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Man of endless projects
9,872 Posts
Discussion Starter · #1 ·
so I know alot of people that want to go to a bigger stronger axle but don't want to go to the 8-lug due to various reasons. its not very easy to convert the front TTB to 8-lug, 5lug-to-8lug wheel adapters are risky, don't want to get rid of your expensive tires/rims you love soo much. there's plenty of reasons to want to stay 5-lug.

So here it what I did to convert my truck to 10.25" and stay 5-lug because I knew I am going to be building a 418w stroker that's going to put out way too much for my little 8.8". Simply put, I took a semi-floating 10.25" Sterling axle and got custom axleshafts made for them with the 5-lug pattern on them. then I did a disk brake conversion on it. pretty easy and simple really but abit costly but worth it in my book. This can be done to pretty much any semi-floating axle like a Dana 60 but just remember THIS WILL NOT WORK ON A FULL FLOATING AXLE

This is my Semi-floating Sterling 10.25" axle I pulled form the junkyard. It is from a 97 F250 with the newer body style. As you can see it was raining when I pulled it so I was rushing and didn't notice that the gear ratio was actually 3.73 instead of 3.55 but this isn't too big of an issue, ill just change the front at some point to match.

Also something I missed due to rushing in the rain is that surprisingly enough, the axle is 7-lug instead of 8-lug you would expect from a 10.25". again this wont matter in the long run but its interesting that Ford did use a 7-lug pattern on 3/4 ton trucks

First thing to do is pull the axleshafts. the semi-floating axles use a c-clip so you need to pull the cover, remove the crosspin, remove the spider gears and the axleshafts will pull right out once the c-clips are taken out. I also went ahead and pulled the brakes which just uses 4 bolts per side. the gears and everything looked still good so the axle had plenty of life left

the other axle is a full floating 10.25" dually axle. it was my backup plan incase things went south. Being I am using an axle from a newer generation I wasn't too sure how to easy this was going to be to make shafts for. was going to swap it in my 90 F250 then use its current 10.25" semi floating axle but luckily I didn't need to do that.

This is why it is better to use an axle from our generation trucks. this being from a newer generation 97 F250, the leaf springs were about 3/4" different width apart and I didnt like that. I was planning to replace them anwyays but if you don't want to then make sure you get an axle from the correct generation.

I cut the older perches using an angle grinder. its not too hard to do then I used a big hammer to bang them off breaking any weld I couldn't reach. just avoid cutting deep into the tube cause the tubes are thin.

got both perches cut off and tubes ground smooth and ready to weld

These are the leaf spring perches I got from Ruffstuff. as you can see there nice and long that helps alot with axle wrap. very nice quality and very happy with them. they even have 3 holes so you can position them on the leafspring forward or back some

I am going to wait to weld these on till after the axle is under the truck and weight is on the axle. Once its under the truck with weight on the suspension, im going rotate the axle so I can get the pinion angle of the driveshaft perfect. This will eliminate the need for the factory angle blocks found on the broncos and it will also make it better for 3" lift I got from my F250 springs. The factory angle blocks on my old axle crushed to dust and caused all sorts of damage and I don't want to repeat that.

this is my weld on disc brake bracket from Ruffstuff. this one specifically is for a 9inch axle with 3.0inch tube which i accidentally ordered instead of for the 3.5inch version. I had to modify it alot to work correctly by cutting the circle in half and grinding it alot. even then the complete brakes didn't want to fit inside my rims so I had to grind them even more. you can try to use the 3.5" brackets and hope they fit inside the rims or you can modify a weld-on disk brake kit designed for an 8.8"

So here is the main part of the conversion. the axleshafts themselves. I had these custom made by Dutchman Motorsports and I highly recommend them. they were great to work with. There are a few things you will need to know to get them made.

-Axle Type (C-clip)
-Axleshaft Lengths (there are a few different way they can be measured, my axle will be different than most)
-Bearing journal size (which is 1.705 for 10.25")
-Spline count (should be 35 but double check to be sure, not sure if other counts were offered)
-Button Width (distance between c-clip and very end of axle. 10.25" is 0.305")
-Pilot Width (the hub at the end of the axle. you want this to be the same as the inside hole of brake rotor/drum you plan to use so its hubcentric)
-Flange OD (the overall diameter of the axle flange. just make sure your rotor will fit over it)
-Bolt Pattern (5x5.5 or whatever you plan to use)
-Stud Size (1/2" press in or whatever you plan to use)
-Brake Kit (list if your using OEM or aftermarket drum or disk brakes)
-Hardware (if you want studs included. can also provide new bearings and seals)
there might be other things I cant remember. they may call asking for other info

The shafts themselves cost $335 for the pair, $20 for the 10 studs, $110 for the pair of bearings and seals, and about $80 shipping. so about $550 for everything

when I ordered my shafts, I made the mistake of making the pilot match the 8.8" axles. I planned on using the same rotors used by the front brakes so they all match. I made my pilot 3.440" but the rotors for the front brakes are actually 3.88" so the rotors were no longer hubcentric and unusable without causing issues. so make sure the rotor inner hole and the pilot are the same. I had to get some rotors custom made for this and you do not want to be doing that.

