Full Floater vs. Semi-Floater Axles (1 Viewer)

[60 toy ota]

fwiw, my dad (a mech. engineer) did a stress-analysis on the 60 SF, and came up with a safety factor of either 2 or 4, but i want to say 4. seems pretty tough to snap an axle like that, at least if you're going stock.

 

[ntsqd]

Just the shaft, or the whole thing? Did he do it old school, or with FEA? If FEA any chance of getting that graphic posted?

My concerns:
The flange is a massive change in cross-section, which makes it a massive stress riser.
The flange is cantilevered, not by much, but still it's there. Axle rotates, so rotary bending stress fatigue.
Surface is hardened at the start of the massive change in cross-section and into the zone where the rotary bending fatigue occurs.
Partly reversing torsion over the whole length adding to the other cyclic stresses.

 

[lcwizard]

fwiw, my dad (a mech. engineer) did a stress-analysis on the 60 SF, and came up with a safety factor of either 2 or 4, but i want to say 4. seems pretty tough to snap an axle like that, at least if you're going stock.

Yes it's hard to snap a NEW axle like that given the potential of an FJ60.
Toyota worked out the particulars so that you'd have a safe, reliable experience with your cruiser. Most axle shafts on the road,however, are pushing 200,000
miles plus. The fact that the semi-floater is subject to more fatigue just makes it more of a concern than the full float. I've only personally repaired a half dozen failures, four of which happened while traveling at highway speeds due to bearing
and race failures. The wheel didn't stay in place on those. No accidents resulted.
Apparently the 60 is manageable on three wheels. It is hell on backing plates.
One shaft I broke was while rock crawling, low range, first gear. The final drive was 64:1, air lockers and 33's. It barely made an audible pop when it went.
After inspecting it , on one side there was rust present about 1/4" deep suggesting
it was about to go anyway.
Whenever you do your rear brakes you should pull the axle shafts and inspect the race. I personally replace the bearings and seals at that point.

 

[brian]

Seeing as Full Floater Axles in the US are very hard to find, would it make sense to beef-up a semi-floater axle with modern chromoly axles shafts or pursue the near unobtainable or at least very expensive FF?

not sure what you call very expensive but ff housings and axles can be found on either side of the country for right around 600 bucks.
other than the axles and bearing(which are the same as the front bearings) they use the same stuff as the sf axle housing and brakes.

edit
i did not realize sor was now selling them for 900 bucks. i picked two up from a vendor over here for about 600 each shipped, a few years ago.

 

[TemboTusk]

not sure what you call very expensive but ff housings and axles can be found on either side of the country for right around 600 bucks.
other than the axles and bearing(which are the same as the front bearings) they use the same stuff as the sf axle housing and brakes.

My current research so far puts the costs of a FF including a bearing/gasket kit at about $1,200. ($950+ 150+tax) This does not include shipping. $600 or less would be a reasonable price, keeping in mind one might still need to spend another $500 in parts before it is road worthy.

I don't mind spending the money, just need to decide if it is worth while.

From some of the above comments; my break may have been fluke. My axles have at least 280,000 miles on them. Is it possible to find new stock (non-cromoly) axles?

 

[Spike Strip]

Yes, I believe new SF axles are avail from Toyota, at least last time I checked a year or so ago... FF, too. But $400 or so, about the cost of a pair of chromoly.

Aftermarket Japanese, I dunno. Chinese aftermarket, yes. EMPI ? Probably others.

 

[StevoJonesFJ60]

If you want a full float axle on the cheap, you could always swap in a FZJ80 axle. You should be able to pick one up at a local junkyard, and all you would need to do is cut the coil bracketry off and weld on some spring perches.

Its not too difficult to do.

 

[Dynosoar]

If you want a full float axle on the cheap, you could always swap in a FZJ80 axle. You should be able to pick one up at a local junkyard, and all you would need to do is cut the coil bracketry off and weld on some spring perches.

Its not too difficult to do.

Good way to go esp. if you could get an elocker with it. The 80 axle is about 5" wider, so 2.5" stick out on each side.

