Should I paint the inside of a bell housing?

[averagef250]

Aluminum bells, even when painted, seldom last more than a few years in the weather before they are corroded beyond hope.

Aluminum corrodes instantly in contact with oxygen to form aluminum oxide, one of the hardest substances on the planet. The reason why aluminum is used so extensively in marine applications and corrosive environments is because it forms it's own protective layer to slow further corrosion.

To state that natural iron has a higher degree of corrosion resistance than bare aluminum is false. Iron oxide does not form a protective layer over the base metal, iron parts continue to corrode at the same rate regardless of the thickness of iron oxide that's there.

I think it's being rather anal to clean spray paint from a bellhousing flange. I've torn many a transmission out of a vehicle with hundreds of thousands of miles on it to find wires and other things pinched between bellhousing/block with no ill effects to the parts. I'm sure there was a significant alignment issue there and everything still worked as it should.

Paint looks pretty, if you like things painted then paint away.

[mmerlinn]

Aluminum bells, even when painted, seldom last more than a few years in the weather before they are corroded beyond hope.

Aluminum corrodes instantly in contact with oxygen to form aluminum oxide, one of the hardest substances on the planet. The reason why aluminum is used so extensively in marine applications and corrosive environments is because it forms it's own protective layer to slow further corrosion.

Then explain to me why I can throw a cast iron bell outside on the ground and 20 years later still have a usable bell with no visible disintegration while when I throw an aluminum one on the ground next to it the aluminum one will be full of HOLES because of the corrosion in LESS than 5 years? If you need to see samples, come and see me.

[Levis]

Now that this post is two pages long, I thought that I would tell everyone how funny I think it is that we are now involved in a two-page discussion about the inside of a bellhousing. Maybe we should ask the pressure plate and throwout bearing how they feel about the situation? Not trying to offend anyone, I just got a kick out of it.

[peanutman]

My question would be why paint the inside of a bell housing. No one will ever see it and it's just going to get dirty and oily and whether you use alum or cast it will last longer than you will live unless you blow a clutch at a high rpm, so robroy i wouldn't paint it, but looking back looks like you already have so i would leave it as is, i don't think it will throw anything off.

If you are concerned just remove the paint where it butts up to your motor and tranny

[Alvin in AZ]

I would paint it.
I would paint it pink (on the inside only) to match my panties.
But that's just me. :/

--------------------------

"all corrosion is electrical" -Richard "Curly" Hastings metallurgist

If the aluminum is touching iron stuff it'll corrode away and protect the
iron (like zinc does) "sacrifice itself to protect the more noble metal".

Adding stainless steel parts and/or fasteners to a situation where
corrosion is already a problem can worsen the situation.

The statement "all corrosion is electrical" pertains to pipelines and ships
and bell housing left out in the weather but also on a microscopic scale
like in the grain boundary between two grains of stainless steel. :)

Funny thing about tin plating iron is the tin is the more noble metal.
Who dreams up these things? LOL :)

Alvin in AZ

[robroy]

Try removing the paint from inside the round hole where the bearing retainer fits. You MUST remove any paint there, so that will tell you how hard it comes off. The big round hole fits the retainer relatively tightly so as to index the bell to the case.

Hey Mmerlinn! Thanks for your great advice.

Yeah just today the guy I hired to rebuild my transmission made a special point out of telling me to be careful with the tolerance around that opening (to make sure it's a perfect, snug fit there). I'll try my best to remove any paint that got in there. Thankfully I wasn't super thorough with the paint spraying inside that area since it wasn't easy to shoot the paint in there anyways.

Using a power WIRE wheel to remove paint won't hurt your bell. Don't use a power SANDING wheel.

A wire wheel won't hurt the cast iron, machined surface huh? I've never tried this before so I'm not in a position to know. I'll avoid the sanding wheel--thanks for the tip!

My question would be why paint the inside of a bell housing. No one will ever see it and it's just going to get dirty and oily and whether you use alum or cast it will last longer than you will live unless you blow a clutch at a high rpm, so robroy i wouldn't paint it, but looking back looks like you already have so i would leave it as is, i don't think it will throw anything off.

Hey Peanutman! I see your point about painting the inside of the housing. I guess I just did it for the heck of it since it was all immaculate from abrasive blasting anyways.

If you are concerned just remove the paint where it butts up to your motor and tranny

Yeah I may test this to see how difficult it is to remove. This isn't regular rattlecan paint; it's Rust Bullet and includes isocyanates (hardeners).

I would paint it.
I would paint it pink (on the inside only) to match my panties.

Hey Alvin! It's funny that you'd mention that because I was actually thinking of painting the outside bright pink, since it would look the most shocking that way next to the bright yellow engine. And if I'm going to the bother to decorate the bell housing it may as well be a truly unusual color! Now if I could only find bright pink paint that's heat resistant and contains hardeners I'd be all set.

Thanks!
-Robroy

[willowbilly3]

Ford didn't paint the mating surfaces and you shouldn't either. Take a block sander and clean it off. They also didn't paint the inside because it is pointless, as mentioned, doesn't need protection or cosmetics. If you want it painted then no problem but don't paint mating surfaces on either side of the bell housing. Did you ever watch American chopper, how many times the stuff didn't fit when it came back from the powder coater? It makes a difference.

[robroy]

Ford didn't paint the mating surfaces and you shouldn't either. Take a block sander and clean it off.

Hey WillowBilly3 thanks for your reply! Do you think a wire wheel would be safer than a sander? I read in another post to this thread that sanding the paint off could damage the cast iron.

They also didn't paint the inside because it is pointless, as mentioned, doesn't need protection or cosmetics. If you want it painted then no problem but don't paint mating surfaces on either side of the bell housing. Did you ever watch American chopper, how many times the stuff didn't fit when it came back from the powder coater? It makes a difference.

I see your point! I'll give a whirl to cleaning the paint off; it might come off more easily than I think. Especially since those surfaces are so flat and smooth.

Thanks!
-Robroy

[willowbilly3]

I think a wire wheel would be ok too. I don't think a block sander would do any damage but I wouldn't go nuts with a powersander on it. I have a wire wheel for my 4 1/2 and it works good but I don't like to use it much because it flings wires so bad. One on a drill motor would be a lot safer.