Why a full floater? Very simply the semi-floating rear differential as found on all 40, 55, and 60 series Land Cruisers sold in our market use a rear axle that keeps the axles in place by holding them in with "C" clips in the differential unit. The weight of the vehicle is supported by the axles, which turn in a single roller bearing located at the outer end of the axle housing. On a full floater there are no "C" clips holding the axles in. Instead, at the end of the axle housing are spindles similar to the ones on the front axle (and use the same wheel bearings) of the Land Cruiser. These spindles support wheel hubs that have two tapered roller bearings in each hub. The bearings are adjusted with a nut just like the front wheel bearings, and the axles are held in/onto the hub with six studs, washers and nuts. This system makes for a much stronger rear drive axle setup for those that need or want the extra load carrying potential.
Mini-truck SF has a steel retainer (1-2" long) that's pressed between the bearing and end of the axle. To remove the retainer, one needs to grind it off or press it off w/ a SST. That's how difficult it is to remove. I've only heard of SFs on mini-trucks having problems when people remove the retainer, and reuse it (FSM says to replace it). What holds the real axle into the diff on a FF?
think of the rear axle shafts on FF axles as giant nails. The pointy (splined end) sticks into the side gears of the diff carrier. The flanged (head of the nail) has holes in it that engage studs in the bearing hub. these studs hold the shaft in place.
Okay, I see, Dan. The axle is bolted to the hub, which is secured to the vehicle via the spindle axle nuts, and the spindle is secured to the vehicle (either bolted on or, in this case, part of the axle housing). I was thinking about eventually installing that Front Range Offroad FF kit on my mini-truck. This kit contains the axles and a bracket that bolts to the SF axle housing and holds the caliper. It requires one to use a front spindle off a solid-axle mini truck (spindle bolts to the bracket, which bolts to the axle housing where the inner drum used to be attached), as well as the front hub w/ bearings. In this case, I think the axle is being held in by the little snap ring (doesn't have the "flat head" like on the mini-trucks w/ dual rear wheels), just like for the front axle. Is this setup risky?
I have a very similar FF conversion kit for my FJ40, and know a two of others out there, personally. I talked with the owner, think his name was Mike (couple of years ago), at Front Range, and had them machine the adapters to my spec's - made my FJ40 axle the same width as a FJ60, best price & already had the tooling for the spindle side.
It has the same components as the Front Range kit, just a different bolt pattern to attach to the housing flange, and thickness / clearances, etc.
This setup is different then the OEM 80's FF in that the "manual hub" replaces the "Nail Head" of the axle, and the axle shaft is similar to a "finish nail" wit splines at each end.
It has survived a run through the rubicon with crawler gears, etc. I do know one person who broke his axle earlier this year in the snow. Pranksters may turn your hubs on the rear axle and you just sit there, spinning, & perplexed!
I did mine mainly because I flat tow it to certain trails, and was running out of things to do to the FJ40, but, now with the 80, hmmm!
Joe, I think FROR now sells a bolt-on cap (probably replaces the manual locking cap on the freehubs) to prevent these pranks. What if you're parked on an incline in gear, no e-brake on, and someone unlocks the rear hubs? I guess the idea of having the unlocking rear hubs is you can tow your rig and only the wheels will spin and the odometer/t-case/rear drivetrain won't be turning.
In my design, the rear axles can run with either the manual "asin" hubs, or the front drive plates of the FZJ80 on the rear axle. I have a e-brake, electric solenoid e-brakes for just that type of situation. Luckly the pranksters (friends) only do it at the beginning of the trails. Retribution is fun on the pranksters
Thats the main benefit when flat towing - no damage to the drivetrain.
Also makes changing busted pinions a lot easier in the field, and also allows you to drive out of breakage situations, where the semi-floater does not.