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Old 03-22-2017, 06:52 PM   #1  
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Default V8R STR42 Caliper with 11.75 Rotor...

V8R stepped up and produced a 11.75 kit for the new Stoptech ST42/STR42 calipers. They offer two different bore sizes. One will be the 36/30mm and the other 38/36. The smaller one is better suited for stock rear calipers the larger one is a good match for sport rears. I had great luck with Sport tech calipers on other cars. I look forward to seeing if these live up to the same standards.

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Old 03-22-2017, 07:37 PM   #2  
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Link?
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Old 03-22-2017, 07:52 PM   #3  
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Nothing on the website yet. Google Stoptech ST42/STR42 and you'll see the caliper. Same V8R 11.75 rotor as before.

I'll post pics when mine arrives.

Last edited by k24madness; 03-23-2017 at 12:37 AM.
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Old 03-22-2017, 09:00 PM   #4  
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Pic:

Looks like the NA/NB brakes to have.
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Old 03-23-2017, 12:33 AM   #5  
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Installed on my car today. Will post pics and some more details tomorrow

ST's recently released 11" setup has a lot of great elements, but just about a decade behind the curve on rotor size. ST42/STR42 over 11.75" rotors needed to happen. So it did.
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Old 03-23-2017, 05:18 AM   #6  
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Cannot wait to see how these come out.
I'll be out looking at brakes later this summer.
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Old 03-23-2017, 02:05 PM   #7  
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Quote:
Originally Posted by ThePass View Post
Installed on my car today. Will post pics and some more details tomorrow

ST's recently released 11" setup has a lot of great elements, but just about a decade behind the curve on rotor size. ST42/STR42 over 11.75" rotors needed to happen. So it did.
I've seen this mentioned a couple of times but don't really understand why 9mm larger in radius makes all the difference?
-Pretty much irrelevant for brake torque output?
-Negligible for thermal capacity?
-noise level difference in weight but assumed to be heavier?

StopTech's 11" rotor was based on fitment to the (3rd gen) 15" 6UL. Any larger rotor caused the ST42 to have less than 3mm clearance to the barrel of the wheel, which is StopTech's minimum clearance for design. Using that wheel as the standard, the rotor can't be bigger - the StopTech team tried a 290mm rotor during testing and had caliper contact with the wheel.

On other wheels... maybe, but then we are no longer weight optimized in wheel or brake selection.

I have yet to see a side by side comparison out on the track but have been watching for any write-up. Emilio started one with "Big Brake Fun" but hasn't updated for a while. Not sure what he is doing with the StopTech kit, if anything.
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Old 03-23-2017, 02:37 PM   #8  
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I'm also curious about wheel clearance with the V8R kit. A friend asked me to make him a bracket a few months ago to put a Stoptech caliper on an 11.75" AP rotor. We tested wheel clearance first by putting a 3/8" spacer on a Stoptech 11" BBK. The caliper was touching the barrel of a 15x9 6UL with the spacer in place, so we gave up on the idea.
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Old 03-23-2017, 03:23 PM   #9  
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Quote:
Originally Posted by Jumbosrule View Post
I've seen this mentioned a couple of times but don't really understand why 9mm larger in radius makes all the difference?
-Pretty much irrelevant for brake torque output?
-Negligible for thermal capacity?
-noise level difference in weight but assumed to be heavier?

StopTech's 11" rotor was based on fitment to the (3rd gen) 15" 6UL. Any larger rotor caused the ST42 to have less than 3mm clearance to the barrel of the wheel, which is StopTech's minimum clearance for design. Using that wheel as the standard, the rotor can't be bigger - the StopTech team tried a 290mm rotor during testing and had caliper contact with the wheel.

On other wheels... maybe, but then we are no longer weight optimized in wheel or brake selection.

I have yet to see a side by side comparison out on the track but have been watching for any write-up. Emilio started one with "Big Brake Fun" but hasn't updated for a while. Not sure what he is doing with the StopTech kit, if anything.
Based on my reading of old threads, I believe it had more to do with rotor ring costs. Wilwood has cheap 11.75" rings available, which do fine for the turbocharged street/occasional HPDE Miata. That option brings down purchase and operational costs down enough to attract more Miata owners.
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Old 03-23-2017, 03:37 PM   #10  
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Quote:
Originally Posted by dleavitt View Post
Based on my reading of old threads, I believe it had more to do with rotor ring costs. Wilwood has cheap 11.75" rings available, which do fine for the turbocharged street/occasional HPDE Miata. That option brings down purchase and operational costs down enough to attract more Miata owners.
Now that logic makes sense... but

StopTech's 11" blank rotor ring is about $65 each. Slotted or Drilled with ST hat mounting hardware included they are $90 each.

Wilwood's ultralite 32 is around $40 and the HD36 is $100.
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Old 03-23-2017, 04:50 PM   #11  
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Details and wheel clearance info posted in the Race Prep section because that's where it's relevant. Street guys should stick with the 11" kit for wider wheel fitment options.

V8R Stoptech 11.75" BBK
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Old 03-23-2017, 07:12 PM   #12  
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I was not sure where to start this thread. I flipped a coin and it ended up here.
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Old 03-23-2017, 07:19 PM   #13  
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Quote:
Originally Posted by ThePass View Post

ST's recently released 11" setup has a lot of great elements, but just about a decade behind the curve on rotor size. ST42/STR42 over 11.75" rotors needed to happen. So it did.
I am not sure who else hit up Shandelle with the request but he said I was one of three people within days of each other. That pushed him over the edge to jump right into production. It was an impressively short period of time from first e-mail to delivery!

Now lets do the same for front and rear hubs!
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