Is it a problem to have the break drums sand blasted and painted?
I certainly hope not! I've done it for years without any problems. Just be sure to keep the braking surface clean and free of paint. Otherwise blast away.
Rick
PS: You can blast the braking surface. It won't hurt it. In fact, if the drum has a glazed surface it will help to create a better braking surface. You can achieve it this way instead of by sanding it with paper.
Can't be too aggressive on the lining surface, it can cause some pitting. This would require resurfacing the drums.
Plus, don't paint drums as this spoils the heat dissipation process.
Bruce. >:D
Quote from: The Tassie Devil(le) on January 16, 2020, 07:25:53 PM
Plus, don't paint drums as this spoils the heat dissipation process.
Bruce. >:D
Bruce, I was unaware that painting them hindered the heat dissipation. How does it do that? I've always painted mine. It tends to get cooked off over time though.
Curious about this, Rick
Rick,
The paint tries to reflect the heat back into the drum from whence it is coming.
The only reason engines are painted ids to make them look good, but engines have water to cool them, unless it is air cooled, then no paint.
Bruce. >:D
Quote from: The Tassie Devil(le) on January 16, 2020, 07:53:41 PM
Rick,
The paint tries to reflect the heat back into the drum from whence it is coming.
The only reason engines are painted ids to make them look good, but engines have water to cool them, unless it is air cooled, then no paint.
Bruce. >:D
That makes sense. I've noticed that the paint won't last that long anyway, but it's nice to keep them from rusting before you ever get to use them. That's the main reason why I paint them.
Once you take the vehicle out and perform the shoe burn in/break in procedure, the paint begins it's disappearing act anyway.
But that's just me. Thanks for the correction.
Rick
So just sand blasting is kind of a waste because they will rust pretty quick.
They are hidden anyway. ( Not going for a show car. )
I wouldn't think painting would cause too much heat. The only time you use breaks is to stop. Red light, stop sign your garage. All at a slow rate of speed.
But you made me realize no one will see them anyway.
The same goes for the rims, hidden by hub caps. But i am going to blast and paint them.
Thank you all. Saved me some money ! lol
Quote from: spolij on January 16, 2020, 08:47:17 PM
So just sand blasting is kind of a waste because they will rust pretty quick.
Well that's why I paint 'em. If I didn't blast 'em, then they wouldn't have to be painted.
I guess it boils down to personal preference. I wanted it to look like it was new, even though I know better.
I blasted all my drums and the wheels.
The wheels needed it more so than the drums.
And yes, it is all hidden, but maybe it's just me, but it bugs me to leave the stuff all rusty.
I never really thought about the paint keeping the parts from cooling. But how much can it block?
Something to look into now.
Rick
Quote from: spolij on January 16, 2020, 08:47:17 PM
So just sand blasting is kind of a waste because they will rust pretty quick.
Only need cleaning if they are really crappy, as in the steel part in the centre is rusting.
Quote
I wouldn't think painting would cause too much heat. The only time you use breaks is to stop. Red light, stop sign your garage. All at a slow rate of speed.
If only that was true. So you never brake hard, or have experienced brake-fade?
QuoteThe same goes for the rims, hidden by hub caps. But i am going to blast and paint them.
Rims are different. need painting as these things will rust if not treated.
Bruce. >:D
Quote from: Cadman-iac on January 16, 2020, 08:59:48 PM
...... I never really thought about the paint keeping the parts from cooling. But how much can it block?
.... Rick
Depends on what sort of paint is used, and how thick, till it burns off, then it stinks for a while, and makes a mess.
If they were supposed to be painted, then the factory would have painted them, or the replacements would be painted when one buys them from the shop.
All the makers put on them for the replacements is a protectorant finish, which had to be removed before fitting.
Bruce. >:D
Quote from: The Tassie Devil(le) on January 16, 2020, 09:05:12 PM
Only need cleaning if they are really crappy, as in the steel part in the centre is rusting.If only that was true. So you never brake hard, or have experienced brake-fade?
Bruce. >:D
Hey Bruce,
Yes, I have had that happen before. But it was on my old 66 truck when it still had the original drum brakes. I hadn't done that to it back then as I didn't have any way to blast them, and what was the point of painting them if they were rusty?
That's when it got converted to discs.
As for the Cadillac, the parts were very rusty. Thus the blast and paint.
Rick
Quote from: The Tassie Devil(le) on January 16, 2020, 09:08:46 PM
Depends on what sort of paint is used, and how thick, till it burns off, then it stinks for a while, and makes a mess.
If they were supposed to be painted, then the factory would have painted them, or the replacements would be painted when one buys them from the shop.
