rear gears
Elder User
Joined: Aug 2000
Posts: 597
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From: Burke VA
rear gears
Hello all,
I have a 2 wheel drive 78 that originally had the I-6 with a 3 on the tree standard trans. Anyone know what gears would be in the rear? I have since changed the 6 out for a 351W and I am wondering if I should do anything to the rear.
Jayson
78 F100
93 5.0 GT
96 Taurus Wagon
Die Hard Ford Fan.
I have a 2 wheel drive 78 that originally had the I-6 with a 3 on the tree standard trans. Anyone know what gears would be in the rear? I have since changed the 6 out for a 351W and I am wondering if I should do anything to the rear.
Jayson
78 F100
93 5.0 GT
96 Taurus Wagon
Die Hard Ford Fan.
New User
Joined: Aug 2002
Posts: 19
Likes: 0
From: Clarkdale USA
rear gears
Usually those trucks come with low 3.xx gears. pull off your rear cover, and there should be three sets of #s under were the pan bolts on. first two are two digit #s, those are how many gears are on the pinion and ring. the pinion is your smaller #, ring is bigger. divide your ring # by pinion at that will give you your ratio. I'm sure you shouldnt have to change it, but if you want more go off the line, go a little lower, but dont go too low, so you have some top end.
Posting Guru
Joined: Mar 2001
Posts: 1,494
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rear gears
79F100 that had a six behind it...you most likely have a nine in the rear. Good luck trying to get the "cover" off. Check for a metal tag that usually is on one of the third member bolts. I'm sure it'll be grimey...post the numbers exactly how they appear the tag. You could also try raising the rear end and counting the number of driveshaft rotations for each tire rotation...beats tearing into the rearend.
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Elder User
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From: Burke VA
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rear gears
Jayson, the reason they said good luck with the cover is that a 9" rear axle does not have a cover, the whole diff assy (pig) unbolts from the front of the axle assy. Most of the time the diff ID tag is on the passenger side under one of the bolts at about the 8 o-clock position. If you have a door tag there are numbers on it that will identify the axle assy also.
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