Calipers without dust boots - Page 2 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

bhmax · 01-15-2016, 01:38 PM

Here's the numbers I used for stock.

toast · 01-15-2016, 02:10 PM

According to FSM, front pistons are 42.8mm, front rotor effective diameter is 247mm
Rear piston is 38.1mm, rear ED is 254mm. Converted to inches that is 1.685 front and 1.5 rear. I don't know how ED correlates with diameter, so I just used outer diameter which for stock I thought was 11.5 front, not 11.58.

Regardless, both of our calc's show a tiny shift forward which can easily be offset with rear pads if necessary.

bhmax · 01-15-2016, 02:27 PM

Interesting how the FSM shows those piston sizes. Mine are what I measured with a caliper. I guess by using effective diameter for rotor, pad height maybe wouldn't be as important for a comparison.

Keep us updated if you get the Wilwood kit. I'm thinking about staying stock for a while but increasing pad friction in rear to move the bias by about 5%.

01-15-2016, 01:38 PM	#15
bhmax Senior Member Join Date: May 2015 Drives: 13 BRZ, 16 FiST, 05 WRX Location: AL Posts: 291 Thanks: 377 Thanked 96 Times in 68 Posts Mentioned: 2 Post(s) Tagged: 2 Thread(s)	Here's the numbers I used for stock. Attached Images

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01-15-2016, 02:10 PM	#16
toast Senior Member Join Date: Jul 2014 Drives: 14 BSP Edelbrock BRZ Location: Lon Gisland Posts: 806 Thanks: 113 Thanked 450 Times in 256 Posts Mentioned: 12 Post(s) Tagged: 0 Thread(s)	According to FSM, front pistons are 42.8mm, front rotor effective diameter is 247mm Rear piston is 38.1mm, rear ED is 254mm. Converted to inches that is 1.685 front and 1.5 rear. I don't know how ED correlates with diameter, so I just used outer diameter which for stock I thought was 11.5 front, not 11.58. Regardless, both of our calc's show a tiny shift forward which can easily be offset with rear pads if necessary.

01-15-2016, 02:27 PM	#17
bhmax Senior Member Join Date: May 2015 Drives: 13 BRZ, 16 FiST, 05 WRX Location: AL Posts: 291 Thanks: 377 Thanked 96 Times in 68 Posts Mentioned: 2 Post(s) Tagged: 2 Thread(s)	Interesting how the FSM shows those piston sizes. Mine are what I measured with a caliper. I guess by using effective diameter for rotor, pad height maybe wouldn't be as important for a comparison. Keep us updated if you get the Wilwood kit. I'm thinking about staying stock for a while but increasing pad friction in rear to move the bias by about 5%.

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