OzVMX Forum
Clubroom => Tech Talk => Topic started by: HeavenVMX on May 05, 2014, 07:13:06 pm
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Anyone ever seen a circlip loose its tensile strength (loose its spring) and just become malleable instead of spring out when compressed?
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yep, the one my mate "reused" in his 350 triple quacka ...not a pretty result
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You Bet I have ..Just on the weekend a Gloster at a VMX meeting a Guy on a Monty
The Bike Look better than New Very Nice .
I was Just behind Old Mate on the Monty he went over the 3rd Jump and it all turn to shit ..
The front forks came a part I think it was a Circlip fault .
he got a way ok but the Monty did not look the same ..
I bet Old Mate will puting New ones in Next time .
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Never but what keeps a circlip in place is the chamfer on the end of the gudgeon, when the chamfer comes into contact with the circlip(C shape) it expands the circlip. Forcing it harder into the groove.
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You're a bit mean oz555ktm.
But then again you didn't run the poor sod over to add to his misery did you!
Hope you're ok Greg.
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Never but what keeps a circlip in place is the chamfer on the end of the gudgeon, when the chamfer comes into contact with the circlip(C shape) it expands the circlip. Forcing it harder into the groove.
You are thinking of the wire 'c' type clips which work on that princple. I am thinking of the square type with the eyelets for circlip pliers to remove/install. which just rely of circlip tension for retension
You Bet I have ..Just on the weekend a Gloster at a VMX meeting a Guy on a Monty
The Bike Look better than New Very Nice .
I was Just behind Old Mate on the Monty he went over the 3rd Jump and it all turn to shit ..
The front forks came a part I think it was a Circlip fault .
he got a way ok but the Monty did not look the same ..
I bet Old Mate will puting New ones in Next time .
Yes that poor bloody Monty rider I believe the only part of his body not sore today are two hair follicles on the crown of his head!!!!! A very rude awakening when I he hit the ground
One fork circlip just lost all tension and fell out and the other was then overloaded and failed. The one that fell out now seems like it is just mild steel and has very little tension :o it actually falls into the fork tube (the little eyelets are almost touching)
Yes the bike is somewhat more second hand.
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Geez Scrivo, spokes at Lake Glenbawn, forks at Gloucester, & didn't you do something to a four stroke at Bulahdelah ? You are pretty hard on the equipment. Hope you bounced OK.
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Geez Scrivo, spokes at Lake Glenbawn, forks at Gloucester, & didn't you do something to a four stroke at Bulahdelah ? You are pretty hard on the equipment. Hope you bounced OK.
Bloody Chinese spokes never again!! Ordered Japanese spokes got Chinese should have chucked them in the bin ::).
Was exonerated on the four stroke thing (work of the devil anyway :P) appears the oil pick up blocked.
Shit happens. Have never face planted off a jump like last Sunday though :o that is now crossed off the bucket list :o ::) :-[
Not one person rush up with a Snickers bar either bloody cheap skates
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Thats pretty funny ;D
Good to know you are well enough to about joke about it now, dam shame about the Monty though. It was absolutely stunning, was ::)
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Greg
If the Circlips were new and fitted correctly in my experience they must have been worked to hard. Spring steel loses it properties when heated or hammered. Maybe you can machine into the forks a new method of holding it all together?
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The BSA that I posted the shots of that the forks had come apart on turned out to have been assembled with circlips that were slightly too small so they weren't actually pressing against the outside of the groove properly, my guess is that they would have turned without needing to be compressed at all.
Could be worth checking that this wasn't the case here & that your replacements lock up on the outside diameter before reassembling the forks if they are fixable
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In such a critical application you need everything correct and going with you. More importantly not one error going against you.
We were taught as a general rule of thumb that cir-clips are cheap and always to be replaced. Indeed that is also stated in just about every bike manual I have read. Although I don't always do so.
It is very easy to fatigue, bend and stuff a cir-clip when removing or from past fittings and reasons why they are recommended to be discarded.
