Given that the car had been lying up for a few years out in the damp, and that it was now 14 years old, some chassis rust was to be expected. While it was up on axle stands, it was worth giving it a good inspection and treatment, rather than doing a bodge job, especially since there was so much other work to do anyway. The first job was to power wash everything underneath to get rid of as much dirt as possible. Once this was done, the car was jacked up, put on axle stands and I tackled half the chassis at a time, starting with the front. Once up on the axle stands, the plastic covers from underneath were removed and put aside. Arch liners were removed so that I could inspect the arches to make sure there was nothing sinister there. To my relief, all seemed ok in the front arches, aside from a small bit of bubbling around the holes for the snap fit plastic fasteners for the liners. These were stabilised with a stabilising compound and touched up with touch up paint. A good inspection on the front chassis legs and subframe was next, and again while not pretty, the condition of the main structural members seemed to be in good condition with the ugly visible corrosion being seemingly limited to surface corrosion and the metal was sound underneath. Having said that, I resisted the urge to just do the basics and rush it back into service, so I made the decision to treat this work like a mid-life refurb that would see the WRX return to the road in solid shape. Given that it would need an annual NCT, I didn’t want to be patching it up every year to pass, better do a solid job that would last years and then deal with whatever (hopefully) minor issues that came up (hopefully) rarely.
Around this time, I was reading the odd issue of Car Mechanics magazine, and came across an article on how to rustproof cars. The article was sponsored by a company called Rust Buster (www.rust.co.uk) and showed how they do a full rust treatment in 50 steps. I was never going to be able to replicate this type of job which had access to all their products, 2-post lifts, spray booths etc but using the principles of rust treatment, combined with the kits the company sold for DIY’ers I reckoned I could do a thorough job that would give me another 10 years of motoring without worrying about rust (assuming I didn’t screw it up obviously). The Rust Buster guys were extremely helpful in advising and I took the plunge and bought a kit to do the job. Rust treatment can be broken down into the following steps:
Wash – Remove loose surface dirt to make sure there’s nothing that’s holding any damp patches and hiding little pockets of rust.
Dry – Dry the metal thoroughly – there’s no point sealing in damp obviously.
Brush – Grind away the loose brown/orange surface corrosion to get back to sound metal
Neutralise – Despite the above, there may still be residual salt residue at a molecular level on the metal, so this needs to be neutralised to stop any residual chemical activity.
Stabilise – Treat the metal to make sure that the surface rust is stabilised
Protect – Apply a coating to protect the metal
I won’t insult your intelligence by giving huge detail on the washing and drying steps. So on to the chemical neutralisation step. This was done using a product called Chlor-X, sprayed liberally to the metal and allowed to react and dry. There’s no visible effect after this step, but at least if the theory is right, then it gives assurance that all the remaining steps won’t be in vain.
Now for the heavy artillery, my trusty, cheap little 5 inch grinder was fitted with a knotted wire brush and put into several nights of service brushing the surface rust away. The knotted brush attachment is important as a grinding disc leaves a very shiny finish which doesn’t give a great key for the next step. The stabilisation step actually reacts the chemical with the residual rust so removing one part of this reaction obviously lessens its effectiveness.
This part of the job was a pain without a car lift. Axle stands can only give so much ground clearance, so this work involved lying on my back, arranging lighting of the area, grinding and brushing the chassis members. During this step, it was important not to damage anything like rubber boots, brake lines, fuel lines etc. It was a dirty, messy job, but really worthwhile to clean up the metal and get it ready for stabilisation.
Once the metal was cleaned up, it was brushed with a product called FE-123 to stabilise any residual corrosion, which makes a sound surface for the final protective coat. The FE-123 had to be left to cure for 24 hours, but since most of this work was being done by grabbing a couple of hours here and there, curing time wasn’t a problem. Finally, the treated metal was inspected to make sure there was nothing missed, and anything that was missed was re-treated to get it ready for the final coat.
Epoxy-mastic was the product used for the final coat, which was a two part epoxy paint, thinned to about 10% to let me brush it on. Again, without a lift or spray booth, this was a messy job but seeing how well the chassis came up after all the treatment was a great reward for all of the hardship to date.