Touring rack screws sheared

[chris__P]

Hey

So my rear rack fell off my bike. The screws holding it in at the bottom sheared, so that what is left of the screws are stuck in the holes. The stays snapped off.
So my plan is to replace the stays (the rack is Tubus Logo and is still generally good) and to drill through the sheared off screws with 5mm drill, then bolt the bottom part of the rack to the frame through these new holes. I am not very happy taking a drill to my Surly frame but I'm not sure of any other options. As a question, I'm wondering if there is a screw/bolt I can use that will be stronger than standard stainless steel to hold the rack without shearing again.
Chris

 

[cyberknight]

Let me know how this goes , i did the same on my virtuoso so i have a bolt with no head stuck in the frame but its is not long enough to cable tie the rack bottom to the frame to hold it in place.
I resorted to using a seat post rack for now and TBH its a pain as the arms that hold the bags off the wheels bend so i have to regularly pull them apart or the bags catch in the spokes,along with the weight being a bit high so it affects handling in the corners.
What about a seat mounted saddle bag ?
My frames aluminium though so i am a bit wary of trying to drill the bolt out and i do not currently have a metal drill bit the right size

 

[growingvegetables]

I'd the same - sheared bolt holding the bottom. Used P-clips instead. Ugly as sin ... but then so am I, so no worries there!

 

[Randy Butternubs]

Take the frame to a machinist and ask if they can remove the screw without damaging the frame threads. I had a similar problem once and they were able to drill out the center of the screw with such precision that the frame and screw threads were left undamaged and interlocked. The screw threads could then be teased out like a wire.

If that is not possible they might be able to drill and re-tap a new, larger threaded hole or use a helicoil insert if there is enough material around the hole.

Cheap stainless bolts are pretty cheese-like. You could go with A4 (rather than A2) stainless or grade 8.8 high tensile steel (non-stainless). These will have a higher tensile strength, which apparently gives proportionally higher shear strength.

Good luck

 

[simon.r]

Take the frame to a machinist and ask if they can remove the screw without damaging the frame threads. I had a similar problem once and they were able to drill out the center of the screw with such precision that the frame and screw threads were left undamaged and interlocked. The screw threads could then be teased out like a wire.

There's every chance that you'll be able to do that at home, with a 2mm or 3mm bit and a steady hand.

 

[cyberknight]

I'd the same - sheared bolt holding the bottom. Used P-clips instead. Ugly as sin ... but then so am I, so no worries there!

Like that idea, i will have to look into it, how do you know what size to buy ?

 

[growingvegetables]

how do you know what size to buy ?

I went round several bike shops, and tried whatever they had in stock - Evans had 22mm ones which fitted perfectly.

PS I'm guessing - but P clips are probably fine if you're NOT planning to carry heavy panniers long distance? They're fine for my fairly light needs, though.

 

[compo]

I had the same problem with a sheared bolt. I centre popped it then ran a tiny drill through using a dremel. This gave me a pilot hole for a bigger drill bit which actually snagged in the screw and screwed it all the way through the frame. Problem solved.

 

[02GF74]

be careful when drilling - ideally you want to clamp the frame in a drill press as the last thing you want is to have the drill snap - then it becomes more difficult as you need to remove not lonky the remainder of the screw but the drill bit.

4 mm would be about the right size - leave enough lee way so as not to damage the frame if you are not totally central - you can then use a round file to file away the screw until the trheads can be picked out.

 

[Tim Hall]

If you have an aluminium frame and have stuck a broken steel bolt in it, this link describes how to get jiggy with (safe) chemicals and SCIENCE to dissolve it out. Zigzag on YACF (not sure if he's here as well) did it as described here.