Lost a motor bolt!

[b33k34]

This is a new one for me - 3 year old bike. I fitted a replacement motor back in November with a new set of bolts (which come with thread lock pre-installed). All done up with a torque wrench.

Getting the bike ready to ride yesterday morning noticed that one of the front most bolts was missing, and the one on the opposite side was loose.

I've removed and refitted our motors a fair few times over the years, but never had a bolt come undone or be anything but fully tight.

 

[theremotejuggernaut]

I'm waiting for this to happen to me. My daughter seems to enjoy 'fixing' my bike with me whenever I'm out in the garage. She's figured out where the allen keys fit and it's only a matter of time before she's strong enough to undo something important .

Those bolts, well actually all of the bolts on the bike are really soft alloy as I'm sure you've found out. Reckon you might have stripped the thread reinstalling the motor?

 

[b33k34]

I'm waiting for this to happen to me. My daughter seems to enjoy 'fixing' my bike with me whenever I'm out in the garage. She's figured out where the allen keys fit and it's only a matter of time before she's strong enough to undo something important .

Those bolts, well actually all of the bolts on the bike are really soft alloy as I'm sure you've found out. Reckon you might have stripped the thread reinstalling the motor?

no - I bought a new bolt set for the new motor. (so still have the old set with slightly damaged heads to replace with.)

maybe the motor thread was slightly greasy, or maybe the pre installed thread lock isn't up to the job. Or something stopped it completely tightening (perhaps after installing the other motor bolts - I normally do a second round and tighten them all a bit at a time).

 

[theremotejuggernaut]

Maybe onto something with the factory loctite? I fitted a new linkage recently. Most of the bolts came with thread lock applied. After a couple of rides I went back over everything with a torque wrench and they're were a couple of bolts that had loosened off.

I know it's a lightweight bike but I reckon they could have made the bolts a little stronger for the 7 grams it would have added!

 

[Weeksy]

Did you reapply thread lock? Or leave it to the stuff that was there ?

 

[theremotejuggernaut]

Moi?

I removed and cleaned the bolts which had loosened and put some blue Loctite on them.

I'll check the rest again before I ride it next. If they haven't moved, I'll leave them. If they've loosened them I'll treat them to some new Loctite and check them again after a ride or 2.

 

[Binhill1]

This is a new one for me - 3 year old bike. I fitted a replacement motor back in November with a new set of bolts (which come with thread lock pre-installed). All done up with a torque wrench.

Getting the bike ready to ride yesterday morning noticed that one of the front most bolts was missing, and the one on the opposite side was loose.

I've removed and refitted our motors a fair few times over the years, but never had a bolt come undone or be anything but fully tight.

Agreed I do check probably not as often as I should but never had a loose one yet , dare I say that. Long ago a favourite was pedals i stripped the threads on a few.

 

[b33k34]

Agreed I do check probably not as often as I should but never had a loose one yet , dare I say that. Long ago a favourite was pedals i stripped the threads on a few.

my worst was wrecked bottom bracket threads on a shimano crank. The cranks were tight which covered up the fact that one of the cups was just slightly loose. Over time it was enough to complete destroy the threads. (sleeved and rethreaded to solve it)