Scott gearbox question

[Richard Moss]

I don’t know what I was looking for exactly but yesterday I came upon a recent article (April 8th) on ‘The Vintagent’ blog about a Scott reputed to have been used by Phil Vare in the 1929 TT.

https://thevintagent.blogspot.co.uk/2014/04/the-1929-tt-ex-works-scotts.html

A nice looking bike, which I can see from the comments, now belongs to Brian.

My question is about the caption on one of the photographs in the article, the gearbox number. In the caption the author states ‘The modified Velocette gearbox, as used by Scotts for years, here marked ‘TT8’

Is this right? In the years of random Scott information osmosis I don’t think I’ve ever seen that suggested. Is he just getting mixed up with the fact that with modifications you can actually use a Velocette cluster in the Scott box to give you four gears, because the clutch position as dictated by the high gear/ output shaft assembly is nominally compatible?

I’m guessing that this information is incorrect. Given that it would have given Scotts a viable four speed box it would have been a good idea though!

[Martin Heckscher]

Hi Richard,
This is the 1929 TT machine which we (Bonhams) sold last weekend at Stafford. I think Paul (“thevintagent”) must have been getting confused with Silks which were fitted with a modified Velocette gearbox. The Phil Vare machine has a Scott gearbox.
Best wishes
Martin

[BRIAN MARSHALL]

Hi,
Just to clear up a bit more confusion…. It is WX 179, 1929 TT3, that I own, bought four years ago from Paul d’Orleans, “The Vintagent”, from San Francisco, NOT the ex-Geoff Lee machine just sold by Bonhams. Who bought it ? Incidentally, the provenance of the 1927, 1928, and 1929 Works Senior TT Scotts is nothing like as clear-cut as the Bonhams descriptions would have one believe. After the TT events were over the team machines were taken back to Shipley, and dismantled. I have copies of the letters sent by Manager Matt Rowley to the West Riding of Yorkshire Taxation Office, saying that the machines had been “scrapped and dismantled”. Obviously that was an untruth, and they were not scrapped. They were RECYCLED, in every sense of that word. In 1930 an emergency replacement team was put together, using an amalgam of the ’28 and ’29 bikes, due to the total failure of the intended vertical-engined machines. Later they were again dismantled, and because the factory was desperately strapped for cash, they were reassembled again, and at this time registration numbers, frame numbers, engine and gearbox numbers, etc., were jumbled up !!! To make matters even more complicated, several of the engines and gearboxes were replaced by Dirt-Track Model items, plenty of which were gathering dust on the shelves due to the Scott DT Model being eclipsed by the DT Douglas and Rudge machines. They were stamped-up to look like TT units, and sold off as ex-TT machines. I have been trying for years to get my head around all this confusion, and I’m still a mile away from the full story. For instance the machine just sold by Bonhams has a DT type box, and a standard Flyer clutch, not pukka TT items…. The engine in the ex-Geoff Lee machine is stamped TT3, and if that is original it is the engine originally in my frame, numbered 3M… I could go on and on about all this !
Brian

[Richard Moss]

Thanks Martin.

Brian, I’ve got a two year old girl and our second due in August.I’m perpetually confused.
I have a question for you though… We’ve got a gearbox from one of the vertical TT engines (this alone is not a good design) and I actually built the cluster into a modified standard three speed box a few years ago to try it. I’d done the maths and saw that it was a very close ratio, but really wanted to try it. I took it to Cadwell and completely destroyed my clutch getting it off the line throughout the day. The ratios were exactly the same as 2nd,3rd and 4th on the four speed box. Did you find similar gearbox ratios on the TT stuff you’ve been working on?

[BRIAN MARSHALL]

Hi Richard, Works TT gearboxes usually have normal ‘vintage-close’ ratios, as used on TT Replicas, Sprint Specials, Dirt-Track Models, etc.. Sometimes however I have come across boxes with a lower bottom gear pair. Bear in mind that these vintage era boxes have a solid one-piece layshaft as opposed to the later built-up layshafts. This means that these rare gearboxes must have been very special toolroom jobs. I suspect, but as yet cannot prove, that they were built for the handful of Sidecar TT outfits, and intended to get the relatively much heavier outfits off the line and around slow hairpin bends without burning out the clutch. In 1928 this would have been 28TT1 and 28TT2, built for the 1928 Sidecar TT that never took place due to lack of manufacturer support. In 1929 I believe the same thing probably happened. There was of course plenty of other sidecar racing, so these outfits would have had a life elsewhere ! As I mentioned in a previous posting, the majority of gearboxes in surviving 1928/9 TT machines seem to be actually Dirt-Track gearboxes stamped to look like the Real McCoy. Genuine original TT boxes are VERY rare indeed, and they have hollow mainshafts and layshafts and no high-gear bush. Instead they have a double-row caged roller bearing in a special bolt-on housing. If run with a tight chain these would soon break up, with disastrous results.
In addition, they have a ball bearing on the outer end of the layshaft, instead of the bronze bush used on production bikes.
Brian

[Richard Moss]

Yes, the ‘box I’m talking about has some of these features but not all. The case is a different design, but it’s basically a standard three speed box stood on it’s end with the mainshaft uppermost. It does have the double row bronze cage for the high gear but (I’m pretty sure) the layshaft is solid as you say and not built up.The mainshaft has a larger diameter at the cover supporting a larger bearing. I had to have the relief around the mainshaft bearing’s bore in a spare standard 3 speed cover welded and then I re-bored it to take the new one. They were excellent ratios once you got going and although I’d spent a lot of time to find that it just wasn’t going to work, it was an interesting exercise. I run vintage close ratios now and though they still give you a high first when you have to gear up for a long straight, they are at least usable in all areas. Roger used to run the hybrid set on my bike.. I can’t remember the name (is it modern close?) or the mix, but the sprinters used it. First and second close together and a bigger gap to third. I couldn’t get on with it. To be honest one of the biggest performance mods I’ve done recently is to improve my clutch by fitting gauge plate plain plates that Roger has, each of which I had to dremel slightly to get to fit with between 0.005″ and 0.010″ clearance on the centre. Well worth an hour or two. With three gears on a circuit with a long straight it’s going to take a beating at the start and the more metal there is in contact and the less hammer there is between surfaces the better it is. My clutch is superb now, ultra light action and quiet. The great thing about using gauge plate is that you don’t have to wind your springs in just to flatten your plates to get drive as they are flat already. You only have enough spring tension to do the job they should be doing. I think I digressed…

[TedParkin]

😀 😀 😀 Thanks Brian for the Gen on the TT bikes! Wot Larks Eh!! 😀 😀 😀

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