what would you do : transmission carrier coating

[Bukowski]

here's an easy "color of the bike shed" question: just got the transmission carrier sand blasted. next I'll use a clean metal primer. next, primer sealer.

question is : what to do after that - standard paint, or use the Wurth High-Build Underseal I have had laying around for a while?

Pelican Parts sells the Wurth stuff, not plain paint AFAIK, so there's a bit of free advertising in this post. so if you think the underbuild is going to work better give reasons, and if you know a competing paint in Pelican, refer to that one. think high T paint is necessary, or if standard paint is inadequate? or metal plating?

[jeffrsmith]

I would undercoat with POR15, then paint with whatever paint you want from your favorite german paint supplier.

[thumbdoctor]

If the case was "sand blasted", I'd bake it (heat it) and give the inside a good cleaning before assembly.

[rhett]

Hi - If you are talking about the transmission crossmember that the gearbox mounts on, then as this is made of steel I would make sure that a good coating of either zinc or lead based primer is applied first. I have heard good reports of POR15 as advised above, but never used it - but it does appear to be recommended many times on this forum

Once it is all primed up, I would recommend that you use a hard-wearing paint such as an enamel or synthetic. There are many paints that are developed especially for chassis components, so you should be able to source something suitable quite easily.

However, you can use practically anything you like really, but if you want the finish to last (as it's a harsh environment under there) spend a few extra bucks and get a tough paint. That said, Porsche just used basic black most of the time...!

High-temp paint is unnecessary, underseals are generally a bit sticky and on a component they never leave a good finish (IMHO) - great for floors, chassis rails, etc...but, as always, it depends on what finish you want to end up with .

[Bukowski]

these are interesting comments.

unfortunately, by the time I got to the piece, spots rust had started to appear! tried the wire wheel on a drill, steel brush on a rotary tool, then gave up. quickly put the primer on (the can said "bare or lightly rusted metal"). we shall see.

[Gawernator]

Spray rust converter?

[rhett]

Originally Posted by Bukowski

these are interesting comments.

unfortunately, by the time I got to the piece, spots rust had started to appear! tried the wire wheel on a drill, steel brush on a rotary tool, then gave up. quickly put the primer on (the can said "bare or lightly rusted metal"). we shall see.

Ah, didn't know it had already started to rust. Gaw is right ^^ the thing to have done was use a rust convertor product to stabilise the rust first. Problem with bright shiny steel is it oxidises real fast, and once 'blasted' or wire brushed it has a rough surface that promotes rust forming in the very small pits and holes..

Never mind, at least you can keep an eye out on the rust and deal with it on a regular basis if it becomes a problem again.

[Bukowski]

Gawernator, rhett, I think by the time the rust converter - which was on hand but in limited quantity - were on the piece, so much more finger grease, dust, and probably more rust would be appearing, not to mention Mother Nature holding the rain - barely - for me to get it done. hence the "quickly" putting primer on.

certainly learned to get the timing better when doing this Next Time.

what would you all use to heat it anyways? I would have used a standard looking bbq grill.

[tamathumper]

I would have tossed it in the electrolysis tank - I have one that uses a simple RubberMaid tub and a battery charger and it gets paint, grease and rust off anything. Then I would have removed it from the tank and dried it quickly using a blow dryer to avoid "flash rust" and coated it with rust-inhibiting primer. You can Google for instructions, very easy to put one together and priceless during old tractor restorations (or for car parts).

[Bukowski]

Originally Posted by tamathumper

I would have tossed it in the electrolysis tank

yes, electrochemistry - another one of my long-term projects.

the cross member would need a long tank - what'd you do, cut/paste two bins from Walmart together?

[tamathumper]

No, I just have one of those really long under-the-bed ones for long parts, and a big deep one for bulky parts.

[Bukowski]

Originally Posted by tamathumper

No, I just have one of those really long under-the-bed ones for long parts, and a big deep one for bulky parts.

OK, I'm going to drive this thread off-road for this question : your power supply - will the thirty-dollar battery chargers at Sears work *well*? I have heard "trickle" chargers aren't any good for electrochem, but it isn't clear if a charger has a trickle function whether that means it doesn't have ... well, whatever the alternative is. I have never heard of a non-trickle battery charger - what are they called anyways besides "battery charger"?

[tamathumper]

Little 1A trickle chargers are no good for electrolysis in my experience. I use a big float/smart charger with a 2, 10, and 50 amp surge mode. I use the 10 amp for heavy crud and the 2 amp when I'm pickling overnight or for a few days because I don't want too much gas building up in the shed all at once. Hydrogen is explosive.

[Bukowski]

Originally Posted by tamathumper

Little 1A trickle chargers are no good for electrolysis

so if the charger says "trickle" at all, avoid? even if it was 10A?

[tamathumper]

Sorry, I can't say, as I have never seen a 10A "trickle" charger, only the little 1A wall wart ones, and that's not enough juice to get things done. There might be such a thing as a 10A "float" charger, but 10A is way bigger than what I would consider a "trickle". Maybe I need a "vocabulary adjustment".

In my experience, it takes a large "box" charger for power and heat dissipation. It all comes down to amps, surface area of your anode (the + side), and "line of sight" to the corrosion to get it done. If you don't have enough amps, or you have a puny anode, or you don't have literal "line of sight" between the anode and the corrosion on your part, it will take inordinately longer.

Here's a quick-and-dirty explanation with good pictures. Electrolytic Rust Removal aka Magic He's getting away with a 1.5A box charger, which might be OK in something as small as a 5-gallon bucket, but for larger parts, it would take way too long to get results, IMHO.

[Bukowski]

a small update - hopefully a few pics when this is complete: but I put a gloss finish on it. looks like it should be in a museum.

however, after all that - I think this finish is going to be sticky. I don't think that would be good for where the bolts squeeze it - I guess the paint could shear off. is it worth it to put a flat finish over the gloss? or actually go strip it down and re-do it?

[v2rocket_aka944]

Rustoleum red on the iron trans case...has been fine for 6 years now. Trans before that got rustoleum'd too for 2 years, until it ate its R/P...