Air bags and towing?

[1972]

[random useless thoughts]

Here's the deal: I have a K20 (5600 pounds) that I want to haul around on a goose neck trailer, but buying a newer 3/4 ton truck can't happen right now. So, time to improvise. I have a coil spring long bed C10 that I could use to tow it. I want to put some air bags on the back instead of coils, a small electric compressor under the hood, and a couple tanks under the bed. I have a couple concerns though.

1. Will the air bags handle the extra weight?

2. How much weight can my 1/2 ton rear axle handle?

3. Will I still have my current ride height or will it sit lower?

4. My truck only weighs 4100 pounds. Is this enough weight to control that much weight behind me?

[/random useless thoughts]


Opinions? Comments?

[72gord]

Here is my opinion on these ???? I have a bumper hitch 18 foot car trailer and a 16 foot gooseneck cattle trailer and my brother owns a 24 foot gooseneck flatbed which I have pulled many times in the last 10 years, this is what I draw my opinions from.
1...As long as you buy heavy enough air bags they will handle the weight just fine, they use them on semi tractors and trailers
2...This is a little more of a challenge, but in my opinion your 1/2 axle will handle that, tires might be another issue though... JMO
3...Ride height will stay as long as you put more air in the bags, and the bags are rated for the weight.
4...Only if your trailer has excellent brakes and you use common sense!!!
2 & 4 would be my main concerns for you, can be done...have seen it done, but must use caution and common sense.
These are only my opinions, Gord

[72gord]

Certainly not the optimum situation for towing but could be done as long as your truck and trailer are in good condition with proper tires and brakes.

[1-PU70]

This is a good question since I would like to bag the rear of mine too for towing. Im running a 70 C/10 with 3/4ton coil springs and a 12bolt in the rear. It has the auxilliary leaf overload in the rear too. I tow about 2 to 4 times a year about 1000 miles each way and I gross about 10000 to 11000 pounds. Thats car,trailer and what ever I can load in both. It does quit well in the towing but not that great in the stoping. Its been upgraded to dics in front. It would be better if the trailer had som brakes but I make do with what I have. I just added some overload schocks to the rear but havent towed with them yet. They did however improve the role in turns for now. Good luck and use your head.

[4x4Poet]

My city's local spring maker has pics displayed in the office of 67-72 GM truck frames that had cracked from the stress of rear air bags used for hauling heavy loads or towing. They say that 67-72 GM truck frames are not strong enough for air bags in hauling or towing applications. Lowered trucks for fun is another matter. I'm pretty sure all the airbags were used in conjunction with leaf springs, so I can't claim an exact comparison with your C10.

In any case, I would think a gooseneck trailer, by its good load-bearing design, would not put much tongue weight over your C10 axle with the K20 aboard the trailer. The tongue weight would also be well-distributed right above the axle. I doubt very much that you need to change a thing unless you intend to make cross-country trips. Just putting around town to take the K20 around to local shops wouldn't stress the C10's suspension enough to worry me. I'd definitely load everything up first to check for any severe spring sag. I wouldn't be surprised if you reported no significant sag and good highway capabilities with the K20 loaded gooseneck attached. Brakes may be another matter.

[1972]

Thanks for the responses. I drive a semi for a living so I am used to towing a trailer and leaving extra stopping distance. My stopping power may be ok if I am sure to get heavy duty brakes on my trailer. I don't need to tow it very often, maybe 3 or 4 times a year and only about 300 miles round trip. I guess I could always just set my goose neck plate in the bed and drop the goose neck loaded with my K20 on it and see how much it squats.

My city's local spring maker has pics displayed in the office of 67-72 GM truck frames that had cracked from the stress of rear air bags used for hauling heavy loads or towing. They say that 67-72 GM truck frames are not strong enough for air bags in hauling or towing applications.

I looked under the back of the truck at the frame and it looked too weak for a receiver hitch and a bumper mount trailer. I was thinking that by putting a goose neck mount in that it would put most of the stress on the frame right above the air bags. I would sure hate to crack my frame though because then I will have nothing.

[SCOTI]

I don't buy the frames can't handle it. The only diff between 67-72 1/2 ton & 3/4 ton trucks is the HD suspensions, not the frames. My little 1/2 ton hauls my 18ft trailer around w/no probs (I know it's not as much weight as what your talking about).

