When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I only know 3 bolt are for 1/2 tons and 5 bolts for the 3/4 and 1 tons. My F-350 has the bolt auto which you know and yours has the manual 6 bolt. Ive only known there was a 3 and 5 bolt.
Don't know the difference, but my '90 F150 has the 6 bolt. The most common of the Warn replacement hubs (I converted mine from auto to manual.) will fit only the 6 bolt hub. I don't know if the 3 bolt hubs can be converted or not, but if they can they take a special hub.
My '96 F250 (3/4 ton) has factory 3 bolt locking hubs. Honestly after having just packed the gears, locking rings, shims, spacers, etc... while doing the brake job. I don't think the locking hub bolts really matters. It's basically just holding on the free/lock selector. Everything else is already held in with threaded rings, retaining rings, shims, spacers, locking rings, etc. I really don't think an extra 2 or three bolts will make that much difference.
The 5 bolt and 6 bolt can be swapped auto to manual quite easily. Simply change the hub and the piece held in by the big snap ring and you are good to go. The 3 bolt takes a little more work. You have to take out a couple extra things and add something (can't remember exactly) but it's no big deal. New hubs for the conversion come with instructions.
I still don't know why who got what on the 3-5-6 bolt deal. Maybe somebody does!?
The bolts hold the cap to the hub body. The hub body just slides into the splines, where it's held by the large retaining ring, and the bolts then keep the cap in place. So I don't think there's any deep hidden meaning behind the number of bolts, or necessarily any correlation to the axle or truck model. It just depends on what hubs the truck has. And as long as you get the correct hubs for your axle it doesn't matter how many bolts your replacement hubs have.
Some later auto hubs had self-locking spindle nuts, and these hubs could be identified by the three bolts in the cap.
All other hubs had the regular spindle nut setup using a lock ring and lock but. These could be identified by having anything other than three bolts in the cap.
The only significant difference that I know of is that if you have three bolt auto hubs and want to convert to ANY style of manual hubs, you have to replace the self-locking nut with the standard nut/lock ring/lock nut. Super easy conversion, I did it on mine when I ditched the auto junk.
The bolts pull the O ring to the hub to seal it and the bolts provide the resisting force to the springed center locking piece...
That's what I said, they hold the cap on. The cap has the O-ring which is what seals it, and the center piece that is splined onto the axle shaft is pushed in and out (through springs) by the dial in the cap. So if the cap isn't held on the springs would just push the cap off.
Originally Posted by LeoJr
...They are important but not under much of a load. I believe 3 bolts to be sufficient.
Doesn't answer the question as to "why" though.
These bolts thread into the hub. The differences must be in the differing hubs.
You gave the "why" right there, which was also what i said. Different hub manufacturers just chose to do it differently.