SWINGARM BUSHING SPECIFICATIONS
- Thread starter aceaceca
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Josh Cox said:I notice you have grey hair and live in the US, please do not give me a hard time, I am a product of the metric school system.....
Seriously all you had to do is press one button to unmetric it. :roll:
:mrgreen:
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It should be said that the typical issue with "swing arm bushings" is not the bushings but the pin.
Generally, the bushing picks up grit that cuts the pin such that the bushing is not appreciably worn while the pin is. Moreover, if you press new bushings into your old swing arm then you really should ream them after installation.
So, IMO, the fix is to buy an over size pin (or "spindle") and use an adjustable ream to bring the old bushings out to the size of the new oversize pin. As a bonus, that reaming removes the aforesaid grit that cut the old pin.
Generally, the bushing picks up grit that cuts the pin such that the bushing is not appreciably worn while the pin is. Moreover, if you press new bushings into your old swing arm then you really should ream them after installation.
So, IMO, the fix is to buy an over size pin (or "spindle") and use an adjustable ream to bring the old bushings out to the size of the new oversize pin. As a bonus, that reaming removes the aforesaid grit that cut the old pin.
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aceaceca said:
I agree. Josh's response is another reason that this forum is one of the best anywhere.
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Assuming that they are sintered bushes, they should never be reamed.They are after all just compressed flakes of bronze. Reaming them pushes the hills into the vallies, smoothes the surface, removes the porosity and subsequently their ability to absorb and release lubricant. (Always oil, never grease)
The correct way to install them is with a stepped mandrel type press tool, so that the ID and OD remain the same.
I dont want to apper like a know it all, But I had my arse kicked badly as an apprentice for reaming a sintered bush. The shit you remember ...
The correct way to install them is with a stepped mandrel type press tool, so that the ID and OD remain the same.
I dont want to apper like a know it all, But I had my arse kicked badly as an apprentice for reaming a sintered bush. The shit you remember ...
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Good point about reaming and installing. I thought I would find the bushes to be common as most ball bearings are but after a short "google" no measurements seemed to match. Revise my initial query.
Anybody able to source these from a bearing or bushing supplier?
Anybody able to source these from a bearing or bushing supplier?
Norvill have them, certain someone in the US would have them.
http://www.norvilmotorcycle.co.uk/
Swooshdave, you have a new avatar, taking jingoism to a new level.......britsh or american ?????. Clan member by chance ? .
http://www.norvilmotorcycle.co.uk/
Swooshdave, you have a new avatar, taking jingoism to a new level.......britsh or american ?????. Clan member by chance ?
.
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Combat Col said:
Interesting. It was my understanding that sintered bronze was actually porous, not just high spots and low spots. In my experience, reams cut, they do not compress. I have assumed that they cut into the porous material, leaving holes open to receive the oil. I suppose a dull ream might smear high spots into low spots.
Pressing a thin wall bushing into an interference fit with a stepped mandrel necessarily results in a smaller bushing ID.
In taking a Commando swing arm's bushings out to the size of an oversize replacement pin, with a ream that cuts, In the first pass (of a used bush), I first see dark black contamination being cut out, then with successive passes, I see clean, virgin bronze, being being cut and removed. That fresh cut surface, I assume, is porous and will absorb and hold oil.
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When not fitting new bushings, should the old ones be oil treated somehow?
As it placed in a small pot of very hot oil?
If so, what weight oil, and how long on simmer?
As it placed in a small pot of very hot oil?
If so, what weight oil, and how long on simmer?
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highdesert said:
It wouldn't do any harm to give them a "top-up" I expect?
highdesert said:
That shouldn't be necessary. Just soak overnight? I onced placed a drop of light oil on a dry S/A bush and then watched in amazement as the bush completely absorbed the oil in around two to three minutes with no visible trace left on the surface of the bush!
highdesert said:
Same as the recommended lubricant EP140.
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The idea of the mandrel is to maintain the ID size. Press it in, pull out the mandrel. Done. Bush ID size will be that of the mandrel OD.
The characteristics of sintered bronze are nothing like solid bronze.
SteveBorland
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Seeing as how I am in the process of changing my bushings, I was wondering if it would be possible to use the swingarm spindle as a mandrel. If this method is correct, that would only leave a thou or so to remove instead of the rather larger amount I currently have. May save me having to find a piloted reamer.
I.e. I remove the bushes and press them in again with the spindle in place. Sound like a neat idea, but where is the catch? I'm certain someone who knows more than I do has tried this.....
/Steve in Copenhagen
I.e. I remove the bushes and press them in again with the spindle in place. Sound like a neat idea, but where is the catch? I'm certain someone who knows more than I do has tried this.....
/Steve in Copenhagen
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Risk is getting part way installed before crush factor and microscopic bore misalignment binds up the works for even more heat and fierce force needed to back out to try again with more initial clearance. The swing arm is not strong enough to withstand much pressure against both bush ends outward or tends to get sprung out of alignment which is a total non issue for life time of no lube road going but next fella will curse you after they force worn spindle out and hunt down your relatives and pets after attempting to put back in. A couple mo's ago I got stopped short at 1/4" insertion of the new oil holding groove graphite lubed bushes in Peel RGM ally swing arm - even though bores and bushes measures very close to stock I had bushes OD relieved .015" to try again soon but suspect will have to hand sand another ~.005" off to avoid shearing alloy bores and stuck up again. Thank goodness these bushes don't have to be in very tight to do their job a long time, as long as spindle surface retains enough rust preventing protection, which is *only* thing the various "lubes" do in this area.
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IF you press two new bushes into a welded fabrication called a swing arm, and can then install the pin without a sledge hammer, then good for you, you lucky bastxrd. Two independently installed bushes are not likely to be on the same axix. Most of the time you need to ream them on a long piloted reamer or some other machining process.
Maybe I'm to fussy?
Wheres that hammer :mrgreen:
Got to admit when I did mine, that I did not examine the welded swing arm to see of they did a proper machining to align the bores. It was slick like a wrist pin after I got done. slight hand press fit.
Maybe I'm to fussy?
Wheres that hammer :mrgreen:
Got to admit when I did mine, that I did not examine the welded swing arm to see of they did a proper machining to align the bores. It was slick like a wrist pin after I got done. slight hand press fit.
I don't remember if it was in the machinery handbook or my lathe manual but the notation regarding reaming sintered bronze bushes was to use only the sharpest cutter available as a dull tool will gloss over the pores. Reaming is possible however and more often necessary on these.
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Can use what ever at hand to ream in this case as this is not a high speed or even full rotation application that needs any oil trapped in pores, just dry bronze against very hardened polished spindle is plenty slick and wear resistant enough, its only rust flaking off spindle one must worry about and only reason for 'lube' here. In tranny ream method and type of lube does matter.
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