All the makers put on them for the replacements is a protectorant finish, which had to be removed before fitting.
Bruce. >:D
Good points all. But not to be argumentative, I was watching the Barrett-jackson auction today and they had several cars that had had the drums painted as you could see it thru the wheels.
Not that it is right or correct, but it was done for who knows what reasons.
I guess what it boils down to is what do you want. If you want a 100 point vehicle, don't. If it doesn't matter to you, go ahead.
If you're concerned it will effect the operation, don't.
I do it to preserve the parts since I don't have any way to coat the drums with cosmolene or another preservative. Oil would work, but oil will collect dirt quickly.
Paint is cheap, stops rust, and doesn't collect dust, so to me, it's the best option.
Please don't think I'm arguing with you about this. All I'm saying is that it's up to you if want them painted, and I probably should have said as much initially.
I hope that clarifies things.
Rick
Bruce
"If only that was true. So you never brake hard, or have experienced brake-fade?"
I understand. But if your doing 55mph and have to hit the breaks hard it only lasts a minute. You think that's enough heat to hurt the painted drums?
If they were supposed to be painted, then the factory would have painted them, or the replacements would be painted when one buys them from the shop.
Good point.
Rick my rims and drums are SUPER rusty. I never really thought about the paint keeping the parts from cooling. But how much can it block? That's how i feel. I guess what it boils down to is what do you want. If you want a 100 point vehicle, don't. If it doesn't matter to you, go ahead.
If you're concerned it will effect the operation, don't. Very informative LOL
OK It's cheap enough I'm back to blasting and painting the rims and drums.
1: Just because the factory never painted the brake drums doesn't mean it was for brake performance reasons. The factory did a lot of
stupid stuff to save $$ in production.
2: I've gotten brake fade in all my cars with drum brakes-- even the ones with unpainted drums.
3: Heat retention may be a fact but how much? Guys have happily done mods to their engines and have boasted of a 8HP increase--- that
was completely unnoticeable while in the driver's seat.
I guess you could apply the same theory to the exhaust manifolds. Never painted from the factory. But there are plenty of guys running exhaust manifolds that have been ceramic coated and high temp painted without engine overheating issues.
just my .02
I'll spare the dissertation on heat transfer.
Always check the dimensions of those brake wear parts, so that they're in spec for thickness and roundness. They are cast, so are brittle. No sense putting work into a worn out/bad drum. The preferred method for dressing the interior of the drum is "turning", not sand blasting.
Coloring drums was not an issue until the wheel designs allowed viewing the brakes. Steel rims & hub caps covered everything back there. Only the purview of the mechanic.
Once "mag"/wire wheels arrived (again) someone thought they looked a bit dodgey and wanted to dress them. '50s designers even got in the act with wheel well color, etc. But we're not allowed to talk about the competition here... Now we have powder coated calipers, etc. in every color of the rainbow.
It was not uncommon in the hot rod days to see chromed exposed brakes. I think another manufacturer even used aluminum drums and those were adopted too.
Brake fade comes from expansion due to temperature increase. Plus lining stiffness changes a bit w/ temp. ie, Why some linings are better than others. I doubt anyone's running trans AM with their dyno-soar. Much ado...
Don't know if this is true or not, but my radiator shop advised to use radiator paint. It seemed to work and stay on m drums a long time.
Ken what is break fade?
Quote from: spolij on January 17, 2020, 04:21:56 PMwhat is break fade?
Are you actually asking what brake fade is? Or just poking a little fun at how confusing the English language can be?
TJ no kidding. never heard of break fading. :-[
And i changed my mind no drums. :D
Quote from: spolij on January 17, 2020, 07:45:30 PM
TJ no kidding. never heard of break fading. :-[
And i changed my mind no drums. :D
I think it's when you get tired from too much break dancing. :P
I paint my drums with engine enamel or caliper paint.
I'll offer my .02 likely worth nothing so take it or leave it >:D
Looking at it from another perspective, if there was an application I was intending to retain heat in would paint be an effective solution?
I would say no.
That being said, I think a drum brake is a better heat absorber than heat exchanger, and by that I mean it has enough mass to absorb the heat energy of braking but being a smooth exterior with no fins or ducted air to it not efficient at exchanging heat real time.
I don't think painting drums could have any bit of measurable reduction in braking performance.
They will stop very well until overheated and paint isn't likely to change that.
Just my opinion ;D
Quote from: INTMD8 on January 17, 2020, 11:13:39 PM
That being said, I think a drum brake is a better heat absorber than heat exchanger, and by that I mean it has enough mass to absorb the heat energy of braking but being a smooth exterior with no fins or ducted air to it not efficient at exchanging heat real time.
