Heavy Half Capacity

[Letters]

How's it going?

I have a 77 K10 Heavy Half (3/4 axles, brakes, and springs), and I'm wondering what the towing and weight capacities would be for it.

The frame, suspension, brakes, and driveline (350/sm465/np205/10 bolt axles) are all in good shape (just put in a new engine), and I'm looking for a class 3 hitch to put on it. I've had around 1800lb in the bed a few times and it seems to handle that fine. The owners manual says a K10 can tow 6000lb, but I'm wondering if the Heavy Half (F44) option raises that number.

Thanks.

 

[MadOgre]

10 bolt axles are not 3/4 or heavy half axles they are strictly 1/2 ton axles. The 1/2 ton axles are your limiting factor. The outer wheel bearings and axle diameter affect the downward loading force that can be applied before breakage occurs. Or excessive wear.

 

[Letters]

Alright, thanks. Thought they were since it says online they come on some 3/4s, but that's good to know.

 

[MadOgre]

No 3/4 ton came with 10 bolt rear axles.....however all 3/4 tons came with 10 bolt front axles. but with bigger wheel bearings and spindles if I remember correctly

 

[Letters]

Got it, thanks.

 

[Letters]

If I found a used 14 bolt rear and put it in, what kind of capacity would that give me?

 

[Georgeb]

What are you trying to do with the truck?

 

[Letters]

It's used as a daily driver as well as for moving things. Mostly moving things in the bed (dirt, gravel, wood, etc), but there's a project coming up where I'd like to be able to pull a trailer to the dump. I also have a car I'll need to move at some point.

It did come with the heavy half package (based on the VIN) but now I'm thinking some of that has been swapped out before I bought it.

 

[Georgeb]

Thats exactly what I used my 78 heavy half for. It has a 12 bolt rear and the larger brakes. I typically loaded around 1500 to 2000 lbs in it but never did go really far. I can tell you It caused damage to the axle bearings and shafts. The shafts are grooved pretty good from the years of hauling wood, dirt and towing trailers. Depending on how far you need to go you could do ok but I would reccommend making more trips with more reasonable loads than load it to the hilt and take off. Even somthing as simple as a flat tire becoms a big deal with 2000 pounds in the truck. A heavier axle is only part of the equasion. Properly functioning brakes are even more important.

 

[Letters]

The short-range ~1500lb loads sound good for what I need it for. You think it would do fine pulling a 2 ton curb weight Northstar on a trailer?

 

[Georgeb]

Depends on how heavy the trailer is, what the tounge weight is and if you have trailer brakes. I am not too knowledgeable about towing alot so maybe someone else will chime in here. I do know I pulled a trailer with an 82 suburban on it with no trailer brakes or load leveling hitch and I was glad I was only going across town with a maximum speed of 35 mph. It pushed me along pretty good when stopping.

 

[jetman]

No 3/4 ton came with 10 bolt rear axles.....however all 3/4 tons came with 10 bolt front axles. but with bigger wheel bearings and spindles if I remember correctly

Nope. K10 & K20 front 10 bolt axles use the SAME wheel bearings, seals and spindles.

 

[jetman]

If I found a used 14 bolt rear and put it in, what kind of capacity would that give me?

Which 14 bolt? There are two 14 bolt rear axles in common use; 14 bolt semi-float and 14 bolt full float. The 14 bolt SF comes with a 9.5" ring gear, the FF comes with a 10.5" ring gear. The SF is durable, the FF is super durable.

In terms of "load capacity" you will need to factor in what gear ratio your axle has as well as spring capacity and tire size/type. Smaller diameter 10 ply work well when moving the heavy loads.

Before committing a lot of time and money on a new axle with matching wheels and front spindles (you will most likely be going from 6 lug -> 8 lug if going to a 14 bolt) you may want to reconsider keeping the corporate 10 bolt till it gives up the ghost. Assuming it's ratio is acceptable, the 10 bolt axle is a reasonably robust unit that can hold up to a surprising amount of abuse.

Load capacity is dependent in part by road condition (rocky ranch roads?), terrain (you can pull a lot more weight around Houston than the Rocky Mountains), and how far you travelling (coast-to-coast vs around town). With an older square, trailer brakes come in VERY handy when the occasional emergency stop comes along...

Not sure what a Northstar is, but if you are moving lots of heavyish equipment a 5th wheel/gooseneck trailer makes a big difference in load capacity and safety.

 

[MadOgre]

The advantage of the 14 bolt SF is that it is twice the axle a 12 bolt is EASILY! But you can use 6 lug axles in it and use it with your 6 lug front 10 bolt with out having to do any thing but swap in the rear axle.

The 14 bolt FF design though is a much better design in that the axle no longer carries load weight only the torque is transmitted through the axles. The weight is totally absorbed by the FF wheel bearing design which has 2 bearings and races on each side of the axle very similar to a front wheel set up

But there is a reason that 3/4 ton and up vehicles use a 8 lug wheel. Its stronger than 6!

If you want the best then go with the 14 bolt FF with its 8 lug wheels. As it sounds like you really want to push the limits, that is what I would recommend!

 

[MadOgre]

Nope. K10 & K20 front 10 bolt axles use the SAME wheel bearings, seals and spindles.

Ya I couldn't remember. Thanks Dave