Rear brake is f***ed.. please help!

Good evening LFGSS,

I have a weird brake problem.. please see pics 1 & 2 for reference - will try my best to explain!

Basically, one of the pivots of the brake is really loose, and falls down from the position in picture 1.. to the position in picture 2 - making braking impossible.

Suspecting that it was because of being covered in road crap, I've tried removing the whole thing, give it a good scrub in the sink, and re-attached. All visible bolts seem to be tightened up - but problem persists!

Would appreciate any help given..

Muchos gracias in advance!

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You need to close the quick release?

^I wish it was that simple - problem occurs in any position..
the whole left part of the caliper stays still.. only the right.

Looks like the cable may be slipping. Do you have a front brake to compare it to?

Have another rear brake on adjacent bike in pic to compare to! Everything looks normal - cable seems fine too. Levers pull the cables fine without any slipping, just that the right pivot goes loose.. and then the whole cable slacks.

Your rim isn't centred in the frame. Make sure it's in the dropouts properly. From what I can see there's nothing wrong with the brake.

What happens when you move the lever on the left side of the caliper to point downwards like in this picture? (not exact same model)

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What happens when you move the lever on the left side of the caliper to point downwards like in this picture? (not exact same model)

See post#2 ^

Your rim isn't centred in the frame. Make sure it's in the dropouts properly. From what I can see there's nothing wrong with the brake.

This wheel has always been like this.. and problem came up yesterday! Also tried on another set of wheels, and same problem :(

and thanks for the help so far!

Looks like the pivot point is fucked, for the £16 price of a new one it's hardly worth fixing

Other than the bolt the cable will be holding that half of the brake in position. Try letting the cable off, pull it tight again and retighten, check the ferrule is still attached at the lever end. Although if you've had it all off and cleaned it up I would have thought that all this would have been done....

1 - unclip spring
2 - remove brake from frame
3 - insert allen key into center pivot bolt from front, (normally covered by the front arm)
4 - loosen serrated alloy nut (between parts 6 and 7 on this diagram)
5 - lube central pivot
6 - reassemble
7 - ????
8 - profit!

Don't know about Shimano (I'm not an angler) but with Campag there are 2mm Allen key bolts on each caliper that help to fine-tune alignment.

I've got one of these (spare) in front of me right now. As provenrad said, it can only be the pivot point/ slack arm spring at the back if everything is tightened as you say. Unless there are washers missing etc.

Just had a check.. spring round the back seems fine (apart from an odd bit of corrosion). I've done provenrad's procedure.. and problem unsolved :(

..Perhaps I'll just take Dovvles' word and just get a new one.

Many thanks guys for the patience!

bad luck mate.
Sell it on Ebay.

Just Googled these.

http://www.wiggle.co.uk/shimano-tiagra-4500-brake-caliper/

£20 for a new pair?

Replaceable brakes....

LOL 'maintenance-free'. When they're fucked buy some more.

bad luck mate.
Sell it on Ebay.

I could.. not sure if anyone would actually want a broken brake though!

Just Googled these.

http://www.wiggle.co.uk/shimano-tiagra-4500-brake-caliper/

£20 for a new pair?

Replaceable brakes....

LOL 'maintenance-free'. When they're fucked buy some more.

Very maintenance free indeed! Oh and that's for a single caliper, btw :)

Brake calipers share the designation of "pair" with things such as a pair of compasses.

i.e. a pair of brake calipers is a single unit.

Oh and that's for a single caliper, btw :)

He only needs one pair (so far).

You must check the wheel is correctly in the dropouts, if it is, your wheel needs dishing this would bring the rim to the centre of the chainstays and seatstays and directly under the centre bolt of the brake, if this is done the brake will probably work correctly, I cannot see how all of a sudden yesterday the brake packed up, with the wheel so far out of alignment which as you say has been like this for a long time.

The cable length after the clamp shortens in the second pic. So either a) the clamp needs tightening or is bust, b) the cable has snapped somewhere between the lever and caliper, c) something has happened to the outer cable (i.e. it has broken 'free'), or d) something else associated with a, b, or c.

Have a read of the park tools guide to setting up caliper brakes. helped me out a lot when i couldn't understand why one arm was moving rather than both....

Doesn't it look as if the free end of the cable shortens as the pad moves away from the wheel. That would mean the anchor bolt isn't holding it. Even if a pivot is loose the cable would normally hold the arm in position.

Where are you? You could take it here:

http://www.lfgss.com/newpostinthread19588.html