Author Topic: Powder coating swing arm - bushings, clearances and threads  (Read 3284 times)

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Offline mycb750k6

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What are the swing arm bushings made of and will thy survive powder coating the swing arm? Mine is a 71 CB750 with the flanged bushings. I looked this up and really wasn't clear form the postings if I could just leave them in there. Same goes for the shock bushings. Also this is my first powder coating so are there clearance problems once the coating is done? I had my chain adjuster stoppers chromed and don't want problems with the fit. Also how about threads? Should they be plugged?

As always, thanks in advance!

Offline HondaMan

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Re: Powder coating swing arm - bushings, clearances and threads
« Reply #1 on: July 17, 2009, 08:32:51 PM »
The 71 CB750 did not come with flanged bushings. They do have an end cap that resembles a flanged bushing: it is about 5mm long and comes off of the ends of the tubes. Inside that is a pair of felt washers: handle them gently when taking them out and they can be reused. Inside those is where the bushings reside.

DON'T get powdercoat on the ends of the swingarm tube, its end caps, or the collar that goes through it. It will mess up the clearances on reinstallation, causing the arm to lock solidly in place.

The collar inside the arm's pivot tube is about .010" longer than the
[pivot tube+grease washers+end caps] all stacked to gether: the big bolt clamps this collar to the frame and the rest of the assembly pivots around it.
« Last Edit: September 12, 2009, 07:20:39 AM by HondaMan »
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Offline mystic_1

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Re: Powder coating swing arm - bushings, clearances and threads
« Reply #2 on: July 17, 2009, 09:36:20 PM »
Remove the bushings, felt rings, and bushings, then use a pair of washers just larger than the pivot section of the swingarm, plus a length of threaded rod and some nuts, to cap things off.  That way the ends of the swingarm's tube are covered nicely and it will survive the heat of the curing oven.

For the lower shock bushings, regular plugs should be just fine as you only need to protect the inside surface.  Press out the old bushings plug em up.

Chrome is much thinner than powder coating and so is much less of a factor.  I like to mask off the area of the swingarm ends that the axle rides against otherwise the axle will muck up the finish, but I'm not sure how you'd do that with powder.


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Offline mycb750k6

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Re: Powder coating swing arm - bushings, clearances and threads
« Reply #3 on: July 18, 2009, 04:50:58 AM »
Thanks Hondaman and mystic. I'm going to find another part for my first powder coat project. I have a friend who is good with a rattle can and will go that route until I'm better at this. Sure glad I asked.

Offline mcuozzo

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Re: Powder coating swing arm - bushings, clearances and threads
« Reply #4 on: July 18, 2009, 11:29:53 AM »
The bushings could probably withstand the heat, but that's not the real problem.  Before you powdercoat anything you have to make sure it its free of ALL contaminants - grease, dirt or anything else.  

So its best to remove everything from the swingarm, degrease it, blast it (mask the areas not to be blasted with painters tape and avoid that area as much as possible), remove the tape, blow it off with air, wash it down with either acetone or denatured alcohol.  Then preheat the part to a few degrees higher than you powder says to cure at.  Use an IR temp gun to make sure the part (not just the oven) reaches temp.

If nothing ugly rises to the surface of the part during the preheat, let it cool, wash it with acetone again.  Use tape to mask off the parts mentioned above not to be powdercoated.   I use blue painters tape but there are specific high temp tapes made for powdercoating.  I use the blue tape because it sticks better and is cheaper.  However it won't stand up to the temps for very long.  Not that it matters anyway because as soon as you see the powdercoat gloss over you have to stick your hands in the oven and remove the tape.  Any tape left on during the full process is tough to remove after a full cure.

Also it's money well spent to get some silicone plugs and caps to cover up threaded holes and other parts you don't want coated.  They work really well and don't have to be removed until after the curing process.

Hope that makes sense and helps.

Check out this forum if you haven't already:

http://forum.caswellplating.com/powder-coating-questions/

And here's my gallery.  I have a lot more pc'ed parts I need to add.

http://gallery.sohc4.net/main.php?g2_itemId=306724

Let me know if you have any pc questions.

Matt
« Last Edit: July 18, 2009, 11:35:28 AM by mcuozzo »

Offline mycb750k6

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Re: Powder coating swing arm - bushings, clearances and threads
« Reply #5 on: July 19, 2009, 05:51:44 AM »
thanks mcuozzo,
You've opened up a whole new world to me  :o

Offline mcuozzo

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Re: Powder coating swing arm - bushings, clearances and threads
« Reply #6 on: July 19, 2009, 07:44:28 AM »
no problem, you'll be cursing me later when you're broke from buying different color powders and all the accessories that go with it...

Right now I'm sourcing the parts to build a big enough oven to powdercoat motorcycle frames...

Offline HondaMan

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Re: Powder coating swing arm - bushings, clearances and threads
« Reply #7 on: July 19, 2009, 08:49:14 AM »
no problem, you'll be cursing me later when you're broke from buying different color powders and all the accessories that go with it...

Right now I'm sourcing the parts to build a big enough oven to powdercoat motorcycle frames...

Then next, you'll have to tell me how much it might cost to ship a K3 frame to you from Colorado...  ;D

HS#2 Cafe' begins this week...  ;)
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com