Help Identify Rear Axle and Load Capacity

[Hackjob]

Hey all, I just purchased my first diesel truck, an 88 F-250 (Super Duty?) with the 7.3IDI and about 159k it has a 3 speed automatic (I think the C6). I purchased it in PA and it ran great on the 200 mile return trip to upstate NY, getting about 9.5mpg. Her new name is Stella! The previous owner puchased it from his grandfather, who used it to haul a 5th wheel camper. He then swapped the rear axle to a dually he got from a junkyard, added an aluminum dump bed, and a 8' Western plow. So that's a quick history, now the question...

When I went to register Stella in NY, I mentioned to the clerk that it had been converted. She then noticed the title had not been amended to reflect this, and told me I had to get it weighed to accurately reflect the new weight (and to re-register it as such). The title for the truck as it originally was configured says it weighed 4,800 lbs, on the local truck scale (without the plow) it weighed 7,160lbs! Wow, that's over a ton heavier.

Now I am trying to figure out what rear axle I have so I can figure out how much weight I can carry and pull. Member Leeland posted a picture of a bunch of differentials on another thread (thanks!) and it looks to me like a Ford 10.25 or 10.5. The housing has 6021 cast into it. It also looks to have been opened up, 'cause there is a bunch of caulk-like stuff squeezed out between the back of the pumpkin and the rest of the housing. There is also a metal tag under one of the housing bolts, looks like it says:

2 V-166A
55 10 2 6805

Can anyone tell me what the ratio is? Also it would be great if anyone can tell me how much weight I can safely load in the bed.

Thanks!

-Hackjob

 

[riotwarrior]

Well it's NOT a superduty cause it's an F250.

You likely have a Sterling/Ford 10.25 rear and without pictures one can't say for sure...is the rear cover blank with no fill hole? If so that's a 10.25/10.50 style.

As for ratio is the truck a 2wd or 4wd? If 4wd they would ONE WOULD HOPE...replace the rear diff with correct ratio. If it's 4x check the tag on the door and read the axle code, that will tell you what it was...and if 4x works it's same..but it may or may not have a posi.

The best way to check, and really you should do this anyway, is replace rear diff fluid and inspect in there. You can jack truck up, place jack stands under rear axle, drain the fluid and then once it's drained you can rotate the ring gear and read the stamping on it 44 10 or what have you. Then do the math to figure it out. This will allow you to make sure no chunks are in there and to check if posi or not

 

[Hackjob]

Thanks! I forgot to mention it is a 4x4, and the 4wd works, so I guess it's the original rear ratio. I will check the door tag. The reason I put the Super Duty in there, is the previous owner said it was a 250 SD and thusly had the same shackles and springs as a 350, and so could handle a full ton instead of only 3/4. Was there anything like that in 88, or a towing package that would beef up the springs in a 250? I'm not worried the axle can't take the weight, but where the springs attach to the frame.

 

[cpdenton]

One other thing to look at. The axle COULD be the original with dually adapters bolted on. You could take off one side and have a look. If the brake drum is all the way out against the wheel face, it is a dually axle, if there is a three inch or so spacer between the wheel bolting surface and the face of the drum, it has adapters.

 

[madpogue]

The "55" PROBABLY means the r/p ratio is 3.55:1. The left end of the tag usually has "3 55" or "3L55", with the L meaning limited slip. But sometimes that first part is missing on account of the tag being cut, or a new hole punched to (re)mount it on the diff cover.

If it's an original F250 Dana 50 twin-traction beam front end, look on the REAR side of the passenger side "beam", there MIGHT be a sticker with a bar-code and some other computer printed text on it. See if there's a "3.54" or "4.11" on it somewhere. And +1 above; knowing the axle code from the door jamb sticker will help.

Are there dually hubs and wheels on the front axle?

"Super Duty" means something completely different from what it used to. Up until 1997, the "F-Superduty" was a particular model, the "beyond one-ton" truck, a cab-and-chassis truck. It's now known as the F-450 and F-550. A lot of owners of these trucks just refer to them as an F-450. Starting in 1999, Ford used completely different cab/bed designs for the F-150 vs. F-250 and up models. To help "brand" this distinction, they began to use "Super Duty" (two words) to refer to the whole F-250 and up _family_. Ford has a long history of doing this, using a name in one context for many years, then re-applying it to something completely different later. In the '70s, "Explorer" and "Ranger" were trim levels of the F-100 and F-250 pickups. Later, of course, they were completely different vehicles. "Zephyr" was a model of Lincoln in the '40s, and a cheap compact Mercury in the '70s.

 

[crashnzuk]

As far as the original title saying 4800 lbs, I'm pretty sure that was what Ford assigned to it when it was built and sold as a pick-up truck. I think they just used a "standard" weight for each line of truck, like the weight of the base model standard cab 2wd. My Dodge is registered in the under 4800 lb class, but it actually weighs about 5800 lbs in stock form. I'm sure they made you weigh it because it's no longer a "pick-up". Out here in CA, if you change from a pick-up bed to a flatbed, dump, utility bed, etc, they make you weigh the completed truck and it comes out like yours did with higher weight and higher fees.
Travis..

