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Shimano Br-7402 Dura Ace, brake pivot bolt torque

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Shimano Br-7402 Dura Ace, brake pivot bolt torque

Old 09-22-22, 01:48 PM
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Ric Toronto
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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
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Old 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
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Old 09-22-22, 07:44 PM
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Originally Posted by Andrew R Stewart View Post
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
Thanks, and as I suspected re the "locking" washer. I had hoped there might be some sort of torque measurement for the moving arms. But as you suggest, trial and error. I've bent the pivot bolt in a bad fall, and took things apart to figure out why the brakes were noisy. Parts are pretty much unavailable so, I've figured out how to straighten that bolt and wanted to get correct torque etc after clean and lube etc. Thanks for your reply
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Old 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
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