Narrowing f100 axle set 20 bearings and axles

[bigperm2]

I am knee deep into narrowing a 1977 f100 rear axle to stock EB width. the f100 axles have set20 tapered roller bearings. I have read that the retainer plate creates the preload on the bearing. I have the QP axle ends (big bearing old style) and as I understand, it will accept either set20 bearings or the sealed roller bearings. It seems in most applications, such as a front axle hub and the carrier and pinion bearings, tapered roller bearings are in pairs. Since they are conical races, the thrust is only resisted in one direction. so when used in pairs, everything is held together. If the thrust force on the axle is pushing the axle shaft into the housing, the set20 bearings are loaded resisting the thrust. What is resisting the thrust if the force is pulling the axle shaft away from the housing (tapered bearing unloaded)? the retainer plate will prevent the axle from falling out, but does the inner race rub the retainer and/or seal? I would think this would cause a lot of wear. The old style sealed roller bearing is easy to visualize and makes sense. while the roller bearing does not resist side thrust as well as a tapered roller, it does resist load in two directions.

Everything I have read on the interwebs says the set20 bearings are the heavier duty bearing, they work, and I am probably overthinking it. Right now I am planning on buying the 1976-1977 31 spline EB shafts from WH with Timken set20 bearings installed. The only axles I can find with the sealed roller bearings are from Bronco Graveyard, but they are out of stock right now.

To anyone who has done this, am I on the right track? Let me know what you think!

 

[bigperm2]

I actually just realized this is my first post. I am not new to 60's and 70s fords. I had a 1968 bronco years ago and regrettably sold it. In the past, I have been somewhat active on the vintage mustang, 1969 mustang and FTE forums, and have been lurking on this forum.

Early this year I picked up a super rust free, titled and straight 1969 bronco frame and GB door from a friend whos bronco the burned 25ish years ago. My plan is to build it ground up from scratch. Axles are closest to the ground and are first!

 

[661buster1963]

Welcome, don’t have great insight in cutting the axle, but do share love of F100, broncos, and early mustangs

 

[Yeller]

Set20’s still have a bit of free play, some say they shouldn’t, but most do. I don’t like either design but the Set20 is the lesser of the evils and what I am running. I have had and witnessed a bunch of axles with the sealed ball bearings walk out of the housing, I don’t believe the retainer is large enough and there is not enough room for a larger one like on the Set20 because of the inner seal. On the other hand I’ve never had an axle walk out with a Set20 unless the bearing completely failed and came apart, even then the restainer stayed in place. I have seen plenty of axles break at the flange with both bearings. I have also side loaded them hard enough to crush the seal, something that 99.9% of people will never do, I was just challenged and special lol.

Run the Set20 and be happy. The only thing better is to build an axle with Set80 bearings (expensive) but at that point might as well go all out and build a full float.

and welcome aboard

 

[Madgyver]

stock full width 77 F150 9" rear axle here.
stock full width 77 F150 high pinion dana44 front