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Searoy
69 bug (parts)
66 bug (daily driver project)
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Jeffery Brady <67vdubN...@msn.com.invalid> wrote in message
news:142ac100...@usw-ex0101-005.remarq.com...
> Is this a good/bad
>idea?
Very bad. Your brake drums are meant to convert rotary motion into HEAT.
That's what makes them work. Anything that interfers with coupling that heat
to the atmosphere reduces your braking ability.
Practical methods of protection are to have the outer surface of the drums
aluminized (Buick usta do this) or to have aluminized fins heat-shrunk onto the
machined drums. Kinda expensive.
If you absolutely gotta paint them, apply a THIN coat of flat black paint. Do
NOT use 'high-temp' paint. It makes an excellent insulator.
You can paint the HUB AREA any way you want. But keep it off the rim.
-Bob Hoover
>anybody has ever put some type of coating on the outside of their
>drums to protect them from the elements. Is this a good/bad
>idea?
It more of an esthetic thing. It makes your drums look a little better. In
some cases the drums are made of some type of plastic so
rust prevention isn't an issue. I painted mine nevertheless, it's a nice
subtle detail.
>If anybody has done it what did you use?
They sell special paints for painting drums and disk claws. They come in
different colors. That's what I used at first. Later I thought the
bright red looked a little tacky (my car is all black) so I used black heat
resistant paint (can stand up to 600 degrees celsius) to repaint them.
While I was at it I also painted parts of the engine.
regards,
allard
[http://vwg.cjb.net]
> In
>some cases the drums are made of some type of plastic so
>rust prevention isn't an issue.
You mean the drums are already coated with an anti corrosion coating, if the
drums were plastic................the less said the better.
Nachi
> Hi, Please do not paint the brake drums. This rates right up there with using
> WD-40 to prevent brake discs (rotors for Americans) from flash rusting in damp
> weather.
How about the outside of the drum? The inside I can see why you wouldn't
want to paint it.
Hi,
I believe Bob Hoover just posted an informative reply to this question (seems
to me that all his replies are informative).
The drum is a heat sink. Any coating that is a thermal barrier will cause the
drum to get *a lot* hotter than it was designed to, causing at the very least,
distortion of the drum, and complete brake system failure when the fluid boils
at the worst.
You could paint the hub area, how are you going to be sure about the paint
thickness under the wheel bolt seating area ?
My car has the wide 5 wheels, the drum has a machined area where the wheel is
bolted to the drum.
Nachi
I have an article Mr H wrote about the virtues of painting your engine where he
says: "Rusty or corroded metal makes a fine heat insulator, as every weldor
knows. A few ounces of paint judiciously applied prior to assembling your
engine is not only the mark of an experienced mechanic, it is one of those
tricks so simple it is often overlooked".
- So rust insulates the drums and increases operating temperatures as well.
I'm not trying to twist words around or anything, but if this is true wouldn't
it be advantageous to paint the drums with a light coat of flat black or
something rather than leaving them bare cast iron?
Aaron Guinn - the "Scat(\/)an"
aguin...@aol.com ae...@technologist.com
"Zero to sixty? Sometimes..."
In truth, there is no reason to worry if you drive your Bug the way it was
intended, which is what the brake system was set up to handle. If you
overuse the brakes and drive it like a race car, cooling the brakes will be
among the least of one's problems.
Oh, and don't ever paint your engine. Routine maintenance should include a
wire brush that is used to clean off oily buildup at each oil change, 2000
miles. Paint itself might be OK, but the typical person doesn't clean his
engine often enough so you end up with two insulating layers, one paint
layer and one oily gunk layer.
--
Eric D.
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http://www.geocities.com/eduhachek
Scatman <aguin...@aol.comREMOVE> wrote in message
news:20000512003207...@ng-ff1.aol.com...
Yes, I have been doing that for years, not only on VWs but other cast iron drum
brakes as well.
>Routine maintenance should include a
>wire brush that is used to clean off oily buildup at each oil change
Well, I use a spray engine cleaner or *simple green* on the fins etc. after
removing the fan shroud.
Then wash the stuff off and there you have it, no muck or twigs in the fins and
a shiny engine !!!!
Nachi
The normal operating temperature of your cylinders is under 400 degrees,
maximum with the nominal probably under 300. At those temps normal paint does
not break down. An engine I built came back to me for overhaul after 17 years
of service and the paint on the jugs was still in good condition.
Brake drums on the other hand can (and do) exceed 700 degrees. In extreme
cases the drums on a heavy truck will glow dull red. These high temps are why
we use the stuff we do for brake fluid. Read it's specs; it is can withstand a
lot of heat (and DOT-5 does even better).
At those temps normal paint simply blows away like dust.
Paints designed to withstand high temperatures use eutectic metallic solids or
a high clay content or both. These act as insulators. Indeed, they are not
very good protection against rust because they tend to be porous. There are
some thermal barrier compounds that provide good corrosion protection
(Ceramichrome, etc.) but they are even better insulators; some are so good you
can put your hand on the exhaust manifold of a V8 racing engine right after it
comes off the track. It's hot but without the TBC it would be literally
glowing.
It is standard practice to wire-brush the flakey rust from a brake drum when
you do a brake job. I usually give my drums a spritz of flat black primer to
protect the stud/hub. Within a few days any overspray on the rim has vanished.
You may forward this to the Newsgroup if you wish. AOL has gone wonky on me;
it took 54 minutes to get on-line tonight, more than an hour last night. At
that rate I soon won't be; wastes too much time.
-Bob Hoover