Thread: Powder Coat Prep

Finally, I've managed to unbolt everything from the frame, hammer out the steering bearings, and after hours of fighting with the swingarm, remove the bushings! This thing is ready for powder!

I've decided to have all the painted parts blasted and powder coated. Is there any guidance I should be giving to the powder coat shop? I'm concerned with some of the rust that lives down inside the frame. I want to be sure we get it all. Does powder coat prevent any existing surface rust from spreading, or will it keep going even through the powder coat? I've also been told I should go for "media" blasting as "sand" could cause warping.

How about plugging all my bolt holes? My current plan is to use high temp RTV (the orange stuff). Is this a good idea or should I leave in my old bolts?

Prep should be the same as for paint, all rust, grease and dirt must be gone. Any remaining rust can spread beneath the finish, with paint you can at least remove it with relative ease, should the need ever arise. Apply RTV and you'll have captive rust, even worse than leaving it alone There are rust-converting primers (such as Corroless), but they cannot be used with PC; they'll burn below the curing temp. Bodywork (filling dents, deep scratches and rust pits) is almost impossible with powdercoat and going over it will look awful. Decent bodywork, including careful block sanding and thorough prep are essential to getting good finished results. Application counts, too, doubly with candy paint. Keep in mind that how it looks when you get it back is as good as it's going to get...it's all downhill from there and you're going to have to live with it. One universal is that what looks go to you now, may not look as good in the not-so-distant future. Even journeyman painters aren't immune from this. I've yet to see a powdercoated CT70 frame that didn't have an orange peel texture.I have seen a number of larger pieces including bike tanks and CT70 frames that came out looking like they were painted with latex and a roller. Take a good, close look at the work coming out of the shop you plan on using and don't expect anything better than the worst piece you see there. Perhaps your chose shop turns out amazing work and new improvements happen all the time.

As for media blasting, most commercial blasters are geared to removing rust from salt bins, dumpsters and garbage trucks. That takes super heavy-duty balsting equipment that can cover large areas very quickly. 1/4" plate steel doesn't warp or weaken very quickly from metal erosion. A CT70 frame is thin sheetmetal, easily warped and even more easily thinned. The best media are soda, fine steel grit and glass bead, used with small (<30cfm) nozzle and no more than 90psi. Soda is pretty well goof proof, since it's the softest, but it's expensive becuase it cannot be recycled. Where 20lbs of glass or steel might get the job done, you'd need closer to 200lbs of soda.

Any good Powder coating shop will media blast the frame and parts prior to powder coating. Also they will plug the holes and mask off threads prior to coating. If you plug them with silicone, you will just contaminate the job.

Make sure your frame is straight and free from dents. Otherwise it will look bad. As far as rust, when i had mine media blasted, I was quite impressed as there was no paint, rust, or anything but bare metal.

I am curious, how did you get out the swingarm bushing and is it in good enough shape to replace or did you find replacements?

Thanks for the advice. I'm pretty much set on the powder coat. I've read the pros and cons in numerous threads. I've worked with both before, and I've settled on the powder mostly for durability and cost.

I am curious, how did you get out the swingarm bushing and is it in good enough shape to replace or did you find replacements?

Now that's the real question! I was curious too once. These things are awful. The bushings butt flush up against each other, so there is no way to access the back and press them out. I tried all sorts of stuff, but finally succeeded in drilling out the thick steel centers. Then drilled out the rubber with a larger bit. And finally, drilled out the outer casing.

THIS WAS NOT EASY! The outer casing is very thin and practically grafted to the swingbar tube. All said and done, the bushing are out, but I'm very very concerned about putting new bushings in. I'm worried I've opened up the ID too much , though it's hard to tell if I'm just being paranoid as I don't have the new one's here yet. I never want to do this again.....

I've had a few frams powdercoated. Here are my suggestions.

Blast it all thoroughly inside and out. If you have any major dents or rust repairs, do so using JB Weld. For those that don't know, there are metal particulates in it and powdercoat will stick to it no problem. I have a JB Weld little guy I made and it sticks to my magnets.

Powdercoat is thick, so if you have some minor imperfections it will fill them in. Any deep gouges or scraps should be done with the JB Weld.

Buy a bunch of 6mm bolts from mcmaster.com and put them in all the places. Get some nuts too and put them over the threads. People miss this stuff and then you struggle trying to get you stuff bolted back on. Best to just put a perishable nut in there instead.

Remove your bearing cups.

I had my swingarm done and left the rubbers in there. It didn't cause a problem, but no guarantees on yours.

Fatcaaat, great advice. Glad to hear from someone who's gone through coating before. I would never have thought about the JB Weld, but that seems like it would work great! Yeah, I really wish I had left my swingarm bushings in. Oh well. So you think I should use perishable bolts instead of the RTV? I was worried I might not be able to break them free after coating.

I'm curious how your frames turned out. What sort of media did you use to blast? Did the powder coat make it all up inside the hollow frame? I'm also still deciding on a color. I'm trying to match the Orange Topaz as best as possible.

Don't use rtv. Get some bolts and put them in . Yes...a good sandblaster will get everything including up in the inside. And they will get the powdercoating up in there too.

My bike came out really good with only one small imperfection on the frame and it was the coaters fault. I think the gun must have overloaded with the metal flake a little bit and it left an inch where it was a little heavy on the flake.

The only other thing is that the paint didn't come out liek the picture. I was expecting it to be much darker However, after I got it back and considered that it was a 1974 bike, the disco green was fine with me.

Here's your replacement swingarm bushings if any of you guys need them:

http://monkeybike.co.uk/acatalog/Hon..._Rear_Swingarm

Originally Posted by Pony Express

Here's your replacement swingarm bushings if any of you guys need them:

http://monkeybike.co.uk/acatalog/Hon..._Rear_Swingarm

dan your links not working but this one might.

Monkey Bike UK Honda 6V Dax Rear Swingarm Bushes