Headstock bearing cups - Powdercoated?

[loply]

Hi folks,
I've just got my frame back from powdercoating, and I stupidly forgot to come up with a solution to the coned bearing "cup" things that the headstock bearings ride in.

Luckily the powdercoater evidently wiped the powder off them before baking it, but they're still a bit contaminated. I've attatched a digital picture to try and illustrate.

Can I just polish these up to smooth again with a dremel and soft bit, or is a replacement needed?

If the latter, how do you remove them, and what do you bond new ones in with?
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[stinkwheel]

It's the outer race for a tapered roller bearing. It's made of REALLY hard steel so you could safely scrape any bits off with an old screwdriver or a small wire-brush attachment on your dremmel.

They are included when you buy a new set of tapered rollers for the headstock. They aren't bonded in, just pushed into place and they are an extremely tight fit. Total bastard to remove. If the surface isn't damaged or pitted, I'd leave them where they are. There is every chance you'd need to use heat in the process of removing them which would knacker your powdercoating.

Hindsight dictates you should have removed them and masked off the hole before taking the frame in then fitted new ones when you got it back.

On most bikes, there is a small lip that you can just get a drift onto and you hammer them out from the inside (and hammer and hammer and hammer and go away and hammer again and throw the hammer across the workshop).

It's still classes the most awkward job that seems easy when you look at it you can do on a bike (worse than refitting airbox rubbers and removing tubeless tyres). Some bikes don't have a lip and need a special slide hammer tool.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[kestrel]

As Stinkwheel says, leave them in. Scrape as much of the powdercoat as you can off them and if necessary finish off by gently wiping with 1200 grit emery soaked in light oil. Surprised that your powder coater didn't mask the neck tube, they usually do.

[Cillit-BANG]

Note that if you ever come to needing to get that race out, it will be an absolute a-hole. The powdercoat will have created an incredibly strong bond where it will have run over. Make sure you scrape all this out with a woodworking chisel before even attempting to bash them out or your do yourself a mischief.

I'm suprised the powder-coater didn't advise that you removed the cups beforehand.

[loply]

Thanks for the advice folks, relieved to hear I can just polish them back up. I think I'll use some fine sandpaper followed by polishing bits on my dremel.

Incidentally someone IRL gave me a tip that drilling two holes at opposite faces of the race might help to remove them, in so much as the race would either crack or thereafter become deformable and so easily removed. Ofcourse you'd need a sharp drill and would be drilling into whatever is behind the race too.
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[stinkwheel]

Good luck finding a drill that'll mark a case-hardened bearing race is all I can say to that.

Best tip I got is to run a ring of weld round the inside surface of the race. The metal contracts slightly as the weld cools and they may even drop-out by themselves. If not, the heat hardens the metal even further and a sharp smack with a hammer will make them either drop out or shatter.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[loply]

That sounds like a good idea, but I'm immediately thinking that I would end up welding the race into the frame!

Actually come to think of it the frame is aluminium, I guess that's unlikely.

Anyway, thanks for the help again!
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[loply]

I know we're getting into a downwards spiral of suggesting (incidentally unneccessary) methods here, but I wonder if you could weld a big nail (or some other object) onto the race, then pluck it out with a clawhammer.
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[stinkwheel]

[kestrel]

A method I've used in the past is to take a piece of flat bar just long enough to span the diameter of the bearing cup with a 10mm hole drilled in the centre. Weld the flat bar across the bearing cup and use a slide hammer attached using the 10mm hole as the anchor point.

Before fitting new bearings, file two small notches 180 degrees apart in the inside corner of the shoulder that supports the bearing, this will allow you to drift them out during subsequent bearing changes.

[Cillit-BANG]

Why not weld somthing accross, then belt it up from the other end of the head stock?

[MarJay]