Hey everyone!I hope everyone is having a great day today. My new to me F150 SCREW has an 8.8 rear axle, seeing as I have the 4.6 V8. I am curious about this axles strength. I have had this axle before in my Rangers but this is the first example in a full size truck. My previous F150 had the 9.75 rear axle and it never gave me any issues. What is am scratching my head about is the strength of this 8.8 because the RAWR on this 8.8 is about 3,900 ish lbs which is nearly identical to the 9.75 rear axle rating. I know that these 8.8's handle a lot of HP in muscle car applications but I don't know how this applies to weight carrying. Basically, do I have a noodle under the back end of my truck or is this a pretty stout axle for a truck?And no, it is not hauling a fiver or a large TT or anything like that. I am going to limit the pulling to around 5,000 lbs max...and that's mostly going to be a car trailer to haul my 65 mustang project. Just trying to figure out how 'weak' this axle is compared to a 9.75.Thanks!Jeremiah

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.

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 systemDaughter 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...

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.

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?

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.

Ford 8.8 Rear Axle Strength | Good Sam Community

15 Replies

Sloop_Smitten
Explorer
May 31, 2017
I forgot how far underneath the vehicle the differential was on this cutaway. Tucked forward of the 36 gallon fuel tank. I would have to crawl literally to the middle of the vehicle to snap a picture and I was not dressed properly to do so. I will see if I can try again this weekend.
Sloop_Smitten
Explorer
May 30, 2017
Camper G wrote:
Grit dog wrote:
It'll tow as much as the little 4.6 will put out. It's not how much you're towing, it's how heavy on the axle and the input from the north end of the truck. Not something I'd consider worrying about. There's about 5milion f150s getting ragged on everyday. Don't see them sitting with broken axles on the side of the road.

8.8 dually 1 ton app is something I've not seen before and likely never will without a pic of the underside of that camper. Not saying it's impossible but it's laughable from a load carrying standpoint.

Agreed, I've never seen an 8.8 with dual wheels either. Somethings not right

I apologize. I have been on vacation at the North Rim. I'll see if I can snap a picture of the cover for perusal to confirm it is actually an 8.8 and not something else. Would not be the first time I was mistaken.
Camper_G
Explorer
May 20, 2017
Grit dog wrote:
It'll tow as much as the little 4.6 will put out. It's not how much you're towing, it's how heavy on the axle and the input from the north end of the truck. Not something I'd consider worrying about. There's about 5milion f150s getting ragged on everyday. Don't see them sitting with broken axles on the side of the road.

8.8 dually 1 ton app is something I've not seen before and likely never will without a pic of the underside of that camper. Not saying it's impossible but it's laughable from a load carrying standpoint.

Agreed, I've never seen an 8.8 with dual wheels either. Somethings not right
Grit_dog
Navigator II
May 20, 2017
It'll tow as much as the little 4.6 will put out. It's not how much you're towing, it's how heavy on the axle and the input from the north end of the truck. Not something I'd consider worrying about. There's about 5milion f150s getting ragged on everyday. Don't see them sitting with broken axles on the side of the road.

8.8 dually 1 ton app is something I've not seen before and likely never will without a pic of the underside of that camper. Not saying it's impossible but it's laughable from a load carrying standpoint.
noteven
Explorer III
May 20, 2017
You should be fine with the 8.8:
Ford axle test
Camper_G
Explorer
May 20, 2017
I had several mid-late 80s 5.0 mustangs with the venerable ford 8.8 in them. I ran those cars HARD and track raced a few in stock form, no mods. I also had a few F150s with them also.

I never had one single failure, despite all that abuse. I think it's a great rear.
garyp4951
Explorer III
May 20, 2017
I've used 8.8's in several Jeep projects, and they did great.
They are C clip axles, and you can get C clip eliminaters for them if you want.
1320Fastback
Explorer
May 20, 2017
Don't know if they changed internals but my 68 Mustang used to eat 8.8s for dinner. Went thru a few before I swapped in a 9".
jerem0621
Explorer II
May 20, 2017
Thanks everyone! I appreciate the feedback!

Thanks!

Jeremiah
dodge_guy
Explorer II
May 19, 2017
As you know there are plenty of products out there to strengthen it. Diff covers with bearing cap preloads, stronger carriers. However the real thing to consider is axle bearing size, which in an F150 is larger than in a mustang.

If you are really concerned a 9.25 would be a direct bolt in!