Cleaning up and refurbishing the frame, subframe and swingarm proceeded largely like my previous project the R65. Like that frame, this one was very dirty. It also had worse rust and pitting in a few areas, particularly on the left side of the swingarm, the cross bars at the back of the frame and a few other areas.
I removed the steering head bearings and the swingarm bearings and had everything completely stripped down before I started.
First up I degreased everything with degreaser and the high pressure hose. This got most of the thick grime off. Then I meticulously cleaned with solvent and wire brush until I was sure there was no dirt.
Then I stripped 90% of the paint back to bare metal. I started on the areas where I could see rust coming through the old paint but found that there were only a few areas where the paint was truly good. To do this I used a plastic abrasive wheel on my angle grinder, Dremel attachments for difficult corners, and 400g sand paper.
It took ages. And I mean ages. Like nearly 3 days.
Eventually I was convinced that there was (almost?!) no rust anywhere. There were some deep pits in the above mentioned areas- the wire wheels got the rust out but the pits remained. It should be noted here that some form of media blasting probably would be a better way to go for prepping the frame and subframe as they have many very awkward spaces to get into…. some kit to buy for the next project!
I found a small crack in the back of the frame where the “ears” for the exhaust and rear footpegs meet the frame. Apparently this is very common on /5s. I welded it with a fine stick welder and ground it down.
After cleaning up all the dust and setting my garage up as a paint shop (read; putting a lot of plastic everywhere) I started with the primer.
I have read a lot about different kinds of primer, specifically the etch primer vs epoxy primer. Most seem to lean towards epoxy as it gives an impervious seal. It certainly seemed to be the better choice in my case for two reasons:
- Mixed substrate (I still have some areas with lightly sanded paint on them, and lots of bare metal)
- Possibly some small areas of surface rust (almost microscopic) in the depths of pits and in some of the very tight corners.
The product I chose was this Eastwood 2K aerosol epoxy primer. This stuff sprays on really nicely and I’m hoping it will give a good base seal to this old frame. There are more and more 2K paint systems in aerosol cans and the spray nozzle technology is becoming very advanced meaning that for small jobs they are a good option. BUT they are expensive AND remember- 2 pack paint contains ISOCYANATES which are VERY toxic for your respiratory system. They can also be absorbed through your skin and eyes. I think I mentioned this in my last post about painting (I used a 2k spray can system on the R65 tank) but these paints are not strictly meant to be used for the hobbiest and some say isocyanate products should only be used with a supplied air respirator system. So DO THIS AT YOUR OWN RISK. I used a full face N2P2 rated fully sealed mask, full spray suit and gloves and minimized my time in the spray booth (er, garage).
For the first spray I masked off all the bearing races and the main threads in the frame for the swingarm. I also masked the identification plate on the headstock, the steering lock cover and the drive shaft which wasn’t removed from the swingarm. I didn’t however mask all the screw holes as I thought a light coating of epoxy primer might be a good idea. For all hole masking I used Bluetac.
After letting the Eastwood primer cure for 12 hours (a bit more cause it’s a little cold here in Melbourne, Australia) I inspected all the surfaces and gave a very light rub with some 600grit paper. The areas that had the deep pitting could still be seen through the primer, which I had anticipated.
To fix this I proceeded with another coat of primer, this time a product I had used before called UPOL High 5. Its an ultra high fill sprayable primer. It goes on really well, thick but never seems to sag. It flash dries in 20 minutes and can be sanded and either recoated or topcoated in about an hour (at 20c) . Before adding this high fill sandable primer I did go ahead and mask most of the holes and screw holes with bluetac.
The High5 did a pretty good job of hiding the pitting.
I then gave everything another very light sand and wiped down with pre paint degreaser before applying 3 coats of topcoat. For this I used DULUX Metalshield Epoxy Enamel Gloss Black.
Excellent write up about the frame repaint procedures. I have decided to use the same paint used on the tins to match every thing up. Have found it difficult to find a.pure black to match the BMW paint. Most black paints have either a blueish or brownish tint.
Thanks Greg- restoring frames “by hand” is tough work but it is possible to get excellent results if you are patient. Like all painting jobs 90% of the final result is in the prep work. Which sucks. Media blasting would make it suck less. Good luck!