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14 bolt axle swapology info needed

pma4x4

pma4x4

AKA Yankeeroad
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I have a 1991 v1500 sub 4x4 with a 10bolt rear. I have brand new 33s on 6 lug 15s.

I want to swap to a 14 bolt semi or Full with 4.10s. What i need to know is this

What years (if any) are direct bolt ups?
What years/models are 6 lug?
What are the details in the swap.

In regards to using a newer axle I understand that the newer 3/4tons in the 90s were 6 lug and the spring perches and shock mounts were all in wrong spots.

1) Move the spring perches.
2) if the shock mounts are different can I use the ones from the 10 bolt?
3) is there anything else i need to worry about if I go with a newer axle?


The reason I am pushing for the newer axle is they are more abundant and 6 lug. I have no problem with moving and welding perches and shock mounts.
 
No direct bolt in for a 6 lug SF. Your best bet is find a later model (88-96) 14 SF axle from a donor truck, cut off the perches/shock mounts and re-weld on some new ones. Keep in mind that there are two widths out there. Typically the 4x4 is wider than the 2wd but the 2wd will match more closely your existing 10 bolt width. If you want to match your front axle more closely, go with the wider ones.

Your pinion yoke will also need to be swapped out or a conversion u-joint added to your existing driveshaft......
 
You by chance know the measurement of the two different widths? and any idea on the Yoke number and U-joint number needed?
​
 
64" WMS to WMS and 67" WMS to WMS if I recall correctly.

I think the yoke on the 14 SF would be a 1350 joint and your driveshaft is a 1310 joint. Don't know the u-joint number though. Do a search and you'll probably find one here.
 
You know that the wheel studs/nuts don't match up on the 6 lug 14SF to the 10 bolt stuff, and the 14MM 14SF lug nuts don't really fit the 1/2 ton wheels appropriately, right? Just another consideration. I don't know if that applies to aftermarket wheels or not, I would assume it would, but it definintely does to stock wheels, as the hole is too small for the lug nut shoulder to bite properly.

You can either run two different sized lug nuts (wheels probably won't be safe to swap front/rear afterwards) or convert the fronts and rears to 1/2" lug nuts and wheel studs. No other options that I consider "safe" exist right now in regards to lug nuts/studs.
 
dyeager535 said:
You know that the wheel studs/nuts don't match up on the 6 lug 14SF to the 10 bolt stuff, and the 14MM 14SF lug nuts don't really fit the 1/2 ton wheels appropriately, right? Just another consideration. I don't know if that applies to aftermarket wheels or not, I would assume it would, but it definintely does to stock wheels, as the hole is too small for the lug nut shoulder to bite properly.

You can either run two different sized lug nuts (wheels probably won't be safe to swap front/rear afterwards) or convert the fronts and rears to 1/2" lug nuts and wheel studs. No other options that I consider "safe" exist right now in regards to lug nuts/studs.
Click to expand...

I ran my aftermarket wheels on my 14 sf just fine with new lug nuts for the rear.
 
On my stock wheels the 14MM studs barely fit through the wheel, so the untapered portion of the shoulder of the lug nuts bit into the "top" of the wheel, instead of into the "countersunk" portion. I suspect aftermarket wheels tend to be a bit more universal in what lug studs they can use, it makes more sense.

I never had one come loose, but it messed up the countersink on the two wheels.
 
ok so going with a 88-98 FF 6 lug I will have to bring a tape measure with to verify width. then relocate the spring perches and shock mounts.

Why cant I simply change out studs to custom size or find narrow axles and add 6 lug to 6 lug adapter ring.

A local yard is selling 14bolt FF 4.10s for $350 so I think once i sell my jeep I am going shopping.


err wait... can i get a FF in 6 lug in the newer years? Ahhh crap confused again:doah:
 
AFAIK no 6 lug 14FF's factory. I suppose it kind of defeats the purpose of a heavy duty axle to have fewer lugs. :)

No custom size studs. Been down that road before. 7/16" I would guess is considered light duty, all the "custom" stuff is 14MM, 1/2" or 5/8" that I saw. The knurl diameter of the 7/16" studs available is smaller than the 14MM stud knurl. It's not crazy expensive to have a machine shop re-drill the flange for a different stud, if you wanted to keep the 7/16" stock ones.

