OldIHC

I am rebuilding my R-110 pickup using a completely rebuilt stock silver diamond 220 motor. I would like to have more speed than the 50mph without it sounding like it is going to blow up. Do I change the transmission gears or the rear axle gears or both?

Both I believe but mainly the rear axle, im told that the Ford Explorer 4.10 rear axle fits perfectly, what transmission is it?

You need to determine which axle ratio you already have! Just pulling an IH 4.10 for a Ferd 4.10 does nothing! If it has never been replaced the top of the housing just above the pinion gear will show the ratio. If the 3rd member has been swapped out it will possibly be wrong. The end of the pinion gear will have a number of teeth on the ring gear and number of teeth on the pinion gear dividing the two will give the ratio. You probably will have to pull the drive shaft rear u-joint to see the numbers stamped.



this is a 9-43 tooth rear axle, or a 4.77 axle ratio.

I have the original 4 speed transmission on the floor.

a friend of mine said a 3:73 rear end would make a world of difference

Remember that when you change the speed possible from the truck you need to also address the brakes - the original brakes are only built to handle the lower speeds expected from a "farm truck". You don't want to learn about that at 70MPH - Bob

I have added a disc brake kit to the front of my R-110! Thanks for all of your input. It is greatly appreciated.

I have a factory overdrive transmission from a '55. You could try and find one of those--I am sure they are around. I haven't decided if I am going to use mine yet, because the original is a floor shift and this requires a column shift.

Hey guys, 3.73 wont be much, maybe 250, 300 RPMs, from 4.11, but from 4.77-- 500-- 550 you will notice the change. I dont know what tire size you guys have. Here is a calculator to go by. Be accurate.
http://www.ringpinion.com/Calculators/Calc_RPM.aspx