Ford 8.8 Rear Axle Strength

rjstractor wrote:

Sloop Smitten wrote:
I have that same differential in my Class "C". The GAWR (Maximum permissible weight per axle) for the rear is 8,800 lbs per the RV placard. Of course it has tandem wheels on the rear if that factors into it. I tow a VW bug behind the motorhome and have had no problems with the rear. I was surprised to see the 8.8 under there as that was the standard rear for E150 vans and this RV is built on an E350 cutaway chassis. Would of thought a more substantial unit would have been in order. Hope this is of some help.

That is very surprising, are you sure that's correct? The F250/350 of the same vintage had a 10.5" full floater with 8 lugs. I suspect that's what your E350 has. Do you have a picture of the differential housing?

I do not have a picture but I did spend several days researching which gasket I needed so I could change out the gear oil. The pattern was definitely the 8.8 and that is what I purchased when I changed the oil. There appears to be some bastardization involved with the E350 cutaway as I also found I had a power steering pump for a diesel rig when I had to replace it. Not complaining just stating some unusual findings.

Sloop Smitten wrote:
I have that same differential in my Class "C". The GAWR (Maximum permissible weight per axle) for the rear is 8,800 lbs per the RV placard. Of course it has tandem wheels on the rear if that factors into it. I tow a VW bug behind the motorhome and have had no problems with the rear. I was surprised to see the 8.8 under there as that was the standard rear for E150 vans and this RV is built on an E350 cutaway chassis. Would of thought a more substantial unit would have been in order. Hope this is of some help.

That is very surprising, are you sure that's correct? The F250/350 of the same vintage had a 10.5" full floater with 8 lugs. I suspect that's what your E350 has. Do you have a picture of the differential housing?

My '97 F150 had the same rear end. I re-geared it to 4.10 which is even weaker than the original 3.55. It was stout and worked well for years. I towed my 6000ish lb trailer while carrying two small ATVs in the bed along with all the regular camping gear, including gas, generator, coolers, etc. Yeah it was overloaded in every regard often but continued to work flawlessly as I towed through the northern US Rockies.

It even withstood a rebuilt, supercharged engine routed through a strengthened, hard shifting transmission for all those years. It did finally fail in grand fashion when my teen-aged son was showing off for his friends and dropped it into gear while revving the engine.

Just stay within the OEM's ratings and you will be fine...and use the best maintenance materials and schedule you can afford...willing to afford...

That is what any OEM's ratings/specifications/limits/etc are for...to tell you their customer the HOW2's of using their product...that they will stand behind it (know you know this Jeremiah...it for the lurkers out there)

Of course if in good condition and if worn, then the ratings go down. How much is the gamble trying to 'push it'... Plus, how the previous owner(s) have used it, maintained it, etc...

Differentials are pretty stout and one of the forgotten component systems...but here on a towing forum...a much more important component system

Daughter has my old 98 Mazda B2500 (Ford Ranger half ton) and has zero problems with it...other than the Michelin flotation tires cracking....oh yeah...SIL went 'stock' on their last brake set and it wore down to the rotors in about 1/4 of the miles of what I put on there.

They used to tow a Coleman PUP and rent U-Haul motorcycle trailers. Now that they are parents...no more track days till my grandson is much older...

I have that same differential in my Class "C". The GAWR (Maximum permissible weight per axle) for the rear is 8,800 lbs per the RV placard. Of course it has tandem wheels on the rear if that factors into it. I tow a VW bug behind the motorhome and have had no problems with the rear. I was surprised to see the 8.8 under there as that was the standard rear for E150 vans and this RV is built on an E350 cutaway chassis. Would of thought a more substantial unit would have been in order. Hope this is of some help.