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Bewarethemoon

Bewarethemoon

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Good evening gentleman (depending on your time zone of course)

I'm sure one of the knowledgeable folks on here have the answers I'm after.

I'm undertaking a swingarm swap and space is a premium so I need to design some of the caps that keep the grease in and the dust out.

After a little research it seems that lip/rotary shaft seals are the best for this purpose but they tend to be a little wider than I was hoping for (4mm or so).

Are there any alternatives? Am I overthinking it and will a simple o-ring work? Or do I need to stick with what's proven to work (lip/rotary shaft seals)

Daniel.
 
I'll vote for a simple Viton O-ring, just get the sliding surface good n smooth.
Guess if you can find a square o-ring in the right size that'd work and easy to machine a square internal groove.
 
gggGary said:
I'll vote for a simple Viton O-ring, just get the sliding surface good n smooth.
Guess if you can find a square o-ring in the right size that'd work and easy to machine a square internal groove.
Click to expand...

I felt like I might of been over engineering things a little bit in my mind especially considering manufacturers design these things with long service intervals. I’ll only be riding in the dry (hopefully) and happy to keep on an eye on these areas that have potential for problems if not checked.

Square o-ring sounds like a go to me! Any ideas of how deep in a groove to sit one to get a sufficient seal?

Daniel.
 
I saw a pic of your swingarm - very nice! Is there a reason why the stock caps won't work?
 
jpdevol said:
I saw a pic of your swingarm - very nice! Is there a reason why the stock caps won't work?
Click to expand...

The swingarm is quite wide, considerably wider than the stock XS650 item. The caps (from memory) are 12mm wide each and there’s just not the room for them.

Daniel.
 
Of course I can't find one when needed, IIRC the overall width may be ~10-12mm but most of that spans the OD of the pivot tube and what remains between swingarm bushing and frame is a thickness ~1mm
coverthrust_medium4472212800-01_2422.jpg
 
jpdevol said:
Of course I can't find one when needed, IIRC the overall width may be ~10-12mm but most of that spans the OD of the pivot tube and what remains between swingarm bushing and frame is a thickness ~1mm
View attachment 233554
Click to expand...

I may only have 5mm from where the welding ends and even that’s being generous.

Daniel.
 
I’ve scoured the internet for the answer and a lot of the information I’ve come across is a little beyond me if I’m honest.

So I’m going to use a square profiled o ring in my swingarm caps with a cross section of 3.0mm and an inner diameter of 39mm.

Can anybody enlighten me as to the depth of the groove required in the caps so sufficient pressure is exerted on the seal to provide an adequate seal.

I keep stumbling across figures of no more than a 3% decrease from the width of the cross section of seal, therefore I would be looking at machined groove depth within the bore of 2.91mm.

Can anyone offer any insight into this before I scramble my brains further?

Daniel.
 
You may be over-thinking the need for a perfect seal @ that location; the OEM set-up is little more than a rubberized tin cup that mostly seals, but will certainly pass grease if overdone in the slightest:shrug:
 

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