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 Post subject: KTM Duke Brake recall
 Post Posted: Sat Jan 27, 2018 4:14 pm 
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Hornet Lord

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http://www.visordown.com/motorcycle-new ... ke-failure


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 Post Posted: Sat Jan 27, 2018 4:34 pm 
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Front brake failure would definitely ruin your day . . .

Wonder what it would take to crack the piston? Cases presumably arose from track use where very hard braking is the norm?

It's also worth taking a periodic check of your caliper bolts (among other things) - there was a guy I knew of who went on a ride out and pulled into a cafe car park for a coffee break with his mates about half way through - on returning to his bike (Suzuki B-King I think) he noticed one of the calipers dangling around the front wheel suspended only by the brake line - sounds crazy that both bolts would work out like that - but he had the pics and witnesses to prove it.


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 Post Posted: Sat Jan 27, 2018 6:41 pm 
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HOON98 wrote:
Front brake failure would definitely ruin your day . . .

Wonder what it would take to crack the piston? Cases presumably arose from track use where very hard braking is the norm?

It's also worth taking a periodic check of your caliper bolts (among other things) - there was a guy I knew of who went on a ride out and pulled into a cafe car park for a coffee break with his mates about half way through - on returning to his bike (Suzuki B-King I think) he noticed one of the calipers dangling around the front wheel suspended only by the brake line - sounds crazy that both bolts would work out like that - but he had the pics and witnesses to prove it.



You mean like ? :eek

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 Post Posted: Sat Jan 27, 2018 7:02 pm 
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Holy crap, think of all the times you have been really going for it on the bike and then imagine that happening . . . :(


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 Post Posted: Sat Jan 27, 2018 9:01 pm 
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HOON98 wrote:
Holy crap, think of all the times you have been really going for it on the bike and then imagine that happening . . . :(


It was a Kawasaki GPZ 500 the bolts probable dissolved in the rain. :rollin


Because i don't buy new bolts every time i strip and clean a caliper (which is regular this time of year) I use blue loctite on mine. You need a socket on them all the way out as they don't ever become finger tight... so no chance of them unwinding themselves.

Clean threads with a wire brush and a drop of the blue stuff to refit. :)

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 Post Posted: Sun Jan 28, 2018 9:44 pm 
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Isn't the reason they recommend new caliper bolts after refitting the calipers is that the new bolts stretch (as they are meant to do) when properly torqued up and develop a thinner stretched 'waist' in the middle of the threaded length - which means that if you re-use old bolts they will not torque up properly second time round (because they are now stretched) and are more likely to work themselves loose?

I'm sure I read this somewhere - it was also reinforced when I examined my old caliper bolts which on close inspection did exhibit a thinner waist due to stretching of the bolt as a result of torque around the middle of the threaded length.


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 Post Posted: Sun Jan 28, 2018 10:23 pm 
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HOON98 wrote:
Isn't the reason they recommend new caliper bolts after refitting the calipers is that the new bolts stretch (as they are meant to do) when properly torqued up and develop a thinner stretched 'waist' in the middle of the threaded length - which means that if you re-use old bolts they will not torque up properly second time round (because they are now stretched) and are more likely to work themselves loose?

I'm sure I read this somewhere - it was also reinforced when I examined my old caliper bolts which on close inspection did exhibit a thinner waist due to stretching of the bolt as a result of torque around the middle of the threaded length.


Good point Hoon :)

Thouigh in my experience i've only seen that 'stretching / thinner waist' once and that was the first time i removed the calipers after purchasing the bike. Since replacing with new bolts I've had the calipers off and on countless times (I'm anal about routine maintenance and have fit 3 new front tyres) i always use a torque to spec (On wet loctite threads) and have never seen the stretch again. :blahblah

I put the stretched bolts down to some monkey boy hanging on the ratchet... it's worth checking for though or if in doubt just buy new ones 8o

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 Post Posted: Sun Jan 28, 2018 11:09 pm 
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Yeah - I can't say it's something that I've ever lost any sleep about - In the past I just put it down to Honda cynically screwing as much money out of the customer as possible by specifiying excessively high maintenance standards, consequently I never bothered checking out the bolts that closely - as long as the threads looked ok I always put them straight back in after re-fitting the calipers and never had any problems - I only decided to take a closer look at the bolts after reading about the stuff discussed above e.g. the bolts being specifically designed to stretch when torqued up - and that used bolts wouldn't torque up properly due to their being stretched previously - I'm not sure if the last sentence is true - it might be a figment of my imagination - I'll have to do a bit more research and check it out.