 

[ironworker40]

I will add you do not have a F-250 super duty, you have a F-250 HD. Back then Ford had HD F-250 which is what all F-250 diesels were with full floater rear axles and F-250 that has semi floating rear axle like a F-150. I don't think you can raise the gvw so go with what's on the sticker. As far as how much she can haul if you are talking about putting it on the flat bed it depend on your springs, if you have the auxiliary springs 4-5000 lbs. Towing depends on hitch too many variables there, you will have to let us know what you have.

NY dmv can be a pan in the ass. Were are you in NY? Can you go to a different dmv? I have had to do that many times. Example , try and register a snowmobile in Staten Island dmv it was a Nightmare. Go to Schoharie County they gave me resident transferable registration and made me pay sales tax which Albany told me was wrong and revoked the transferable registration gave me a non transferable one and kept the tax money. Then I had to go to NJ to register so I could sell them and pay tax again. Now I went to Catskill dmv and walked in and out in 10 min no problem. It depends on who you get behind the counter.

 

[Hackjob]

First, thanks to all you members for taking the time to help me and post some actually usefull information. This is a way better response than I anticipated! It looks like the gear ratio is 3.55, since that's the original rear axle ratio and the 4wd works. It looks like the rear end is a true dually axle, no drain plug -so a Ford/Sterling 10.25/.50? I didn't take the wheels off, but was able to reach my hand (and look) through the holes cut in the wheels to feel that there is no extra room. The P.O. said he put dually hubs on the front, but I'm not sure if he meant wheels w/ adaptors or not. There is a metal tag on the front pumpkin that reads:
3 54 Upsidown triangle E.......
Upsidown triangle 610312-......
Can't read the rest- too rusty, but it looks a lot like the pictures of a Dana 50 twin traction beam front end on Google image search.

So it looks like the rear end might be a Sterling 7400, capacity: 7,400 lbs, plus the original front axle with a capacity of 4,410lbs is 11,810 lbs minus the total weight of 7,160lbs equals 4,650lbs load capacity. Sounds like I can safely load it with two tons (that would be great). However, I want to make sure I don't overload the springs or brakes. Can I just count the leafs (leaves?) on the springs to know if there are enough? Rear has 5 and the front has 2. The front springs look kinda tierd, I'm considering replacing them now that I looked closer. they bend up and have under an inch of travel before they hit the chocks. Do I need to replace or add more springs? Also, are the frame and mounting points on this '88 250 sturdy enough to take the weight of a 350 (or 450), are they the same?

On the subject of braking, it looks like the rear brakes are bigger now since they go with the dually axle, but I know the front brakes do more work. Sould I be concerned about the original front brakes being underpowered? I don't mind driving like a grandpa...


I guess now my question is, do you guys think I should rate it for 1, 1.5, or 2 tons?

Thanks again!

 

[ironworker40]

250 and 350 frame are the same so are the front brakes. The front springs you described are normal 250 TTB springs. You need to post some pics of your rear springs and front hubs so we can tell you more. If you post axle code and spring code from sticker on drivers door or jam I can tell you what the original ratings were

 

[riotwarrior]

F250 never came in dually and never in 4x4 dually.

It could be a true dually rear but front isnt

To be sure you need to jack up rear n remove otter and inner wheel one side and see if an adapter is bolted to hub or not.

Same for front remove wheel and inspect.

Regardless if is bolt on adapters then your g w remains same as srw stock axle.

 

[FORDF250HDXLT]

Sould I be concerned about the original front brakes being underpowered?


I guess now my question is, do you guys think I should rate it for 1, 1.5, or 2 tons?

Thanks again!

yes.the truck is far more capable now than the vacuum brake system is designed for.
if you want to make full use of the trucks setup now,you'll need to swap to hydroboost.
you can haul 2 ton with ease then.

 

[laserjock]

Just FYI, here's what a set of adapters look like. If it's rusty and you aren't sure what you are looking at, you might mistake it.

You must be registered for see images attach

You must be registered for see images attach

And adapter removed.

You must be registered for see images attach

With the inner duals on.

You must be registered for see images attach

You might be able to see the spacer with the wheel on but it's not easy.

 

[crashnzuk]

The easiest way to tell if there are adapters on a Sterling rear is how much of the hub is sticking through the wheels. 1 or 2" means theres a spacer, 4"-ish means no spacer. Sterling rears have very long hub stickout, so anything less than lots means a spacer.
Travis..

 

[Hackjob]

Thanks again everyone! I'm pretty sure I have a true dually rear and spacer for the front end. The axle ratings a posted ealier are from the door sticker for the front (4,410), and assuming the rear is a Sterling 7400 (7,400). The original rear axle code is 39, that's how I confirmed the 3.55 gear ratio, the spring code is 9 A. I think I going to register it for 2 tons, but I won't max the weight untill I upgrade the brakes to hydroboost. I'll get to posting some pics asap.

-Hackjob