Hi guys, just reread Clint's original thread on the subject (stickie in Tech & Resto section, and a great read), which is what I based my quantities on:
http://www.radbmx.co.uk/forum/index.php/topic,178383.25.htmlI only double checked, and offer the additional post here, as obviously you've received slightly conflicting information, and whilst neither is wrong information, it might help explain a little more.
Basically, my early recollection was slightly inaccurate, Clint's original advice was to use approximately 250g (0.25kg) of citric acid for 20L of water, not the 40L I stated. So, when I did my frame I ended up using 0.5kg of CA for a planned 40L of water. But, because I didn't subsequently also fill my pool with lots of tins, bricks, bottles, etc. (to artificially raise the water level to make sure the whole frame was submerged) I ended up only covering just over half the submerged frame height. Hence soaking it for 24hrs on one side then another 24 hours on the second side.
So, as a minimum, you'll want to:
Get hold of a 1m diameter pool, or similar.
Put all your proposed parts in
(And if not filling the pool with additional items in the gaps to save on absolute water volume & CA) Put in ~1kg of CA crystals, I used these ones, but plenty of other sellers available:
https://www.ebay.co.uk/itm/CITRIC-ACID-2KG-BAG-100-Anhydrous-Powder-GMO-Free-BP-FCC-Food-Grade/183511231815'ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649Then fill the pool with water to cover all your components and wait for the chemistry to take effect, around 12-24 hours depending how bad the parts are to start with.
It's also worthwhile having an old toothbrush to hand, to rub over the bad areas every couple of hours, to loosen off any of the 'dissolving' corrosion.
As I mention, neither answer you received is wrong, it's simply a matter of the stronger the concentration the quicker the process, I've personally experimented a bit, and found that as strong as 50g/litre strips all rust of concern in a couple of hours.
Have fun