my '81 f150 has got the 9" and im swapping in a Gear Vendors OD for added driveability, the '80-'86 guys told me that the 4.10 ratio will work really well and get me the driveability. Now what i need from you guys is; what heavier-duty axle is a good candidate for a swap? sterling 10.25? dana 60 (of course)? what will be easy to swap in with the desired gear ratio?

what is a floating rear axle? semi floating? i used to know but i just deleted it from memory.

 

The term "Heavier Duty" is relative, and really is a matter of perspective.
Your 9 inch is pretty strong with regards to axle strength. You mentioned the Dana60, and bracketed 'of 'course' implying that the rear 60 is strong, and most are not. The axle tubes are fairly strong, and the full float design can handle decent weight capacities, but the small 30 spline axles are rather weak.
Know that the 7 inch toyota axle shares the same axle shaft diameter, That should put things into perspective. Does this mean that the toy aaxle is real strong, or that the Dana is weak? You decide.
At any rate, a full floating axle has a spindle at the end of the housing, and a hub that supports the vehicle weight. The axle shaft is only responsible for turning the hub / wheel.
A semi float axle has a bearing that rides directly on the axle shaft, and the shaft itself supports the weight of the vehicle. This means that the axle shaft is responsible for not only the torsional requirements of motion, but also has to carry the weight of the vehicle.
An axle shaft in a full floater, can be removed without removing the wheel, or the hub.
Nice to replace axles if they break on the trail with a full floater.
Even broken axles do not render the vehicle useless, and with a FF, the vehicle will still roll.
Semi floaters, especially c-clip axles will allow the axle to pop out with the wheel, and drum and everything. This is a real bummer on the trail.
Both Dana60 and Visteon / Sterling 10.25 axles are available in semi, and fill float design.
Also keep in mind that a larger 3/4 or 1 ton axle will have 8 lugs, so you will also have to address this issue.

 

do you think a 9" will stand up to a 5th wheel trailer or a car trailer w/ a 2 ton chevelle? lookin for reliability and not a cracked axle shaft like my bros 9" on his bronco.

 

The 9" is not the weak point of an '81 F-150 for sure.

If you have the swiss cheese frame, I wouldn't tow either trailer with that truck. If you have a real frame, I would think long and hard about towing either trailer.

What does the 5th wheel weigh?

 

i used to tow demo cars all over the creation with a 302/aod/8.8 and never broke any of it. as long as your not stupid about what your doing it will be fine. i dont think the frame will bend on you with that setup towin a trailer. 4000 lb car on a hauler, most of the weight will be on the trailer. the 5th wheel would depend how big it is.

 

well i dont got the swiss cheese frame so im good there. well what axel code will tell me if a junkyard truck has a 4.10 (or is it 4.11?) ratio

no 5th wheel, Nor Nev is gonna buy a trailer that goes on the hitch.

 

the 9" can be made stupid strong, some 40 spline shafts and you're talking Corp. 14 bolt strength, the question is whether it is worth it or not. If you want to keep your 5 lug pattern, it might be. If you don't mind some 8 lugs, drop $100 on a junkyard 14 bolt and never think about it again

 

i really wanna step up to the 8 lug differentials, but i have to do some more research on if a f250 2wd front end swap is really worth it at all, if it'l bolt up like a 4wd ttb swap, kinda like that

 

Until you're trying to get a driveshaft to fit this creation.
As has been stated, the rear axle isn't your weak point. In fact, it's probably a strong point. The frame is what I'd worry about, then brakes, then the gearing to get it off the line. Also don't even think for half a second about towing with the bumper, you need a real frame-mounted receiver hitch setup.

 

I thought he said he was using a 5th wheel, but can't find it, must have smoked way too much crack yesterday, oh-well

and the 14 bolt was available in both 1310 and 1350 Ujoints, so long as he gets one with the 1310 (same as his 9") all he'd have to do is cut his D/S down some. I do most mine myself, but worse come to worse a driveshaft shop would charge about $50 to cut and re balance a shaft

 

well, my choices are these;
get the 4.11 9" case, $60 from pick n pull that may be messed up/ may grenade the whole axle.

spend like $500 on a "refurbished"/brand new case with the 4.11 from summit

or get a sterling 10.25/dana 60 and have peace-of-mind because nobody messed with it (grease on the bolts). followed with a front-end f250 upgrade.

i dunno, i dont have a problem doin a little work if it will work in the end. I mean if i look hard enough i can find a couple 4.11 cases for the 9" but that is gonna take alot of work/money getting one that dosent howl, so ive heard from guys who have got some from the junkyard. plus the added towing capability is always a plus.

when the bed is off for paint i am going to do a full box of the frame along with bigger springs if im lucky enough to find the 9" gearing i want cheap, so it wont collapse/bend in the back.

also its inevitable that i am gonna need a shorter d/s with the gear vendors, so its whatever goes

 

Sterling 10.25" is by far a stronger axle than the Dana 60.

If it were between a Dana 60 swap and keeping the 9", I would keep the 9" every time. The 9" is about 90% as strong as a Dana 60 and with some upgrades is MUCH stronger.

Junkyard or new is your call, but you are definitely rolling the dice with a junkyard axle that can't be any newer than 25 years. I don't blame you for being nervous. But on the flip side, you just need *any* 9" axle to replace yours. The housings aren't ratio-specific. You can pay to have a pro set them up or you can attempt it yourself for whatever you can get the tools plus the R&P and seal kit for.

If you're planning on hauling more weight than a 9" can handle, then you need a bigger truck. The brakes and frame of a 1/2 ton just aren't going to cut it in the long run.

 

well we shall see when i go to the junkyard and pick through the 9" cases, see if its well worth the effort to get the 10.25