The Ford Barn - View Single Post - Rear End Gear Ratio--39 Ford

JM 35 Sedan · 10-20-2013, 08:20 AM

There should be numbers stamped on the bottom of the banjo housing on the center web near where the torque tube bolts up. Divide the larger number by the smaller number will give you a final gear ratio. Example: 39 ÷ 11 = 3.54:1 ratio, 37 ÷ 9 = 4.11:1 ratio, and 34 ÷ 9 = 3.78:1 ratio. However, these stamped numbers on the banjo may no longer be correct if someone has previously changed the original gears. A couple other methods are:

1. Drain the oil by removing bottom pipe plug. Remove rear pipe plug and wipe one tooth clean on the ring gear. Mark that tooth with a felt tip pen. Count the number of teeth on the ring gear and that number should match one of the three ratios above.

2. Jack up the left rear tire enough to clear the ground. Mark a line on the front face of the tire with white chalk. Put the transmission in third/ high gear. Turn the engine two revolutions by using a socket on the crankshaft pulley hex bolt and note how much the tire turns based on the chalk line. I will come back and add a link here that gives more details on this method.

http://www.btc-bci.com/~billben/reargear.htm

10-20-2013, 08:20 AM	#5
JM 35 Sedan Senior Member Join Date: May 2010 Location: Near Rising Sun, Maryland Posts: 10,859	Re: Rear End Gear Ratio--39 Ford There should be numbers stamped on the bottom of the banjo housing on the center web near where the torque tube bolts up. Divide the larger number by the smaller number will give you a final gear ratio. Example: 39 ÷ 11 = 3.54:1 ratio, 37 ÷ 9 = 4.11:1 ratio, and 34 ÷ 9 = 3.78:1 ratio. However, these stamped numbers on the banjo may no longer be correct if someone has previously changed the original gears. A couple other methods are: 1. Drain the oil by removing bottom pipe plug. Remove rear pipe plug and wipe one tooth clean on the ring gear. Mark that tooth with a felt tip pen. Count the number of teeth on the ring gear and that number should match one of the three ratios above. 2. Jack up the left rear tire enough to clear the ground. Mark a line on the front face of the tire with white chalk. Put the transmission in third/ high gear. Turn the engine two revolutions by using a socket on the crankshaft pulley hex bolt and note how much the tire turns based on the chalk line. I will come back and add a link here that gives more details on this method. http://www.btc-bci.com/~billben/reargear.htm __________________ *John* *"Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein* Last edited by JM 35 Sedan; 10-20-2013 at 08:31 AM.