Dyno

 

[brian]

If you want a full float axle on the cheap, you could always swap in a FZJ80 axle. You should be able to pick one up at a local junkyard, and all you would need to do is cut the coil bracketry off and weld on some spring perches.

Its not too difficult to do.

with a stock drive train?
the 80 has more of a centered rear diff, where on a 60, the right wheels bolt on to the ring gears.

 

[StevoJonesFJ60]

Good way to go esp. if you could get an elocker with it. The 80 axle is about 5" wider, so 2.5" stick out on each side.

Dyno

To counter that you could run 5" backspace wheels with spacers in on the front axle.

with a stock drive train?
the 80 has more of a centered rear diff, where on a 60, the right wheels bolt on to the ring gears.

Yup, I ran that setup for a bit before my motor died. And had no issues with vibrations or anything. The gearing on the FZJ80 axles is 4.10 so you would need to swap gears in your front axle.

 

[darthvincor]

I have a FF axle, and would gladly change it over to a SF.

The FF has separate lubrication, and a seal to keep the diff oil and grease separate. If maintenance has ever been neglected, the spindle will wear, and there are no new diff housings out there.
As I understand it, SF is lubricated by the diff oil. If you change the diff oil regularly, the bearing should always be fine.

In my view, the SF is less of a headache than a FF.

 

[ntsqd]

I just didn't bother with those tiny little seals. Let the diff lube run down that axle housing and lubricate those bearings. That is how all of the Dana FF's and large truck FF's work.

 

[TobyB]

Heck, I got a ff from Tor WITH a lsd (yes, I know, but for what I do, they're perfect)
for not much more than a new locker would have been.

They're out there, and I think, worth it. Because, if an axle twists off, you just drive home
on the front. And then, there's the load rating...

...since you asked...

t

 

[snowboardonsnow]

Tor sold one for that cheap? A housing or a shaft? Dang what a steel!

 

[rchalmers3]

I'll accept whatever axle comes in the truck. But I do like the way a FF is assembled. It makes more sense to me.

The thing about the FF design that causes failure for most owners is the rear wheel bearing pre-load. If the bearings are allowed to run loose, the stresses on the drive axle flange rise tremendously, and either an axle failure or pulling of the studs in the hub can occur. This detail may explain the failures others have experienced with the FF.

Rick

 

[ntsqd]

A friend of mine who owns a 4X4 specialist shop once told me "Those bearings are large, they can take a lot of pre-load." After I heeded that advice I quit spinning bearings on the front of my '84 Xcab. The FSM method is for those who have all day to set the pre-load. I now crank the nut down as tight as it will go while spinning the wheel hub with a driver in the socket. Then I back the nut off until slightly loose. Remove the driver and using just the socket in my hand I tighten the nut as tight as I can reasonably get it. That's been working for me for ~10 years.

The FF does need an SST for it's stock wheel bearing nuts. I made a tool, it's either in an older FF thread, the home made tools thread, or my build thread - don't recall which.

 

[Wyoming]

There are a couple of things I like about the FF rear axle and housing: I like the fact that the FF runs on two bearings per side instead of one like the SF. I like the fact that the weight of the truck is not riding on the axle. I like the ease whith which I could change an axle if I needed to. If I have to work on or decide to change the ring and pinion, getting it out will be much easier.

I bought mine from Cruiserparts.net. I think it was $550 4 or 5 years ago. If you buy from him, inspect and verify as soon as it comes in. I waited a year before building it and discovered he had sent me the wrong long side axle. Luckily, the guys (Steve) at Man-A-Fre hooked me up with a good one for a great price (but still an extra cost) - just happened to have one laying around.

I can't get wicked technical like some of these guys. I just feel like the extra sets of bearings will cause less wear per bearing, thus extending the life of the rebuild and I would think it makes it easier for the truck to go down the road, which could help gas mileage.

I like mine a lot and would do it again. You will have to build the tool though.

 

[brian]

and I would think it makes it easier for the truck to go down the road, which could help gas mileage.

I like mine a lot and would do it again. You will have to build the tool though.

really with the extra drag of two more bearings, i would think that would be the opposite.

 

[ntsqd]

really with the extra drag of two more bearings, i would think that would be the opposite.

Could go either way, no way to know for sure without some pretty dedicated testing.