10 Bolt to 14 Bolt Full Floater Swap

[Crankshaft Brad]

First, I apologize in advance for my ignorance.

After changing the leaf springs on my 91’ 1500 this weekend, I now have a leaking axle tube. The junk from the roads over the past 30 years had collected in the lower plate that bolts to the axle. When I had to pull the plate off to change the leaf springs, I realized I had a problem. The bottom plate was severely rusted, and the axle tube was rusted to the point it was barely leaking.

I have gone back and forth on repairing the rusty axle tube by sleeving it from the inside, or carefully cutting the rusted section out and TIG welding in a new piece, but both are a hell of an undertaking. I had also thought about swapping in a Ford 9 inch, but the swap parts I would need could really draw out this project longer than I want. (I am still waiting on fittings I ordered in March)

My thought is this... Pull the 10 Bolt, and replace it with a 14 bolt that is a full floater. But, I want to keep my 5x5 bolt pattern. I want to use a 14 Bolt because the junkyards near me are full of trucks that have 14 bolts. Yes I know that is a very questionable decision, but I will be keeping the wheels I have on the truck.

I work in a machine shop, with access to lathes and vertical mills, along with all of the other toys that are in a machine shop. I have never dealt with a floater rear end, and do not know how the hubs work exactly. I would like to be able to simply turn the hubs to a slightly smaller diameter to fit in the wheels, and re-drill the 5 lug bolt pattern on the hubs. Will the spring perches line up?

To me this seems too easy to do, and I must have to be missing something to this equation. If it was easy somebody smarter than me would have done this by now.

 

[b454rat]

It will bolt in, perch width is the same, think even the shock mounts are the same. GM didn't change things around like they did in the square trucks. But, I don't think you can turn the hubs down enough to get even an aftermarket wheel to fit. And I don't think you can just redrill the hubs to 5x5, there are bosses or extra material on the inside of the hub where the holes are for the stud. If looking at it you'll understand what I mean. Plus, the diff is gonna be inches off the ground. Hit a speed bump the right, or wrong way, you'll get hung up on it. Going to a 9" isn't really that hard. If you work in a machine shop, you can make the perches and shock mounts, weld em on, get a conversion joint, and redrill the axle and drums to 5x5 bolt pattern. IMO, alot easier than the 14ff...

 

[df2x4]

IMO the 9.5" 14 bolt semi floater would be a much better option than the 10.5" full floater. There are even five lug axle shafts available for them from Dutchman. I've looked into that swap in the past. The only thing I haven't figured out is how to make the 10 bolt brakes work in that application.

Is there a reason you're looking at the full floaters?

 

[454cid]

Why do you need a 14BFF on your 2wd 1500? If this is just a daily driver get another 10-bolt, or maybe the 14b semi-floating axle.

 

[stutaeng]

Aside from ease of availability, is there another reason why you want the full floater version of this axle?

There's a thread on performance truck.net where a guy made the 14 bolt/10.5" into 5 lug. If you have the machining capabilities, no problem. The factory brakes are fairly massive, however. I don't know if your wheels will clear. https://www.performancetrucks.net/f...-22/10-5-full-floating-14-bolt-6-lugs-528236/

And axle itself weighs somewhere around 450# with drums in stock form. It's heavy because it's meant to be worked. Think Mule vs Quarter Horse, LOL.

Another candidate is the 14 bolt 9.5" as was mentioned. It's a semi float design, but still plenty strong and they also made a lot of those. I believe you just need custom axles for your 5 lug, or modify them yourself. I'm not sure on the brakes. They'll clear 16" wheels and they are better than the basic 10 bolt brakes. They are still 6 lug, but they are a direct swap to the 10 bolt. I helped my brother swap one into his '90 C1500. He also swapped the front knuckles/hub/brakes and converted the truck to 6 lug.

I don't think a disc brake 14 bolt would be that much more difficult than a drum version. I think I read just the spring perches are a bit off between the two, but in the grand scheme of things, that seems like a minor thing if you have welding capabilities.

 

[RichLo]

I just did this swap, this thread below shows my progress. I had to move the spring perches out on mine but I dont know what it came out of either. but it was s single rear wheel axle, not a dually.

Like everyone else has said, if you want to keep your 5-lug wheels you are better off with a different axle, the hubs on these are too large to take those wheels unless you use 3" spacers/adaptors.

Anybody see this before??

So this axle has lived a hard life and been asked to do things no 1/2 ton axle should ever have nightmares about doing. But I have never seen an axle 'clock' on one side like this!! The other side is fine, it's the last picture.

www.gmt400.com

 

[b454rat]

you can run 15" wheels on a 14ff. Even on the biggest of brakes. Or look for an 8.8. They have factory discs, posi, and decent gear ratios. Prolly a baker's dozen in a junkyard...

 

[MrPink]

you can run 15" wheels on a 14ff. Even on the biggest of brakes. Or look for an 8.8. They have factory discs, posi, and decent gear ratios. Prolly a baker's dozen in a junkyard...

To get an 8.8 that is the same width as what is needed for our trucks he'd have to go with a 84-96 F150. And at that point I'd go for a 80-85 Ford F100 or F150 9" rear end.

 

[Crankshaft Brad]

IMO the 9.5" 14 bolt semi floater would be a much better option than the 10.5" full floater. There are even five lug axle shafts available for them from Dutchman. I've looked into that swap in the past. The only thing I haven't figured out is how to make the 10 bolt brakes work in that application.

Is there a reason you're looking at the full floaters?

For the safety factor when I end up snapping an axle, the wheel doesn’t make an abrupt exit...

 

[Crankshaft Brad]

Why do you need a 14BFF on your 2wd 1500? If this is just a daily driver get another 10-bolt, or maybe the 14b semi-floating axle.

The long game on this truck is to piece together a sprint car engine, that will scream to 8700-9000 RPM. I have a few rotating assembly pieces right now, but a long way to go. Right now the 14ff is absolute overkill. I am trying to slowly build up the truck to handle that kind of abuse.