Tapping caliper pin thread

[mrtomsv]

The brake pad retaining pin on my rear caliper cannot be withdrawn to change the pads without removing the caliper from the frame due to interference with the chainstay. Obviously this is a bit of a pita. I’m thinking about tapping a thread on the rhs of the caliper to be able to insert the pin from the other side. Before I do, can anyone think of a reason this wouldn’t be a good idea? The pin doesn’t take a great deal of load, its purpose is just to stop the pads falling out when the brake isn’t applied, so can’t see that removing metal for the thread will have any effect on function. Frame is a Spesh Epic Evo, and caliper is a Sram G2.

[Lotobear]

Doesn't answer your question (so sorry for that) but I would always remove the caliper as a matter of course to replace the pads as it's much easier to push the pistons back with it off and, generally, just more convenient to do the job that way

[Benson11]

Should be fine, some callipers (Magura I think) have this design anyway with a circlip on the end of the bolt, there is normally also loctite on the threads for just in case

[ian in lancs]

Any chance of a photo or two?

As for loctite on the pad retaining pin the standard procedure is to lightly grease the thread to prevent seizing (pin/caliper dissimilar metals) which is a common PITA. Whilst loctite could help re seizing using the wrong one would have the seizing effect. The spring clip is used to prevent the bolt and possibly the pads / falling out.... The shimano Ultegra part number for the spring clip is https://www.sjscycles.co.uk/brakes/shimano-smmar16...

[BOR]

The risk is if the bolt unscrews itself while you are riding, and makes contact with the spokes/locks up the wheel, but I think you be very unlucky to have that happen, but that is the reason.

IF you are going to go down this route, you could try filing the thread on the pin down, so that the pin can be inserted from the "spokes side" then using the circlip to retain the pin, if you can get enough access to it through the frame.

You would be relying on the circlip alone, which might be too much risk.

Possibly, you could file the thread on the pin down to the same diameter as the hole on the spoke side, to achieve a very light interference fit, which should be enough to retain the pin safely.

[mrtomsv]

Thanks all for your thoughts. The problem with removing the caliper to change pads is that the rear mounting bolt is barely accessible either, I can only get at it with a cheepo Allen key, the chainstay above it precludes getting a proper hex and rachet on it.
I did think about the interference between pin and spoke should it work lose, hopefully it wouldn’t, especially with a circlip, but it it did, I imagine it’d take out a spoke or two rather than causing a catastrophic accident.