Vincents - A New Interest For Me

[roy the mechanic]

Speedos

Ok ,80 feels like 60. Sounds like a good advert for "the product" !. with mainly front-facing money-makers(speed cams) who gives a rats. Roy.

 

[Robert Watson]

I would take exception to your blanket statement about Smiths Instruments. If they are put together by someone who knows what he is doing and properly calibrated the can be spot on.

In fact I say that my TomTom GPS unit on my Vincent is pretty good, but not perfect because all through the speed range it is within 1-2 mph of my Smiths speedo!


Robert

 

[Tom Gaynor]

Smiths Instruments

This is not true. Vincent ones read fast (by something like 1600/1550), for reasons explained in FYO - basically, by accident or design, Vincent got the rolling circumference of a 20" tyre wrong. As Robert has suggested, get the tyre size right and the speedo is suddenly accurate... (The ultimate tachometer, "the Smiths conical" was a magnetic instrument fitted as standard equipment to Manx Nortons and Matchless G50s. I have one. Independently tested, it is spot on. They were never, however, cheap. Nor indeed were the Veglia instruments fitted to Italian race bikes.)
What is remarkable is that an instrument of such high quality as the chronometric lasted so long. Luckily no-one realised that something cheaper would meet the British motorcycle industry's quality standard of "barely adequate". All instrument makers made instruments down to a price for OEM, and up to a standard for other applications. Smiths magnetic "road" clocks are probably as good as you can get for 2 1/2d per clock. That's down to BSA's accountants, not Smiths. See also under "Lucas electrics", anything you want so long as it is the cheapest on the market. Shaft drive Sunbeams have dynamos made not by Lucas Industries Ltd. (like wot you poor folks have), but by Lucas Special Equipment Ltd., and the MC45 is indeed a superior bit of kit, beautifully made. Sunbeam were prepared to pay the extra for something that worked. QED.
Modern car speedometers however read fast with a consistency that means they are made that way. Every car I've had in the last 15 years has had a speedo that registered 80 when the car was doing 74 mph, and pro-rata. Maybe the clinching argument is that one can drive without paying "optional taxes" by setting 80 on cruise control, and be sure the cameras won't flash. They will at 85...

Never trust a Smiths instrument!! all of them are 10 per cent fast!! but better than a"vaguely" Veglia!!

 

[Robert Watson]

Tom re read what I said. If they are calibrated properly and a couple of other small tricks, they read speed very accurately. Mine on the Woolly Mammoth always within 1-2 mph of a GPS unit. By adding or subtracting weights to the balance wheel you can make the speed read exactly where it needs to be. A little trial and error is required. I know excatly what a speedo should read when driven by one particluar drill in my shop, as Danny Smith knows exactly what they should read when set up on his distrubtor machine.

The odometer on the other hand is dependent on the ratios of the gears and is not adjustable (except by changing tire sizes or cutting new gears!) hence my mileage is out by about 4%.

These two things are independent as the speed can be changed downstream from the initial drive speed, the ododmeter cannot!

Robert

 

[Tom Gaynor]

Smiths speedos

I knew what you did (or must have done) although I've never done it. Jacqueline told me how. (Nor did I say that I used to check my Smiths instruments with a Smiths hand-held laboratory taco, which alas I neglected to steal before my buddy did, certified to within an inch of its life.) However, while you may not have changed your tyre size (I plead dramatic licence, but a 3.00 x 21 would reduce the error to 2%) 1) that would do it and 2) Vincent did specify the wrong tyre circumference. I concur about the odometer. I just find it easier to multiply both readings by 0.96. Keeps me occupied on long journeys...
My point, with which I know you agree, is that chronometrics are actually bloody good instruments, and if many of the accessories on British bikes were crap, it was invariably because the OE buyers would only pay enough to buy crap. (Vincent are in a slightly different class: they weren't a big enough customer to demand their own superior kit at a reasonable price.)
I suppose we should be grateful that the nature of a magneto is such that making crap magnetos is extraordinarily difficult, they either work or they don't, or we'd all be bedevilled by Lucas 6 volt alternators and Gothic regulator / rectifier systems. Aaaarrrghhh!!
It's 8 degrees C here. We're all in tee-shirts. Tony Cording is in hospital with heat-stroke. (Joke...)

 

[Alan J]

Speedos!!

I didn't mean to be toooo serious!! speedo numbers, wheel rims and tyre sizes have been changed over the last 50 years!!we all like to think we go faster than we do!! Kilometers sound better, don't you think??

 

[peterg]

Howdy Jeff,

....no need to scratch your head here. You should be flattered that your post on whistful yearnings for a Vincent seemed credible enough to the assembled here to anchor a discussion 3 forum pages later on the nuances (vaguries) of Lucas instrumentation.

On the other hand, more telling would have been several hundred views..but no responses. That said, you're destined to get a Vin and fit right in, so proceed kind sir. The next Jerry Wood's auction is in only 6 wks.

 

[Bracker1]

Greetings Jeff, Don't get discouraged about the speedo. It is a beautiful instrument. Mine looks great on my desk. The Vincent speedo bounces up and down with the suspension, can be mesmerizing and distracting. I think speedo placement was an afterthought, should have been fixed and rubber dampened on the steering head. To accurately gauge speed, pass everything but the police. Good luck with your Vincent quest, Dan

 

[Simon Dinsdale]

I fitted a after market bicycle speedo onto the handlbars of my Vin. Its made by Sigma and rated up to 186mph, so that should just about cover it. After calibrating is as per instructions and against the local village sign that shows your actual speed, my 5" speedo is consistantly 10% fast. The other advantage of the Sigma is it displays the time and speed at the same time so no guessing when to stop for lunch.

Cheers,
Simon.

 

[Tom Gaynor]

Speedo mounting

The speedo is fully sprung - that's your bike bouncing up and down...

Greetings Jeff, Don't get discouraged about the speedo. It is a beautiful instrument. Mine looks great on my desk. The Vincent speedo bounces up and down with the suspension, can be mesmerizing and distracting. I think speedo placement was an afterthought, should have been fixed and rubber dampened on the steering head. To accurately gauge speed, pass everything but the police. Good luck with your Vincent quest, Dan