mforget Posted September 16, 2018 Share Posted September 16, 2018 (edited) Hi, im doing my brake setup on my 280z build using S12W calipers front and maxima calipers rear, 15/16 front master, stock proportioning valve delete. I tought i had to put my proportioning valve on the rear brake lines as usual but now ive read on another thread that the maxima calipers are not well matched to the S12W resulting in too much front bias........ Any confirmation on this and is there a fix for the problem? Thanks in advance! Edited September 16, 2018 by mforget Quote Link to comment Share on other sites More sharing options...
Miles Posted September 16, 2018 Share Posted September 16, 2018 3 hours ago, mforget said: Hi, im doing my brake setup on my 280z build using S12W calipers front and maxima calipers rear, 15/16 front master, stock proportioning valve delete. I thought i had to put my proportioning valve on the rear brake lines as usual but now ive read on another thread that the maxima calipers are not well matched to the S12W resulting in too much front bias........ Any confirmation on this and is there a fix for the problem? Thanks in advance! Should have researched this more. Lots of info in the brake section. Stock brakes are fine. The Toyota vented/solid front and Maxima/240SX rear is biased towards the front 60% front and 40 % rear. This is based on my own calculations and actually experimenting with the following: Stock front 240SX rear Stock front Maxima rear Solid Toyota Stock rear Vented Toyota stock rear Vented Toyota 240SX Is there a fix? No, but people have tried putting more aggressive pads on the rear to achieve better front - rear balance. Probably ok for racing. No, you can't put a proportioning valve on the front - that would be dangerous. Recommend that you use Carbotech AX6 pads front and back. They have excellent cold bite for city driving and get better as they heat up. My current set up is Toyota solid front, 240SX rear, 280Z 8.5 in booster, 79 280ZX MC and Carbotech AX6 pads. With the Carbotech pads, 280Z booster and 15/16 MC my brakes are like stock. Quote Link to comment Share on other sites More sharing options...
mforget Posted September 16, 2018 Author Share Posted September 16, 2018 (edited) 1 hour ago, Miles said: Should have researched this more. Lots of info in the brake section. Stock brakes are fine. The Toyota vented/solid front and Maxima/240SX rear is biased towards the front 60% front and 40 % rear. This is based on my own calculations and actually experimenting with the following: Stock front 240SX rear Stock front Maxima rear Solid Toyota Stock rear Vented Toyota stock rear Vented Toyota 240SX Is there a fix? No, but people have tried putting more aggressive pads on the rear to achieve better front - rear balance. Probably ok for racing. No, you can't put a proportioning valve on the front - that would be dangerous. Recommend that you use Carbotech AX6 pads front and back. They have excellent cold bite for city driving and get better as they heat up. My current set up is Toyota solid front, 240SX rear, 280Z 8.5 in booster, 79 280ZX MC and Carbotech AX6 pads. With the Carbotech pads, 280Z booster and 15/16 MC my brakes are like stock. Do you run any proportioning valve at all? Edited September 16, 2018 by mforget Quote Link to comment Share on other sites More sharing options...
Miles Posted September 16, 2018 Share Posted September 16, 2018 (edited) Do you run any proportioning valve at all? Yes. I installed a Wilwood proportioning valve only because I was experimenting with different caliper and pad configurations. I now leave it wide open. I would remove it, but I am too lazy to crawl under the car. A proportioning valve reduces pressure to the rear brakes. All of these brake swaps are biased towards the front not rear (60%F 40%R to 70%F 30%R) so a proportioning valve makes no sense UNLESS you plan on racing with aggressive pads on the rear which you "dial-in" while racing. You have a 280Z with the larger 8.5in booster which will help with the stiffness caused by the larger bore 15/16 MC. Go with the Carbotech AX6 pads and you should be ok. Don't waste your money on Hawk or Porterfield street pads - they do not perform well in traffic. See attached brake bias data: BRAKE BIAS CALC INPUT and RESULTS.docx Edited September 16, 2018 by Miles Quote Link to comment Share on other sites More sharing options...
walkerbk Posted September 17, 2018 Share Posted September 17, 2018 If you use the s12+8 calipers from the later years, they were machined to fit vented roters like the s12w ones but have smaller cylinders making for more of around 57% to 43%. This is what I run and am very happy with the setup. 1 Quote Link to comment Share on other sites More sharing options...
Miles Posted September 17, 2018 Share Posted September 17, 2018 (edited) 45 minutes ago, walkerbk said: If you use the s12+8 calipers from the later years, they were machined to fit vented roters like the s12w ones but have smaller cylinders making for more of around 57% to 43%. This is what I run and am very happy with the setup. Good point. Edited September 17, 2018 by Miles Quote Link to comment Share on other sites More sharing options...
Miles Posted September 17, 2018 Share Posted September 17, 2018 Quote Link to comment Share on other sites More sharing options...
rabrooks Posted February 23, 2019 Share Posted February 23, 2019 (edited) On 9/16/2018 at 1:46 PM, Miles said: Do you run any proportioning valve at all? Yes. I installed a Wilwood proportioning valve only because I was experimenting with different caliper and pad configurations. I now leave it wide open. I would remove it, but I am too lazy to crawl under the car. A proportioning valve reduces pressure to the rear brakes. All of these brake swaps are biased towards the front not rear (60%F 40%R to 70%F 30%R) so a proportioning valve makes no sense UNLESS you plan on racing with aggressive pads on the rear which you "dial-in" while racing. You have a 280Z with the larger 8.5in booster which will help with the stiffness caused by the larger bore 15/16 MC. Go with the Carbotech AX6 pads and you should be ok. Don't waste your money on Hawk or Porterfield street pads - they do not perform well in traffic. See attached brake bias data: BRAKE BIAS CALC INPUT and RESULTS.docx So based on the spread sheet you supplied wouldn't it be best to run the toyota vented up front and the toyota solid on the rears. If I understand this correctly, that would give a 55/44 brake bias. So I wonder how hard it would be to mate the toyota solid fronts to the rear of a 280z? My numbers may be skewed because I was focusing on the front line PSI. Not sure what the rear would be or if the volume from the master affects the overall numbers Thanks Edited February 23, 2019 by rabrooks Quote Link to comment Share on other sites More sharing options...
Miles Posted February 24, 2019 Share Posted February 24, 2019 Not sure how you arrived at Toyota front and back. Won't work. The Toyota calipers only go on the front because they have no parking brake function. The 240SX calipers have a parking brake function. So they only go on the back. Quote Link to comment Share on other sites More sharing options...
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