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Front wheel bearing spacer


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I got a nice set of spare wheels for the Café Sport - Thanks @KINDOY2 :notworthy:- Originally from a Scura which has a different front axle configuration even though they both have Ohlins forks. The Scura front wheel has the two size bearings - 20/25mm ID - with the sleeved and shouldered spacer, the CS has two 25mm bearings with the spacer sandwiched between the two inner races.

I pulled the bearings out and was looking for the latter spacer (GU01615290) and found it is still available from most usual suppliers but at a premium, ~$130+.  Ouch!

So, what are my options; 1_ Trying to find a used one is the simplest and most obvious solution but my Google-fu didn’t yield any result so far. 2_ Have one fabricated which give me the choice of material (more options here, suggestions welcomed) and probably gonna end up with a similar price tag as a new one. 3_ Cough-up the mulla and be done with it...

Anyone here with a spare spacer gathering dust on a shelf?

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Just to clarify, you are looking to mount the Scura wheel to the Café Sport?

Will the forks accept the different axle? Seems that "shouldered" axle only uses a small spacer on the left between the bearing and the inside of the fork leg?

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8 hours ago, Speedfrog said:

Anyone familiar with these spacers or fabrication in general have suggestions as to having one made?

In a previous life as a poor kid racing flat track bikes, I've made more than a few axle spacers. At it's simplest, a piece of steel water pipe, a hacksaw, sandpaper and a caliper will get it done. For a more ... precision ... application such as this, a proper lathe would be nice. The rings around the spacer are for no other purpose than to facilitate assembly- it takes a bit of wiggling and fishing from the opposite end to get the spacer in front of the axle without them. So, pretty much anyone with even a small benchtop lathe can make the spacer and rings. Your only real concern is for the proper length and proper diameter so the bearing race is supported around the entire surface. If I was at our shop, I'd say send along your sample and I'd pop it out, but I can't say how long it would take them to get at it if I had you send it there. 

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1 hour ago, docc said:

Just to clarify, you are looking to mount the Scura wheel to the Café Sport?

Yes Docc, The wheels are the same aside from color. It just takes different bearings and inner spacers to accommodate for the different axles. Essentially adapting the wheel to your fork/axle configuration. There’s no concern about the spacers between the bearings and the fork legs as you can just reuse them.

 

@Pressureangle yes, a pretty simple thing once you’ve got the proper tubing stock to cut to length. I need a tube that’s 104 mm long with a 25 mm id. It has to be smooth inside, but how close in diameter to the axle OD? The oem is steel but could it be made of aluminum? It would be lighter but would it be strong enough? 

 

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1 hour ago, Speedfrog said:

@Pressureangle yes, a pretty simple thing once you’ve got the proper tubing stock to cut to length. I need a tube that’s 104 mm long with a 25 mm id. It has to be smooth inside, but how close in diameter to the axle OD? The oem is steel but could it be made of aluminum? It would be lighter but would it be strong enough? 

 

I wouldn't make it of aluminum for a street bike, though I'm sure certain grades of aluminum are more than sufficient. Steel won't compress or fret away, and the weight difference is meaningless.
I.D. doesn't have to be a slip fit, 1" = 25.4mm so an inch is pretty close to perfect.
Give me an ID from the wheel hub for the rings, or measure the sample and I'll ask about getting one. Even then, you should fit the new one very carefully with the idea that the spacer is precisely the same length as the distance between the outer bearing races, to hold the bearings centered with no preload. With that in mind, it is always better to have the spacer a bit long (a very little bit) than to have it at all too short. That way, the bearings can relieve any side pressure by moving a few thousandths out in the wheel, which you'll never know about elsewise.

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That’s what I needed to hear, thank you @Pressureangle and I appreciate your offer to have one made for me.:notworthy:

I found some 1” id wheel spacers in different length, actually an HD part that’s readily available and cheap. I have a good friend machinist that I can tap to have it cut to the right length. 

