Bolt re-use.

[milleplod]

I'm in the process of fitting a new front suspension unit to my 1200ST. The workshop reprom says to use a new bolt. I think that's because a new one comes with blue threadlock already applied, rather than for any 'you'll die horribly if you use the old bolt' reasoning. Torque setting is a moderate 40Nm. Am I missing anything?!

Pete

 

[Bushman666]

Take it it's not a stretch bolt ....? If so it would need replacing !

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[Deleted account 191119001]

Its my believing Pete that most of the bolts are Aluminium and stretch when used again, although I have no 100% proof, but I guess for the price of a bolt better to be safe.

 

[milleplod]

I think the parts fiche gives the bolt material spec, I'll have a look when I get home. I should add that I'm not being a tight-arse! The unit's ready to go on, I only noticed the new bolt mentioned when looking for the torque setting!

Pete

 

[tanneman]

Probably 8.8 or 10.9 rated. More likely an 8.8. In that case, no worries, but if inspection of the thread reveals anything out of order then replace it.

 

[milleplod]

Probably 8.8 or 10.9 rated. More likely an 8.8. In that case, no worries, but if inspection of the thread reveals anything out of order then replace it.

I've just looked on the fiche, it doesn't mention a material spec for the bolt (a 'fit bolt', what's that?!) unfortunately. I've just got off the phone to Motorworks, its a bolt they don't supply, which is a bit odd as they supply all the others - the guy there said he's always re-used them as long as there's no visible damage and the old threadlock is completely removed first. Re-use it is then!

Pete

 

[Slipperyeel]

I'm new to the 1200, but I can't imagine most of the bolts are aluminium?! Especially not for that job. It's almost entirely sheer on that bolt surely? Which would almost definitely mean steal (not Ali)...

I think you're right, it's shown for replacement just because of the thread lock on the new. I'd just reuse the original with some new thread lock applied.



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[dean0n0]

A fit bolt is made to a size and tolerance, to fit a bush or locate something acurately (not a standard bolt out of a bin). If it's not worn or scored it should be good to reuse.

 

[Deleted account 191119001]

I'm new to the 1200, but I can't imagine most of the bolts are aluminium?! Especially not for that job. It's almost entirely sheer on that bolt surely? Which would almost definitely mean steal (not Ali)...

I think you're right, it's shown for replacement just because of the thread lock on the new. I'd just reuse the original with some new thread lock applied.



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I believe the aluminium ones are something to do with not mixing alloys, I know Harley does this also.

 

[GORILA]

I would fit without the thread lock. So long as you torque it up sufficiently everything will be ok! If worried you can check it periodically.

 

[milleplod]

A fit bolt is made to a size and tolerance, to fit a bush or locate something acurately (not a standard bolt out of a bin). If it's not worn or scored it should be good to reuse.

Learnt something there - ta!

Thanks for the replies and thoughts chaps, much appreciated! I do check nuts and bolts fairly regularly tbh.....especially the ones that I might have had undone at some point...

Pete

 

[UturnTony]

Re-use the bolt, it'll be fine.

 

[Bendy toy]

Those that are likely to loosen or be dangerous if they do should be threadlocked. My rear frame to engine bottom bolts have both fallen out though not at the same time thankfully. All such like that have been removed cleaned and threadlocked. So far so good.
Checking them for tightness is not entirely a good idea. Use any force and they could become over tight and any movement will break the threadlock.
Just to be confusing, my front and rear brake calliper screws are coated with anti seize so can’t be threadlocked but have never shaken loose.

BMW pretty much across the bike use zinc plated carbon steel fasteners. Zinc is just below aluminium on the galvanic scale and steel just above so corrosion is minimal. If the bolt is clean and not worn in any way I would re used it. Clean off remnants of the old thread lock and use some blue thread lock on assembly.

Stainless would probably be up to the task, but it causes the aluminium to corrode jamming the thread and generally weakening everything.

 

[MikeO]

Having had a used bolt break on a cam belt tensioner (not my work), I always replace bolts when the spec says to. If it's a safety critical area then a few bob spent on replacing the bolt seems a good investment...

 

[Bendy toy]

It depends why they are slated for replacement. In many cases it’s because they come with pre-applied threadlock. They can be cleaned up but dealer maintenance time costs are so high it’s cheaper to fit new bolts.

 

[Greg Masters]

How much is a new bolt?

 

[milleplod]

How much is a new bolt?

£5.46

Pete

 

[Greg Masters]

£5.46

Pete

What? You mean less than the cost of a gallon of gas?

Is there a touch of tightwadism going on here?

 

[milleplod]

What? You mean less than the cost of a gallon of gas?

Is there a touch of tightwadism going on here?

No! It was a case of removing the old unit and having the old bolt to hand - I only noticed the 'use a new bolt' instruction when looking up the torque setting on the reprom....ordering in a new one would prevent the immediate fitting of the new front suspension unit, that's all.

Pete

 

[Bendy toy]

My shocks have both been out twice. Still got the original bolts at both ends.