Dunno about the adapter ring, never went down that road. Might be possible, bunch of things to consider. I'd assume it would need to be as steel ring, with the same bolt pattern on both sets of holes, and then find the proper length studs. I think there are quite a few different length/styles of 7/16" studs, so that would be the easy part I imagine, since the rear studs are the simple ones.

Personally, I think getting the rear the same width as the front is a good thing.
 
Keep your wheels/tires? Stud swap cost maybe $100 and some work. I had to replace the rotors anyways, so timing-wise it worked out.

No downside to 8 lug, just have to swap the front end, or front end parts, and get new wheels/tires.
 
I'm assuming because the OP said this:


pma4x4 said:
I have brand new 33s on 6 lug 15s.

The reason I am pushing for the newer axle is they are more abundant and 6 lug. I have no problem with moving and welding perches and shock mounts.
Click to expand...


Maybe he doesn't really need the additional strength of the 8 lug setups too?
 
82355 said:
8 lug 15's are cheap, and much less hassle.

Martin
Click to expand...


I hear ya. I was in the same sort of dilemma as the OP and really was stressing out over the thought of abandoning my newer 33's and nice rims. In the end I knew I'd have to ditch them though if I wanted nice axles and parts interchangeability.

So there's always craigslist to sell them rims and tires! :D
 
Well I got the set of 5 BFG AT 33x310.50x15s for 160 each so there is no way I could just toss them on Craisglist when they still have the nips on them. I can get new white spokes for around 44 each so changing wheels is not too bad of an issue.

I do plant to go to 16s once these wear out as there is a better selection fo tires in 16s, but at the rate I use our offroad rig I will get about 3-4 years out of them. and I plan for gears and lockers for next tax season.

All I am worried about is load carrying capacity. I am not going to be thrashing this thing on the rocks or WOT through the mud. With that I am thinking just weld up a full width truss, weld the tubes to the housing and order stronger shafts and keep the originals for spares.
 
I don't see it in this thread, how much are you looking at towing/carrying?

The 14SF, while still a c-clip/non-FF axle, is beefy. Other than problems on some of them with a pinion bearing or something, I don't recall ever hearing one fail, and you know they have had the hell beat out of them by now.

Unless doing something absolutely crazy with one, I don't see why a truss or new shafts would be needed. My opinion of course, but being around for as long as I have, if beating on these things resulted in failures, I think I'd have seen at least a few.
 
Yeah I am thinking of just going with a 14SF out of a newer C/K They are cheap and it will cure my load issue.

As for your question dyeager535, It will have at all times at least a estimated 600lbs additional weight.when fully loaded for a trip its at 1/2 ton capacity. now add all the bouncing around and banging. 300-400 alone just in roof rack, rear bumper, ladder, spare tire/ tool mount and interior slide cabinets.

I will find a 14SF out of a newer truck, get the axle kit from Ruffstuff.

I just need to make sure I find it with OUT the factory locker.




2 more questions for you all

1) even though i may find a 6 lug 3/4ton 14SF will a 15" wheel with a 3.75" BS clear?

2) is there a disc brake conversion for the 14SF and again will my 15" wheel work?
 
Thought of this earlier...if you wanted to swap the axles still, you COULD have custom shaft built by Moser or someone, with the proper 7/16" stud holes. Been a few years, but I think Moser only wanted like $125/axle back then.

You going with some other locker? I can't complain about the 9.5" gov-lock, it's held up where the 8.5" hasn't, and I'm not particularly hard on it, but I'm not easy either.

Can't say I've put a ton of weight in mine, but I guarantee you are nowhere near the load limit of that axle. 1/2 ton is nothing but a badge and/or name. The new Silverado with the 9.5" is rated for ~2000lbs PAYLOAD, and ~10,000lbs trailering. http://www.chevrolet.com/silverado-1500-pickup-truck.html

I know it will clear stock wheels, but I don't know their backspacing, sorry. The drum is pretty well tapered towards the wheel, so I suspect it would clear quite a bit. Only a guess though.

Disk brakes...there are probably kits out there TSM, etc. Depending (perhaps) on year, looks like the later 10 bolt stuff may work http://www.gmfullsize.com/forum/showthread.php?t=222488

I know one of the 2000+ vans were running 13" disks in the rear (may have been the Astro? it was either an 8.5 or 9.5) it just depends on if the axle flanges are the same whether the swap would be easy or not.
 
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