Sunday, 25 July 2010

The glaringly obvious thing that I need to make for the BMW at this point, is the seat hump. While most people who have seen the motorcycle in the flesh have expressed approval, their ideas about what the rear of the seat should look like have varied considerably. While it's quite a short looking motorcycle, my feeling is that proportion is a more desirable quality than shortness, so while the rear end styling needs to have an element of "short" about it, it also ought to look like it belonged there. Given that I'm using a (more or less) standard BMW frame, with a standard BMW fuel tank, forks and wheels, then the seat hump is what has to make the motorcycle stand out. Which is a lot to ask from a seat hump...

Bearing all that in mind, I chickened out of making the seat hump for a bit and made this battery tray instead. Once you've established that it's a tray, and the battery goes in it, there's not a lot left to say about it. It's going to accommodate a YTX-9 gel battery, led on it's side, and the standard BMW ignition switch, which will end up positioned under the left lower rear of the fuel tank. where hopefully it'll be discrete, but accessible. With the tray made, I drilled it to accept some mounting bolts, then made some brackets to mount it from. I made the brackets from some 3/4" x 1/8" steel strap. Bolting the brackets to the tray, positioning the tray, and then welding the brackets to the frame made the task relatively easy, and ensured that all the holes lined up.

All relatively straight forward and quite soon over and done. Which meant it was time to tackle the seat unit.

Rather than a card template, I cut out a piece of steel and drew a profile straight onto that. To my mind, this is the difficult part, getting a clear idea of the shape that you're going to make. Copying another shape is one thing, evolving the shape, working out how to make it, and then making something that matches up with your concept requires a different level of skill. A simple flat template can look ungainly, but adding some shape to it alters the profile slightly, and makes quite a dramatic difference to the way it looks, which means that the template has to drawn with that in mind.

To get the shape into the components of the seat hump, I think I used a ball peen hammer, the arbor press, a bench top English wheel, a big rubber hammer, a piece of timber , and my thigh, with the moral being that whatever works, is "correct".

After what might have been four hours of work, the seat unit looked something like this. Somehow it ended up being a lot more rounded than I meant it to at the rear, which is slightly problematic. I'm a little disappointed that the rear end isn't as flat as I wanted it to be, which is colouring my judgement of the overall effect. It also begs the question, how am I going to mount the rear light? The idea of heat forming some red perspex to the shape of the seat hump and then cutting a window in the hump and having a flush mounted lens for a built in light, possibly using LEDS as a light source crossed my mind, but I don't really want to do that, because I've done that sort of thing before, and I don't really enjoy it. It's a thought, but it's a last resort sort of a thought.

I think that by the time the seat unit has foam and upholstery, it ought to flow reasonably well with the tank, and everything below that will be quite skeletal and exposed, especially if I get a bit more vicious with the engine castings. I'm giving some thought to what I want to do with the frame, even going as far as buying a tapered reamer with a vague idea of making some Tony Foalesque tapered bosses to mount some frame braces on. I also ought to start looking for a bent, busted, or otherwise discarded Suzuki Bandit frame that I can cut the frame splice joints out of with an eye to grafting them into my frame so that the oil filter can be accessed without removing the engine from the frame. Though, other more radical, Team Incomplete inspired, ideas wander across my thinking spaces from time to time....

For now, finishing up the hump and another trip out into the daylight are the priorities.

Sunday, 18 July 2010

I closed the last post with the line "If it doesn't work well, it doesn't matter who made it, it's still crap.", and coincidentally, this weeks mission was to reattach the side stand. If you've never owned a BMW Boxer (or at least a /7 age one) you may wonder why you normally see them parked on the centre stand. This is because while the BMW side stand is clearly to one side of the motorcycle, and therefore justifies that part of it's name, it's a little less clear as to how it came by the "stand" part of it's name. If you'll accept my definition of "crap", then "side crap" would be a better title for the thing.

The problem is that the side stand has been designed to meet some spurious regulation that assumes that the worst thing that can happen to you is pulling away with the side stand of your motorcycle extended. In their enthusiasm for making the stand idiot proof, BMW seem to have sacrificed it's ability to be gravity proof.

Since I'd already disposed of the centre stand mounts, then I was left with a choice between always parking near a wall, or improving on the side stand somewhat. I took a section of 1 1/2" OD, 1/8"wall tube and cut in half length ways to make a "saddle" to sit over the BMW's lower frame rail. Then I cut the original bracket at an angle so the stand would be further over centre when it reached the end of it's travel. My idea was that by increasing the amount the stand moved over centre, and by arranging for the motorcycle to lean over further, then things would be a lot less precarious while the thing was parked up.

The point of the "saddle" is three fold. Firstly, it's around 50% thicker than the factory frame rails, so welding it to the cast steel bracket is a lot easier, and welding the saddle to the frame doesn't present a problem either. Secondly, welding the saddle to the tube distributes the forces into the frame in a much happier fashion than welding the bracket directly to the frame rail. Thirdly, and possibly most importantly, two tacks on the inner most edge of the saddle will locate it firmly enough to support the weight of the motorcycle, allowing you to test out the positioning. Should it prove unsatisfactory, extending the stand and pushing down on it, will easily break the two tacks off.

