Rear axle to match TTB front

[carringb]

Originally Posted by b. rock

Sounds like the 99-01 D70 with the 4.10 is the best way for my van.

I'm assuming the 09+ Axle was directed at Flux? For an '05 w/o RSC that seems like it'd introduce the headaches of new brake lines and dealing with different abs sensors, no?

Also looking around at the locker options, there definitely seem plenty for the 9.75 RG - just have to deal with the spline count, which seems reasonable enough since if I'm getting an axle from a 99-01, it'll need some reconditioning anyway. That part I can deal with, van down time is a bit harder to manage.

Correct. The '09+ axle is for flux. You wouldn't want one of those. Definitely more hassle than its worth. Randy's Ring and Pinion seems to the easiest as far as putting together a locker that will work with 32-spline shafts. Or, as mentioned, just swap the shafts if you're set on a 35-spline locker like the ARB.

[b. rock]

My last rig was ARB'd, I'd be more inclined to go e-locker this route, maybe Eaton or Ox. Much simpler system. However, when I get down to it, I'm pretty sure I'd be just fine with a limited slip as well. That part can come after I find an axle.

[Idamanzz101]

Not to derail the thread to much but im wondering why do so many people run a 4.10 gear ratio? Im running 3.73's on my 2000 7.3 with 33" tires (285/75-16)
It turns 1800 rpm at 65mph (the sweet spot) and low range is plenty low for everything including steep technical downhills with compression braking only....
Maybe you need 4.10 if you are running 35's or ? Maybe the 7.3 is better for low RPM torque than the v10?
Thanks

[carringb]

1,800 RPM might not make enough HP for a really heavy or higher aero-drag rig. It doesn't even make 150 HP at that RPM. Which means the PCM unlocks the torque converter frequently, or it downshifts.

The V10 does make peak torque at a much higher RPM, but its also capable of spinning much faster. The 7.3L can make 160 HP at 2,000 RPM but a stock V10 has to spin about 3,400 RPM to make the same power. Which makes sense, considering peak torque on the V10 happens about twice the RPM of the 7.3L (3,400 vs 1,800). But... The V10 can also downshift 2 gears, and pull away at that point.

Lower gears basically makes more HP are cruising RPM, which reduces the need for downshifting, but at the expense of more fuel used for cruising in OD. But increasing RPMs a little, through a lower rear end gear, will use less fuel than needing to cruise around with O/D locked-out.

[b. rock]

The TTB front comes 4.10, and yes - larger than 33s are likely on the table. I am also playing at altitude where the n/a engine is derated a bit, and will be putting on a high top. It's great with 3.73's now, but the math points to 4.10's going forward.

Side note, what's the usual failure method of a semi float 60? Blown bearings? Busted axle shaft?

[b. rock]

Also interesting: https://www.polyperformance.com/soli...g-rear-end-kit . I doubt the economics are there but neat concept.

[carringb]

Originally Posted by b. rock

Side note, what's the usual failure method of a semi float 60? Blown bearings? Busted axle shaft?

Usually the bearings wear, which causes play at the axle end, which wallows out the seals. Then either of these can happen: 1) Bearing spins, overheats the axle shaft, and the entire hub breaks off. 2) Bearing doesn't cause sudden failure, but instead wears a groove into the axle shaft. At which point it cracks and the entire hub breaks off.

The potential for catastrophic failure is real, and has been posted on this forum several times in the past. Sometimes, the caliper contains it long enough to pull safely(ish) off the road. Best case, you notice the play while rotating tires or doing brakes.

[Geesh]

Heya -



Good technical content on this thread. I come from a rock crawling background and are doing the swap on my '93 SMB short-body. I am putting in a '99 F-350 D60 front and will be replacing the rear with a FF, '79 D60 Ford Rear. I won't be rock crawling the van as much as mild-to-mid off-road and snow. I am thinking of leaving the rear axle open because of the last word in my previous sentence: snow. I find feathering the brakes best for gaining and holding traction in very low friction ground, such as snow.



Selectable lockers such as ARB (I have one front and rear on my Jeep) are sweet, but as you mention: are a hassle. Detriot and other, 'I'll lock/disengage when I think so' lockers can be problematic and critically load up. Limited slip can burn up under huge loads....


The 10.5" Ford Sterling axle is a competitor to the D70 so far as my limited knowledge goes.



good luck!

[Vanimal]

I hope this helps!
To answer your question 1st a Sterling is made by Ford in Sterling Mich. The dana Is made by DANA Corp. separate companies. None of them make a 3rd member drop for our classification.
I got a little confused, because you said this:
"Closer to a weekender than a full time rig. Overland style wheeling - not rock crawling." You asked about swapping out a 60 to a 70 or a sterling! You said you were going to run 33's. A Sterling on 33's is a giant rock magnet and overkill for a "Weekender" because of the pumpkin size diff limiting clearance. You want to beef up the rear but then you are running a TTB which if I am not mistaken is a 1/2 ton Dana 44 Pickup/Bronco set up, meaning weaker parts, smaller ring gear and axle joints, especially on a EB body. That would not make sense. The bolt pattern can be changed but will be a 5 on 5.5. The van has 8 on 6.5 or 8 on 170mm, depending on the year. The TTB is great for the ride comfort but that can be done with a 4 link front 60 on factory rated coils as well. If you are going to spend the money for the TTB mounting and cut up of the brackets/frame then run a stronger solid front diff, which has less stress on your existing frame and less mods needed. The 60 is sufficiently strong for a "weekender". If you are worried about it get some alloy axles! 3.73 on 33's is why most want to upgrade to 4.10. I had 4.10 on my 7.3 now I run 4.30 which is perfect. I was going 4.56 but retracted and I am happy.

[carringb]

Originally Posted by Vanimal

You want to beef up the rear but then you are running a TTB which if I am not mistaken is a 1/2 ton Dana 44 Pickup/Bronco set up, meaning weaker parts, smaller ring gear and axle joints, especially on a EB body.

The Agile setup is typically a Dana 50 TTB, out of an F250. The big change was adapting it to coils rather than leafs. It was rated at 4,600# which is suitable for most vans, especially gassers. An EB puts less weight up front, not more.

That said... I'm not sure I'd want one under a diesel. But for a gasser, it should hold up fine. The big problems stock were the inability to adjust camber, and fast wear on bushings. Agile addresses both shortcoming I believe.

Off-roading aside... IMO most EB camper vans should have a full float, since it doesn't take much to max out the semi-float even before more tire is put on.