powder coating question

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powder coating question

#1

Post by custom shadow »

had my gl1200 brake calipers powder coated and the guy got blast in piston chambers is this a bad thing or will they be ok? any help please
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Re: powder coating question

#2

Post by robin1731 »

Don't know. If it is thick enough it could cause interference problems with the piston. I also don't know if long term exposure to brake fluid would harm the powder. You could use silicone brake fluid to maybe eliminate that.
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Re: powder coating question

#3

Post by Placerville »

So, your saying that when the parts were blasted, some of the media got into the piston chambers and did.....what? Is it badly damaged or is there just a small blemish to the wall? Either way, I don't think you're going to know how bad it is until you've reassembled them and at least done a stationary test to see if the piston moves and the pads back off the rotor. The damage is done, the question is, how bad is it?
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Re: powder coating question

#4

Post by robin1731 »

Placerville wrote:So, your saying that when the parts were blasted, some of the media got into the piston chambers and did.....what? Is it badly damaged or is there just a small blemish to the wall? Either way, I don't think you're going to know how bad it is until you've reassembled them and at least done a stationary test to see if the piston moves and the pads back off the rotor. The damage is done, the question is, how bad is it?

OOPS! I was thinking they got some powdercoat in the piston area. DOH!!!!!!!!

Let me say this. I have used my bead blaster to clean the brake caliper piston area's. But, most/many powder coaters use sand to blast the parts. Which is harsher on the surface. I don't think you'll have any trouble though. As long as like Placerville said they didn't get carried away.
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Re: powder coating question

#5

Post by custom shadow »

thanks guys. i should have explained a little better he did get blast in the chambers and instead of the smooth and polished bore it is like 1000 grit wet/dry sandpaper
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Re: powder coating question

#6

Post by robin1731 »

custom shadow wrote:thanks guys. i should have explained a little better he did get blast in the chambers and instead of the smooth and polished bore it is like 1000 grit wet/dry sandpaper

Yeah, I think it will be fine. Like I said I sometimes do mine with the bead blaster.
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Re: powder coating question

#7

Post by fish »

put the pistons in there dry and with out the seals...
See if they slide smoothly in the bores
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Re: powder coating question

#8

Post by sunnbobb »

run a fine emery cloth around the inside and you should be fine.
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Re: powder coating question

#9

Post by tomk1960 »

I always tape over the bores of master cylinders and calipers, and I put bolts in the bleeder and banjo bolt holes before I blast them with aluminum oxide. It's too bad that he was careless and blasted the bore, but I think you'll be ok. With no seal in a clean caliper, the piston will "drop" right into the bore with no real friction. The fit isn't very tight and the rubber seal is what's doing all the work during piston travel. If you wanted, you could put a 3-stone brake cylinder hone in your drill press and just clean up the bore - it would only take a few minutes. Use a little brake fluid for cutting as you run the hone up and down.

In any event, blow out the holes with compressed air, rinse them out with hot water, and then blow them out again to make sure you got all the grit out. Then you'll be good to go.

Were the threaded holes blocked off, or is there a powder coating on the threads?
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Re: powder coating question

#10

Post by custom shadow »

tomk1960 wrote:I always tape over the bores of master cylinders and calipers, and I put bolts in the bleeder and banjo bolt holes before I blast them with aluminum oxide. It's too bad that he was careless and blasted the bore, but I think you'll be ok. With no seal in a clean caliper, the piston will "drop" right into the bore with no real friction. The fit isn't very tight and the rubber seal is what's doing all the work during piston travel. If you wanted, you could put a 3-stone brake cylinder hone in your drill press and just clean up the bore - it would only take a few minutes. Use a little brake fluid for cutting as you run the hone up and down.

In any event, blow out the holes with compressed air, rinse them out with hot water, and then blow them out again to make sure you got all the grit out. Then you'll be good to go.

Were the threaded holes blocked off, or is there a powder coating on the threads?
I used a little wire wheel on a dremel to clean out the grooves where the seals go and then i used 600 wet
dry paper on the bores but even without seals i dont think they will "DROP" in
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Re: powder coating question

#11

Post by tomk1960 »

Well maybe "drop" was too strong a word. The pistons should slide in quite easily - let's put it that way.

Is that powder coating I see on the threads of the banjo fitting holes?
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Re: powder coating question

#12

Post by custom shadow »

tomk1960 wrote:Well maybe "drop" was too strong a word. The pistons should slide in quite easily - let's put it that way.

Is that powder coating I see the threads of the banjo fitting holes?
yeah i tapped the bleader holes i have to do the banjo fitting holes
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Re: powder coating question

#13

Post by rcmatt007 »

I have smoothed up the inside of mine with some 1000 grit. but time will tell....

they sure look nice
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