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SEMI-FLOAT 14 BOLT

M

MEANSTREAK K30

1/2 ton status
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Feb 26, 2016
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Hello, everyone. My nephew is wanting to replace the 12 bolt in his k5, that is giving him problems. He wants to retain the 6- lug wheels . Is a semi float 14 bolt an easy axle swap, so he can retain the current wheels? What vehicles should we look for in the junkyard?I thought I heard somewhere that a GMT Z71 would work , but the spring perches would have to be moved. Anyone know where we can get the proper size spring perches ?Any thing else /advice would be appreciated.
 
You can get 6 lug 14 bolt semi float axles out of this generation of truck as well. They are found in heavy duty half ton trucks (more common in the later 80s vehicles). They are a bolt in swap in that case. If you get one out of the newer body style you'll need to cut the spring perches off and re-weld them back on in the correct position for the older truck. DIY4x is able to supply high quality spring perches to do so if you so desire.

Definitely a solid upgrade in axle over a 10 or 12 bolt axle. I run one in my wheeler with a Duramax out front and I've never managed to hurt it even though I've broken the D60 up front multiple times.
 
I geuss I should tell a little about the truck. It has a mild lift with 33's , 4.1o gears.The rest is stock.We heard a noise coming from the diff,dropped the cover,and sure enough the pinion gear is cracked. The FF14 bolt would be better, of course , but the conversion hbs to 6lug are 2 expensive.
Russell said:
You can get 6 lug 14 bolt semi float axles out of this generation of truck as well. They are found in heavy duty half ton trucks (more common in the later 80s vehicles). They are a bolt in swap in that case. If you get one out of the newer body style you'll need to cut the spring perches off and re-weld them back on in the correct position for the older truck. DIY4x is able to supply high quality spring perches to do so if you so desire.

Definitely a solid upgrade in axle over a 10 or 12 bolt axle. I run one in my wheeler with a Duramax out front and I've never managed to hurt it even though I've broken the D60 up front multiple times.
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Yes, I have seen semi-floats on square bodies , but they have all been 8 lug 3/4 tons. They made them heavy half? I have never seen one.
 
I trust what Russell says most of the time ( I mean he is Canadian) but I think your wrong here @Russell. Never seen a 6 lug SF in a square.

Only seen 2wd heavy halfs though never really looked at the axle cause they were 5 lug
 
My 92 2500 z71 heavy half 7200gvw has a sf14 6 lug, the nice thing is they're pretty wide compared to the 10/12 bolt. I wanna say 67-69 wms(not 100%) on this. Very strong considering..
 
The only other things I could think of not working , besides the spring perches,are the u-joint size,which can be fixed w/ combination joint , the brake line fitting, and the lug nut studs being a different thread.So Idon't know if the lugnuts will have the right taper to work with the existing wheels or not
 
blazinzuk said:
I trust what Russell says most of the time ( I mean he is Canadian) but I think your wrong here @Russell. Never seen a 6 lug SF in a square.

Only seen 2wd heavy halfs though never really looked at the axle cause they were 5 lug
Click to expand...

You're most likely right. Didn't realize that they were 5 lug only in the squares. The last 6 lug diff I pulled was from a mid 90s 1500 diesel half ton.
 
Phil513 said:
Is the 14bsf part of the Z71 package?
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Supposedly, the sf 14 bolt was available on 2500 trucks -regular and z71 -according to an article I just read on Four Wheeler .com .The wheels were 6 lug , even though the trucks were 3/4 ton.The article also said they started using them in 86, so our man from Canada just may be right.Although a 6 lug might be pretty rare in square bodies; I have never seen one in all these years I have been a junkyard scrounger. But then again I have never looked for any till now.
 
They sell 6 lug and 8 lug axles for them (9.5")...
 
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Phil513 said:
Is the 14bsf part of the Z71 package?
Click to expand...

The 14SF was not a standard part of the Z-71 package. I believe the option code for the 1500 series trucks that had this axle was F44. I have seen non-Z71 1500 trucks with this axle but in general the 14SF is not overly common in 1/2 tons. The 2500 trucks with 6-lugs should always have the 14SF axle but don't take it for granted it is still there.

Fortunately it's really easy to identify as compared to the 10-bolt.
 
It was a 5 lug though so a really rare bird.