I read on this forum that not all wheels have the exact same dimension between the shoulders were the bearings outer races sit, hence the pursuit of a custom made spacer.

https://www.v11lemans.com/forums/index.php?/topic/1201-hollow-front-axle/

On page 8 of this excellent FAQ thread @Paul Minnaert writes: “The spacer in the wheel, has to be measured on the wheel, the length is different on each wheel.” “And because all wheels are different, you need to measure the length first. Guzzi makes the spacers all equal and there we see people’s wheel bearings break.”

 I measure 104.5mm pretty consistently on my wheel and I already knew it’s better to err towards a bit longer, but how much longer?

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58 minutes ago, Speedfrog said:

That’s what I needed to hear, thank you @Pressureangle and I appreciate your offer to have one made for me.:notworthy:

I found some 1” id wheel spacers in different length, actually an HD part that’s readily available and cheap. I have a good friend machinist that I can tap to have it cut to the right length. 

I read on this forum that not all wheels have the exact same dimension between the shoulders were the bearings outer races sit, hence the pursuit of a custom made spacer.

https://www.v11lemans.com/forums/index.php?/topic/1201-hollow-front-axle/

On page 8 of this excellent FAQ thread @Paul Minnaert writes: “The spacer in the wheel, has to be measured on the wheel, the length is different on each wheel.” “And because all wheels are different, you need to measure the length first. Guzzi makes the spacers all equal and there we see people’s wheel bearings break.”

 I measure 104.5mm pretty consistently on my wheel and I already knew it’s better to err towards a bit longer, but how much longer?

I never thought of the H-D spacer, probably a good start. Also, because the H-D uses tapered rollers instead of ball bearings, they make a great selection of spacer shims to get the precise bearing clearance they want. Not a bad option for us, perhaps to be explored. If you have a short spacer, which is the real problem situation, just add the correct H-D part number to it. 
Ball bearings in our bikes do not tolerate a great deal of axial load- there are ball bearings made with that more in mind; so the perfect situation is that the outer bearing races are perfectly parallel, and the inner races are held at the distance which holds the balls dead neutral in the outer races with no preload in either direction. Neither of these conditions are likely present in something as mundane as a motorcycle wheel, but they don't die early so the dimensions are adequate for reasonable life. 
So to make a new spacer, I'd drive the bearings home in the wheel and measure the distance between the inner races, then make a spacer that's exactly the same length to no more than +.010". On my Sport, with the bearings driven home hard in the wheel, the spacer is tight enough between them that you can't move it by finger but you can move it with a screwdriver. It's as close as you can be certain about unless you get crazy about measuring the wheel bores. Again, 'sufficient' is good enough for wheels, with only the worst offenders reducing bearing life. The problem with a short spacer is that the bearings take the entire load from the axle nut, rather than the bearing race; if the spacer is a tiny long, the outer races can relax against the wheel bores a couple thousandths which limits the force they can be subjected to. 
Don't overthink it with me unless you have a bunch of measuring equipment and like self-flagellation. If you drive the bearings against the spacer and it's tight between them, it's ok. I always give the inner race a light whack to be sure the opposing bearing has moved the outer race if it has to before installation. 
I noticed just today that my '89 Mille spoke wheel has snap rings on the bearings, at least on one side; that may change the metric a tiny bit. I'll stop now, I'm falling down the well again.

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Thanks P.A., I think I'm gonna pursue the H-D spacer route, order one longer than I need and have it cut as precisely as possible to length. I'm hesitant to reinstall the bearings just to mesure the wheel hub and then pull one out again to fit the spacer. 0.010" = 0.25mm, that's the range I was thinking about. I think I can get a pretty good measurement with a depth micrometer and as you imply we are not trying to send a rocket to the moon here.

I didn't use to care one bit about those details when I was a young lad, as long as it rolled, I'd ride it. OCD only developed proportionally with age and enough accumulation of tools and knowledge that I can't always find either or. Do I detect common traits about folks a certain age with accumulated wisdom working on their bikes...

That well is bottomless...

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