Quote:
Originally Posted by Jeepwm69
Just to necro a thread, finally put a GPS on my truck.
Speedo reads 45 when I'm going 57. That means I need a 1.26666 adapter right?
Speedo reads 35 when I'm going 45, so looks like the 1.26666 or the 28% increase adapter either one would put me close.
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Depends on whether there is an adapter on there already. If it is a K truck, there is probably already an adapter there, in which case, multiply the existing adapter ratio by the correction factor to get the required new adapter ratio. You don't want two adapters on there. If it is a C truck, yes, a 1:1.26 or 1:1.28 or 1:1.3 speed-up adapter is what you need.
GM didn't have a 1:1.26 or 1:128 adapter as standard parts on these trucks. The GM part number they would have used is 1565179, 1:1.300. These original adapters are very strudy, and also hard to find and expensive, $150 or so.
However, I did find this:
http://www.ebay.com/itm/1965-66-67-6...0eb813&vxp=mtr