Bicycles Network Australia - Australian Cycling Forums

by **MattyK** » Tue Apr 30, 2013 2:15 pm

crap.

Found a loose bolt on the forward stay of my rear rack that was the source of some squeaks. Tightened it up no problems, while I was there with the 5mm allen key I thought I'd check a few others. Nipped up the mounting bolt of the rear v-brake and it rolled the pad onto the rim. And stayed there.

Busted the little pin off the southpaw claw that goes in to the little hole next to the male bit

Assuming I'm up for a new brake now... Current one is a Tektro RX3, but if there's clearance I might get a Tektro 926AL which is 5mm shorter but probably better suited to drop levers if I ever get round to that conversion...

by **BNA** » Tue Apr 30, 2013 2:30 pm

by **twizzle** » Tue Apr 30, 2013 2:30 pm

New brake... but I'm confused as to how it broke tightening the bolt, as the bolt only holds the inner sleeve of the arm, and shouldn't have applied any force to the return spring assembly. Weird... Also - I'd hit the tip and find some V-brakes on something bound for metal recycling.

by **MattyK** » Tue Apr 30, 2013 2:52 pm

The tip that goes in the hole is a separate stud to the wire of the return spring (though it's deceptively similar size). That little stud bears all the torque when you tighten the bolt down.

Broken stud is the lower dot. Return spring tip is the upper dot.

by **twizzle** » Tue Apr 30, 2013 3:13 pm

The Inner plate (with adjuster) floats. The bit you broke off is the "other end" of the spring assembly, as it were. Tightening the bolt should only clamp down on the inner sleeve that the arm of the V-brake rotates on, if shouldn't put any force into the spring/adjuster assembly.

by **MattyK** » Tue Apr 30, 2013 3:38 pm

The bit that broke is not the end of the adjuster spring. It's a stud pressed into the inner sleeve (which has the two ears at 12 and 9 o'clock on it). It definitely gets a load when tightening the mounting bolt.

The end of the spring goes into the top hole as shown, the outer silver ring is a floating collar to which the tension spring attaches.

Not sure what you're arguing about, I have these pieces in front of me...

by **twizzle** » Tue Apr 30, 2013 3:47 pm

Ah, O.K., got how it works now - that's an unusual design. Not as ugly as the usual ones... but doesn't help if it can shear that pin off!

by **Dan** » Tue Apr 30, 2013 7:03 pm

MattyK wrote:Not sure what you're arguing about, I have these pieces in front of me...

Each time I read one of your posts, I think to myself 'why does he bother asking?',as inevitably, (and proven once more with this thread) you appear to know more about whatever issue it is you have than those of whom you're seeking assistance.

For what its worth, I think its due to overtightening as a result of a design flaw, but you already know that, don't you?

by **MattyK** » Tue Apr 30, 2013 9:31 pm

Thank you for your useful and well considered contribution Dan.

This post was more of a vent than a request for assistance. I can see pretty well what's going on and replacing the whole thing is an obvious solution, but hey, there are plenty of people out there who know more than me; maybe someone might chime in with "you only need to buy this 50 cent widget to fix it"?

by **MattyK** » Wed May 01, 2013 5:04 pm

New brake ordered - another RX3. The 926AL at 80mm high won't clear my mudguard.

Intrestingly, the RX3 arm has "RX5" cast into the inside of it; the only difference I can see to this up-specced version is the brake pads. But since I have other pads anyway...

by **WyvernRH** » Thu May 02, 2013 7:55 am

You could have fixed that you know? Just drill/tap out the remains of the pin and push in a piece of hi-ten rod and it's ready to go, 20 minutes work at most.
Cheers
Richard

by **MattyK** » Thu May 02, 2013 11:05 am

Didn't look quite so easy to repair. I have temporarily borrowed the same part of my wife's dust collector; the pin can't be pressed out because there's no way to get to the back side of it. Pus it's a nice serrated/knurled section to bite in when pressed in place, then tapers to a finer tip. Plus my handy supply of hi-ten rod just ran out. Figured for $25 for a new one it wasn't so big a deal.

by **MattyK** » Mon May 06, 2013 10:49 am

OK, so I'm feeling like an idiot this morning. First order of parts they tell me they are out of stock. So last night I bit the bullet and ordered an RX5 brake from bike24. Then this morning on the ride to work I remember that I still have my original front brake in the garage after doing a front disc upgrade... doh.