Speedo drive with Viva hubs / discs

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Nigel Webster (anrw)
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Speedo drive with Viva hubs / discs

Post by Nigel Webster (anrw) » Wed Jul 20, 2011 5:33 pm

Hello
Has anyone found a foolproof way of engaging the speedo cable on a car fitted with the Viva hubs /disc setup. With mine, every time I get full right lock the cable drive pulls out of engagement with the plastic pawl. I have no real need to know what speeds the car is going but I do need a accurate mileometer - or rather I need the drive going to a Terratrip that will give me distance covered. With the extremes of stage rallying I suspect the conventional Imp speedo drive system is always going to lead to problems. I have toyed with the idea of bicycle computer which uses a hall effect sensor but mounting it to pick up an impulse on the Viva hub (unlike the Fiesta disc brake conversion the disc sits inboard of the hub) is difficult. The other thought in the back of my mind with VOSA's computerised and realtime MOT records - it may be that they have built into their system an alarm if mileage doesn't change from year to year. Historic rallying regulations mean I must keep the original speedo head but the actual recording of miles covered would be far better handled electronically.

Does anyone have experience of these issues or a better way to get a feed to a Terratrip (or even a bike computer!)?

Regards

Nigel Webster
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Re: Speedo drive with Viva hubs / discs

Post by Meltdown » Wed Jul 20, 2011 5:50 pm

There should be a retaining clip and screw on the back of the stub axle that holds the outer cable in place. I have Viva discs and have had no problem in the (albeit limited) time driving it. I presume the terratrip is fixed somehow to the speedo cable.
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Re: Speedo drive with Viva hubs / discs

Post by Nigel Webster (anrw) » Wed Jul 20, 2011 7:40 pm

Nick
Thanks. Yes the Terratrip involves a transducer that takes the mechanical input from the speedo drive and converts it to an electrical impulse that feeds the unit itself. I am glad to hear your installation works well but one of the problems is the Viva hub / disc is wider than standard Imp (hence the increase in track) which means that the standard cable is inclined to be pulled tighter and therefore more inclined to pull out of contact with the drive pawl. Stage rallying of course involves all the axle travel at the same time as full lock sometimes which exaggerates the problem.

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Re: Speedo drive with Viva hubs / discs

Post by colin rooney » Wed Jul 20, 2011 8:11 pm

I HAVE HEARD THAT A SPEEDO CABLE FROM A LEFT HAND DRIVE IMP IS LONGER THAN OURS SO MAY BE WORTH ASKING SOME OF THE DUTCH LADS
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Re: Speedo drive with Viva hubs / discs

Post by Meltdown » Wed Jul 20, 2011 9:05 pm

I see what you mean, Nigel. I should think that a longer cable such as Colin suggested could then be modded so that more of the inner sticks out of the outer at the hub. Or perhaps machine the point where the outer butts to the stub axle by a couple of mm?
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Re: Speedo drive with Viva hubs / discs

Post by Mike Hanna » Wed Jul 20, 2011 9:28 pm

Hi. As the stub axle position is unaffected by fitting Viva discs perhaps you have a mk 1 cable fitted to the wider track mk 2 suspension mounts. It may be that the mk2 cable might be a little longer?? Anyone out there know? Cheers. Mike
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Re: Speedo drive with Viva hubs / discs

Post by Meltdown » Thu Jul 21, 2011 5:23 am

Mike Hanna wrote:Hi. As the stub axle position is unaffected by fitting Viva discs perhaps you have a mk 1 cable fitted to the wider track mk 2 suspension mounts. It may be that the mk2 cable might be a little longer?? Anyone out there know? Cheers. Mike
Does the Viva hub put the dust cap further away from the stub axle, though? Hence allowing more end float for the pawl?
One other thought, is the pawl worn in the cable aperture?
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Re: Speedo drive with Viva hubs / discs