[lukecp]

Originally Posted by SCOTI

I don't buy the frames can't handle it. The only diff between 67-72 1/2 ton & 3/4 ton trucks is the HD suspensions, not the frames. My little 1/2 ton hauls my 18ft trailer around w/no probs (I know it's not as much weight as what your talking about).

Very true. I've been underneath a '70 C20 before, the frame was EXACTLY the same size as my '72 C10's. Only differences were that the C20 had much stiffer coils, a Dana 60 axle, 8-lug wheels, and much bigger brakes.

I've never towed with my C10 but i have over-grossed it while hauling before. While the truck itself has no problem hauling heavy loads, stopping is another thing. Even with front power disks my truck has a hard time stoppign with 2,000 lbs of cargo in the bed...not to mention with weak stock coils the back is practically dragging on the ground.

Have you thought of upgrading to some 3/4 ton coils in the rear? Would be cheaper than airbags...

[powell72]

The airbag kit from ECE is worth looking at for your application. They are big piston style bags that bolt in place of your coils. I had them on my c-10 and pulled a 18 foot car trailer with another c-10 on it. Just put a little extra air in the bags and it shouldn't sqaut.

[bisquik65]

I put 3/4 ton coils under my 69 cst s.b. to tow all my cars down from de to here with my 18 foot car trailer,worked fine.And a trannsmission cooler if yours is auto

[1972]

Have you thought of upgrading to some 3/4 ton coils in the rear?

I hadn't thought about it, but 3/4 ton coils does sound like a good idea. It would be a lot easier than going air. Thanks for everyone's input, I have some options to think about now.

And yes I have an auto, so I guess I'll need that tranny cooler. 350 engine and a th350 transmission. I think the rear is a 3.07 or 3.08 There is nothing on the glove box sticker indicating what gear ratio it has and someone on this board told me that means it is the standard ratio.

[4x4Poet]

Just to be clear, 67-72 frames are plenty strong for towing. They have good frames for attaching rear bumpers and rear mounted hitches. But adding air bags for towing purposes adds a degree of stress unreleated to whether the truck is a 1/2 ton or a 3/4 ton, especially since the frames are identical within 2wd or 4x4 model lines.

The snapshots displayed at the spring shop showed with graphic clarity how brackets for air bags that were bolted to the frame above the axle had twisted the frame up and in causing it to crack. The frames are not boxed above the rear axle, so they can't handle towing weights upon airbags attached with hanging brackets. And again, airbags used with dropped trucks have no such issues since they're not in a high-weight towing set up. Different needs with much less stress.

[86SILVERADO]

I have done exactly what you are proposing in my 86 silverado. 3 or 4 times a year would be fine. The frequency of use is not your main issue though. The biggest problem you will find is that the loaded trailer will toss that truck around on the freeway. Sway is the biggest problem here. I know I have done it and that is precisely why I bought the 67 Dually. You cannot get 15" tires rated to haul what you are proposing and with a single rear wheel axle you are asking for problems which could be potentially deadly. I know how it is to be limited on funds. I did this for my business hauling an 18' 10000gvw trailer and john deere tractor locally for a year. I had springs and bags and even the couple times I took it out on the highway were not enjoyable to say the least and this was a brand new Big Tex Trailer with Flawlessly set up electric brakes. If you are only on back raods then You could pull it off but at highway speed it is a whole nother story.

[SCOTI]

Originally Posted by 4x4Poet

Just to be clear, 67-72 frames are plenty strong for towing. They have good frames for attaching rear bumpers and rear mounted hitches. But adding air bags for towing purposes adds a degree of stress unreleated to whether the truck is a 1/2 ton or a 3/4 ton, especially since the frames are identical within 2wd or 4x4 model lines.

The snapshots displayed at the spring shop showed with graphic clarity how brackets for air bags that were bolted to the frame above the axle had twisted the frame up and in causing it to crack. The frames are not boxed above the rear axle, so they can't handle towing weights upon airbags attached with hanging brackets. And again, airbags used with dropped trucks have no such issues since they're not in a high-weight towing set up. Different needs with much less stress.

