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Discussion Starter #1
Have developed a new problem as of late. It used to only raise it ugly head on the highway but now seems to want to be a part of my everyday life, at least when I have the cougar out for a ride. It is a 68 XR7 with a 302 C4 Auto. The speedo likes to be a little on the indecicive side while going down the road. It will bounce around between 40 and 60 mph when I am going somewhere in that range and as I go faster the "bounce range" seems to get a little larger. I am thinking it is possibly the cable from the transmission to the speedo but don't know for sure. It did it occationally before I put on the new heads, headers and intake, carb and exhaust but now seems to do it all the time. There is nothing touching the cable that I can see, maybe all that new power has it intimidated and it is afraid to commit to a speed now. I have also changed the wheels to the 15"X7 that are available from wccc and mounted a set of radial BFG's on all 4 corners. I imagine the speedo will be off a little because of the change but with all the bouncing that it is doing, who knows how fast I am going....
Charlie
 

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You can try greasing the cable or you can purchase a new cable. If you have a portable GPS most will also give you an accurate speed. I had to use one for a while when I installed the 3.55 gears but had not yet changed the speedo gear.
 

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If greasing the cable does not help (good to try though because it is not too hard to do), the more likely candidate is the speedo itself. I had to change mine out for another for the same reason, don't know if there is a procedure for cleaning the mechanism that would fix a problematic unit. The speedo is magnetically coupled and I understand that sometimes dirt or debris (possibly magnetic and that is how it gets/stays in the works) gets between the drum (what's connected to the needle) and the hub (what's connected to the cable) and can cause the jumpy behavior you are seeing.
 

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Discussion Starter #4
Thanks will give the grease a try, can't hurt.. My car looks a lot like your C7X7, Polar White without the vinyl top and tires look about the same width. I had one just like it back in high school ('75-'76) really missed it so bought another. The speedo is weird, seems to be fine at low speeds, gets really weird at about 40-60mph and settles back down once it gets up close to 100mph. Hope it is just the cable, working in the dash is not one of my favorite things....
 
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