Post by Mike Hanna » Thu Jul 21, 2011 7:40 am

Hi. Anwr does say that it pulls out on right lock.If the outer is fixed to the stub axle properly this would suggest the outer is stretching on lock thus pulling the inner out of engagement. IIRC when I rallied an Imp with Viva hubs all I did was to fix a pin in the Viva dust cap, but I used the higher, narrower mk1 suspension mounts. Cheers. Mike
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Re: Speedo drive with Viva hubs / discs

Post by Nigel Webster (anrw) » Thu Jul 21, 2011 8:49 am

Mike I am using low pivot point front suspension mounts - would that make a difference? I suspect that I have a home made retaining clip and I see in the workshop manual mention of a rubber washer (which I don't have) - maybe I should start again with a new screw, new clip and a rubber washer? I guess these are available used only - anybody got any spare? The other point is that there is no flange on the end of the outer cable for the clip to locate into - should there be?

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Re: Speedo drive with Viva hubs / discs

Post by Mike Hanna » Thu Jul 21, 2011 12:52 pm

Hi Nigel. The low pivot mounts will add approx 16mm to the track, add Viva disc also and you have nearly 1.5 inches extra track on the front compared to a standard mk1 Imp. I would always use the mk1 high pivot for any sort of competition Imp, especially for rallying as it gives greater ground clearence. I would never run negative camber on the front either as seems to be the current fashion. Looks don't count, results do!! Cheers. Mike
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Re: Speedo drive with Viva hubs / discs

Post by imporium » Fri Jul 22, 2011 10:51 am

colin rooney wrote:I HAVE HEARD THAT A SPEEDO CABLE FROM A LEFT HAND DRIVE IMP IS LONGER THAN OURS SO MAY BE WORTH ASKING SOME OF THE DUTCH LADS
Hi, thats the Irish LHD version then ..... :lol: as the proper LHD ones I have here are shorter at 51" & the new complete RHD ones we have had remade now with Dr Bob are 57", screw on head type.....£15........... Malcolm
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Re: Speedo drive with Viva hubs / discs

Post by The Nun » Fri Jul 22, 2011 3:49 pm

Meltdown wrote:
Mike Hanna wrote:Hi. As the stub axle position is unaffected by fitting Viva discs perhaps you have a mk 1 cable fitted to the wider track mk 2 suspension mounts. It may be that the mk2 cable might be a little longer?? Anyone out there know? Cheers. Mike
Does the Viva hub put the dust cap further away from the stub axle, though? Hence allowing more end float for the pawl?
One other thought, is the pawl worn in the cable aperture?
Ive got Viva hubs low pivot suspension later dash with standard push on speedo cable, standard cable retainer on stub axle , and mine never pulled out, it doesnt if you do it properly.
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Re: Speedo drive with Viva hubs / discs

Post by cov_climax » Fri Jul 22, 2011 4:31 pm

if it's just the terra trip that matters, you could consider an electronic pick-up off the front wheel, i have a proximity sensor that sees the passing heads of the wheel studs for my electronic speedo, there is another type where you glue magnets on and use a read switch
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Re: Speedo drive with Viva hubs / discs

Post by colin rooney » Fri Jul 22, 2011 6:25 pm

imporium wrote:
colin rooney wrote:I HAVE HEARD THAT A SPEEDO CABLE FROM A LEFT HAND DRIVE IMP IS LONGER THAN OURS SO MAY BE WORTH ASKING SOME OF THE DUTCH LADS
Hi, thats the Irish LHD version then ..... :lol: as the proper LHD ones I have here are shorter at 51" & the new complete RHD ones we have had remade now with Dr Bob are 57", screw on head type.....£15........... Malcolm
oh yes you know us paddys mate were like the texan every thing is bigger :mrgreen:

col
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Re: Speedo drive with Viva hubs / discs

Post by Meltdown » Fri Jul 22, 2011 6:35 pm

/\/\OOER missus :o :lol:
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Re: Speedo drive with Viva hubs / discs

Post by Nigel Webster (anrw) » Fri Aug 12, 2011 11:05 am

Many thanks for the helpful comments on this subject - now sorted (I hope) and will be put to the test at the Neath Valley Stages this weekend - see separate post.

Regards

Nigel Webster
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