Somewhere down the line, the original side stand bolt had gone missing and been replaced with a hex headed set screw that had had it's head ground to a countersink and a slot hacksawed in the end of it. That meant that the stand was pivoting on the thread of the screw, which isn't ideal, so I took an 8mm countersunk Allen bolt, and threaded it further up it's shank and cut the threaded portion off to the correct length. With that sorted out, I re-assembled the stand onto the modified bracket and got Ben to hold the bike at the angle I wanted it while I tacked the saddle to the frame. After a couple of goes at finding a position for it, I eventually had the stand positioned so that the motorcycle didn't appear to be in any danger of falling over, and the stand itself stowed away neatly missing the exhaust and gear change.

Many people would feel that was an inordinate amount of trouble to go to over a simple side stand, but I don't agree. Many of those same people would happily go to immense amounts of trouble, and expense, over a paint job. If the motorcycle is prone to committing Hari Kari every time it's left on the stand, how long is that paint job going to remain unmarked? Coming back to the motorcycle and finding that it has not only decided to lie down and have a rest, but also leaked the majority of the fuel that was in the tank all over the tarmac doesn't do much to improve your day either. I may have mentioned that it's not enough for a thing to work, it has to work well.

Something the motorcycle is clearly lacking, is a seat, and since the object of the exercise is to build something that makes the average passer-by think "Oh! Look! A Café Racer!" it needs a bum stop seat. I could just buy one, but there are a couple of snags with that, to whit, my knees and the point.

My knees would prefer it if the seating position was nearer to the standard height, and not the sort of height that an after market bum stop mounted on the seat rails would dictate. The point is that, at heart, this is a styling exercise and slapping some random piece of fiber glass on there doesn't contribute to a cohesive look. Now that it has a stand I can wheel the motorcycle out into the fresh air and stand back far enough from it to make some sort of a decision about what I want the seat to look like.

Because I need the seat height, I might as well stow a gel battery on its side under the seat, in which case, some of the other electrics might as well live there too. Hopefully I can stow the coils under the tank, I'm planning on dumping the standard electro-mechanical regulator and the diode board for the much more compact (and cheap) components from the inside a car alternator and there will probably be some trickery with relays involved. Unless I have some electronics made to do the same job...

The seat unit is going to be a bit problematic. It has to raise the seat height, provide for hiding some of the electrical bits, look like it belongs with the tank and at the same time it has to say "Cafe Racer" loudly enough to overcome a certain amount of handle bar prejudice that is sadly rampant in the population at large.

And it has to do all that well.

Sunday, 11 July 2010

What I really need to do is to buy myself one of those big wall planners, and mark in the deadlines for the stuff I write. That way I'd probably spend less of my time in a low grade panic. I needed to do something for an article, so I started making a random petrol tank, and there's only so much metal bashing I can comfortably put up with in one week, and I'm not massively attracted to the idea of doing a job more than once. So, as you might imagine, the prospect of bashing out the third version of the front mudguard for the R65 didn't fill me with enthusiasm.

So, I went shopping instead. I needed some bits and bobs to finish off the rear sets, and chased most of them down on the Internet. I was a little dubious about the left hand thread M6 x 1.0mm stainless steel nuts I bought off of E-Bay arriving in time as it did say "seller usually posts within 5 days", so I stopped off at my local supplier and bought some from them. The Rose joints, two right hand, two left hand thread, were ordered on the Thursday night, and arrived on Saturday, and the left hand M6 x 1.0mm die and die holder were ordered Friday afternoon and showed up on Saturday too. Sadly the other thing that showed up on Saturday, was a hangover.

In some sort of an attempt to rationalise what I was up to, I also decided to do a little more shopping on Saturday, and hunt out a 1930's-40's petrol can, so I could use the neck and brass cap as a filler cap on the random fuel tank I'd started making. The idea being that if I stick with it and finish the tank, then my "To Do" list will have one less thing on it. I did manage to buy two petrol cans, and the forward planning paid off, as I hadn't realised the necks on the can were brass, and I'm going to need to solder them on to the petrol tank.
The upshot of all that was that by about mid afternoon on Saturday, I'd made it to the workshop, clutching two petrol cans, assorted parts for the R65's rear sets, and my head. The logical thing seemed to be to connect the rear sets I'd made to the things that they needed to operate, using the recently arrived bits and bobs and some of the 6mm stainless rod leaning up against the wall by the drill press. Naturally, once I picked up the 6mm stainless steel rod, it turned out to be 6mm mild steel rod.

Luckily Rob has been quite busy lately and was working on the Saturday too. Luckily because one of the things he makes are grilles to protect stained glass church windows from assorted air born hazards, and he makes them out of stainless steel mesh welded to a 6mm stainless steel rod framework. A short walk across the yard, and I had a couple of feet of material to do the job with.

