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Scott Project Bike (Part 1.): 1929 specification Sprint Special Replica

I have always fancied owning a Sprint Special ! Some say these are the most desired Scotts of all because they combine light weight with three gear speeds. Whether this is true or not I don't know but one way of finding out is to build one and see for myself (the chance of a real Sprint Special turning up on my doorstep being extremely small).

At the 1998 Scott rally I purchased a box of rusty Scott bits ! I squirted them with WD40 oil, packed them into a couple boxes, started saving and then spent a lot of time deciding what to do with them. In the meantime I came across an article (by Brian Marshall) in a old 'Yowl' describing what was needed to build a Sprint Special Replica. Looking at my pile of bits it appeared that I did indeed have the makings of one of these machines. So was born my latest (and, I'm afraid, still ongoing) project.

As it turned out, the box of bits appeared to be the remains of at least two Scott machines: a single down-tube three-speed Flyer dating from around 1931 and an engine/gearbox from a 1929 TT replica (I think ?). Looking more closely at the parts I realised that a LOT of work needed to be done if this was to develop into a roadworthy machine. Knowing that many basket case projects fail I reasoned that if I could get this bike to the point of assembling a mechanically fit rolling chassis fairly quickly then this would spur me on to complete the task. It wasn't that simple...

... almost everything was worn, damaged or incomplete with many of the parts requiring specialist work beyond my own ability: I realised this very early on and decided that the wheels, engine, magneto, tank and forks required professional restoration leaving me to concentrate my few skills and limited facilities on the repair, painting, assembly and fabrication of the remaining parts.

Looking at the RZ type engine which had been dismantled and stored in less than favourable conditions for many years. Whoever had stripped it down for storage ensured that the main bearing cups were well greased. After 20, 30 maybe more, years of storage the grease had turned into a hard varnish and the only thing which would shift it was a mild household paintstripping jelly which didn't react with alloy. The grease/varnish had done its job and after removal a pair of shiny main bearing cups were revealed. I collected all the engine parts together and took the whole thing up to Tim Sharp for re-assembly.

Meanwhile I started to look at the wheels, these were a Webb 19inch WM2 (front) and an Enfield/Scott 19 inch WM3 (rear). The spokes were virtually falling apart but the rims and hubs were in sound, but rusty, condition. Reading up on Sprint Special wheel sizes it seems most of them were fitted with skinny 21inch rims front and rear. I decided for reasons of practicality (ie. obtaining tyres that could fit) to opt for 21 inch WM1 (front) and 19 inch WM2 (rear) and packed the wheels off to Central Wheel of Birmingham to be finished in Black with Stainless Steel Spokes (not original, but I'm being practical !).

Fortunately the rear hub bearings were in remarkably good condition and after a thorough clean in paraffin looked as though they had a few more miles left in them (just as well because they're obsolete and the quote for one-off manufactured patterns brought a tear to my eye). A wanted advert in Yowl yielded a front and rear final drive sprocket (thanks to Geoff Harrison) and I discovered that Burton Bike Bits (the Enfield specialists) had a large stock of suitable cush rubbers and rear sprocket retaining rings. The brake shoes were to be relined to the original specification but removing them in the first place wasn't straightforward - the shoes were very tightly seized on the brake plate shoe pivots: I had to heat the shoe assembly repeatedly, apply penetrating oil, damp down the asbestos material (to prevent inhaling) and gently drift the shoes along their axis of movement. This took about an hour per shoe and resulted in separated, damage free components (though the original metal wired linings inflicted a few injuries on my hands). After all that, and with a rear brake shoe spring from Ken Lack the rear wheel was more or less complete.

I was not so lucky with the the cup and cone bearings in the front Webb hub, these were badly cracked and pitted. John Underhill supplied me with ¾ of a new set but in the end I opted to fit a set of modern taper rollers instead. Also, the front brake actuator was very badly worn on the shaft which passes through the brake plate. Roy Lambert very kindly re-sleeved the actuator and reamed the bronze bush in the brake plate to suit. The front brake shoes were relined and the front wheel was complete.I then turned my attention to the Webb girder forks. The fork spindles were badly worn, were fitted with the wrong linkages and the friction dampers had all but disintegrated. To compound the problem further the forks were designed for a cup and cone headstock but my single down-tube frame was fitted with with larger diameter taper roller bearings. Ray Daniels (Girder Fork Repairs) in Birmingham saved the day and repaired, rebushed and replaced the incorrect parts as well as making up some spacers to match the cup and cone fork steering bearings to the tapered roller headstock.

On examination and cleaning of the gearbox it was a contemporary 3-speed version fitted with 'Ultra-Close' gears and stamped "UCRG". As far as I can make out it was no different to any other 3-speed Scott box of the period except for the ratios (8.14, 6.12, 4.63). I stripped the gearbox and replaced the kickstart boss and bush, the quick thread bearing and race and reassembled. The clutch appeared to have new linings and was in excellent condition so I just cleaned it up and fitted it onto the gearbox.

Things were going very well: I received a phone call from Tim sharp saying the engine was ready and fitted with the 600cc longstroke barrels, he had measured the geometric compresion ratio as a high 11.x:1 so correct ignition timing for the engine would be crucial. Starting the engine was still a long way off, but at least now I was at the point where I had sufficient parts for the first 'dry' build. On a lovely dry summer day last August I laid all the parts out in the garden ready for assembly to the point where it could be bolted together and pushed around the garden (and imaging riding it). Whilst assembling the forks and wheels I noticed that the rear wheel was leaning at an odd angle with respect to the rest of the upright machine. On closer examination I discovered that the rear sub frame was twisted several degrees away from the vertical axis. I couldn't believe my eyes, no matter how long I contemplated the situation I couldn't pretend that the frame was straight. I knew things had gone too well.

There was nothing for it, I put the parts back in the shed and sent the frame off to be straightened. At the time of writing I'm still waiting for it to be returned.In part two I'll describe some of the jobs I'm doing in readiness for a nice straight frame arriving sometime in the Spring.

Paul

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