Semi-Floating rear axle
 

I am buying a '05 E350 Chateau to replace my '98 extended club wagon for towing my race car. I just found out it has a semi-floating rear axle. I pull an enclosed trailer weighing about 8,800lbs (max allowed by van). Will this axle hold up. The new van has the V-10, torqshift and tow package. I am quite surprised it is not a full floating axle. I destroyed a semi floating axle in my '03 half ton dodge towing this before I got the club wagon.

Also, did the '05's have disk rear brakes? If not I could just swap my full floater from the club wagon.

Thanks,

Michael

That is very strange, I wouldn't have expected an E350 with the v10 to be rocking a semi-float. Swapping axles shouldn't be too hard as long as they both have tone rings, etc. Drums vs Discs in the rear is an interesting discussion. Honestly, on my van, the rear axle drum brakes are ~12x3. I thought about swapping axles for a disc setup, but I opted to improve my front brakes with cryo treated slotted rotors, high quality pads, and a nice rebuild of the calipers. Even when my 7000lb car hauler's brakes failed, I was able to easily, and safely stop the rig. With only 50% brakes on the trailer, I had no difficulty driving, and stopping, for the last 300 miles of the trip.


Either way, I have an E150 with a ford 8.8 inch semi-float on 31 inch tires. I have had a 7000lb trailer hooked up to it(also with 31 inch tires,) and dragged that trailer over 300 miles of unpaved, ungraveled desert roads in the nevada, and through death valley. It made the 1800 mile trip each way to get there. The rear axle held just fine.

I also have an E450 cutaway with 4 wheel discs, smply gigantic rotors, a Dana 70 rear axle, DRW, and I blew out the drivers side bearings with an empty box and a 3000lb trailer.

Just take care of it, maintain lubrication, and the axle will do what ford designed it to do. If you are not towing over your limits, you will be fine.

I confirmed the van has rear discs so I cannot just swap axles with the '98 club wagon. I guess I will just run the semi-floating axle till it gives me trouble then buy a full floating with maybe limited slip. They are around $500-$800 from the wrecking yard. Part of me wants to go ahead and do this as part of developing my "perfect" tow vehicle. I guess if I do it now I can get some money out of the existing axle while it is in good shape.

Decisions...

Michael

Found some interesting information out.

Here are the weight ratings for my existing '98 E350 Extended club wagon, V-10, 3.73 axle code 34
Front: 3800 lbs
Rear: 6084 lbs
GVWR: 9300 lbs

Here are the weight ratings for my recently purchased '05 E350 Non-Extended Chateau, V-10, 3.73 with axle code 34

Front: 4200 lbs
Rear: 5545 lbs
GVWR: 8700 lbs

The GCWR for both I think is 15,000 lbs but nothing on the van indicates that. The axle in the club wagon is a full floating and the Chateau has a semi floating. I am kind of disappointed with this as I was expecting to have a least as much capability with the new van and considering it is the short version assumed it would be slightly more.

Michael

Start saving your pennies.

I just had the rear axle on my 2004 E-350 overhauled. It is a Dana 60 semi-float with a GAWR of 6084 pounds that had the optional limited-slip differential (a Trac-Lok?). I had been towing a trailer with a tractor on it extensively. The trailer and tractor totaled slightly over 10,000 pounds at maximum loading.

A creaking sound during tight turns and backing began at around 53,000 miles. The differential fluid was replaced with Redline 75W140 at 54,000. The factory fluid was black and smelled burnt. There was quite a bit of grease-like sludge (metal filings and oil) on the fill plug magnet. Unfortunately, the damage was done. The differential didn't have the creaking sound from the LSD any longer but by 58,000 miles there were various moans and clicks emanating from the rear end. It was time to get it looked at.

The rebuilder found a substantial amount of metal grit in the bottom of the differential housing. Teardown revealed that the LSD clutch plates were ground up and the spider gears had numerous chunks out of them. The pinion gear shim pack was also badly battered and torn resulting in it sliding fore and aft when changing from drive torque to compression braking. That resulted in a clunking sound.

The rebuilder said that he had seen problems like this when towing with an LSD, particularly the Trac-Lok. Since the installed LSD was already trashed and needed replacement, I decided to spend a couple hundred extra bucks and have an ARB air locker installed. I had previously installed an ARB in the front axle so there was minimal extra work to add the second. It seemed reasonable that if the first LSD went out in 50,000 miles, it was unlikely that another one of the same design would do much better. Changing the differential fluid more often would probably help but would not be a cure.

Honestly, the damage described sounds more like someone was running with different sized tires on the rear. For example, swapping front tires onto the back when the van has alignment issues, which results in one tire being 1/4 of an inch or more smaller than the other.

Towing with LSD should cause no more wear and tear than towing with an open diff or unlocked locker. Even if you vaporized the clutches, the diff just becomes an open diff. That wouldn't cause the additional damage. Tearing chunks out of the spiders, on a D60, usually that abuse. Overloading enough to cause the axle to flex and become misaligned internally, bad setup of the diff from a repair, or seriously different sized tires left to right. A factory defective pinion bearing, or some seriously torque forces (like running up a curb) could do it I suppose.

I have heard of axle damage on lifted vehicles after running an OEM sized full size spare for only a few miles.

The van was delivered from the factory with LT 245/75R16 tires. Those were removed as part of the conversion. When I picked the van up after conversion it had about 40 miles on it and a set of Firestone Destination M/T's in LT 285/75R16 mounted on the stock wheels. Those tires were run for 20,000 miles with rotations every 5000 miles. In an effort to get a little bit better mileage, a set of Firestone Destination A/T's were installed on aluminum wheels. They have been run since with only short, off-road trips on the old M/T's. Again, they have been rotated every 5000 miles. The tread wear is consistent on all of the tires with no indication of misalignment. It has never run on a spare tire.

It appeared to the rebuilder that pieces of the LSD clutches had run between the spider gears.

The empty van weighs 9400 lbs. so it is loaded to maximum GVW with the fuel tank full. I have never even "rocked" the van and always let the drivetrain take up slack before applying throttle.

I am only reporting that this rebuilder told me that he has seen several Trac-Loks worn out, mostly on vehicles that towed extensively. For what it is worth..........

Conversion company should have specced a higher GVWR base to start with. If it was 9400 empty, you were running essentially at max, and would not have been able to tow the trailer while keeping under GVWR.

What kinda conversion was it? I have not heard of any wheelchair or SRW ambulances clocking in at 4.5 tons dry.

My 02 E350 XLT also has the semi-float, which was a huge surprise to me first time I pulled the rear hub caps. I never looked when I bought it because I assumed, like my previous 92 Chateau HD, that it would have a full floater.
It does have discs as well though, so all E350s probably have both from 02 up at least.

It's not uncommon for Sportsmobile 4x4 camper conversions to max out weight limits as converted.