In the 88 and newer trucks I have seen them in half and 3/4 tons.
 
Pretty sure BlazinUK is right in that the only semi-float 14 that came in the square bodies was the 8 lug version. I think people get that messed up because most sites list the 6 lug version as starting in '88 instead of saying they started with the OBS/GMT400 trucks...

If you want a 6 lug version you'd have to look at the OBS heavy halfs or light duty 3/4 ton trucks and then relocate the spring pads and maybe the shock mounts(?). Just pay attention to which truck you get it from because the 2wd trucks had narrower 64" rear axles and the 4x4 tucks had the wider 67" axles that match the width of your axle. Or you could also pick up an 8 lug version out of a late 80's Suburban and throw in a set of 6 lug axles if you wanted to. I picked up a 6 lug version from an early 90's 4x4 and have it sitting on some stands in my garage waiting on my buddy to bring over a welder so I can relocate everything and swap it in.

There's a few guys on here that have already done this swap if you want to poke around and search the forums. Here's a few threads I saved for doing my swap:
https://ck5.com/forums/threads/88-95-14bsf-axle-swap.311473/
https://ck5.com/forums/threads/setting-up-14-bolt-sf-under-k5.293767/
 
Also, the 6 lug 14SF's are 14MM lug studs. Using the matching lug nuts screws the wheel up, and does not clamp them properly as they don't fit the wheel hole taper.

I was never able to find a solution to that which was easy, so I converted both front and rear to 1/2" studs, the only "easy" solution I could come up with, to run the same lug nuts front and rear.

Buying new axles with the proper lug studs would be less work.

Sucks, but if you want to keep stock wheels, or just the ones you have, the only options I'm aware of.
 
14 SF 8 lugs can be converted to 6 with axles but you will need to space the brakes out. There are multiple length axles available also.
The best fit will be a 2 wd 14sf 6 lug out of a later truck. The 4x4 version is wider like the front if you want or like that. Change the studs to 1/2 and move the spring and shock mounts as needed if you are set up to do that.. You will need the u bolts and spring plates also.

Do search, lots of info on here for that.
 
Mine came out of a 90 k2500, 4.10 from the factory.

Got new perches from ORD

Mine wheels are from a 1990 though
 
dyeager535 said:
Also, the 6 lug 14SF's are 14MM lug studs. Using the matching lug nuts screws the wheel up, and does not clamp them properly as they don't fit the wheel hole taper.

I was never able to find a solution to that which was easy, so I converted both front and rear to 1/2" studs, the only "easy" solution I could come up with, to run the same lug nuts front and rear.

Buying new axles with the proper lug studs would be less work.

Sucks, but if you want to keep stock wheels, or just the ones you have, the only options I'm aware of.
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OK, after reading quite a bit on here about it , we can locate a 8 lug SF 14 housing from a 3/4 ton square body , that way we won't have to worry about spring perches / shock mounts. Then install the axle shafts /brake drums/backing plates/spacers out of a 6 lug 1988-up SF 4x4 housing , drill out the holes in the axle flanges/drums for the use of 1/2 "-20 studs, swap the pinion yoke from the 12 bolt to the semi-float , and we should be gold, right?
 
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MEANSTREAK K30 said:
OK, after reading quite a bit on here about it , we can locate a 8 lug SF 14 housing from a 3/4 ton square body , that way we won't have to worry about spring perches / shock mounts. Then install the axle shafts /brake drums/backing plates/spacers out of a 6 lug 1988-up SF 4x4 housing , drill out the holes in the axle flanges/drums for the use of 1/2 "-20 studs, swap the pinion yoke from the 12 bolt to the semi-float , and we should be gold, right?
Click to expand...

You actually would use 7/16" studs if you were matching the stock front. I went 1/2" because I had a 6 lug 14SF already and the knurled portion of those lug studs matches the 14MM hole, the only other options were to redrill the bolt pattern or get new axles.

I suspect you can't redrill an 8-lug axle for 6 lug, but I don't know what the 8 lug pattern is. Most likely close enough to screw up that idea.
 
No spacers on a 6 lug for brakes, you make your own depending on what axles you get.
Conversion u joint will also work instead of replacing the yoke, which I don't know is swappable or not.

Also the 14 SF is a little longer at the pinion so take that into consideration.
 
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