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ZUKIWORLD Discussion Forum => Technical Discussion - Beginner / Repair => Topic started by: WesP on October 25, 2011, 03:42:39 PM

Title: Speedometer 10 MPH fast
Post by: WesP on October 25, 2011, 03:42:39 PM
1988 Samurai (early model)
Speedometer works fine except it reads 10 mph too fast. Stock size tires. Everything on it is original as far as I know. Any ideas?
Title: Re: Speedometer 10 MPH fast
Post by: Skyhiranger on October 25, 2011, 05:44:56 PM
Does it set at 0 when you are stopped?
How do you know it is 10MPH off?
Title: Re: Speedometer 10 MPH fast
Post by: Drone637 on October 26, 2011, 12:04:16 AM
A buddy of mine has his like that as well on a 95.  His solution was to put bigger tires on.  :D
Title: Re: Speedometer 10 MPH fast
Post by: WesP on October 26, 2011, 04:31:35 PM
It goes back to zero when stopped. We have lots of radar signs in Southern California so it gets checked every time I drive it. It seems like a gearing problem in the speedometer drive. Are there different gears available for the speedometer drive?
Title: Re: Speedometer 10 MPH fast
Post by: Skyhiranger on October 26, 2011, 05:03:43 PM
Quote from: WesP on October 26, 2011, 04:31:35 PM
It goes back to zero when stopped. We have lots of radar signs in Southern California so it gets checked every time I drive it. It seems like a gearing problem in the speedometer drive. Are there different gears available for the speedometer drive?

Only one set of speedo gears available, as far as I know.  All samurais came with the same gearing, so no need for different speedo gears.  I've never heard of anyone being able to get different speedo gears.
Title: Re: Speedometer 10 MPH fast
Post by: tuxblacray on October 27, 2011, 01:22:51 PM

I like the bigger tires idea....  :laugh: But, if you know it is 10mph off is it really off then? (since you are aware of it) I run 35's and mine is 5 mph off at 60. Compared to the 2011 chevy truck running side by side with me.....

Ahh... the wonders of cell phones and good friends...
Title: Re: Speedometer 10 MPH fast
Post by: ack on October 27, 2011, 05:41:24 PM
I would believe that the cops are tweaking the RADAR displays before I would believe that there is something funky in your speedo system.

The proper way to test the speedo's accuracy is to compare it to a GPS unit set to display MPH.


Then, there is something that might be causing the bad indication that is not related to tires or gearing....

There is an adjustment screw on the back of the speedometer case that some people use to "correct" the speedometer reading after adding bigger tires and gears.  It may have been played with by someone at some time.  It is a stupid mod as it has NO effect on the odometer...

If doing a GPS run shows a descrepancy and you are SURE that the t-case and/or differentials have not been monkyed with, I would look at that adjuster screw for a fix.

I hope that this helps!