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 Post Posted: Mon Jan 29, 2018 2:23 pm 
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Hornet Lord

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I tend to use copper slip or some such anti-sieze compund on the bolts (or dry) and then paint mark them.

I do tend to do a glancing once over of the obvious bolts when I go to ride.


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 Post Posted: Wed Jan 31, 2018 10:22 am 
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Victor Meldrew
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Honda caliper bolts come ready coated with some sort of dry threadlock compound, which is why they say you should use new ones each time.

As Biggabit says, wire brushing and blue Loctite works just as well.

Caliper bolts don't stretch in normal use, torque settings too low for that to happen. That said, and I'm sure I've said this before, in my early days of Hornet ownership I managed to stretch mine. I copper greased the threads, copying what I'd seen the dealers mechanic do. Then set my little 3/8" drive torque wrench to correct figure, and heaved away. And continued to heave, wrench just would not 'click'. Bolts stretched to the point at which they were visibly wasp waisted.

I now use threadlock and tighten by hand. For similar reasons, I do not use torque wrench on sump plug, can't see how you could possibly get an accurate torque reading on a thread lubricated with super slippery synthetic bike oil.

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 Post Posted: Wed Jan 31, 2018 10:35 am 
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Hornet Lord
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I'm glad you said that Richard, I was reading this thread and thinking that I either didn't understand which bolts you were all talking about, or Honda brake carrier bolts must be made of cheese.

I mild threadlock mine though I've come across a fair amount that have been copper greased.

With regards the sump bolts, I now only use hollow crush washers, similar to the ones used on brake line banjo bolts. I find that I can actually feel the point at which they start to deform, and that is all that's needed. One crush washer is good for about 4 oil drains.


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 Post Posted: Wed Jan 31, 2018 11:18 am 
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Victor Meldrew
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Picture of bolt, taken from CMNSL website.

Image

Interesting if you look at parts for 1998 Japanese PC34 Hornet. That bike came with four pot calipers, we were short changed with our 2 pot sliding calipers.

https://www.cmsnl.com/honda-cb600f-hornet-1998-w-japan-pc34-100_model49746/partslist/

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 Post Posted: Wed Jan 31, 2018 12:33 pm 
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Quote:
Caliper bolts don't stretch in normal use, torque settings too low for that to happen. That said, and I'm sure I've said this before, in my early days of Hornet ownership I managed to stretch mine. I copper greased the threads, copying what I'd seen the dealers mechanic do. Then set my little 3/8" drive torque wrench to correct figure, and heaved away. And continued to heave, wrench just would not 'click'. Bolts stretched to the point at which they were visibly wasp waisted.

I now use threadlock and tighten by hand. For similar reasons, I do not use torque wrench on sump plug, can't see how you could possibly get an accurate torque reading on a thread lubricated with super slippery synthetic bike oil.


Absolutely spot on - the effect of grease and oil on threads and torque is something I've only really become conscious of relatively recently - it explains why you do hear of people stripping the threads (or even cracking) their sumps periodically - as you say this is something which is the result of applying the 'correct' torque rating but not taking into account the (by default) heavily lubricated threads of a sump bolt.

Totally agree that it's better to take a more nuanced approach to the use of the torque wrench depending on the nature of the component you are torquing up and what is on the threads, sometimes (as you indicated) it's better to dispense with the torque wrench and go by 'feel' instead (although I would generally use a torque wrench and follow critical torque ratings for engine internal components) - judging by fingers/hand/wrist/arm/shoulder the amount of torque a component needs in terms of safety, size and the material the component is made of (e.g. brass/alloy/stainless steel) is something which only really comes from experience*

*e.g. breaking things . . . :angel


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