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I tired to replace v-brakes on my random cheap frame as spring regulation things started to fall apart. For replacement I picked front+rear set of Shimano BR-T4000 v-brakes because v-brakes are so simple and compatible with each other, right?

New vs five year old no-name part old vs new

pivot boss/stud(?) enter image description here

shallow hole (about half of old ones depth) in new brakes prevent them from fully setting in, which also causes that spring spike(?) to only go halfway in enter image description here

and stud is not reaching all the way through its slot (lacks ~5mm) enter image description here

Fork is aluminium (or at least not reacting to magnets). Pivot stud is steel, but does not seem wrench-friendly as thick part is oval instead of segmented. Random old non-name v-brakes I somehow had on shelf are perfect match, and all around Internet I only see studs same as one I have.

Are new brakes broken/malformed/fake? Get another brakes? Use adapter part? Or should I just get new fork with replaceable studs?

Edit:

When compared with clean classic cheap v-brakes difference in depth is more visible: enter image description here

Length of bore in oldies is ~2cm while new ones are ~2.5cm, wider part is respectively ~6mm vs ~3mm.

(yes yes, got new cables as well :)

  • What do you mean by 'shallow hole (about half of old ones depth) in new brakes'? The brake boss hole should be a constant diameter all the way through. – Argenti Apparatus Jun 3 '18 at 13:53
  • Did you get new mounting studs with the new brakes? – mikes Jun 3 '18 at 14:46
  • @mikes nope, no studs. – PTwr Jun 3 '18 at 15:54
  • @ArgentiApparatus there is wider part in hole to accommodate for wider part of stud in new brakes it is half as in old ones – PTwr Jun 3 '18 at 15:55
  • OK, I see. Is the width of the new calipers more than the old? – Argenti Apparatus Jun 3 '18 at 17:04
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Nothing is wrong here, just put the brake arms on and torque down the bolts. Your old brake arms are the type that pivot directly on the stud, and the new ones are the type that overhang the stud and have an integral pivot of their own. Use more torque than you would on the other type, because with integral pivots there's no risk of mushrooming the stud.

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    I will try again this weekend as having bike in pieces is a problem for daily commute, but I am still worried that recoil pin is only going in halfway. Isn't there some stress put on it by return mechanism? – PTwr Jun 4 '18 at 20:48
  • @PTwr it gets some stress from the return spring but not tons. By all means, if it doesn't seem solid with the bolt torqued down then trust your instincts. But I don't suspect that's what you'll find. – Nathan Knutson Jun 4 '18 at 21:55
  • Yeah this is pretty normal, though I'm not sure that you need more torque. – Batman Jun 4 '18 at 22:22
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    @Batman Cantis and v-brakes that pivot directly on the stud are notably low-torque items on bikes. A number out there on torque charts is 2 ft-lbs, very low, and the reason is the tips can be very sensitive to getting mushroomed with the bolt bearing down directly on them, an unusual fastener application. Whether going down to 2 ft-lbs is wise is another conversation, but one of the nice things about integral pivots is they sidestep the whole issue and let you put a more normal amount of torque on. – Nathan Knutson Jun 4 '18 at 22:41
  • @NathanKnutson - Didn't see "on the other type" -- I was assuming it would be about 5-7 Nm , which is about 5 ft-lbs of torque. – Batman Jun 5 '18 at 0:51

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