This is why I chose to change my drums to a later model year with the fins. They do extend farther from the inside of the wheel into the air flow.
But I still painted them.
I've have experienced brake fade in several different vehicles over the years. None of them had painted drums at the time either. It was probably partly due to the small size of the drums in the first place.
The vehicles I kept I converted to discs in the front.
The only one I have not converted to discs is my Cadillac, for several reasons I won't get into here, I went with the drums.
But I don't expect any problems because of the paint.
As somebody wrote, the factory did not apply paint to the drums because of the costs and at that time, the customer could not see that pile of rust. The drive shafts are not painted either because nobody can see that. Really? Not in Europe! Therefore, for export, the drive shafts are painted since some years.
On all 3 cars I restored, i had a 2-K primer on the drums and then a good coat of black paint. Heat exchange problem? With cars more than 30 years old? you have to drive them accordingly to their age and learn that when going down a hill, the transmission is there to avoid speed increase by using the gear lever and not the brakes.
Bien Roger
Quote from: spolij on January 17, 2020, 07:45:30 PM
TJ no kidding. never heard of break fading. :-[
Brake Fade --> https://en.wikipedia.org/wiki/Brake_fade (https://en.wikipedia.org/wiki/Brake_fade)
Quote from: spolij on January 16, 2020, 04:49:04 PM
Is it a problem to have the break drums sand blasted and painted?
Hello John,
No, it is not a problem to have the brake drums sand blasted and painted. Attached are before and after pictures of one of my '67's rear drums. Note that my car has finned drums to aid heat dissipation (cooling via the flow of air). Also, the rear drum shown has no hub. The drum is held to the axle flange via the wheel lug nuts.
If you are having your drums blasted and painted by a shop, you need to decide if you will have all machining/work (drums turned, new bearing races installed, new studs if needed, etc.) completed before or after blasting and painting. If before, then you have to be careful that any blasting and painting does not damage or contaminate the recent machining/work. If after, you need to be careful that any machining/work does not damage the paint. In this regard the rears are easier than the fronts. The fronts have the hubs with which you need to contend - more risk of damage or contamination.
I did all my own blasting and painting. I had the machining done before blasting and painting, and I took the time to prevent any damage and contamination from blasting and painting by covering any surface where the blast media and paint should not go.
If you plan to drive your car in such a manner as to worry about whether painting the drums will affect the ability of the drums to eject heat, then you should consider swapping to disc brakes. As J. Bozin implied earlier, there are several physics/engineering papers/ articles/discussions about how coatings affect heat transfer in metals. If you are really curious, you can find them on the internet and in a good library. For me, corrosion is a terrible thing. Anything I can do to prevent corrosion (rusting drums) without compromising performance (brake stopping power) is a good thing.
If you did not read in its entirety, Jason's link to an article about brake fade, the synopsis is that brake fade is a decrease in the ability of brakes to slow/stop a car. Brake fade is usually the result of prolonged and or repeated brake application, generating heat build-up, causing the brake drum to expand away from contact with the brake shoes. Fade can also be the result of high heat compromising the friction characteristics of the brake shoe lining or disc brake pad. If you plan to drive often in heavy, moderate speed, stop and roll traffic, you might experience brake fade. If you plan to drive where you regularly encounter a long down-grade, you might experience brake fade. And you would experience the fade whether or not the drums are painted.
You can also experience brake fade symptoms without heat build-up when you drive through standing water and the brakes get flooded with water. Most of the water will drain away quickly once you are on dry pavement, but you may experience no stopping power from the brakes for several applications of the brakes.
As a reminder, our cars weigh on average about 2 tons. This is a tremendous amount of weight standing still. When moving, the effect is of a much heavier object. Please keep this in mind when driving.
Respectfully submitted,
Christopher Winter
Thank you all for the info. The drums are at the vendor. It will take a week or so. $20 each.
Then new tires and top.
BTW Christopher my 66 deville weighs 4,475 lbs so "break fade" ;D would be more of a problem. I was always aware of the condition but now i know the name.
Thanks
Quote from: spolij on January 18, 2020, 02:19:06 PM
BTW Christopher my 66 deville weighs 4,475 lbs so "break fade" ;D would be more of a problem. I was always aware of the condition but now i know the name.
Thanks
Hi John, Not trying to be the grammar police, but it is brake not break. Here's a good definition I grabbed off the internet:
As a verb, the word brake means to stop. As a noun, brake is a device for slowing or stopping motion. The word break means to smash or to shatter as in to break a cup. It also means to take a recess, as in a coffee break.
Jason Break got it! Thanks. JK ;D