Hello all, I put a Cable X Box in my car last year after my T56 swap. I am driving it a little more now and have noticed that the accuracy of the speedo goes down severely after 50-60 mph. I have been using my GPS as a secondary speedo and have noticed that it is spot on till 50 or so then begins to read a slower speed than I am traveling. I took the car for a good rip and saw that my GPS was reading 110 and my speedometer was reading 85 and slowly climbing. I know that most of my driving is done at 65 and below, but I would like to stay away from some speeding tickets.

Any one have any experience with these and how to get them a little more accurate?

I am goin to play around with some different calculations to try and get it more accurate at the top end, but will most likely sacrifice the lower speeds accuracy.

I would really like to modify the T56 tailshaft to take a mechanical cable, but it is just to damn expensive. Not that the Cable X was cheap. Anyone know how to get this done for under $550 ?

 

A guy on the boards here does the tailhousing mod for $300.. (Alloy IIRC ?).

But honestly, after replacing 2 speedo cables that seized, I was so much happier with my electronic Autometer.

http://www.eecis.udel.edu/~davis/z28...s/DCP_3504.jpg

 

That gauge looks pretty good. I was thinking about that as well. How much do you have into setting up that gauge assembly? If I can get that set up for cheap I will go that route.

 

Summit has the Autometer 3989 speedo for $210, not sure if you can find it cheaper elsewhere.

I grabbed a used cluster from classifieds and cut it up to fit the autometer, so I left my stock stuff stock.

It's been a while since I played with the '165 (MAF) ecm also, I don't remember if it can be scaled for the ~40,000 ppm signal the T56 VSS outputs. The '730 (MAP) system can.