Even if you use a new cir-clip, as you should be in such a critical application, take nothing for granted. You need to know it will work. You need to check it. You need to know that it is DEAD flat, that it is round, that its spring tension is strong enough that you are unable to push it around or turn it in its seat once fitted. You need know the locating groove is clear, clean and perfectly formed, an even more critical check when the stanchions are re-chromed.
If it is a punched out(stamped out) cir-clip, which most are, Face the sharp square edge down toward the ground, not the top ever so slightly radiused edge, but first put a piece of wet and dry on your surface plate, a light flat rub will bring to witness any high spots(burrs) left on the sharp lower square edge from the punching process. Make sure there are no burrs on the outer OD edge stopping it from going all the way "home". Give it every chance, use the correct pliers, do not stuff the clip by over compressing it. Lay it first against one side of the bore, then compress it only enough for the other side to come on in, then lower it in to position. Be certain it is home, check the gap between the ends is the same measurement as the other assembled leg. If you can turn it? Start Again!
In the factory the pliers are "adjusted" and set for that job only. On full squeeze the piers will go no further than only what is necessary for the clip to "clear" the inner bore dimension, so that the clip isn't stressed too far and ruined by over compressing it.
You may have fitted valves or lengthened rods to the 7" rule? Whatever? make sure both of the legs come to bare the rebound stop load evenly at exactly the same point and time as design intended. Not one before the other. Obviously when the first fails the full load will then come to bare on the other until it in turn fails as well. To check it: put a zip ty or marker on each stanchion snugly above the slider. Fit the wheel and tighten the axle. Then remove it and see if zippies or dimensions have moved or changed.
You must be certain you are using the correct optimum clip. If for some reason you use, straighten, manipulate or repair an old one, and God only knows why in such a critical application? It is a spring, it relies on spring tension for its safety fitment factor. You will then more than likely, need to re-temper it.
,,,,, checking it for electricity will not help ::) ;D
PS; its a bummer about the bike, but I am glad at least that you are Ok,
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Ouch, I hope you survived okay. I put up a clip of someone else a few weeks back having the same fail due to circlips. The outcome wasn't nice.
As mentioned circlips aren't officially meant to be reused and over stretching to fit won't do them any favours. Also now they have been forced out of the groove the groove is most likely damaged. If the edges of the groove are rounded then a new clip will pop out more easily.
I didn't realize some forks relied on circlips to hold them together, I thought they all relied on the bolt from the bottom!
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In most situations it is recommended to change the circlip at each service interval.(Meaning when the particular apparatus is dismantled )
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I'm thinking that after poor old Greg's mishap (and he's so lucky to have come out of it relatively unharmed and still with his sense of humour) that there will be a whole bunch of people replacing the circlips in their front forks, me being one of them, and I don't even go over jumps...
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Also worth mentioning that circlips are usually stamped out of flat sheet. This makes one side have a slightly chamfered edge, while the other has a nicer/squarer edge.
If its a mission-critical application, then the correct orientation of the circlip can make the difference (DT250 shift shaft when I was 15, for example...).
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Hey Scrivo, I am sure we could organise some new circlips, I hear there are plenty in China, they'd match your spokes.
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Some things I know about circlips
1) Seegar circlips are crap. they loose there tension ,plus the the ends with the eyelets can break of from vibration. I learnt that from a 250 ccT70 that had them at the gudgeon pin. That thing revved.
I always grind a chamfer on the end of the gudgeon pin for use with wire circlips.
Never use wire circlips with the ends bent 'round for fitting/removal on pistons. They brake off at high revs. On other applications the tags can actually lever the clip out of the groove. The chamfer on the pin wont reach the wire.
On larger circlips in gearboxes, fork legs etc flat circlips should be squeezed by hand across their diameter to tell wich way they dish, so that they can be installed the way that wedges them into the circlip groove.
Circlip grooves are machined round for wire circlips and square for flat circlips.
When installing flat circlips, look at the way the ends are cut, they are at an angle to assist circlip pliers to grip.
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Hey Scrivo, been there ( face down in the dirt) and done that before. Yeah those circlips play an important role.