Electrolysis rust removal on diff

[Grrrmachine]

I used the electrolysis method to clean up an old caliper last weekend, and it was awesome - a couple of brake discs as sacrificial anodes worked a treat.

But now I'm taking my back end off the car I'm thinking about doing the diff. Will the process damage the seals or cause other problems? I was planning on putting it into a bucket prop-end down, so the back plate is out of the water since that's aluminium, but I'm worried the rust-removal might damage something around the output flanges.

Any tips?

[capnmchl]

Chuck it in. The seals are designed to keep oil in, which holds no surface tension and will leak much easier than water. Therefore, water, which holds surface tension, won't get in past the seals. Just keep the breather out of the water, and do an oil change after if you're feeling generous.

The process will only remove oxidised iron, nothing else, which means it will simply take away rust, and nothing else.

We did some complete hub assembeleys, with the bearings and backplates still attached and it worked a treat, and the bearings don't seem to of suffered much, although the car hasn't been back on road since.

[Grrrmachine]

If that's the case, would a brake caliper be alright without needing a rebuild? I did it on one caliper already but rebuilt it with new seals afterwards, just in case.

[scjimbo]

I can't really speak for the diff as I stripped mine before electrolysis. I did do my callipers and some on a mates subaru about 6 months ago and they are both perfect.

[Brianmoooore]

Chuck it in. The seals are designed to keep oil in, which holds no surface tension and will leak much easier than water. Therefore, water, which holds surface tension, won't get in past the seals. Just keep the breather out of the water, and do an oil change after if you're feeling generous.

The process will only remove oxidised iron, nothing else, which means it will simply take away rust, and nothing else.

We did some complete hub assembeleys, with the bearings and backplates still attached and it worked a treat, and the bearings don't seem to of suffered much, although the car hasn't been back on road since.

This! If the seals are any good, nothing will hurt. It's only water with a tiny amount of soda added that you'r immersing it in. You also can't do any harm by "leaving things in too long". The only thing affected is rust.
I currently have a 500 gallon tank on the go, with a cement mixer in it.

[Grrrmachine]

Alright, you've convinced me on the diff. How about a brake caliper - would it need a rebuild afterwards?

[capnmchl]

Nope, it's the same principle. Of course, it would be wise to strip something easy like a caliper before hand, but it's not necessary.

[scjimbo]

^+1 rubber is not affected by the soda and doesn't conduct electricity so they will be fine

[ajay]

Is electrolosis the same sort of thing as ultrasonic cleaning? I will be hiring some ultrasonic cleaning equiptment for a project at work, i was thinking this would be a good time to have a go with some of my own parts. Does anyone have any experience with this? All i know is that the parts (at work) to be cleaned are non ferrous and we have been told ultrasonic cleaning will do the job.

[Brianmoooore]

Is electrolosis the same sort of thing as ultrasonic cleaning? I will be hiring some ultrasonic cleaning equiptment for a project at work, i was thinking this would be a good time to have a go with some of my own parts. Does anyone have any experience with this? All i know is that the parts (at work) to be cleaned are non ferrous and we have been told ultrasonic cleaning will do the job.

Not remotely the same. Ultrasonic cleaning is essentially using sound waves to dislodge dirt, whereas electrolysis is actually converting iron oxide (rust) back into iron. It won't 'clean' the item in the slightest, other than any dirt sitting on top of rust will be dislodged, as long as the dirt doesn't electrically insulate the rust from the soda solution.

[harry_p]

Wonder if you could combine an ultrasonic bath with an electrolysis one and have parts come out rust free and sparkling clean?

[ultralinear]

Electrolysis is great.

Another method you can use involves blackstrap molasses. Add a tiny amount of sulphuric acid to a 1:6 solution of molasses:water (this creates 'sulphured blackstrap molasses'). Leave it in a container (preferably in a warm environment, but not indoors as it smells very bad) for a week or so. Occasionally take whatever you're working on our of the solution and brush the layer of reacted material away.

This will also only attack rust. The molasses is mineral-rich and acts as a chelating compound.

Once your item is finished reacting, clean it, then put phosphoric acid solution over the surface. This will create a rust proof-layer... ready to be painted or lacquered whenever you wish. No flash-rusting will occur.

Magic.

[ultralinear]

Beware, as this process does eat aluminium also.

Maybe coat the aluminium in varnish/lacquer that can be removed later (without using dichloromethane... that will also react with the aluminium!!)

[DanThe]

/\ pretty much what happens with the parts I take for de-rusting, you can smell the place from 100 yards down the road! The only problem is they end up with a coating that stops zinc sticking to it, so sandblasting has to be added between the processes

[Neilios]

I used the electrolysis method to clean up an old caliper last weekend, and it was awesome - a couple of brake discs as sacrificial anodes worked a treat.

But now I'm taking my back end off the car I'm thinking about doing the diff. Will the process damage the seals or cause other problems? I was planning on putting it into a bucket prop-end down, so the back plate is out of the water since that's aluminium, but I'm worried the rust-removal might damage something around the output flanges.

Any tips?

Any pictures of the process and finished product?

Thanks.

[Grrrmachine]

Any pictures of the process and finished product?

Thanks.

Finally got round to doing the diff, and the result was... well, have a look.

Last night:



This morning:



Even though the water level was below the breather, it seems I got oil into the water, which led to a dysentry-based reaction. Incredibly, it still did its de-rusting and the diff polished up nicely after a hose-done and brass brush, but there are no finished pics because it's currently coated in Hammerite silver

[aimlessrock]

That is amazing...I'm very interested in doing this to my
Recon diff. What are you using, battery charger?

[Rav335uk]

Lets have a diafram of the set up

[Grrrmachine]

Setup's not hard at all. All the bits of scrap metal you can see are linked together with jump leads, and are then connected to the POSITIVE terminal of a battery charger (mine's a six amp one). The diff is connected to the NEGATIVE terminal of the same charger.

If you look, there are little bits of wood slotted in to make sure the scrap brake disc doesn't come into contact with the diff. There's also a 3mm steel plate in the bottom of the tank, so the diff is supported on wooden blocks to keep it above that.

[Brianmoooore]

All the croc. clips for the anodes (scrap iron) should be kept clear of the solution, or they will corrode. Clips on the negative wire can be submerged without problem.
Strength of the soda solution isn't at all critical, neither is it 'used up'. It's just there to make the water conduct electricity.
Ideally, you should use a variable voltage power supply (one I use is 0-30 volts, with adjustable current 0-2.5 amps), and the voltage adjusted to give a current of 1.5 - 2.0 amps.

[capnmchl]

That actually looks like shit.

[Brianmoooore]

That's just foam on the surface of the water. Usually more orange than brown, but it all settles to the bottom when you've finished, and the soda solution can be decanted or syphoned off to use again.