The gear change side of things was relatively straight forward, I cut a thread on one end of the rod, measured it, screwed on a lock nut and the rose joint, and measured from the end of the thread to the centre of the ball on the Rose joint. That told me that with 7/8" of thread, the centre of the Rose joint was 1 1/2" from the end of the thread once the joint was bottomed out. That meant that the centre of the linkage was 5/8" from the end of the rod, and that the overall length of the rod (without the Rose joints needed to be 1 1/4" less than the required centre to centre measurement. Now do you see why the hangover was significant?

I've seen rear sets on Beemers where the controls are positioned not unlike mine, but the brake rod departs from the pedal and travels off to the rear brake. Don't like that, because the rod is so much shorter than the swing arm, not parallel with it, and pivots about a completely different centre, it's all going to be a little prone to conflicting arc issues. Then the ratio of the pedal is all wrong, the standard BMW pedal (or at least the one I have) has a 5:1 ratio, dinky little concentrically pivoted rear set levers make it hard to achieve better than 4:1.

While that lot won't prevent the rear brake from working, it will mean it doesn't work very well. For a little more effort, it ought to be possible to have a rear brake that performs very much like the factory one. My rear set levers have a ratio of 3:1, so I cut the original brake pedal up and welded a piece of 1"x 1/4" strap to it to turn it into a 1.66:1 idler for the brake mechanism. 3 times 1.66 comes to 4.98, and that's pretty close to the original 5.

As well as sorting out the pedal ratio, this also puts the brake rod in the original position where it's pivot is much closer to the swinging arms and the whole geometry of the set up is a lot happier and the rear brake set up now uses the original pedal stop. I might add that while the maths was getting more complicated, the hangover wasn't getting any better...

As you can imagine then it came as something of a relief to go back to making the link rod from the rear sets to the idler. Somewhere in the week, I did find the time to make the ends for the pedals, but apparently I didn't find time to swap the zinc plated Phillips screw holding the two sections of the pedal together for a stainless, button headed Allen bolt. I think it's fair to say that the finished thing looks quite a lot like a real one, though for the reasons I explained, they're going to work better than some of the off the shelf "real" ones you see.

Clearly, the original "bolt-on" concept I had for this project is long dead, but I'd like to think that the reasons for that aren't entirely due to my reluctance to part with money. If I feel I can make something that works and/or looks better, then I'd rather make it myself than buy it. That's not because of some misguided idea that you have to make it all yourself, it's simply because I know what I want, and I'm not compromising that by buying something that's only nearly what I want. The other part of the equation, which may come as surprise to people who watch a lot of Discovery Channel, is that it's better to hit some notional target of right, than it is to have it done in some notional period of time.

Since I briefly touched on the "DIY Nazis" in the last paragraph, I'd like to share a closing thought with you. If it doesn't work well, it doesn't matter who made it, it's still crap.

Sunday, 4 July 2010

I think I mentioned that I was going to be unexpectedly busy this week, and that BMW related progress might suffer as result. That was before I remembered that my nephew was getting married on the Friday, and my nose was invaded by some sort of nanotech rubber factory. I'm fairly sure there's a rubber factory up my nose. as snot isn't usually thick enough to bounce is it?

I did get the front mudguard made along with some mounting tags to weld to the fork brace as you can see in the picture to the left. Looking at the picture, it doesn't look that bad, but it's not really floating my boat because the radius of it's edge isn't concentric with the tyre.

I've got something over half a sheet of 2mm thick 1050 aluminium that I've been avoiding using for some time now. I suppose that an aluminium mudguard on a café racer is practically de rigéur, and aluminium is much easier to shape than steel so I'm sorely tempted to have another go using the ally.

I can't remember if I mentioned the colour scheme I have in mind? I've been thinking in terms of silver and orange, as when I think of German machinery racing. in my mind's eye I see the 300SL that Stirling Moss, with Dennis Jenkinson as co-driver, drove to win the 1955 Mille Miglia. I think it's fair to say that the win was as much due to Jenkinson's invention of pace notes as it was to Stirling Moss' driving. You can read more about it on Stirling Moss' own site.

Hopefully, the silver/orange paint scheme will make the foam air filters look a little less lurid. Though, in fairness, considered as a whole, and if you can picture the exhaust in black, and the earlier type rocker boxes in place, the overall effect is quite pleasing I feel.

During the course of the week, the nice people at Spectrum Contract Vinyls sent me a sample card of their range of coloured upholstery vinyls, so I ought to be able to find some vinyl for the seat that qualifies as orange without clashing with the filters, and then go and find some paint to work with that.

While I'm brandishing links around, if you're interested in this, you'd probably enjoy yourself at RockerBoxer which is Vanzen's site and has a huge gallery of Airheads both race and café, as well as his own, rather more ambitious, BMW build.

Aside from Version 3 of the front mudguard, I probably ought to get around to doing some shopping for assorted bits and bobs. That said though, I ought to do something about the side stand in the fairly near to immediate future...