|
|
Post by cusqueno on Nov 29, 2016 11:50:19 GMT
Last week, heading for home on my daily commute, going quite slowly (fortunately) round a flat left hand turn, my drive side pedal seemed to fall off. Fortunately I didn't and I was unhurt. On retrieving the pedal from the road I saw that the crank had in fact cracked across at the pedal hole. Photos in gory detail to follow. This was a Viscount crank, but I am not levelling a finger of blame since there are plenty of other instances online of cranks from other manufacturers failing. I understand that at one time Campagnolo had quite a reputation for this.
Now I need to remove the offending item and I wonder if anyone has any particular recommendations. A crank puller predictably stripped the thread and using wedges hasn't worked. Rather than trying to get it off in one piece, I think I'll cut it off. Would readers recommend hacksawing or a Dremel? I have only a battery Dremel and I am not sure it would really be up to the task. Thanks.
|
|
|
|
Post by oldroadietehachapi on Nov 29, 2016 14:43:12 GMT
Now I need to remove the offending item and I wonder if anyone has any particular recommendations. A crank puller predictably stripped the thread and using wedges hasn't worked. Rather than trying to get it off in one piece, I think I'll cut it off. Would readers recommend hacksawing or a Dremel? I have only a battery Dremel and I am not sure it would really be up to the task. Thanks. I would try a pulley remover as used by auto mechanics. They are typically used to remove crankshaft and water pump pulleys. In this country they can be rented; for a few more dollars, they can be bought at Harbor Freight. I would add a bit of heat for the next attempt. Good Luck Jim |
|
|
|
Post by vtchuck on Nov 29, 2016 21:29:32 GMT
|
|
Jem
Viscount
?
Posts: 3,390 
|
Post by Jem on Nov 29, 2016 22:17:49 GMT
Pleased to hear that no injury occurred John.
I am sorry, I have no advice on the crank pulling.
|
|
|
|
Post by sprockit on Nov 29, 2016 23:35:27 GMT
My initial thought would be to say bearing pullers, but from the description you've given they'd be pulling on the chainring and would certainly distort it.
If you can remove the left pedal crank and get the BB spindle out of the right hand side of the BB shell, it should be possible to position the spindle between the jaws of a vice (with the jaws closed as much as possible), with the chainring resting horizontally on top of the jaws. Screw a crank bolt as far as it will go into the end of the spindle, then using a piece of wood to protect the bolt head, it should be possible to break the grip of the taper by whacking the bolt with a hammer.
It may work, it may not, but perhaps it's worth a try.
|
|
|
|
Post by oldroadietehachapi on Nov 30, 2016 0:49:06 GMT
they'd be pulling on the chainring and would certainly distort it. Just remove the chainring. Cheers Jim |
|
|
|
Post by cusqueno on Nov 30, 2016 7:38:05 GMT
Thanks for the advice. I've taken the rings off with no problems. I have a couple of bearing pullers - a very old three leg one and a cheap two leg one. Not tried yet, but I have never yet succeeded in pulling anything with them. On the Viscount/ Lambert crank it seems impossible to get them grabbing properly on the spider because of its five-lobed shape - they have always ended up either coming off or going out of square and losing 'pull'.
Taking the bottom bracket out is not something I really want to do, but it is an option.
Not sure when I will get time to return to the bike due to mother-in-law's visit next week & other domestic issues. It's OK while the weather is dry, I am using another bike, but this one is my only bike with full-length fenders / mudguards so I want to get it going again for the wet weather.
|
|
|
|
Post by oldroadietehachapi on Dec 1, 2016 5:42:41 GMT
This will sound horrific; it is a last resort. if you remove the right crank with the bottom bracket spindle attached, you can place the right crank arm on an open vice and using a soft drift, give the spindle a good old fashioned whack. Just make sure the left crank arm will come off. I would try a bit of heat before pulling it. There should be a market for the left crank arm as that (for some reason) is the one most people lose.
Best of Luck
Jim
|
|
|
|
Post by sprockit on Dec 17, 2016 22:42:35 GMT
Do you think the crank failure could be down to metal fatigue?
The breakage is in a high stress location - but can metal fatigue occur in areas of low stress? I can't say I know a great deal about the subject.
I've often wondered about this with the alloy parts on bikes, and guess that I'll get better longevity from the chrome plated steel parts on my budget Sport than I will from the higher spec Sprint or International.
|
|
|
|
Post by bicyclebits on Dec 19, 2016 15:25:48 GMT
sprockit -
It's most likely metal fatigue. Alloy ranks often fail at the pedal eye as the pedal axle acts as a lever transmitting forces through the crank arm. Lots of stress. They also fail at the spider and Campy Nuovo Record cranks did so due to a sharp angle in the spider arm nearest the crank arm. Cracking across the bottom bracket axle attachment point in the crank arm also occurs due to the stress raiser caused by the machining of the axle flats. You may actually get longer life out of the steel crank arms but a great deal depends on the initial quality of the alloy and steel components under comparison.
|
|
|
|
Post by oldroadietehachapi on Dec 19, 2016 17:35:24 GMT
This thread reminds of one good reason to stay in the saddle while climbing; even if, I no longer expect to father children.  Cheers Jim |
|
