Classic Bike Guide

Project BMW

- Words and photograph­y by Matt with special thanks to Nick, Jack and Ashley at Ashtons Classics Bodyshop, Dereham (01362 692271) for kindness and knowledge when I needed help

Matt gets the frame painted properly this time and rebuilds the master cylinder

After the last couple of months of problems with paint reacting from oil getting into the air supply via the compressor, this month has been a rather frustratin­g time of rubbing down the frame, subframe, stands and fairing mounts. Again. Seems easy, if laborious, yet I cannot help but miss areas of parts on fiddly subframes and fairing mounts – and that includes when I'm painting!

I used an angle grinder with my favourite Norton Blaze discs to remove the old paint and rust on the untouched parts, but the subframe has some niggly areas, like where the shocks mount. So I blasted them with sand and blew clean with the air gun.

The frame was great other than where I'd missed sections (underneath), so that just needed roughing up with 400 grit Scotchbrit­e pads. Then everything was transporte­d to Nick's paint booth at Ashtons Classics, where he kindly allowed me to etch prime, high-build prime and finish in 2K black in his booth. After the amusing game of getting the parts securely held in the frames but without there being unpainted sections, I mixed a better quality paint than I had before as it has less tendency to drip, a constant problem (for me) on thin tubing.

Getting used to different paints when you don't do it all the time takes practice and I got used to the amount, the time and the pressure on the trigger needed for the paint to go on, then ‘merge' into itself to create a lovely finish. And this time I managed to cover almost all the parts – spraying black in a bright booth is not my forte and there's normally a small part I've missed!

I'll leave the frame for as long as I can so it hardens, apart from the masking tape on the chassis plate and paint code sticker on the frame. Why not just give it to a powdercoat company?

It's a personal preference, but I like learning new skills, I like doing things myself, it was paint originally (or enamel), and I feel paint gives a nicer finish. Powdercoat is strong and great, and there's nothing wrong with it; just not my bag.

The painting stops reacting and the brakes are starting to stop – where are the problems?

I'm pleased with the result: it looks original and it's a major part of the build finished. Let's go!

Before I stop talking of painting, I managed to buy two fairing lowers from FleaBay for £40. RS ones are the same as RT, so are not uncommon, especially with all the specials made from boxers. And they all seem to have holes in them for engine crash bars – which I'm going to tempt fate and not have, so I'll either fill, or make a blanking bung. They are in white, so Effie and I rubbed them down ready for a new life in black. I would use flexible primer, but early BMW plastic is so stiff, heavy and solid there's no need!

Once painted and before fitted, I intend to make molds of them so I can make replacemen­ts in carbon fibre at some point. When I get time. In another dimension.

Break, brake, break!

The brakes were seized when we got the bike – it was one of the reasons for the total strip. It is widely reported, even from new, that the brakes are only just up to the performanc­e of the engine, so I really wanted the best brakes possible. The master cylinder seemed to be the culprit, and under investigat­ion it was solid. A master cylinder repair kit cost an eyewaterin­g £57, with a complete master cylinder at £360! But the kit came with all the parts I need and

if it wasn’t for someone making these bits, all our bikes would be in the crusher. Stop complainin­g, you tight git, Hull!

The job was tricky at first, with most parts seized – BMW fitted a rubber cover over the pivot arm, which had done a fine job of protecting that area. I didn’t want to break the reservoir, or round off the solid hoses, which had been in there for more than 40 years. And as I’ve said before, everything that is hidden in between the saddle tank – like the fuses, coils and the master cylinder – have been among the worst affected by rust. Drain those petrol tanks, people!

I wanted to keep the solid brake hoses in one piece to make it easier to recreate new ones, but as they would not come off the flexi hoses, I had to cut them to get a ring spanner on. I left the circlip on one end of the piston soaking in oil for a couple of days, stripped the reservoir, its seating ‘O’ ring, and carefully removed the circlip – success. A waste of time, I know, but I wire-brushed and painted the cylinder. No one will see it but I’ll know. The cylinder bore had no corrosion, so I cleaned with brake cleaner, then a light coating of brake fluid and in with the new piston. New circlip, and another part ready to go on.

The calipers have been trickier to clean, and I haven’t finished them yet. I ended up buying new pistons as years ago I may have reused the old ones with a little superglue in the pitting, but there’s no point now. And they could leak on my newly finished front wheel. But at £120 for a pair, they better work!

Still not sure whether to replace the solid – flexi – brake line arrangemen­t with new, or with one longer braided line yet. Last thing I’ve done is polish the diff housing. On the advice of everyone in the known universe, I’m happy there is little wear and so leaving well alone. But I do like the Exclusiv Sport model’s polished forks and diff, but without spending hours removing the casting pattern. So it’s cleaning, Scotchbrit­e, brake cleaner, GT85, brass wire wheels in a brush, cleaning, and finally, when I’m about to throw it out of the window, I’ll lacquer it.

Looks lovely!

“Once painted and before fitted, I intend to make molds so I can make some replacemen­ts in carbon fibre at some point. When I get time. In another dimension.”

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