getting alloy ready for paint how to?

[nzsimon]

I want to paint my alloy auto gaerbox it has that yukky grey powdery residue all over it that old alloy gets

What can I do to it to get it suitable for painting or will I have to sand it all down ( complicated shape will be hard )

[Sean]

( complicated shape will be hard )

What about Bead Blasting it? That would clean it up nicely, plus leave a surface that should hold paint well.

[enjenjo]

Dupont makes an aluminum metal prep that will remove the residue, making it ready to paint. Sorry but I don't have the part number. As I recall, you wet down the part, spray it on, and after a period of time, rinse it off.

[jakesbackyard]

Check with any paint supply store. Most paint companies recommend a one or two step procedure for prepping aluminum for painting. The first usually cleans and the second preps for applying an undercoat or topcoat.
The cleaner works great even if you aren't going to paint an aluminum part.

A transmission tech friend of mine once told me I shouldn't paint an aluminum automatic tranny, as it would hold more heat in. He said one of the reasons they are made of aluminum is to disapate heat more readily than other metals. If painted, especially primed and blocked many times and then painted, they are apt to overheat more easily. He said they are best just cleaned and polished real well.

There are a couple tranny experts on this forum that might let us know if this is true or not. It would be interesting to know if it makes a difference.

Thanks in advance.