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Confused about axles.

1

1985 K10 Warhawk

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Hello,

So, I chewed up the gears in my stock 1/2 ton rear diff of my 85 burban (4inch lift / 33s), doing a bit of rock crawling. Decided it's time to upgrade. (She makes a terrible clunking noise when ever I turn @ any speed.. so spider gear?)

I've been researching and reading the pirate4x4 14bolt bible (http://www.pirate4x4.com/tech/billavista/14b_bible/) and am unsure of if I need to be worried about the end width of the axles? If some one could direct me to other resources, I'd put the research in too!

These are located on:
  • 73-96 C20, C2573-00 C30, C3573-00 G30, G3573-00 K20, K2573-00 K30, K3584-88 CUCV
  • 88-91.5 V30
It looks like I can pick up a 1 ton van on CL for 850-1grand or an older k3500 for 2grand(I know the perch springs will need to be moved) Do I need to worry about the axles being too wide or too short to fit under my truck?

If I plan to buy all new gears / lockers.. do I need to worry if the vehicles I may get them from have like 200k+ miles on them? Should I avoid any specific one?

I have a friend flying out in 3 weeks to help, so I want to ascertain an axle from CL/junk yard and build it before he arrives. I have access to a work shop with a welder (Although neither of us have done it before, learning experience opportunity)

Help!
 
3/4 ton axles should bolt in w/o moving perches. 1 ton's you'd have to watch out for dual rears. But you should be able to pick up a 14bff for less than 250$ Most of the 3/4 ton rears will be a couple inches (3 or so) wider but that's not usually a problem as it will then match the front axle.

I went another direction and bought a 2005 Silverado 2500 rear (14b w/ disks) for 250 used.... You will have to move perches on that though.

I'm not a bible on these so don't quote me on this, but it should give you ideas.
 
JoshHefnerX said:
3/4 ton axles should bolt in ......... Most of the 3/4 ton rears will be a couple inches (3 or so) wider but that's not usually a problem as it will then match the front axle.

Not true, 3/4 ton (up to 87) width is what you want. Exactly the same width and spring perches as your 1/2 ton axles.

I went another direction and bought a 2005 Silverado 2500 rear (14b w/ disks) for 250 used.... You will have to move perches on that though.
This rear end will be wider than the older stuff and will match the width of your front.

I'm not a bible on these so don't quote me on this, but it should give you ideas.
Click to expand...

The van axles will be wider than yours (i think).

If you want direct bolt in, get a 3/4 ton rear end from a prior to 87. 1 ton rear will require spring perches and shock mounts to be moved. If you do get a 3/4 ton rear end, you have to decide if a 14 bsf or 14 bff is what you want.
 
Van axles are 3 inches wider. Turning radius gets bigger and new axles are harder to find, just because they did not make to many of them, and the perches have to be moved.

They do work fine all that being said.
 
I saw some numbers off on the quotes above in the bible. Just think of looking for a rear for our square bodied trucks when I mention the years. You can use the newer bodied IFS trucks (88 on up) but like others said you will need to relocate mounts and perches.

Now for our square bodies, look for C/K and R/V series trucks if you're wanting a 14FF. In case you didn't know, C is 2wd and K is 4wd. These years for the 14FF run from '73 up to '86.
The R series is a 2wd and V series is 4wd. These years run from '87 to '91. You can find 14FF's under these years of trucks without changing perches and mounts by looking under the 3/4 ton Suburbans but most of them were under 2wd's as the 4wd V series mostly used semi-floater rears.
 
I like the idea of a quick fix, but the 3/4 ton is still a smaller ring gear right? Not as strong?

Eventually, I want to go larger on the tires and lift (long way down the road)
 
1985 K10 Warhawk said:
I like the idea of a quick fix, but the 3/4 ton is still a smaller ring gear right? Not as strong?

Eventually, I want to go larger on the tires and lift (long way down the road)
Click to expand...

Depends on what 3/4 ton truck. 73-80 C/K20s had a 14BFF with a 10.5 inch ring gear and is a direct bolt in. From 81-87 the 3/4 ton trucks had the smaller 9.5" semi float 14 bolt which is still a pretty strong axle and a direct bolt in.

