Hello all. I have been a member for a while, but I usually just read and don't do much posting. Please forgive me. I plan to change that. I have several ford trucks, but the current question is about a ford truck trans I am running in my dirt track car. I have a 3 speed manual trans that I bought from a buddy out of the corner of his garage for $40. I have run it for 3 years in a stock car in 2nd gear. It has worked flawlessly and I have never had an issue with it. My rpms are what I want, but I am fixing to change rear ends and run my final drive in the rear end and run high gear (1:1) in the trans. Here is my question. I need to know what gear ratio 2nd is in my trans so i can multiply it by my current rear end ratio to get my final drive number so I know what gear to get for my new rear end. I have done a lot of searching on the net and haven't found what I needed. There doesn't seem to be a lot of info, but from what I have heard and read some stuff saying these are 3.03 trannys, but I have no idea what that means. My buddy that I got the tranny off of says he took it out of a 1983 2WD Ford F-150 with a 300 6cyl and a 3 on the tree. So far what I can get off the tag looks like this...

RAT EM JK4
EOTRCA 2133

Not sure if this is what is needed to decode the ratios or not, but I am hoping ya'll can help. Any info on this tranny would be appreciated! Thanks!

 

You are correct, there is not much info on this tranny. If you happen to have it out of your car, I would put it in 2nd gear and turn the input shaft counting the number of turns the input shaft makes to make the output shaft turn 1 turn. That will be the ratio.

 

"303" is in reference to the 3.03 inches between the main shaft and the counter shaft.

Ratios MIGHT be 2.99/1.75/1.

That seems to be the truck ratios for that trans.

One trick I saw was to put the trans in gear, and turn the output shaft 10 times. Count the output turns and do the math. You get enough of a "sample" with 10 turns to get it right.

http://classicbroncos.com/tranny-toploader.shtml

 

That makes sense. If 2nd gear was 1.75, instead of trying to judge the input shaft turning 1 3/4 turns for 1 turn of the output,, it would be 17.5 turns for 10 turns of the output.

 

Another way to skin the cat!

 

Dang you guys are quick!!! Thanks for the replies! 1.75 would seem reasonable. I tried the turn the input/count the output thing but wanted to get closer than "somewhere between 1.6 and 2.0" Doing the math using 1.75 would give me 5.72 final drive, which is about right cause most are running 6.20 or 6.33 and are turning abywhere from 1000-1500 more rpm. Thanks again guys. I'll roll with the 1.75. I guess the 9" gear available that is closest to 5.72 is like a 5.67 I think. That should work.