realize it's a wear item, but I don't want to replace them prematurely and throw out good pieces.

Once I can get a digital caliper to measure my current rotor thickness, I'll have a better idea of how much wear the rotors have seen at this point. In my three pad set changes I've replaced all four pads at a time each time, but it was only the fronts that were seeing the majority of the wear. Each time the rear pads still had quite a bit of material left on them (there I go again, throwing out good pieces prematurely...). So I would assume that my rear rotors have not seen the wear that my fronts have, and so my strategy will probably be to just replace the front friction rings at this point.

I started thinking about this because track season is approaching and I'll likely try the Pagid RS29s now as an upgrade from the StopTech Street Performance pads.

Any thoughts or comments welcome.
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      02-12-2012, 01:32 PM   #2
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In the same boat as you ... I believe it is 2mm worth of wear and then the friction rings should be replaced. I have been using ST pads but I am going to run RS29's at VIR in a couple weeks. I am going to measure mine but I doubt they are toast after just a few track days.
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      02-12-2012, 04:09 PM   #3
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Quote:
Originally Posted by AMPowerJ View Post
In the same boat as you ... I believe it is 2mm worth of wear and then the friction rings should be replaced. I have been using ST pads but I am going to run RS29's at VIR in a couple weeks. I am going to measure mine but I doubt they are toast after just a few track days.
Excellent! Keep us posted.

Where did you source the Pagids?

Last edited by paradocs98; 02-12-2012 at 04:25 PM.
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      02-12-2012, 09:51 PM   #4
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Yes sir 2 mm on your rotors.

The min thickness allowance is typically listed on rotors (stock and aftermarket) as well, although they may become hard to read after a while due to rust. Let me know if you need any help with pads, rotors, etc.
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      02-13-2012, 01:52 AM   #5
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So how does one measure this 2mm thickness? Is it the metal on each side of the vent strip?
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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
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      02-13-2012, 02:08 AM   #6
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Yup. Found this on Google. Do note that sometimes a disc could wear unevenly, so be sure to measure the area which has the minimum thickness.

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      02-13-2012, 07:20 AM   #7
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I was told the friction rings can be run pretty low, as long as you aren't having major crack or heat checking. Porsche guys run the rotors down to the slot levels in some cases. Of course, it's a safety preference at the end of the day and $600 isn't much if you consider what could happen if a rotor fails.
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      02-13-2012, 07:36 AM   #8
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what is the thickness of the rings when new?
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      02-13-2012, 08:56 AM   #9
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Quote:
Originally Posted by 4sevens.com View Post
what is the thickness of the rings when new?
Quote:
Originally Posted by paradocs98 View Post
Tried my best searching for this--extensive Google searches and an email to StopTech which was not answered:

What is the minimum rotor thickness for StopTech rotors? My ST60/ST40 BBK comes with 380x35mm front rotors and 355x32mm rear rotors.
The 380 mm-dia ring is 35 mm-thick, and the 355 mm-dia ring is 32 mm-thick.
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      02-13-2012, 09:28 AM   #10
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thanks dbarnes - I scanned the previous posts too quickly
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      02-13-2012, 11:21 AM   #11
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Quote:
Originally Posted by 4sevens.com View Post
thanks dbarnes - I scanned the previous posts too quickly
No problem - we've all done it at some point
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      02-13-2012, 01:27 PM   #12
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Some of the earlier kits for the E9X used 380x32 mm front. Just FYI. When in doubt, check embossed min thickness recommendation on your rotor
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      02-13-2012, 11:02 PM   #13
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So you replace after you wear down 2mm? So for the newer kits, 33mm?
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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
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      02-13-2012, 11:20 PM   #14
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^Yup
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      02-14-2012, 08:44 PM   #15
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Quote:
Originally Posted by paradocs98 View Post
Tried my best searching for this--extensive Google searches and an email to StopTech which was not answered:

What is the minimum rotor thickness for StopTech rotors? My ST60/ST40 BBK comes with 380x35mm front rotors and 355x32mm rear rotors. I'm on my third set of Street Performance pads in just under a year with the BBK setup, and I'm wondering when I need to consider replacing the rotors, or "friction rings" as StopTech calls them (thanks for pointing this out, Richard).

Richard at M-World did a recent DIY for replacing the friction ring component of the rotor assembly (rotor assembly consists of aluminum rotor hat secured to iron friction rings). I thought I may have seen somewhere that 2mm is the allowed wear for the rotor thickness before they should be replaced, but I can't find this reference. I believe Richard indicated he was replacing them after three pad changes.

It's not an insignificant concern because replacing the friction rings alone (and leaving the rotor hat as is) is upwards of $600 per axle. I realize it's a wear item, but I don't want to replace them prematurely and throw out good pieces.

Once I can get a digital caliper to measure my current rotor thickness, I'll have a better idea of how much wear the rotors have seen at this point. In my three pad set changes I've replaced all four pads at a time each time, but it was only the fronts that were seeing the majority of the wear. Each time the rear pads still had quite a bit of material left on them (there I go again, throwing out good pieces prematurely...). So I would assume that my rear rotors have not seen the wear that my fronts have, and so my strategy will probably be to just replace the front friction rings at this point.

I started thinking about this because track season is approaching and I'll likely try the Pagid RS29s now as an upgrade from the StopTech Street Performance pads.

Any thoughts or comments welcome.
On the 35mm rotor your minimum thickness is 33mm and on the 32mm rotor your minimum thickness is 30mm.
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      02-15-2012, 08:07 AM   #16
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Quote:
Originally Posted by Richard@M-World View Post
Some of the earlier kits for the E9X used 380x32 mm front. Just FYI. When in doubt, check embossed min thickness recommendation on your rotor

I just bought a used kit which could be an "earlier" kit, it's already on the car. Where is the min thickness designation on the rotor? Thank you in advance.
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      02-15-2012, 10:57 AM   #17
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On the outer edge of the rotor.
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      02-15-2012, 11:21 AM   #18
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On the outer edge of the rotor.
Great, thank you.
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      02-15-2012, 07:23 PM   #19
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Thanks for all the replies. I'll probably replace the front friction rings for now and keep an eye on the rears this season.
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      02-29-2012, 12:47 AM   #20
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Followup to original post--I got a high-quality digital caliper and measured my rotors the other day. After two sets of the Street Performance pads and 8-10 track days, the wear is less than I would have expected. Front rotors are around 34.3mm (35mm new) and rears are around 31.7mm (32mm new). So I'll keep these rotors for now and measure thickness periodically this season with the new Pagid pads. I called StopTech and they confirmed that this is fine.
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      02-29-2012, 01:07 AM   #21
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Quote:
Originally Posted by paradocs98 View Post
Followup to original post--I got a high-quality digital caliper and measured my rotors the other day. After two sets of the Street Performance pads and 8-10 track days, the wear is less than I would have expected. Front rotors are around 34.3mm (35mm new) and rears are around 31.7mm (32mm new). So I'll keep these rotors for now and measure thickness periodically this season with the new Pagid pads. I called StopTech and they confirmed that this is fine.
You are well above the min. specs so you are ok.
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      02-29-2012, 07:18 AM   #22
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great info guys i can't wait for my stop Tech to go on.
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