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Post by lcmarky on Mar 3, 2021 11:14:03 GMT 1
Not for any of my LC's, but I am in the process of rebuilding two Montesa 1970's twin shock trials bikes and need to replace the fork internals circlips. I thought I was pretty conversant with most engineering terms & technologies, but am struggling with circlips. From the picture below, how do I describe this circlip to buy replacements? I tried ordering from the OD of this circlip, but that came back too large and too thick. Do I go on shaft diameter? Circlip thickness of the one in the picture is 1.2mm. Thanks Folks Circlip by KTM Marky, on Flickr
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Post by Shytalk on Mar 3, 2021 12:43:36 GMT 1
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Post by lcmarky on Mar 3, 2021 16:38:13 GMT 1
I'm afraid to say you've failed the Vernier test... diameter is 33.4mm and indeed I (like you) thought I should order 33.4mm OD x 1.2mm thick and this is what I received: Wrong Circlip by KTM Marky, on Flickr It is not as straightforward as I had imagined..
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Post by lcmarky on Mar 3, 2021 16:38:55 GMT 1
I'm missing the basic principle of circlip nomenclature..
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Post by tony2stroke on Mar 3, 2021 16:57:09 GMT 1
You need to measure the bore of the item they fit in, and I mean the recessed area the clip goes into, that is the measurement that you want, then order that sized clip.
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Post by shaunthe2nd on Mar 3, 2021 17:07:23 GMT 1
Have you checked the dimension when its closed up as the circumference opening looks to be larger than your original so maybe it will close to the correct diameter?
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Post by lcmarky on Mar 3, 2021 17:11:41 GMT 1
You need to measure the bore of the item they fit in, and I mean the recessed area the clip goes into, that is the measurement that you want, then order that sized clip. Thx. Do you mean the internal diameter that the undercut is machined from or that plus 2x the undercut depth? Am I over thinking this?
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Post by midlifecrisisrd on Mar 3, 2021 17:12:37 GMT 1
I think Tony is correct
You need to order the size of where it fits
An internal circlip will be bigger than the size ordered
An external one will be smaller
Its the same with oil seals. You measure the shaft it's going on, not the lip size it's replacing
Steve
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Post by stusco on Mar 3, 2021 17:15:04 GMT 1
Circlips Internal Internal Circlips are a metal ring with open ends placed onto a machined groove to allow rotation but prevent a Lateral Movement. Circlips are generally used to secure a pinned connection. Internal Circlips are fitted inside a Cylindrical bore or a Housing and push outwards. To ensure you get the correct size for an Internal Circlip: Measure from the Outside on one side to the Inside on the other.
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Post by lcmarky on Mar 3, 2021 17:20:53 GMT 1
Have you checked the dimension when its closed up as the circumference opening looks to be larger than your original so maybe it will close to the correct diameter? It's not possible to clamp this closed then measure it.. Well it might be with a vice, but not that you could ever assemble it.
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Post by lcmarky on Mar 3, 2021 17:24:11 GMT 1
To ensure you get the correct size for an Internal Circlip: Measure from the Outside on one side to the Inside on the other. I read this before when I first got confused.. At what point(s) is this measured..
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Post by tony2stroke on Mar 3, 2021 17:32:53 GMT 1
You need to measure the bore of the item they fit in, and I mean the recessed area the clip goes into, that is the measurement that you want, then order that sized clip. Thx. Do you mean the internal diameter that the undercut is machined from or that plus 2x the undercut depth? Am I over thinking this? Whatever it fits in would have say 26mm bore (or hole / gap) then there would be a recessed area in that bore that the clip fits in (you need to squeeze the clip together to get it out) that recessed area is where you take the measurement, it will be bigger than the bore of the item, so measure the ring inside the bore of the part it fits in and use that size clip.
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Post by tony2stroke on Mar 3, 2021 17:38:41 GMT 1
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Post by lcmarky on Mar 3, 2021 17:39:55 GMT 1
So the OD of the undercut then.
That's not possible to access. Maybe if this is how it's done I measure the assembled circlip 'gap', then take it out and compress to the same gap and measure the OD of the circlip under the correct compression.
It aint obvious that's for sure.
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Post by tony2stroke on Mar 3, 2021 17:45:14 GMT 1
So the OD of the undercut then. That's not possible to access. Maybe if this is how it's done I measure the assembled circlip 'gap', then take it out and compress to the same gap and measure the OD of the circlip under the correct compression. It aint obvious that's for sure. OK, if you can't measure it because of access, you can measure the bore, see if you have something that will sit flush in the recess, measure that and double that for both sides, ie if the bore is 26mm and recess is 3mm then 6mm for both sides added to the 26mm would be 32mm total, hope that makes sense.
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Post by lcmarky on Mar 3, 2021 18:32:02 GMT 1
So the OD of the undercut then. That's not possible to access. Maybe if this is how it's done I measure the assembled circlip 'gap', then take it out and compress to the same gap and measure the OD of the circlip under the correct compression. It aint obvious that's for sure. OK, if you can't measure it because of access, you can measure the bore, see if you have something that will sit flush in the recess, measure that and double that for both sides, ie if the bore is 26mm and recess is 3mm then 6mm for both sides added to the 26mm would be 32mm total, hope that makes sense. Sounds logical, so in other words the diameter of the circlip groove.. That's what I thought before as the resting position of the circlip is not far from it's zero compression diameter and I couldn't get the correct circlip. It's a black art this circlip sizing...
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Post by tony2stroke on Mar 3, 2021 18:35:27 GMT 1
OK, if you can't measure it because of access, you can measure the bore, see if you have something that will sit flush in the recess, measure that and double that for both sides, ie if the bore is 26mm and recess is 3mm then 6mm for both sides added to the 26mm would be 32mm total, hope that makes sense. Sounds logical, so in other words the diameter of the circlip groove.. That's what I thought before as the resting position of the circlip is not far from it's zero compression diameter and I couldn't get the correct circlip. It's a black art this circlip sizing... BINGO!!!!!!!!!!!!!!!!!!!!!!!! the clip has to have some compression to keep it firmly fixed in place, otherwise it would spin and wear the part and clip.
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Post by lcmarky on Mar 3, 2021 18:59:38 GMT 1
Sounds logical, so in other words the diameter of the circlip groove.. That's what I thought before as the resting position of the circlip is not far from it's zero compression diameter and I couldn't get the correct circlip. It's a black art this circlip sizing... BINGO!!!!!!!!!!!!!!!!!!!!!!!! the clip has to have some compression to keep it firmly fixed in place, otherwise it would spin and wear the part and clip. of course. I'll try the ordering again as maybe I was unlucky, but can assure you that the in situ diameter of the circlip is pretty close to the open diameter and certainly the difference is nowhere near the increase in circlip diameter if you order a let's say 32mm diameter from the top vernier image.
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Post by tony2stroke on Mar 3, 2021 19:04:50 GMT 1
Don't take it as correct clip at the start, unless you owned it from new, and know its correct, someone may have been in there before, using whatever.
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Post by lcmarky on Mar 3, 2021 21:19:31 GMT 1
Don't take it as correct clip at the start, unless you owned it from new, and know its correct, someone may have been in there before, using whatever. very true indeed. I have x4 forks in rebuild and they're all the same on this occasion.
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Post by lcmarky on Mar 4, 2021 11:35:58 GMT 1
apparently "it’s the size of your shaft diameter" that is used to reference the circlip.
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