All single rear wheel C/K30 trucks from 73-91 had the big 14 bolt with the 10.5" ring gear and require the spring perches to be moved to bolt in.

What tire size are you thinking you will be running and intended use of the truck?
 
Not to be a naysayer, but I'm pretty sure the difference for 14SF vs 14FF wasn't year (edit: after the 9.5" was introduced, 1982?) , but GVW. Light duty 3/4 would have a 14SF, heavier GVW would be FF. No SF's in one tons of course.

Not sure if the implication was this or not, but the 14SF (9.5" ring gear) is a pretty stout rear axle, and if it comes down to it, I'd choose based on availability of same gear ratio (so I didn't have to mess with the front) as opposed to SF or FF, if the idea is to keep tires in that size range.

You don't hear of the 14SF's breaking very often, even with heavy off-road. Not saying the 14SF is all that, but the differences between it and a 14FF are pretty significant (weight and clearance) so something to consider.
 
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Unless you're running big tires, the extra weight and reduced ground clearance of the FF are going to be drawbacks. If you want an avenue to upgrade, FF parts are going to be cheaper, and they're stronger and usually easier to find. I've been perfectly happy with my SF, but I'm on 33's and don't get too crazy with it.
 
What are you planning on doing with the truck? I am running a 14 Bolt SF thats been locked for two years on 37s with no issues at all and I beat on it pretty good.
 
Yep, pulled a 4.10 geared semi float from the JY in aurora, with a 6 lug pattern. $125
 
I hauled a load of paver stones on an '85 K20 with the 14SF once. Drove it about 40 miles like this. I'll see if I can find the pic and post it.
 
thatK30guy said:
I hauled a load of paver stones on an '85 K20 with the 14SF once. Drove it about 40 miles like this. I'll see if I can find the pic and post it.
Click to expand...

Not a 14SF for sure, but probably just a bit more than your paver stone weight?
 
dyeager535 said:
Not to be a naysayer, but I'm pretty sure the difference for 14SF vs 14FF wasn't year (edit: after the 9.5" was introduced, 1982?) , but GVW. Light duty 3/4 would have a 14SF, heavier GVW would be FF. No SF's in one tons of course.

Not sure if the implication was this or not, but the 14SF (9.5" ring gear) is a pretty stout rear axle, and if it comes down to it, I'd choose based on availability of same gear ratio (so I didn't have to mess with the front) as opposed to SF or FF, if the idea is to keep tires in that size range.

You don't hear of the 14SF's breaking very often, even with heavy off-road. Not saying the 14SF is all that, but the differences between it and a 14FF are pretty significant (weight and clearance) so something to consider.
Click to expand...
1981-1987 3/4 ton regular cabs and 1981-1991 Suburban 3/4 tons have the 9.5" 14 bolt except the 2wd's with a 454.
 
rksjd8420 said:
1981-1987 3/4 ton regular cabs and 1981-1991 Suburban 3/4 tons have the 9.5" 14 bolt except the 2wd's with a 454.
Click to expand...

I've never seen a FF in an 81-87 C/K20. I know there is a lot of discussion about their existence, but every truck I've looked at 81+ had a SF rear.
 
MTBLAZER89 said:
I've never seen a FF in an 81-87 C/K20. I know there is a lot of discussion about their existence, but every truck I've looked at 81+ had a SF rear.
Click to expand...
454 was not offered in 81-86 K20's or 87 V20's. Only 2wd 3/4 tons were available with the 454. Had to get a 1 ton to get a 454 in a 4x4. Crew cabs all had the 10.5" 14 bolt ever if they were 3/4 ton. They had the same spring spacing as a 1 ton.
 
LKQ 33rd & peoria. The truck is up, wheels off. I bring the cordless sawzall, cut the u bolts and anything else that looks at me wrong. Plop, load it up on the cart, use the chain fall in the parking lot to load it.

Make sure to watch the u bolts when you cut them, under a ton of force. I lay a floor mat over them to keep them from flying.
 
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