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Author Topic: Cracked Fork Crown  (Read 2586 times)

aidan.f

Cracked Fork Crown
« on: 28 June, 2009, 10:05:55 pm »
No not 'ouch' but nearly.

I have a nice photo  to make you wince, How do I post it???
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Martin109

Re: Cracked Fork Crown
« Reply #1 on: 29 June, 2009, 08:32:29 am »
Make sure it's uploaded to some webspace or other.  Link to its location between [ url ] tags (no spaces).

Click on 'Reply with Quote' on a post with a pic, and you'll see how it's done.
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aidan.f

Re: Cracked Fork Crown
« Reply #2 on: 30 June, 2009, 10:33:53 pm »
 - We found this after a hill, the brake was juddering, cracked right around the rear of the fork





And here it is after a bit of gentle bending apart




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border-rider

Re: Cracked Fork Crown
« Reply #3 on: 30 June, 2009, 10:37:26 pm »
Nasty  :o

It's in an unusual place, I think.  Is that a tandem ?

If it's Longstaff, I'm surprised.
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Ian H

Re: Cracked Fork Crown
« Reply #4 on: 30 June, 2009, 10:52:01 pm »
Rather ironic when you consider that George used to do reports on frame and fork failures for BSI.
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aidan.f

Re: Cracked Fork Crown
« Reply #5 on: 30 June, 2009, 11:09:26 pm »
It is a tandem, & it was one of Georges last. Trying to get it repaired for LEL

I don't think there is enough filler metal (braze) in the joint - if you look at the pics there are voids
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clarion

  • Tyke
Re: Cracked Fork Crown
« Reply #6 on: 01 July, 2009, 03:00:14 pm »
Feeling slightly :sick:
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Getting there...

matthew

Re: Cracked Fork Crown
« Reply #7 on: 01 July, 2009, 03:48:21 pm »
That doesn't look to me like the joint has failed as the third picture shows that the crown has broken level with the top of the fork leg and the first picture shows the 'lug' has remained with the leg.

This looks more like failure of the crown itself, and I am not sure that the 'voids' you mention would have any impact on that.

Glad you came to a controlled stop.
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aidan.f

Re: Cracked Fork Crown
« Reply #8 on: 01 July, 2009, 04:30:42 pm »
Anyone got any good ideas for replacement before LEL longstaff's too slow,
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LittleWheelsandBig

  • Whimsy Rider
Re: Cracked Fork Crown
« Reply #9 on: 01 July, 2009, 10:18:20 pm »
Yep, crap brazing.

The shoulder recess for the fork blade seems to have acted as a stress raiser.  If enough brass filled that gap, the peak stress would have been lower.
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Wheel meet again, don't know where, don't know when...

Thing2

Re: Cracked Fork Crown
« Reply #10 on: 01 July, 2009, 10:53:39 pm »
Wibble. That doesn't look nice (and certainly doesn't bear thinking about).

I guess you're after a replacement fork for LEL?

Doing a quick round of the UK tandem manufacturers would seems to be in order, to see if they have anything suitable. A shop like JD cycles may even be able to find you something, especially if you tell them it's an emergency.

Emma
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California Dreaming

aidan.f

Re: Cracked Fork Crown
« Reply #11 on: 01 July, 2009, 10:58:02 pm »
LittleWheelandBig, 'Stress raiser' Thanks for the confirmation, I thought that, Product Recall time?

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rogerzilla

  • When n+1 gets out of hand
Re: Cracked Fork Crown
« Reply #12 on: 15 July, 2009, 09:25:28 pm »
It's a fatigue failure because the surfaces are dull - no sudden letting go.

Not as bad as a failure near the crown race; you can ride home on one blade, but not without a steerer  :o
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Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.
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