Semi Float > Full Float?

[BrianW]

Small note: Rear disc brakes didn’t start until at least 1999, IIRC. My 1998 E250 has drums. And I’m surprised an E350 Club Wagon doesn’t already have a FF rear... I though most of them came that way.

[carringb]

Originally Posted by neatvan

Is 2005 a changeover year for the ABS with some getting RSC, and some not? (My van is non-RSC).

Any other idea why carpart may be directing me to those year axles?

Can you clarify why I should avoid 02-05?

Thanks and I hope this is relevant enough to not be considered a hijack to JWA's post.

2005 was the changeover calendar year where they changed over to making '06 model year extended-wagons early, which would be have an '06 VIN and would be a full float, as RSC became standard on extended wagons at that point. Non RSC vans through '07 will be interchangeable with '99+ rear axles.

The reason to avoid '02-'05 van axles is they are all semi-floats. Some are incorrectly listed on car-part.com but if you look at the pics, you'll see they are all semi-floats.

[Lilnuts2]

The slightly pre RSC axles only have a electrical connection on top of the differential housing, none near the wheels.

This pic is a 2004 CC Dana 70 FF.

[carringb]

Originally Posted by Lilnuts2

The slightly pre RSC axles only have a electrical connection on top of the differential housing, none near the wheels.

This pic is a 2004 CC Dana 70 FF.

Correct. Non RSC axles (all prior to '06 and the non-RSC '06 and '07 axles) have the differential speed sensor. Starting in '08, none have the differential speed sensor.

[JWA]

Originally Posted by neatvan

Thanks and I hope this is relevant enough to not be considered a hijack to JWA's post.

Nope your questions would be the same as mine so you're spot on and completely relevant!

However I'm almost more confused now than before---and that's saying quite a lot!

Okay so a few questions then...

1. Do the axle ratings shown on the serial tag reflect spring loading capacity or the maximum weight any axle can safely carry continually? Tires are another issue I understand so I guess I'm asking more about SRW's. I don't believe I need or want DRW's in my application.

2. Since my load will remain pretty much as configured now do I really need the FF rear axle OR would the existing SF work over the life of the van? Am I borderline overloading the rear axle now?

3 IF the existing axle is acceptable am I ill-advise adding an extra leaf to the rear spring packs, more to slightly increase the ride height rather than add to weight handling? Keep in mind I never tow and loads will NOT increase from the current GVW?

So then.........IF I need a FF and I do NOT have RSC and want something that'll drop right in place from what donor vehicle(s) would I search? I don't think a wider axle would be a good choice IF it requires any bit of modification prior to or during installation---down time would be of high concern

So far I'm "hearing" something with disc brakes (naturally), model years 2001-2004 E350's OR a later year(S) E350 without RSC. Am I close?

Also would I need another drive shaft or should my existing SM part work?

Guys thanks sooooooo much for the help and comments---I'm learning quite a bit!

[JoeH]

I'll take a stab at #2. Your vehicle weight is not nearly as heavy as most fully converted SMBs or E350s and there are plenty of those running around with semi-floaters. That said, there are also plenty that have broken an axle. The biggest upside to a full floater is it does not carry the weight of the vehicle like a semi-floater does. https://www.fourwheeler.com/how-to/0...loating-axles/


Before it's all said and done your going to spend between $3 and $5k on the conversion. You can find a donor axle that might be plug and play that will only need the shock perch moved but ideally you wouldn't stop there. I replaced brakes and brake lines, rebuilt the differential, an ARB locker, new axle bearings and upgraded to 35" axle shafts.

[Lilnuts2]

The proper replacement FF axle is a plug and play. You don't even have to bleed the brakes. Your existing driveshaft will bolt right back up.

[carringb]

^Correct. A '99-'01 (or '02?... seems like the FFs were a slow phase out that time) van axle, or a wide track SRW cutaway (rear tank) axle '99-'07, will be a drop in affair. You can keep your brakes or use the brakes that come on the axle. You should plan on new U-bolts.

Hardest part is making sure it is the gear ratio you want. The cutaway axles will be all 4.10, but the van axles could be 3.55, 3.73, or 4.10.

As to your "Do I need it?" question... I think if you actually stay within the axle ratings, you're fine as-is. But you only have 1,000 pounds of payload on your rear axle now, which isn't much. As long you keep and eye on things, especially any rear axle-seal leaks, you can probably avoid the catastrophic failures that have hit some fully built-out EB E350s. But once your seal start leaking, don't let the shop just change them out without a thorough inspection of the axle shaft.

The biggest downside of swapping is simply the condition of the eligible donor axle. 20 year old vans and 13+ year old cutaway chassis tend to have a lot of miles and possibly not the easiest life. If might be difficult to find one that doesn't need some diff work and/or heavy clean-up.

[JWA]

Massively helpful and informative LilNuts, JoeH and CarringB too--can't say enough how much I appreciate the info.

To CarringB: weight on my rear axle as it sits now is with almost every bit of cargo I'll ever haul---I'd NEVER exceed the 1K "buffer" that'd put me at the max weight allowed.

Just to be clear (in my own mind) if I found FF from an '05 and later that's NON-RSC E-Serie that'd work as well? I'd have to visually verify it's attributes regarding sensor ports naturally.

My plan would be finding the drop in rear axle but before it was placed having it carefully inspected and renewed as needed would be top priority. If I've not ready replaced rear brakes on my existing axle those too would be renewed most likely the universal joints too. Anything aft or the fuel tank would be replaced or repaired as needed to assure reliability.

U-Bolts a definite replacement as they're just too important to try saving. I have a great local spring shop who'd be my go-to for those.

I can't see this running too much more than $2k only because I'd simply refresh the axle and not be adding a locker etc. I hope to find an axle locally which would be a huge benefit. If I have to go with LKQ and they'd have to ship it I'd have them transfer it here rather than pay for it sent via a commercial carrier. If its within 150 miles I'd fetch it myself. After seeing photos of the exact part that is.

Thanks again all!

[carringb]

Originally Posted by JWA

Just to be clear (in my own mind) if I found FF from an '05 and later that's NON-RSC E-Serie that'd work as well? I'd have to visually verify it's attributes regarding sensor ports naturally.

If you can find an '05-'07, yes. But I don't think they put full-floats in those years except the RSC vans, unless you are referring to a cutaway axle. Starting in '08 all of them will have outboard speed sensors, regardless of RSC or not and will not work with your van.