speedo gears

fireball8

Icecream Man
City
Lewiston
State
Me
#1
i'm new to this internet forum thing so bear with me.I have changed gear ratios in my 81 scrambler with an automatic from 331 to 373 gears, to make up for the sluggish takeoff with whe bigger tires(33x12.5) and for towing a pop-up camper.what can be done about the speedo???/where can i get a new gear to correct the problem??
 

John N

Addicted....Ex-SOA VP
LIFETIME
CJ-8.com Member
SOA Member
City
Rockville
State
VA
#2
Believe it or not, they can still be gotten through the dealerships. They are usually under $20. If you know what tooth count you need, post it. Someone may have one from a swap for you.
Welcome to the group.
 

ibscrmbln

Ken Waters
LIFETIME
CJ-8.com Member
City
Topeka
State
KS
#3
There are several way to determine what gear you need. You can try one of these sites:

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

http://www.sierrajeep.com/speedome.htm

or you can compute it:

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

Then go to the stealership with these numbers:

Teeth Color Part #
24 WHITE 3410024
25 BLUE 3410025
26 RED 2538926
27 WHITE 52068149
28 BLUE 52068150
29 BLACK 52068151
30 YELLOW 52068152
31 GREEN 52068153
32 BLACK 52068154
33 YELLOW 52068155
34 GREEN 52068156
35 ORANGE 52068157
36 RED 52068158
37 WHITE 52068159
38 BLUE 52068060
39 GREEN 52068061
40 ORANGE 52068062
41 RED 2538941
42 WHITE 2538942
43 BLUE 2538943

tthe one's beginning with 5 should show up as "Pinion TR" on the Chrysler computer.

Later, Ken
 

RandyLL

1 Long CJ
City
Highland
State
IL
#5
I was getting alot of conflicting info from different sites. I finally used a GPS to show my actual speed vs. speedo reading. Remember tire diameters aren't exact. I just took my stock 30 tooth out if some one needs it.
 

jpdeuce

Basic User
City
Houston
State
TX
#6
RandyLL said:
I was getting alot of conflicting info from different sites. I finally used a GPS to show my actual speed vs. speedo reading. Remember tire diameters aren't exact. I just took my stock 30 tooth out if some one needs it.
I think that's exactly what I need. I get 29 from one site and 31 from the other...so I figured I would go with 30. Let me know if it isn't claimed yet...and I will check the sites again to make sure.
 

fourdays

4th year Scrambler rookie
City
Danville
State
CA
#7
Thanks for the information and links. I just bought a new gear from the dealer today. It won't be in until next week though. I did check out the Unlimited's while I was there. As I was checking one out I witnessed a 17 or 18 y/o high school student getting one for graduation from HS. Must be nice!!
 
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