3rd member swap
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Joined: Oct 2004
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From: Maggie Valley, NC
3rd member swap
Hey yall...got a couple of questions...I have a 71 F-100 with a 9". My friend has a 78 or 79 with a 9" also. I have 4.11 gears and he has 3.55's. Can we just swap our 3rd members? Also, will this affect the speedo?
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maybe he's concerned with width and spring perch location so that they can just swap out the whole rear end......I'm interested in that so that I can get the whole thing from the junk yard....also which years are more likely to have 31 spline axles.....if your are counting splines on the axle you count the valleys not the peaks right....?
and yes that much of a gear change will effect speedo accuracy....but I don't know what size tires you are using....
and yes that much of a gear change will effect speedo accuracy....but I don't know what size tires you are using....
5th Wheeling
Joined: Mar 2005
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Originally Posted by zsir
maybe he's concerned with width and spring perch location so that they can just swap out the whole rear end......I'm interested in that so that I can get the whole thing from the junk yard....also which years are more likely to have 31 spline axles.....if your are counting splines on the axle you count the valleys not the peaks right....?
I don't believe any of the 67-72 trucks have 31 spline axles.
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From: Destin/Ft. Walton Beach,
I don't believe any of the 67-72 trucks have 31 spline axles.
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Laughing Gas
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From: Roseburg, OR
We're talking about the 9" though, right?
I have heard that SOME '72 F-100s actually had 31 spline shafts, and indeed, the trashed 3rd member that came in my truck (admittedly, on the passenger side floorboard...) had 31-spline side gears and bearings. The truck had 28-spline axle shafts with it, however, so I don't really know what it had from the factory.
I have heard that SOME '72 F-100s actually had 31 spline shafts, and indeed, the trashed 3rd member that came in my truck (admittedly, on the passenger side floorboard...) had 31-spline side gears and bearings. The truck had 28-spline axle shafts with it, however, so I don't really know what it had from the factory.
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From: Creedmoor, North Carolina
Originally Posted by 1bad71F100
Hey yall...got a couple of questions...I have a 71 F-100 with a 9". My friend has a 78 or 79 with a 9" also. I have 4.11 gears and he has 3.55's. Can we just swap our 3rd members? Also, will this affect the speedo?
Yes changing rear ratios will affect the speedo reading.
John
