OBS Dually Swap with Disk Brakes & Ebrake

[96Mattman]

Hey Guys,

I have a 1996 SRW 7.3 F250 sitting on a D60 Kingpin and SRW Sterling 10.25 (4.10 gears). Both axles are actually swapped from a SRW bricknose f350.

This is my currrent brake setup:

• F-Superduty Hydroboost
• F-Superduty Master Cylinder and Brake Pedal
• F-Superduty Power Steering Pump
• Rear Disk Brake Conversion using El Dorado calipers

I recently decided I want to swap to a dually axle to make haulling my heavy camper safer and more comfortable. I am running 19.5 singles right now, and the unloaded ride is terrible. I figure going to a DRW axle allows me to go back to using LT tires for a much better ride since I daily drive this truck. My first thought was to find a DRW Sterling 10.25 for a direct bolt in, but then I am back to having drum brakes that are not compatible with my F-Superduty master cylinder. I refuse to do another disk brake conversion with the el dorado calipers - it's too expensive and the e brake is terrible. So what are my options? It seems every direction I turn there are issues.

Some non-negotiables:
I want to keep my lug pattern at 8x6.5, and have rear disks with a TRUE ebrake. Axle must also have a VSS speedo sensor compatible with OBS trucks.

Option 1:
1999-2003 F350 Pickup DRW Dana 80
I figured this would be a slam dunk. Just redrill the hubs to 8x6.5, move shocks mounts, figure out driveshaft/yoke, etc. But I then realized the SD Dana 80 doesnt use the axle mounted VSS. So this killed my plan here.

Option 2:
E-350/E450 Dana 70/80
I am still researching this possibility, but there seems to be a ton of variables in the different axle configurations. And I am still not 100% sure if these Dana axles use the VSS. But the Van's 8x6.5 lug pattern would be taken care of. I am also not sure about the E-brake. It seems some E-series used a driveline ebrake instead of a integrated drum/hat within the rotor.

Then there is the issue of finding the correct width axle. I dont mind using a narrower axle since I only have a 7ft wide flat bed. Less tire sticking out would be nice. And I dont mind moving the spring perches if there is room to do so on the axle. Are there certain years/configurations to look for that use an axle mounted ebrake? I would probably avoid the Dana 70 unless it is HD. It seems to be a lesser axle compared to the sterling 10.25.

Option 3:
Use a DRW Sterling 10.25 and convert to e350 brakes. This is an unlikely route for me to choose because I dont have access to a machine shop to fab the new flanges required to mount up the e350 backing plates. Is there anyone making these brackets for sale?

Option 4:
Find a DRW Disk brake axle from either Dodge or Chevy. I have the least amount of time researching this route, but it would solve the lug pattern issue I think. No idea on the VSS or other fitment issues.

Option 5:
Use dually conversion adapters. This is something I intially considered since it would be the least involved. But my understanding is this would actually increase loading on the wheel bearings, and the SRW housing is not as strong as the DRW. And it doesnt fix my terrible e brake.... No go.


Are there any other options I am missing? What years and vehicles should I be looking for? How would you solve this riddle?!

 

[psduser1]

Recheck option 1.
Super duties has axle mounted vss until 2010. Bolts in the top of the pumpkin. Whether it's the same style as obs, I don't know that yet for sure, but I'm going to do this swap myself at some point, so I guess I'll know for sure then.

 

[96Mattman]

Recheck option 1.
Super duties has axle mounted vss until 2010. Bolts in the top of the pumpkin. Whether it's the same style as obs, I don't know that yet for sure, but I'm going to do this swap myself at some point, so I guess I'll know for sure then.

That would be a game changer! I was under the impression that the Dana axles did not come with the VSS, only the SRW Sterlings. I will dig into this further. Thank you for the heads up.

If it does have the VSS, it seems like it would be easy enough to swap the connector over to the obs truck-side harness if they are different. It should just be splicing 2 wires... I think.

 

[psduser1]

I've put a few Dana 80 dual axles into single wheel pickups. That is literally a bolt in swap..

 

[96Mattman]

I've put a few Dana 80 dual axles into single wheel pickups. That is literally a bolt in swap..

 

[96Mattman]

Glad to hear it! I may have misread something about the VSS then. It had me finding a roadblock with almost every other axle I was considering. This setup would be the path of least resistance by far.

Did you switch to 8x170 wheels or stay with 8x6.5? If so, how did you do it?

 

[Tiha]

Your wheel bolt patter will be the issue going with a newer axle, just like you are suspecting. There are a couple options, some guys re drill the hubs, or you can use a wheel adapter. But of course both options weaken the wheel end.

 

[Tiha]

I did option 3 to a sterling 10.25 I am happy with it.

Not sure the swap is for everyone. Not difficult but not simple either.

Bought a semi floating rear end from a E-250. Cut it apart. I actually used a chop saw to cut the axle tube behind the flange. Ground what weld I could, then pressed the flange off the tube. It did not come off easy.

After that, the flange fit loosely on the Sterling axle tube, but not loose enough to affect anything.

Had problems setting the flange depth. there was nothing to compare to. No measurements matched up.

So I slide the flange on. Completely re assembled the wheel end, caliper, rotor and all. Used that to set my flange depth and tack weld it in place.

Tear it back apart. Weld it up. Final assembly. I love it. could not be happier. But like I said, it is not a simple or quick job. So it is not for everyone.

 

[psduser1]

Glad to hear it! I may have misread something about the VSS then. It had me finding a roadblock with almost every other axle I was considering. This setup would be the path of least resistance by far.

Did you switch to 8x170 wheels or stay with 8x6.5? If so, how did you do it?

8x170. Haven't done the obs yet.

