Stem face plate bolts full/part threaded?

wishitwasallflat

I'd like to replace my stem face plate bolts cause they're ugly and rusty. I have some stainless ones already in the correct size but the old rusty ones are part threaded - they have a non threaded shaft where they go through the front of the face plate and are only threaded at the end which screws in to grip the stem itself. The nice shiny new ones I have to hand are threaded over their full length. Is there any problem with using fully threaded bolts for this task?

If there is a problem does anyone know where to get suitable (short enough) part threaded bolts? Best I can find is part threaded starting for bolts over 40mm or so which are way too long for this job.

As always any advice much appreciated.

freezing77

Just use them, they will cause some wear on the face plate but nothing of any importance.

wishitwasallflat

Thanks for the reply but what kind of wear isn't important on a part like that? Honestly don't mean to be cheeky but I was thinking, before I posted, that it should be ok. My thinking was that because the extra thread on the new bolts wouldnt actually load bear, or affect the face plate at all, because the holes in the face plate are unthreaded. I was hoping someone would confirm that or point out why that's wrong. I dont trust my theoretical thinking in these situations, but especially here, because Ive never really understood why bolts come part threaded at all unless the bit that interfaces with the unthreaded section is mean to rotate and/or slide - which I dont think a face plate should.

If having that extra bit of thread could cause any kind of wear at all surely that's not good on a load bearing structure like this?

slowbike

It's not an issue - just use the threaded bolts. The worst that could happen is that you'll mark the inside of the faceplate holes - but that's unlikely.

wishitwasallflat

Brilliant thanks, that's what I had thought but don't have confidence when I work this stuff out in theory with no practical experience.

freezing77

wishitwasallflat wrote:

Thanks for the reply but what kind of wear isn't important on a part like that? Honestly don't mean to be cheeky but I was thinking, before I posted, that it should be ok. My thinking was that because the extra thread on the new bolts wouldnt actually load bear, or affect the face plate at all, because the holes in the face plate are unthreaded. I was hoping someone would confirm that or point out why that's wrong. I dont trust my theoretical thinking in these situations, but especially here, because Ive never really understood why bolts come part threaded at all unless the bit that interfaces with the unthreaded section is mean to rotate and/or slide - which I dont think a face plate should.

If having that extra bit of thread could cause any kind of wear at all surely that's not good on a load bearing structure like this?

Yes the thread will load bear as it is in tension all the way along the thread. As the op mentioned it may mark the faceplate this is the insignificant wear that I referred to previously.

The faceplate is in compression due to the tension in the bolts and not shear.

Monty Dog

No problem as once tightened correctly, nothing should move and fret the holes in the faceplate. Plenty of stem fastener kits available online including titanium. I disagree with the above, longer threads don't make any difference to strength, the strength is down to the cross-section area - the load is typically taken on the first 6-turns, the rest is redundant and more to aid assembly - 'play' is deliberately designed into the threads otherwise the surface friction would be so great they'd be impossible to screw-in. Finally, activating pedant mode, we're discussing the difference between screws and machine screws, with a bolt being something made to cruder tolerances!

wishitwasallflat

Thanks to all and pedantry is appropriate here MD! From my pre post searching for the answer I could see there were different names for each but wasn't so sure exactly which was which hence the simplistic approach of calling them all bolts