Speedometer Adjustment

[lineforeman99]

I JUST INSTALLED A DANA 300 IN MY SCRAMBLER. I AM RUNNING 33 INCH TIRES. MY SPEEDOMETER IS OFF. I AM GOING ABOUT 5 MPH FASTER THAN IT SHOWS. DOES ANYBODY KNOW HOW TO ADJUST IT. I NOTICED THERE IS AN ADJUSTMENT ON THE TRANSFER CASE WHERE THE SPEEDO CABLE CONNECTS.
THANKS

BUTCH

 

[GreatCJ8]

Here you go, just use this applet & then take that info to your nearest Jeep Parts counter, I just did & it was like $12 bucks to replace the gear, a true 1 minute job:

http://www.jeeptech.com/javaAps/Speedo.html

 

[tom82cj8]

You are going to need the part numbers from my post on JU:

http://jeepsunlimited.com/forums/showthread.php?threadid=255842

I am TOM85CJ7.

Later,
Tom

 

[hmmj]

Help With Speedometer

Can anyone tell me what I need to do to correct my speedometer.

I see the instructions to determine what gear I need, and the list of part numbers.

The problem is I don't know how big my scrambler tires were originally (in order to calculate the size of the new gear).

And, I don't know what to do with the gear when I get it.

Thank you for whatever help you can offer.


I have a stock 1983 CJ8, with 15x8 rims, and 31x10.5 tires.

(everyting else is stock-except the rust)

 

[tom82cj8]

I have used the calculators, and they haven't been very accurate for me. I ended up borrowing my brother-in-laws GPS to get my actual speed. I checked my speed at 60mph. I used those numbers to get the correct gear. If you don't have access to a GPS, you could find a very straight stretch of highway and check your mileage after a few markers. That would also give you a starting point for how far the gears are off. I have a couple of extra speedo gears if you want to buy one. $7 plus shipping.

Later,
Tom

 

[ibscrmbln]

The gear is located in the rear tailshaft housing on the backside of your t/c where the speedo cable attaches.

You can also use the following formula: Drive the vehicle to a highway with mile markers. Record odometer reading at a mile marker, drive ten or more miles, then record odometer reading again. Calculate miles traveled according to the odometer, including tenths of mile.

Use the following formula to find the number of teeth needed on your speedometer driven gear.
B = Miles traveled according to odometer
A = Actual miles traveled (per mile markers)
T = Number of teeth on driven gear used to calculate miles traveled

(B/A) * T = Number of teeth needed on driven gear (round off to nearest whole number)

Example: B = 16.4, A = 17, T = 41 (16.4/17) * 41 = 39.55 rounded to 40

If you get your speedo withing 2 or 3 mph of accuracy you are doing pretty good.

One other thing. When you install a different size gear into the tail shaft housing, it requires some rotation of the gear keeper to accomodate the change in size. I believe counter clockwise for more teeth and clockwise for fewer teeth.

Good luck! Ken.