Wednesday, July 18, 2007 - 11:38 am, by: Anish Varsani(Yomama)
I was talking to a few brake places about overhauling calipers. They said that they strip down the calipers and acid dip them to clean them, then they paint.
Anyone know what type of acid they use? Will it pit the caliper bore and piston?
Wednesday, July 18, 2007 - 01:24 pm, by: Brian Timms(Turbo_brian)
Acid dip is usually a 0.1 molar Hydro-chloric acid wash, shouldn't hurt the callipers, as long as they are washed off properly, and not left in the bath for an extended period of time.
It's done with complete car bodies as well, and they leave them in overnight to eat out rust and other nasty imperfections, leaving perfect metal.
For painting callipers, I either use a sandblaster, or just sit there for a while with sandpaper, 120 grit wet and dry, to clean the callipers up, then 400grit to prep the surface for painting. (always off the car of course).
Tuesday, July 31, 2007 - 05:09 am, by: Anish Varsani(Yomama)
Phosphoric acid works.
Most rust converters you get at the hardware store are just phosphoric acid.
Some aluminium are phosphoric acid as well but others also have Amonia bifluride and hydrofluoric acid which will eat almost anything, glass included. It leave a yellow stain, much like the calipers above.
Wednesday, August 01, 2007 - 06:12 pm, by: Shane McInnes(Soarin_tt)
hahah Anish. Hydrofluoric Acid has to be one of the nastiest Acids to deal with. (Safety Wise very nasty if you get it on you)
I wouldnt recommend anyone to use this, i absolutly hate having to work with this at work which isnt very often at all.
Plus im pretty sure Hydrofluoric Acid doesnt eat through rust as well as Hydrochloric Acid or Phosphoric Acid. Hydrofluoric Acid is great along with Ammonium Bifluoride to eat through Glass as you mentioned (generally used in Glass Etching not for eating rust)
If anyones keen on Acid Dipping the brake callipers i would be using a Inhibited HCL dip that way you are 100% guranted not to have any of the brake calliper eaten away.
Wednesday, August 01, 2007 - 08:13 pm, by: Shane McInnes(Soarin_tt)
Never heard of it, But please dont try it.
Hydrofluoric Acid does not burn your skin. But actually seeps into your skin and eats your bone away. Im told its VERY VERY Painful. Its defiantly a chemical you have to have 110% respect for.
So you can see why i dont like it. If it only was corrosive to your skin like Hydrochloric Acid i would say give it a try. But to clean brake callipers isnt worth the risk.
Wednesday, August 01, 2007 - 08:20 pm, by: Shane McInnes(Soarin_tt)
I just looked up Septone Alibrite and you can see that it tells you in the MSDS that you have to immediatley apply Calcium Gluconate Gel That helps neaturlize the Hydrofluoric Acid from attacking your bones, But you have to be very quick to apply it.
On another note, what exactley are the callipers made out off?
Tom Kneebone TryHard WA 93 factory 5 spd TT : 91 Auto TT