Fork brake boss holes - No thread?

[HovR]

So I've been upgrading a friends bike from cheap disc brakes to some higher quality V-brakes. I was positive that the fork could accept V-brakes, as I could see the (plugged) holes to accept the brake bosses, and the smaller holes to accept the spring.

I bought all the parts etc, then popped the plug out of the brake boss hole in the fork ready to fit the brake bosses.. But there's no thread?! There's no way to screw the brake boss in to the fork, as the hole to accept the brake bosses is completely threadless.

Doesn't seem like it will be possible to tap out the hole either, as the hole is already large enough to accept the M10 brake boss - But obviously it won't screw in as there's no thread.

Any ideas?

 

[berty bassett]

when you put the brakes together - isn't there a nut/ come bolt that fits inside the hole and goes through brakes and held with another nut - you hold it with a hex key to keep the right position ??

 

[PpPete]

Helicoil may be the only answer... or give up on the V-brake idea and buy some better disc brakes ?

 

[HovR]

when you put the brakes together - isn't there a nut/ come bolt that fits inside the hole and goes through brakes and held with another nut - you hold it with a hex key to keep the right position ??

Not quite sure what you mean, berty. It should work like this: Brake boss/pivots screws in to fork, brake calipers slide on to the pivots, allen/hex bolt with washer screws in to the centre of the pivot securing the caliper in place.

or give up on the V-brake idea and buy some better disc brakes ?

I'd considered this, but it'd turn out very expensive, and here's why. My friend, who owns this bike, trashed the front wheel - and was also not happy with the cheap brakes.

Thought we might as well hit two birds with one stone, so he bought a new front (rim specific) wheel and front v-brake. Now, for some reason unbeknownst to me he thought it'd be a good idea to throw away the receipt. So now we're pretty much stuck with a rim brake wheel and v-brakes.

If we were to go with decent disc brakes, we'd have to buy some good v-brakes (BB5's from £30 at the moment, or BB7's from £50), new disc specific wheel (£30+ at least) and a new rotor to replace the severely warped one (£10 minimum?).

At those prices it'd be cheaper to buy a brand new v-brake compatible fork, and for it to be an upgrade from the current one (it's not an expensive bike).

Also, not sure I'd be comfortable using a thread repair-style kit on the front brake - Never used them before myself.

Thanks for the suggestions though.

 

[sidevalve]

At those sort of prices if the bike is, as you say not too expensive, wouldn't it be an idea to look around on E bay or such to find a donor bike for parts and do a rebuild ?

 

[02GF74]

going from disc to v-brake is a backward step. tis as strange one, having no thread. helicoil should work out cheaper than new forks - there are at least 3 different threads used for v-brake bosses.

 

[byegad]

And don't buy BB5s! The BB7s are so much better that an extra £20 will be repaid by the fact they do many more miles on a set of pads. BB5s=1000 miles on my Kettwiesel, new pads £24ish. BB7s (Fitted to replace the hideously poor and hard to keep in adjustment BB5s.) have covered 4000 miles so far and the pads are still virtually new. Add the fact that they've needed adjustment exactly once since fitting (I once adjusted the BB5s three times in 20 miles.) and it really is a no brainer.

 

[HovR]

I talked to the guy in my LBS and he got me a good deal (better than online) on a pair of forks with proper v-brake bosses - Built it up with the new front end today and it's so much nicer. No horrible noises coming from cheap rubbing disc brakes, and equal if not better braking performance.

We sorta figured that if he was going to spend money on discs, he might as well buy a new higher quality bike.