Speedometer wrong

[nissan4x4]

My speedometer on my 88 vg30i pathy is wrong,on a road thats about 4 to 5miles it will read 20 miles. what is going on? and it has the original size of tires.

Edited April 21, 2008 by nissan4x4

[csutke]

bad speed senor, or broken gear coming off the t-case

Edited April 21, 2008 by csutke

[unccpathfinder]

is the actual speed correct and just the odometer wrong? if the speed is correct and the odo is wrong its probably a bad gear or stop pin that is allowing the single mile counter to turn before the 1/10th mile counter makes a full revolution you could pull the gages out and hook a drill up to it to check and see whats going on

[nissan4x4]

i don't know im starting to think the speed is wrong too, how would you tell?

Edited April 22, 2008 by nissan4x4

[unccpathfinder]

have someone drive in front of you in a neighborhood and go like 20 or 30 mph... if you have a melted speedo needle you'd need to go faster than where it sticks...me and my buddy did that when I replaced my speedo needle to make sure I installed it back at the right place...he was on the CB letting me know what his speed was and I was pretty much bump drafting him just to have fun checking my speeds

 

I dont see how a stripped gear at the Tcase would give you more mileage or more speed I would think it would fail in the opposite direction and stop producing values

[nissan4x4]

yeah its wierd it says on a 4 mile road that i went 20 miles going to and coming back so its off about ten miles and someone told me that there pathy had then in kph

Edited April 22, 2008 by nissan4x4

[unccpathfinder]

even if it were in kilometers 4 miles would only be about 6 km

[IncidentalOffroader]

... if you have a melted speedo needle you'd need to go faster than where it sticks...

 

ahh yes, the "melted speedo needle"... that brings back memories of my '87 Pathy. Over time the plastic needle would curl down and scrape its tip on the gauge face, possibly binding it. I would take off the gauge lens and bend it back up, but the problem would eventually come back. Finally I straightened a paper clip, cut it to size, and placed it on the backside of the needle to keep it from bending back. I kept the wire in place with a piece of clear tubing slipped over both needle and wire, and tacked it all together with a spot of silicone rubber adhesive. That fixed the problem, and it looked fine. The clear tube wasn't noticeable at first glance, and it looked like it could have been part of the original design.

 

The next problem was calibrating the speedo after I took off its needle. The best way I could think of was to follow a buddy cruising steadily at a known speed, and placing the needle on the speedo so it would show that speed. (obviously the gauge's lens must be removed during this procedure). But that was more fuss that I wanted to deal with, so instead I measured my actual speed vs. the speedo speed and kept a mental note that the speedometer reads xxx MPH high or low.

 

A handy way to measure your actual speed is to use a stopwatch and the mile markers on a straight stretch of uncrowded freeway. Cruise steadily at freeway speeds. Start the stopwatch at a mile marker, and stop it at the next mile marker. Don't change lanes. Try very hard to keep a constant speed during that mile: keep the speedo needle at the same place (it doesn't matter exactly what it reads, just that it stays in the same place). Your miles per hour is the 3600 divided by the stopwatch time (in seconds). ex: 60s=60MPH, 62s=58MPH, 55s=65.5MPH. I like this method because you can do it yourself, anytime you are bored on a long drive down the freeway.

[unccpathfinder]

The next problem was calibrating the speedo after I took off its needle. The best way I could think of was to follow a buddy cruising steadily at a known speed, and placing the needle on the speedo so it would show that speed. (obviously the gauge's lens must be removed during this procedure). But that was more fuss that I wanted to deal with, so instead I measured my actual speed vs. the speedo speed and kept a mental note that the speedometer reads xxx MPH high or low.

 

theres a small notch on the "pin head" that the needle attaches to that shows which way the arrow goes but its hard to see that and install the needle at the same way

[nissan4x4]

i still haven't figured it out i checked the gear in the trans. it looks to be fine no wear.

Edited April 23, 2008 by nissan4x4

[unccpathfinder]

pull the cluster and slowly turn the input (where the speedo would go) I am going to guess its a stripped gear or broken part that allows the single mile digit to turn over B4 the 1/10th mile gets all the way back to 0...in fact you could probably watch this while driving and see if the single mile turns over prior to the 1/10th mile cycling all the way through

[nissan4x4]

thanks for all the help i will try.