Speedometer Off

[green_hornet_96]

My 1996 Civic EX manual's speedometer is 5mph too high, and I don't really know why. I've clocked it with radar and 3 other vehicles over a 50 mph range, I'm sure thats where it is. My mom's 2000 Civic EX auto is 5 high also, and so is my friend's 2000 Civic EX manual. Apparently this is somewhat common, methinks...is there a way to fix it that won't mess up the gauges? It really is a pain explaining to everybody I drive around that I'm not doing 15 over the limit.

[chasloa]

many automakers purposefully make your speedo show too high, so that you dont sue them when you get a ticket.
your could just need to be calibrated, however I wouldn't waste the time or the money worrying about it unless it really, really bothers you :wink:

[tec_wiz]

yeah, my delsol is like that also, I've always wondered but didn't care to have it recalibrated. one thing I heard was to pull off the speedo needle and then ride beside someone with cruise control locked at 60 and then put the needle on at 60 when running the same speed.

[green_hornet_96]

Ok, now i'm confused. I found the gear and final drive ratios and made an excel spreadsheet to calculate the speed of the car at any given engine speed and gear, given my tire diameter. Weird thing is, I took pics of the gauges when i was going down the road at various speeds and put the tach readings into the spreadsheet, and every time it comes up with exactly the same number that was on the speedometer. I don't understand because I've clocked the car with three vehicles (via 2-way radio) and two separate radars, and the speedometer always came up 5 high.

Any ideas? I'm really confused. I included one such pic of the gauges in 3rd gear just in case there's a d16y8 driver out there who might compare the numbers.

[green_hornet_96]

Ah i checked the numbers and they all make sense if the tach is 200 rpm high. What a mess.

PS> sorry for double posting again.