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Thread: T5 speedo driven gear

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    T5 speedo driven gear

    I am trying to source a Sierra Cosworth T5 speedo driven gear (partsnr.: 1643124), but with different number of teeth to the original one which is 21 teeth.

    My car has a different rear axle ratio and wheel size and therefor requires a 19 teeth driven gear to make the speedo read correct.

    Anyone know if it is at all available, or a work around using the 21 toothed original?
    67 TVR VIXEN V8

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    Re: T5 speedo driven gear

    http://www.americanmuscle.com/speedo...th-manual.html

    ?

    I have looked for different gears and there seem to be plenty for Mustangs, not sure if the fit a Sierra gearbox but I would think so.

    I gave up though and am working on fitting a Scorpio electronic speedo, an electronic speedo sender on the gearbox and having the Megasquirt output an adjusted signal for the Speedo.

    Regards

    Gustaf

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    Re: T5 speedo driven gear

    Thanks Gustav, but that won't work as the Sierra Cosworth adapter requires a driven gear with a stem/axle that the speedo cable fits into. The stem seals the driven gear against the internal o-rings in the adapter.

    This is what the adapter with driven gear from a Cosworth looks like



    I'd really like to keep the speedo mechanical as my car has some 60's Smiths instruments and none of the electrical ones are accurate copies.
    67 TVR VIXEN V8

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    Re: T5 speedo driven gear

    Ah, I see...

    What about the GM T5 gears then?

    http://www.thegearbox.org/catalog/it...32/3532517.htm

    I think they look more like the Cosworth gear.

    I'm fitting the Scorpio electronic speedo behind a Capri mechanical dash face so the install will be pretty stealth...but it's some work and you'd need an ond Smiths instrument to sacrifice.

    Gustaf

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    Re: T5 speedo driven gear

    The stem/shaft on th eGM-gears are 5mm to short so they don't seal up the outer o-ring in the Cosworth adapter.

    I can buy a custom made GM driven gear from http://www.transmissioncenter.org/GM...eter_Gears.htm

    But I need to know if the gears should be orientated right or left and what pitch for the stock drive gear on the output shaft. I would also need to know what diameter the driven gear needs to be.

    Apparently there is a mechanical speedo drive out there that fits, but I've never seen one, only heard about it and it's rare as hens teeth.
    67 TVR VIXEN V8

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    Re: T5 speedo driven gear

    OK...is it possible to convert the gearbox to a Mustang (or GM) style speedo cable drive? Or is the tailhousing different too perhaps?

    Gustaf

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    Re: T5 speedo driven gear

    The problem is that the hole in the tailhousing is unique to the TVR. It measures 1-1/16". The Ford Mustang uses approx 22mm and the Cosworth box approximately 1-1/8"
    67 TVR VIXEN V8

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