Also I made them with the flange being 7" in diameter without thinking much about it. well it turns out that is too big and my rotors wouldn't fit over them. I had to take them to a machine shop to get cut down to fit. I think there about 6" in diameter now but you want to make sure the rotors you plan to sue will fit over them.

also note that the pilot doesn't extend very far. its designed for the brakes to fit over them to be hub centric but the wheel itself is not. when ordering you may try and order it so they extend more but remember that the wheels inner holes are a different size than the rotors. for example the wheels inner hole will probably be the 3.44" if there stock

I went ahead and ordered new bearings and seals from them also.

another thing to make a note for when ordering is that the c-clip groove is my axle was abit wider than I liked. the c-clip is abit loose and can make you question if it will cause issues. but I can assure you that as long as the Button Width is exact (distance between end of axle and the c-clip) that once installed with the pinion shaft, there is no issue at all with it being loose. but you may make a note when ordering of the thickness of the c-clip to try and avoid it being soo loose

got the shafts, bearings, and seals installed with the axle all buttoned up. I checked the endplay in the shafts and there was none so as I thought the loose c-clip is not going to to be an issue.

I mocked up the brakes to the axle and went ahead and welded the bracket onto the axle. there was about a 1/8" gap between the old flange and the new bracket so I went ahead and filled in the gap.

the brakes assembled to test out.

because the stock front rotors I was going to use was no longer going to work, I had to use these rotors are from a ~96 Dodge Ram 1500 and have the center hole enlarged to fit the pilot. the brakes themselves are JB5 style Chevy brakes commonly from 73-87 Chevy 3/4 ton caliper. you can try to use the larger JB6 if you want but it might cause clearance issues due to being bigger and might have too much braking power.

once one side is done you will want to check that the wheel fits over it without anything scrapping. because my rotors and brackets wernt exactly what I wanted them to be I had to do some modifying to get them how I needed.

i got the axle all swapped under the truck with the u-bolts very loose still.put the tires on temporarily and had the truck sitting on its own weight. using a straight edge i lined the pinion angle to exactly where i need it to be for the best possible angle and least u-joint stress. i was able to angle the axle using a jack under the pinion to raise it up and then a large prybar to pry it back down till it was perfect. it doesn't want to spin easily with the trucks weight still on it but can be done with enough force. once its in the exact spot i need it i welded the leaf perches up and tightened down the u-bolts

I did have to make a new brake hardline for both sides. the brake hoses are pretty long so the driver side hardline is very short. the passenger side wasn't soo bad. i bought a couple weld-on brake hose tabs from Ruffstuff to hold the hoses in place.

Because the 10.25" has a longer yoke than the 8.8" axle, I got a custom driveshaft made that was a few inches shorter and using larger 1350 series u-joints. I got it from a local company called Precision Shaft Technology for $300

Got the driveshaft installed and the pinion angle is about as perfect as i could imagine it would be. and no angle blocks needed either

another issue with using this axle from the newer bodystyle trucks was that the shock mounts are unusable. had to order a pair of shock mounts and weld them on.

I might in the future try and make use of the original mounts for a quad shock or a traction bars.

All done!

Extra: I went ahead and replaced the brake booster and master cylinder. the brake booster is from a similar year F350 and is a direct swap and really helps when using bigger bore master cylinders. F250 used them too but some also ones with smaller booster used by F150/Broncos. This brake booster is actually cheaper than the stock sized ones making it a great choice to swap to even with stock brakes. the brake lines easily flex enough for it to fit. In the pic theres rust on the booster because i installed it a month before this swap

the master cylinder is a Cardone 13-2828 which is designed for rear disc brakes, includes the reservoir and has the port for the sensor on the front used by cruise control. the 13-2827 is the same but without the sensor on the front. it SHOULD fit on a stock brake booster but MAY be too big. its for a 2000-2002 F150 with rear disc brakes (the models with rear drums use the same one as our stock trucks)


Man of endless projects
9,872 Posts
Discussion Starter · #4 ·
this axle being such an oddball, it was wider than my 8.8" by alittle bit but nothing really noticeable. not sure about a normal 10.25 width vs the 8.8 but it shouldn't be very noticeable

I did some research on it when I found out it was 7-lug. it was used in light duty F250 and heavy duty F150. but defiantly an oddball

User that is Registered
998 Posts
The 7 lug sterling Axle was produced from 97-2014ish, it came on the 97 and 98 light duty f250 that looks like a F150. After the Super Duty was released the light duty F250 became the F150 7700. Both vehicles were available as a regular cab long bed or super cab short bed. After the 2004 redesign the 7700 pound GVWR package became the 8200 pound GVWR package and was available as an option on regular cab long bed F150s and was a mandatory option on all Supercab long bed 2004-2014 F150s. All this is from my memory, so it might not be 100%. There is a forum for this package on F150online for more information.

Edit: really cool write up Kingfish, I want to try this on my truck with a pre 97 semi float axle, this is inspiring, I haven't felt the need to log in and post in years.
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