What brackets? Why would someone who has coils already need to mount brackets to mount bags? Bags simply mount directly in place where the coils went.... under the frame, above the trailing arm. I've seen 'air helper' kits for leafs that bolt on the side/top of frames but the original post was....

1972 .... I have a coil spring long bed C10 that I could use to tow it. I want to put some air bags on the back instead of coils ......

So those brackets wouldn't apply to this situation.

1972, you could go the 3/4 ton coil spring route on your 1/2 ton but what about ride quality when your not hauling that 5600# truck + gooseneck trailer? That's the beauty of bags. When you need the capacity, you air them up. When you don't, you can lower the pressure & get a normal ride from the vehicle. The 3/4 ton coils are likely to make the truck have serious rake. Bags won't. You adjust the air so it rides level .... loaded or not.

When the set-up is designed properly, bags are equal opportunity suspension pieces . . .... not just for slammed show trucks.

[1972]

SCOTI - If I do go the air bag route, I was thinking of using the self adjusting valves that semis use. Then I would sit at the same level loaded or empty without ever adjusting anything. The valves may be pricey though, which would make a manual control more likely. 86SILVERADO made a good point about the tires. I'll have to check what they are rated for. Maybe I should wait for a 3/4 ton truck? Or sell my '72 and buy a 3/4 ton or 1 ton? Decisions... decisions...

[1-PU70]

My C/10 rides fine with 3/4 ton springs in the rear. They are the same as HD 1/2ton rear springs.. Now dont get HD 3/4 springs. I tried them and it rode very rough. I also tried variable rat rear springs and they didnt hold the weight very good.

[rockguy]

I put 5000 lb air bags on my 69 one ton dually. The brackets for the air bags isolate the load to the bottom of the fram rail and on heavy loads will twist the lower frame rail upwards causing bending and or cracking. to prevent this either box the frame in that area or weld in a sub frame . I did the sub frame and it works excellent. I almost every day have a gvw of 9000 to 11000 lbs. and the frame is solid . Just my 2 cents maybe more like 4 cents
Steve

[lukecp]

All 1-ton trucks had leaves. 3/4 and 1/2 tons could come with either leaves or coils.

[SCOTI]

Originally Posted by yellow72custom

All 1-ton trucks had leaves. 3/4 and 1/2 tons could come with either leaves or coils.

True . . ... in stock form. That was why I questioned his statement for clarification. Stock coil frames come equipped from the factory w/bracing to prevent frame flex. The coil locating crossmember ties the top & bottom of the rails together along the the rails side to side. Leaf trucks did not come w/the same bracketry, or bracing, which is why they would be prone to flexing & ultimately cracking.

Originally Posted by 1972

86SILVERADO made a good point about the tires. I'll have to check what they are rated for. Maybe I should wait for a 3/4 ton truck?.....

Yes, by all means you'll need to get the right tire combination to safely support that kind of weight. But, why would you have to limit yourself to 15" wheels & tires? They make 6-lug 16/16.5's that come in wider widths & support a much stronger 6 or 8 ply tire that could accomodate your load rating.

[1972]

Originally Posted by SCOTI

But, why would you have to limit yourself to 15" wheels & tires? They make 6-lug 16/16.5's that come in wider widths & support a much stronger 6 or 8 ply tire that could accomodate your load rating.

Do they make affordable (cheap) wheels in a 16x8 for a 5 lug? I searched some online but couldn't find anything.

[Tx Firefighter]

There are differences between a 1/2 ton and 3/4 ton frame. The 3/4 ton frame has extra doubler braces riveted to the frame that 1/2 ton frames don't

I can get pics of each frame if anyone wants to see what I'm talking about.

[SCOTI]

Please do.

[Tx Firefighter]

Here are the first of the pictures I snapped today.

I have a 3/4 ton and a 1/2 ton frame right next to each other so it's easy to compare the two.

The pictures below show braces and lack of, between the frame and trailing arm crossmember.

[Tx Firefighter]

Here are the panhard mount brackets.

Notice the 3/4 ton is much heavier duty and wraps up the side of the frame rail rather than just being underneath it like the 1/2 ton.

[Tx Firefighter]

Here is the real meat and taters of the whole deal though.

The 3/4 ton frame has a long doubler riveted to the bottom frame rail web to strengthen it. The 1/2 ton has a short doubler, no where near as substantial or long as this one.