After looking at the degraded paint on the engine and gearbox I realised how much the surface finish on many of the fasteners and parts had degraded since they were re-plated literally 14 years ago, having been uncovered (albeit in a garage) for much of that time. In addition to this I had a large number of other custom fasteners needed for assembly that would need plating.
I chose to get an zinc electroplating kit from http://janekits.com.au and try it at home and complete batches as I find and gather the fasteners for the Mini. Having multiple small batches of fasteners professionally plated will quickly become expensive otherwise. The plan was to try and get a consistent yellow/gold colour on all fasteners, brackets and parts.
After reading the supplied manual, all 4 Litre baths were mixed into 5 Litre containers to test the process :
- Pickle bath (15% Hydrchloric acid)
- Parts cleaning bath
- Plating bath
- Pre-chromate dip bath
- Chromate bath
Each of the buckets under the table are for rinsing before and/or after the above main steps, and a fish tank heater was used to maintain the plating bath at a consistent temperature.
The first few tests of some random fasteners seemed okay however it took a few trial runs to get familiar with the timing and power supply current/amperage settings. Once zinc plated they were prepped and dipped in yellow chromate for the gold/green/yellow colour as per the OEM fasteners, and all parts were hung for a day to dry and harden.
Testing larger size pieces such as the turbo oil and coolant hard lines turned out well
Replating the wiper motor casing and screws (which was supplied as a flat zinc colour) and screws also worked well.
Over the course of a few months during winter while it was too cold to effectively paint anything without waiting half a day for items to dry, I managed to process an extremely large number of fasteners and many small parts such as engine, gearbox and some suspension parts :
Other misc engine pieces :
I did learn the hard way that overheating the plating bath is not good. At one point I was struggling for multiple days trying to figure out why plating attempts were resulting in the parts looking like a dull grey instead of silver. I eventually found the bath heater was at ~33degC (sweet spot is 25degC) which accelerates the breakdown of the zinc brightener and was having to add far more brightener than expected.
More importantly I learnt how to monitor the plating process once I had the temperature correct. Checking each batch of parts after 10-15mins in the plating solution I could determine if the parts were looking to end up dull or bright. Grey usually meant I'd set the power supply current too low and if I had increased the current by eg 20% and they were still looking dull after 10mins, I'd increase the current a little more or sometimes add 2mL of zinc brightener into the bath. Sometimes I'd just have to scrap the batch, place the parts into the acid pickle bath to remove the zinc coating and start again. This pic is representative of the grey bolt from a failed bath vs bright zinc bolt from a successful one.
If any of the parts come out of the plating bath with a dull grey colour and you attempt to continue to the pre-dip and chromate baths, they will end up very dull instead of the expected bright colour.
I hunted down every other bracket and fastener (quite a few were custom-made or modified from standard bolts) I thought I'd need for reassembly. I found quite a few of them were developing mild surface pitting anyway and ideally needed replating :
Misc bolts for the engine bay, suspension and interior & subframes :
For the large number of washers I tried a "shish kebab" method with washers close together and hung 30+ washers at a time in the plating solution. I used a series of very thin plastic spacers to separate each washer to mitigate the washer surfaces from being obscured. These plastic spacers covered very little of the washer so the idea worked okay but I ended up hanging them with wire in big batches.
The last few lots to be plated were mounting fasteners for misc engine bay, underbody and interior parts
After a multiple months of work over winter I ended up with a large number of labelled bags of plated fasteners, brackets and miscellaneous parts. It was a lot more time than I initially expected as every few weeks I kept finding more items that would benefit from plating so the decision to use a home-based kit was a good one. I did a quick count of how many individual pieces I plated and came to over 900 with another few hundred of miscellaneous bolt & washer spares - far more than I expected!
I'm sure that I've missed a few parts however this kit will be used to replate anything else I find necessary during reassembly of the Mini. Everything (except the chromate pre-dip solution) can be stored long term in plastic containers and set up again within an hour.
Comments
Post a Comment