 

[96Mattman]

I did option 3 to a sterling 10.25 I am happy with it.

WOW this this awesome!!!!

Did you also have to cut the flange off of the sterling? This seems like it could be within my wheelhouse….maybe hah. Seems like a lot of work, but not overly difficult.

However seeing that I already need to source a DRW axle, this option would require me to source a second axle :/ which is not ideal. Have you heard any accounts of failure from folks redrilling sterling 10.5’s or Dana 80’s to the dual lug pattern (8x170 & 8x6.5)? Sure, maybe it’s not ideal, but I wonder if it’s actually a weak spot in the load path? Especially given that some aftermarket axles (Currie?) come with dual pattern hubs. Thanks you for sharing your setup!

 

[Tiha]

Yes, I cut the flange off the sterling. It is not thick and heavy like the dana axle. so it came of very easily.

I shopped rear ends for a while, either a semi float or full float will give you the parts you need. I found mine off market place for $75. I bought all new pads, E-brake stuff and cables off rock auto. rebuilt the calipers. I already had the rotors.
So I didn't have $200 in the whole swap.

I don't honestly know about the strength of dual pattern hubs, or re drilling the Sterling 10.5 hubs. I just see guys do it and get an un easy feeling about it. There may be absolutely nothing wrong with it and I am just paranoid.

 

[96Mattman]

So my non negotiable of stick with 8x6.5 lug pattern might have just changed.

I did not want to add wheel adapters to the rear or front. But I just called arrow craft and they said they can make a front Dually adapter (which I already need to convert the front end from SRW to DRW) that has a 8x6.5 vehicle side pattern, and 8x170 wheel side pattern. This is huge!

Now I can save a ton of time and work drilling the D80 hubs, and upgrade seamlessly to 8x170 wheels. This make going to the SD D80 almost completely bolt on, save for shock mount and some misc items I probably haven’t thought of.

 

[psduser1]

Check rickson wheel, also. They may have some options for you bolt pattern choices.

 

[96Mattman]

Some pics of the rig!

 

[Tiha]

I know the dread of swapping bolt patterns. I have fought so hard to avoid it.

All these years I have been making the truck better, stops better, steers better. But I am at my limit with the ride quality and seriously thinking about doing an 05+ swap.

Did my son's excursion, once we get it on the road we will see how I like it.

 

[96Mattman]

Progress update:

I have changed my approach with this project a bit - last weekend I picked up a 2007 F350 DRW Dana 80. Previously I was not wanting to change bolt patterns, but I also found a complete set of 05+ OEM Ford wheels (aluminum outers, steel inners) for a good price.

So the rear end is taken care of in terms of wheels/bolt patterns, a good e brake, and speed sensor. I still need to work out if I can swap in a OBS speedo sensor into the 07 axle, as I have read that the connectors are different, as well as the readings the sensor provides. But supposedly the OBS sensor in the D80 will make everything work.

Now for the front axle - I have a line on a set of used-(like new) 2019+ Dodge front dually adapters. This is almost the perfect part to make this all work and be bolt in. Dodge still uses 8x6.5 on the inside/vehicle side of the adapter, and 8x200 on the wheel side for 2019+ trucks. The OD hub bore on the wheel side also matches the Ford hub bore (142mm). However, the hub bore on the inside (ID) is smaller (121mm) than the hub bore on my Ford KP D60 axle (124.9mm). My idea is to have the Dodge adapter machined out a few mm to get it to fit over the shoulder of the Ford KP D60 hub. Then everything would be hubcentric and bolt right up!

Has anyone heard of doing a mod like this!? Any reason(s) why this wont work?

I haven't completely vetted this from all angles. I am a little concenered with the wheel offset with respect to the thickness/width of the Dodge adapter. I believe the Dodge adapters are 3.75" from face to face. I am not sure if the OEM Ford dually adapter designed for these wheels is the same width as the Dodge adapter. Then again, the Ford adapter would have been designed for the 05+ axles anyway, so I assume there are some differences in steering geometry compared to the older KP D60 anyway.

Here is the part number and google link to the Dodge adapters I am considering:
Mopar 68449628ab Whee Extension

 

[96Mattman]

I have been doing some thinking about what width my front Dually adapters should be to keep things close to stock steering geometry.

Today I went out and took some measurements from the new (to me) wheels I am going to use. Here are some specs on the 05+ DRW Ford wheel:
17” x 6.5” wide
Backspace is approximately 8.375”
Calculated Offset: 8.375-3.25=5.125” positive offset

My thought was to compare the offset of the dually wheel to the offset of stock srw wheels, and make up the difference with the dually adapter. Here it goes:

Stock SRW Ford wheels:
16” x 7” wide
Backspace is supposedly 4.25” from what I read
Calculated Offset: 4.25-3.5=0.75” positive offset

Calculated Dually Adapter width: 5.125”-.75”=4.375”

DOES THIS MATH MAKE SENSE?!

It seems own dually adapter are around 4” wide give or take .25” or so.

Am I going to regret not using a wide enough adapter to keep the wheel centerline where Ford designed it to be? I am worried abou steering feel and possibility of the tires hitting the leaf springs.

any input is much appreciated!!!

 

[Tiha]

Not a dually guy, you are throwing around a lot of numbers there but I see your logic.

I think I would focus on the overall width of the axle is how I would approach it.

Being narrower, if on a standard wheel, then yes it will rub on the leaf spring.

But there are benefits to being narrow as well. Like less stress on the steering system when turning, but probably not enough to notice.

Tracking straight down the road should not change with axle width.

 

[psduser1]

I've never actually measured the adaptors, but I use a 6" extension to pull them off to get at the axle- hubs, whatever, and thats plenty of length. Id guess the adapters are roughly 4" deep.