Speedo reads 10% too fast

[honestabe]

I confirmed this with my GPS and the CHP in NorCal that my speedo is about 10% too fast. IE, at 70 MPH my speedo would read about 77 MPH. I'm running a 1JZ with a 5-speed swap and an auto tranny N/A gauge cluster. Anything I can do to solve this issue?

Adam

 

[emiliorescigno]

What size tires do you have?

 

[BorHor]

Which diff do you have?

 

[honestabe]

3.90 LSD I think (got the car as a shell, so I'm assuming it's stock). Tires are stock 225/50-16 size on 91-92 5-spoke rims.

 

[dugums]

Sorry man, but that's all I got at 2:30 in the a.m. :icon_bigg

 

[ValgeKotkas]

Actually, you can calibrate the speedo from behind.
http://www.supraforums.com/forum/showthread.php?t=217310&highlight=speedo+calibration
I had to drop the needle to like -x mph to get accurate reading Something was lil off

 

[7MGTEsup]

I think 10% off at 70 mph is pritty normal for most cars, as this way you get less speeding tickets. I just poped the nidle off and put it on about 1/4 lower my car is now spot on up to 50 mph and 2 mph out at 70 (68 mph gps) the funny thing is it's 10% out all the way up to 150mph so it doesn't get any worse.

 

[Jeff Lange]

Confirm accuracy of your odometer before going any further. Check how much it is off, it's a much more important figure at this point.

 

[JustAnotherVictim]

Leave it. That way you have a ticket excuse. Trick your brain, then you won't speed.

 

[ValgeKotkas]

^That's one smart hypnotizer there

 

[honestabe]

I've confirmed the accuracy of my odometer as being 10% too fast as well using a couple highway odometer check signs.