Shimano Br-7402 Dura Ace, brake pivot bolt torque
09-22-22, 01:48 PM
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Shimano Br-7402 Dura Ace, brake pivot bolt torque
In process of dealing with a bent pivot bolt, I disassembled, cleaned and lubed the front caliper.
I discovered a broken "star washer" so am trying to fidn ine, but in process discovered thrust bearing/washers. When re-assambling how do I tighten the forward nut? Is there a torques setting?
Thanks
I discovered a broken "star washer" so am trying to fidn ine, but in process discovered thrust bearing/washers. When re-assambling how do I tighten the forward nut? Is there a torques setting?
Thanks
09-22-22, 07:29 PM
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IIRC the start washer has nothing to do with the "bearing" adjustment that sets the caliper arms' slop and easy movement. The star washer is "outside" the arm's involvement.
The two caliper arms should freely pivot with as little slop or rock between them. This is a trial-and-error process with checks of the setting after the lock nut is tightened. Just like bearing adjustments on cup and cone units.
I suspect the star washer was between the center bolt's fixed part (that also has the spring slot) and the frame/fork. This is a common method to try to keep the center bolt (and that spring) from rotating off center. As long as the center bolt is well secured in the frame/fork this start washer is not really needed. A lot of high-end calipers have had a thick and very solid spacer with serrations on both faces, acting much like a cheap start washer but being far more robust. A good service focused shop likely has these stronger washers/spacers for not too much $. Andy
The two caliper arms should freely pivot with as little slop or rock between them. This is a trial-and-error process with checks of the setting after the lock nut is tightened. Just like bearing adjustments on cup and cone units.
I suspect the star washer was between the center bolt's fixed part (that also has the spring slot) and the frame/fork. This is a common method to try to keep the center bolt (and that spring) from rotating off center. As long as the center bolt is well secured in the frame/fork this start washer is not really needed. A lot of high-end calipers have had a thick and very solid spacer with serrations on both faces, acting much like a cheap start washer but being far more robust. A good service focused shop likely has these stronger washers/spacers for not too much $. Andy
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AndrewRStewart
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09-22-22, 07:44 PM
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IIRC the start washer has nothing to do with the "bearing" adjustment that sets the caliper arms' slop and easy movement. The star washer is "outside" the arm's involvement.
The two caliper arms should freely pivot with as little slop or rock between them. This is a trial-and-error process with checks of the setting after the lock nut is tightened. Just like bearing adjustments on cup and cone units.
I suspect the star washer was between the center bolt's fixed part (that also has the spring slot) and the frame/fork. This is a common method to try to keep the center bolt (and that spring) from rotating off center. As long as the center bolt is well secured in the frame/fork this start washer is not really needed. A lot of high-end calipers have had a thick and very solid spacer with serrations on both faces, acting much like a cheap start washer but being far more robust. A good service focused shop likely has these stronger washers/spacers for not too much $. Andy
The two caliper arms should freely pivot with as little slop or rock between them. This is a trial-and-error process with checks of the setting after the lock nut is tightened. Just like bearing adjustments on cup and cone units.
I suspect the star washer was between the center bolt's fixed part (that also has the spring slot) and the frame/fork. This is a common method to try to keep the center bolt (and that spring) from rotating off center. As long as the center bolt is well secured in the frame/fork this start washer is not really needed. A lot of high-end calipers have had a thick and very solid spacer with serrations on both faces, acting much like a cheap start washer but being far more robust. A good service focused shop likely has these stronger washers/spacers for not too much $. Andy
09-22-22, 07:44 PM
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Look here for a basic help and if you have further issues expand on your issue. Shimano brake caliper mounting torque spec is usually 5 - 7 NM if that is what you mean by the forward nut. Park Tool web site is very good at the basic repair stuff and helpful with the vernacular which helps us with understanding what your issue is exactly.
https://manualzz.com/doc/53871442/sh...ce-instruction
https://manualzz.com/doc/53871442/sh...ce-instruction
