"BiTurbo228 - Dr Frankenstein of Spitfires" (biturbo228)
10/22/2015 at 05:14 • Filed to: Spit6
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"BiTurbo228 - Dr Frankenstein of Spitfires" (biturbo228)
10/22/2015 at 05:14 • Filed to: Spit6 | 4
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Notched the chassis to provide clearance for the speedo drive. Used my favourite method of patch forming which is to cut the patch to roughly the right shape, weld on the bottom edge then bash it with the ball of a hammer until it conforms to the curve that you want. Works perfectly :)
Oh, I’ve also discovered that my overdrive unit is actually from a Volvo which caused a bit of a panic when I discovered that the speedo drive is geared differently and has a smaller socket for the speedo cable.
Then I did some maths and found out that the speedo gearing will over-read by 2.86% compared to the standard saloon gearing.Considering that (depending on tyre choice) my speedo would under-read by between 2.71% and 4.9% so that change cancels some of that out I’d call that an accidental win :)
It has meant I’ve had to grind down my speedo angle drive cable which, with hindsight, wasn’t really the best way to do it as it’ll probably unravel (turns out it’s a coil of spring-steel not a solid rod). I’m thinking I’ll stick a thin layer of chemical metal onto it to stop it from disintegrating and see how long it lasts...
RamblinRover Luxury-Yacht
> BiTurbo228 - Dr Frankenstein of Spitfires
10/22/2015 at 09:21 |
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Your method of patch forming is indeed the correct one. :) As to my project, I very nearly ran into the same trouble with not having the speedo drive clear, except then I realized I could push the whole trans/engine stick further back. So then I had this sort of clearance issue, but on the other side at the reverse selector. DURR. Sorted that out some months ago. As to speedo drive gear sizes, it turns out my trans uses a standard size across GM applications that can be had for every rear axle ratio under the sun. The only trick will be what I have to have made for a cable, as I’m relatively sure the stock cable is too short. Different sort of problem.
davedave1111
> BiTurbo228 - Dr Frankenstein of Spitfires
10/25/2015 at 09:28 |
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Something to note: you get some leeway to have a speedo that over-reads. Having one that under-reads is illegal.
http://www.legislation.gov.uk/uksi/2001/25/m…
1. The vehicle shall be fitted with a speedometer capable of indicating speed in mph at uniform intervals not exceeding 20 mph at all speeds up to the maximum speed of the vehicle and capable of being read by the driver at all times of the day or night.
2. For all true speeds up to the design speed of the vehicle, the true speed shall not exceed the indicated speed.
3. For all true speeds of between 25 mph and 70 mph (or the maximum speed if lower), the difference between the indicated speed and the true speed shall not exceed—
V/10 + 6.25 mph
where V = the true speed of the vehicle in mph.
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BiTurbo228 - Dr Frankenstein of Spitfires
> davedave1111
10/25/2015 at 11:45 |
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Yeah I’m anticipating that the speedo will be producing an over-read from stock so I’ll have a little leeway there. I’d only manage to get an under-read if I’ve put a minus somewhere in my calculations that I sohuldn’t have done...
Besides, I want an accurate speedo :)
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davedave1111
> BiTurbo228 - Dr Frankenstein of Spitfires
10/25/2015 at 12:34 |
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Oh, I must have misunderstood what you meant.
Accurate is good, but you need multiple checks or you won’t know whether to trust the maths or the GPS when they come out different :)
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BiTurbo228 - Dr Frankenstein of Spitfires
> davedave1111
10/25/2015 at 15:43 |
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Hah, if they come out different it’s 100% my decade-plus-old GCSE maths failing me...
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davedave1111
> BiTurbo228 - Dr Frankenstein of Spitfires
10/25/2015 at 15:59 |
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Not sure I trust your maths on the 100% thing either. ;)