T-19 first gear ratio identification - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 05-26-2005, 03:39 AM
Posts: n/a
T-19 first gear ratio identification

Hey gear heads,

I am swapping my 3 speed for a BW T-19 I believe that the first gear ratio is 5.11:1. However I can find no equations that verify this ratio. I have the tranny torm down for rebuilding and have the tooth counts for the gears from input to output. How can i verify by equation the gear ratio.


Sponsored Links
post #2 of (permalink) Old 05-26-2005, 08:37 AM
Jim_Lou's Avatar
Join Date: Dec 2001
Location: Belleville, Illinois
Posts: 11,502
Thanks: 15
Thanked 22 Times in 17 Posts
Re: T-19 first gear ratio identification

Division and multiplication. Start at the front. Count the number of teeth on the input gear. Divide that into the number of teeth on the gear it drives, and save that number. It will probably be around 1.5.

Then go to the output - the last driven gear with the transmission in first - and count the teeth. Divide that number by the number of teeth that drive it. Multiply that by the first number you got, and the result will be the ratio in that gear.

Once you have the transmission ratio, you can do the same thing to get the transfer case ratio and the axle ratio. Then multiply all three together and you have your crawl ratio.

If the gear train is assembled so that you can't count teeth, tape a string to the shaft that turns more, and then turn the other shaft exactly one turn. By counting the wraps of string plus the fraction of a full turn on the other shaft you can get a pretty good estimate of the ratio.

You will almost never encounter an even-number ratio, like 72/18 (4:1) because in that case the same teeth would engage each other with every turn, causing uneven wear. When the ratio is a number like 74/18 (4.11111... :1) every driven tooth will eventually engage every drive tooth.

And welcome to the board!
Jim_Lou is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome