What's this do? Shimano BR560

[cheadle hulme]

http://techdocs.shimano.com/media/t...BR/EV-BR-R560-2590A_v1_m56577569830615760.pdf

The little grub screw that screws upwards underneath the third part of the caliper assembly. Its not numbered but is between 7 and 8.

Having disassembled the caliper for cleaning, it now is not releasing correctly. The dual pivots seem OK in themselves though. I can't figure out what the little grub screw does, although I have a feeling it must do something.

 

[gbb]

It looks as though it locks the short arm to the main through bolt and nut (3)

It looks like the short arm should be fixed to allow the others to pivot against it.

I havnt stripped them that far, so dont quote me

 

[stoatsngroats]

That's really strange - I noticed mine was missing just the other day...brakes work fine tho'!

 

[Mr Pig]

It's hard to tell without seeing it in the flesh, I've never had a road bike.

But it looks to me like the calipers pivot on the bush labeled '3'. If the bush on the far right labeled '3' is what the brake pivots on the grub screw might be there to hold the bush still in the caliper, so that the bush/caliper rotates on the fixing screw and the bush does not sit still on the screw with the caliper body rotating on it. The caliper body is probably too soft a metal to take the wear that would result otherwise.

Like I say, just a guess based on the pictures, but I think it's probably right.

 

[Joe24]

http://techdocs.shimano.com/media/t...BR/EV-BR-R560-2590A_v1_m56577569830615760.pdf

The little grub screw that screws upwards underneath the third part of the caliper assembly. Its not numbered but is between 7 and 8.

Having disassembled the caliper for cleaning, it now is not releasing correctly. The dual pivots seem OK in themselves though. I can't figure out what the little grub screw does, although I have a feeling it must do something.

Its just there to hold another bolt in, basicly.
You might find its not releasing properly because the centre bolt is too tight, or because the spring has lost some tension.
Undo that middle bolt slightly, and you may probably find that the brake releases properly.
Thats if you havent done that already. I wouldnt worry about the little grub screw too much. Its just there to stop that bolt undoing on its own, which i doubt will happen.

 

[Mr Pig]

I have to admit I don't understand how that bolt assembly fits on the bike. The part labled '5' is a lock-nut, which holds the thing to the frame. Fair enough, but what are the washer and cap/bush (3 and 4) 'behind' it for? And why no washer or bush between it and the frame/fork? It almost looks as if parts 3 and 4 should be on the other side of the lock-nut as that would make sense, I can't see any pourpos for a washer etc after the retaining lock-nut?

I guess it makes sense if you see it on the bike but I can't figure how from the drawing.

 

[Mr Pig]

Picture didn't work. Click the link

In the last large picture you can see the assembled brake. Note that the lock nut and two dished washers are not fitted as they are clearly used to hold the brake on, one washer each side of the fork tube and the lock-nut on last.

So what are parts 4 and 5 in the shimano diagram?

 

[cheadle hulme]

Thanks for the replies.

The grub screw is there (and the lock nut behind the fixed part of the caliper) to hold the fixed part of the caliper fixed. ie if you tried to fix the fixed part by tightening the central pivot, it would not allow the LH (as you look at it) caliper to pivot.

This was what i had tightened too much, and as this is the sprung caliper, it wouldn't release properly.

I can't see why the fixed bit couldn't have been manufactured as part of the central bolt iw one piece.

 

[ufkacbln]

Thanks for the replies.

The grub screw is there (and the lock nut behind the fixed part of the caliper) to hold the fixed part of the caliper fixed. ie if you tried to fix the fixed part by tightening the central pivot, it would not allow the LH (as you look at it) caliper to pivot.

This was what i had tightened too much, and as this is the sprung caliper, it wouldn't release properly.

I can't see why the fixed bit couldn't have been manufactured as part of the central bolt iw one piece.

'cos both arms pivot, and the central bolt needs to be tightened. If you fix the bolt to any part you have a "fixed length" and cannot tune the tightness