I've been experimenting a bit more with the plating kit. To show, as much as anything, what can go
wrong as well as go right, these notes may prove useful to others:
I decided to try to protect the rear stub axles with a combo zinc/nickel plate. When I stripped the rear beam axle down, I was a bit concerned to see that there was some rust flake and consequent delamination of the mounting flange, that appeared to result in a forcing apart of said flange and the drum brake backing plate. I'm not sure if it would have affected the wheel camber but it's not something I wanted to get any worse. The mating faces of the beam axle and stub axle had some corrosion too, with more flaking (you can see the remnants of it on the bottom-right of the mating face, below)
I wire brushed the stub axles and left them to bubble away in phosphoric acid overnight. They cleaned up quite well, though the recessed area on the back of the flange (it's sort of star-shaped) was very difficult to clean up, even after it had been in the acid (sorry, no photos of that bit). I think there may have been small pockets of air trapped there, even though I worked some into the recess before leaving them to soak.
I degreased them in GP1 cleaner, which I use in my ultrasonic cleaner. The heater and ultrasound seems to helps things along quite well. Five minutes in a tank pre-heated to 35-40C gets results.
For obvious reasons I didn't want to plate the surface the bearing sits on, or the thread for the hub nut. I could suspend them from a wire wrapped around the thread and only partially submerse them in the plating tank, but I wanted to get a clean cut-off in the plating at the shoulder the bearing sits against. Yet again, google was my friend and I ended up reading a thread about masking on some Indian car forum I'd never heard of. ?One kind soul there mentioned that nail varnish works very well. Wife's collection of old colours were duly raided and that's what you can see in the above photo.
I'm pleased to report that it works really well. The chemicals in the plating tank (and the passivate) didn't touch it at all. What it didn't like was the ultrasound cleaner, which in combination with the GP1 cleaner lifted the pink stuff off in a couple of minutes. So it's probably best to apply the varnish after all degreasing, which means you'll need to wear clean rubber gloves when applying it to avoid getting any traces of grease on the bits of metal that you
do want to plate. I didn't bother to re-mask one of them, and paid the price.....
...by ending up with some plating on the axle shaft. As it happens, this cleaned up quite easily with some very careful rubbing back with wet and dry (photo is part-way through this) as the plating is much softer than the steel. What it did prove to me was that, given a decent surface (such as the axle shaft) the plating kit will delivery
extremely shiny plating. It looked fantastic - before I rubbed it all off
. The yellow passivate took well this time.
The horror show was the back face of the flanges.
In the aforementioned star-shaped recesses, all was not well. The combination of not removing all of the rust and suspending the stub axles by the threaded section when plating them, gave me a very uneven result. There was a lot of gas bubbling coming off of these faces when thay were being plated (don't forget they were facing the bottom of the tank) and I think a lot of the bubbles were in effect trapped by the fairly rough face with all the bolt holes in it. It's not quite as bad as it looks as much of the staining could be removed with some wire wool, but it is a cautionary note: when plating, make sure you hang the part so that no air is trapped. That said, in this case, I'm not sure how else I could have done it, without having to do a load more masking. The nail varnish, by the way, comes off very easily with normal nail varnish remover (thanks go to the wife again).
I will probably mask and paint these now, just to be on the safe side. Then I'm pretty much ready to rebuild the back axle
