750 head bolt

chrisk

chrisk

Hero member
Location
Brisbane, Australia
What is the best way to insert/remove the front M12 head mount bolt, without removing the outside head nut? I was thinking if using a stud with a nut each end.

Seems a silly design fault, to me.
 
chrisk said:
What is the best way to insert/remove the front M12 head mount bolt, without removing the outside head nut? I was thinking if using a stud with a nut each end.

Seems a silly design fault, to me.
Click to expand...

Not really Chris.

Apparently, some numpty has replaced the stock stud/nuts set-up with a stupid bolt!

Seen a lot of stupid things on Lavs, but not that. ::)

piet
 
sfcpiet said:
Not really Chris.

Apparently, some numpty has replaced the stock stud/nuts set-up with a stupid bolt!

Seen a lot of stupid things on Lavs, but not that. ::)

piet
Click to expand...
What he said!! Nut on each end - factory was smart - piece of piss!  :-* :-* :-*
 
At least a stud with two nuts is more secure solution on a shaking bike than a bolt and nut.
The bolt head is typically the weakest link on a screw joint. That's why the most loaded bolt joints have studs and nuts. Very used solution in high power engines.

On 750 there is also no room for a standard bolt on that position.
 
MotoJouni said:
The bolt head is typically the weakest link on a screw joint.
Click to expand...

I've only ever seen a bolt head broken off when it's a fully threaded bolt (or machine screw) that has broken through the thread. I'd argue that the thread root is the smallest diameter part of a bolt and also a stress concentrator. So to my mind, the weakest link is any loaded part of the threaded section.

On a bolt with a (non-threaded) shank, the head is probably the strongest part.

A threaded bar with a nut each end wouldn't be any stronger than a bolt.
 
^On a bolt head, the most loaded (drag tension) section is the corner between head and straight section. This is avoided when using stud and nut. On the thread itself it has small area, but on it a drag tension turns to press tension. Near the thread inside the material the tension is mostly shear tension.

The bolts are usually made  today from a straight round bar. The other end is heated up and striked to a mold to make the bolt head. I think this may leave such weaker sections on the bolt head material.

On many car engines, if it is tuned up more the crank bolts are changed to studs and nuts. The bolt manufacturers also state that those withstand bigger forces and therefore bigger power on the engine.
 
I've snapped a few bolts in my time!

Many times on purpose with a breaker bar because it's much quicker than bloody hacksawing.
Pretty much none snapped at the head and pretty much all where the thread ends somewhere midships.
This is a nut and bolt scenario.

The few times I have seen bolt heads shear off is with 316 stainless bolts that have received cyclic loading or fatigue stress.
Snap like a carrot then!

However! I think you are at cross-purposes!
There are bolts and there are 'set bolts'or 'screws'.
With screws the weak link could be the head, most especially if it is screwed into something solid. The solid lump supports the thread and the weak link must be the head as it is the only part not supported.
 
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