The tach must be lying..

[Derek The Great]

Thanks Hawk,
Those wires don't seem like they'll just pull out. Do I need a special tool to remove it? I'd rather not cut anything, and to avoid that I will probably keep sifting through the junk yard looking for the right one. I'm anal, and although the new set up looks better, it bugs me that the redline isn't 5500...

 

[Hawk1339]

Thanks Hawk,
Those wires don't seem like they'll just pull out. Do I need a special tool to remove it? I'd rather not cut anything, and to avoid that I will probably keep sifting through the junk yard looking for the right one. I'm anal, and although the new set up looks better, it bugs me that the redline isn't 5500...

There is a retaining bar on the connector that simply snaps off to allow the individual pins to be easily removed. This bar then snaps back in place to retain the pins. It has been a while since I took one apart so I can't precisely remember how this retaining bar works but it is there, and it is easily removable. I think, trying to remember through the fog of advancing age, that the retainer is on the bottom of the connector, on the side where the wires enter, in between the two rows of wires. I also seem to recall that the bar is a different color than the black body of the connector, red perhaps. There may be little tabs or detents to release it. Don't force or break anything, be gentle and it will pop right out.

Once you get the bar off, take pin 9 (blk/yel) out and tuck it safely out of the way so it doesn't touch anything. It is at ground potential so it won't matter if it touches the truck body but you don't want it to hit something hot. Make sure you're on the correct connector- you want C250, the vertical connector on the "passenger" side of the cluster. Try that and post back here what your results are. If that doesn't do it then the next step would be the 8/9 connection.

 

[thantil]

When I put mine in I saw an adjustment ont the back of the tach.
You could try another tach for ref then adjust if you choose.

I have Scan gauge2 and there is very little difference between that and the cluster

 

[sbsumerix]

Huh? The diameter of a fourteen inch rim is... fourteen inches.

Here's the math without the calculator:

A 205/70/14 tire has a tread width of 205 mm or 8.07 inches. Section height is 70% of that, or 5.649 inches. Multiply by two (two sections of tire, one on either side of the rim), 11.298 inches. Add rim diameter, 11.298+14= 25.298 inches total tire diameter. Round it off to 25.3 inches.

another way is 205*70/1270(i dont know why exactly why 1270 its part of the big caculation but it works) + 14 =25.3

 

[triumphrider-1]

another way is 205*70/1270(i dont know why exactly why 1270 its part of the big caculation but it works) + 14 =25.3

1270 is just the conversion factors all multiplied together.

converting from mm to inches = 25.4
converting the height ratio from % to decimal = 1/100
then there are two sidewalls = 2

(25.4*100)/2 = 1270

 

[Hawk1339]

another way is 205*70/1270(i dont know why exactly why 1270 its part of the big caculation but it works) + 14 =25.3

1270 is a metric conversion constant. 205/1270=0.1614. The tread width in inches, times two, is 16.14 inches.

Multiply the 1270 by 2 and shift the decimal place and you get 25.4, which is the number of millimeters in an inch.

A little mathematical trick, but yeah, it does work, and for any size metric tire.