Author Topic: Racing Plates  (Read 2560 times)

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Offline giz.neal

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Racing Plates
« on: 09 Mar 2016 at 13:59 »
Gents,

I am currently building a 90+, trying to present a machine as it might have taken part in the Clubmans TT circa 1950. What colour would the racing number plates have been in period?

Looking at photos (black and white) they all seem to have a white front plate with black number(s). The rear (side) plates seem to have white numbers? did they therefore have a blue background for the Junior class?

Yours in hope

Offline cardan

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Re: Racing Plates
« Reply #1 on: 09 Mar 2016 at 21:19 »

Yes, please, I'd be keen for an answer on this question too. In the 1932 Senior TT the plates (in black and white) were dark-on-light at the front, and light-on-dark FOR THE RACE. During practice the plate combinations seem to have been reversed - light-on-dark at the front and dark-on-light at the sides.

No doubt a copy of the TT regs of the era would have the answer?

Cheers

Leon

Offline David Lawrence

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Re: Racing Plates
« Reply #2 on: 11 Mar 2016 at 22:10 »
Hi,
Regarding the colour of the 350 class plates, during the 50's the plates were light blue with white numbers, 500's yellow with black numbers, 250 green with white numbers. The different "grey" front number plates seen in photo's is because for the races the fronts were changed for all bikes to black on white, for the practice sessions numbers were all 3 the same colour to differentiate the machines passing the time keepers. In later years the front number was issued by the ACU and stamped so that the scrutineers could  be certain that the bike had qualified. Pre war I think that the system was different, to be certain someone is going to have to dig out some pre war programmes. It may be that the TT used a different system to the Manx.
Giz, If you care to email me directly I do have a few photo's of my 90 which I built many years ago modelling it on one of the versions! that Don Chapman actually rode in the Manx, small fly screen, large tank and rev counter mounted on an aluminium disc on the handlebars. It is the bike shown in my avatar rounding quarter bridge. The black engine has never had a satisfactory explanation the truth lost in the mists of time!
Dave

Offline cardan

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Re: Racing Plates
« Reply #3 on: 11 Mar 2016 at 23:25 »

Thanks Dave - very interesting, and as a non-racing person very enlightening. Here's my (non-Douglas) bike at the start of the 1932 Senior TT, and in practice, showing the different plates. I'm sure I can hunt down the proper colour for the pates, but if anyone here can help I'd be appreciative.

Leon


Offline oil baron

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Re: Racing Plates
« Reply #4 on: 12 Mar 2016 at 01:51 »
Hi Dave

Regarding the picture of the Plus with the Black painted crankcase, I remember talking 90 pluses with Don Chapman and Eddie Withers at an annual dinner in Russell Square in the late 1960's.  They mentioned that the works built up a works 90+ with cast iron crankcases, presumably this was to try and overcome the cracking on the foreward left hand side of the early plus crankcase, I think my old dad must have welded up four or five crankcases over the years for various people.
Eddie & Don also mentioned an experimental crankcase with a finned sump, which may have even been the cast iron crankcase as the cast iron would hold the heat more and matt black paint would also help. 
They reckoned the best advancement was the fitting of the timed breather which improved the power output by quite a measurable amount.
Don said that the iron crankcased bike handled well and was able to to rev higher than the normal engine, but I suspect the weight penalty may ended its use. Maybe the Plus crankcases were stiffened up to overcome the crack problem.
Cheers  Steve.L
Steve L

 

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