Ok what would make the Speedometer a constant 5MPH over what it actually is? at 5MPH it reads 10MPH, at 75MPH it reads 80MPH so it does it at all speeds

Yes I have the stock tire size, and Ive never changed or really messed with the Speedometer gears

 

Not a whole lot. Does the thing set on zero when stopped?? Most speedo errors are proportional, or erratic, a steady 5+ is a little unusual.

 

the question i have, is how do you know how fast you are actually going?

 

Mine is constantly 6MPH over what I'm actually doing. There is a road here that is pretty twisty, good for racing, and it has a few of those pernament speed boxes. You know, it says what the speed limit is, then what you are going. I'm used to my cars reading about 2MPH faster than I'm going(which is a tactic so you THINK you are speeding when you are really doing the limit), but not 6MPH. I've not tested at high speeds, but I know it does it at 30MPH, 35MPH, 45MPH, and 50MPH. Mine sits at 0 when I'm not moving. It bounces a little bit at lower speeds and when I slow down it bounces fairly bad. At a steady speed it stays steady.

I think its got to do with the cable. A new cable(or take out the old one, recondition, relube, etc) will probably fix it up.

--Ryan

 

My speedo sits on 0 when stopped and Ive triple checked to see that it is always 5 over. I cleaned the cable once, I'll try it again and see if it helps. But I doubt thats it.

Anyone know the stock speedometer gear for a 80 280ZX with an R200 3.9 Gears?

 

seems like alot of 280zx speedos are 5mph over at higher speeds, generally not at low speeds

 

You know, maybe these things are SUPPOSED to be like that. Afterall, it is a sportscar. Maybe they wanted to trick us into thinking we're going quicker than we really are?

Or we just need to buy new cables.

--Ryan

 

now its just new cars are getting slower


80's SPEED FTW!!!!

 

I had an old Ford PU(complete with 235 Chev 6, and NO, I did not put it there) that the speedo read 37% slow on. Wasn't any big deal, just one equation and you were set. Then I went to see a buddy, in Canada. Now I have to divide by .62 also to get into km. by the time ya got the math done it would be easy to be to late.

 

lol Nice
Well I wonder if its not the the speedo itself now. I have a spare and I'll change it out when I pull my dash. and clean the cables