Question for a leaf spring expert

[502ss]

I am wondering if someone can tell me what the flat leaf spring located directly above the axle is for? The vehicle in question is an 84 c30 dually. The leaf in question can be seen in the attached photos. I am thinking of removing this leaf.




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[Tx Firefighter]

It's called an overload spring. There used to be two brackets on each side of the frame that the ends of that spring pushed against. You can see where yours used to be. When the truck is loaded heavily, it squats enough to let the brackets touch the overload spring which offers extra capacity. When there is no load on the truck, the spring end are several inches away from the brackets.

[502ss]

Originally Posted by Tx Firefighter

It's called an overload spring. There used to be two brackets on each side of the frame that the ends of that spring pushed against. You can see where yours used to be. When the truck is loaded heavily, it squats enough to let the brackets touch the overload spring which offers extra capacity. When there is no load on the truck, the spring end are several inches away from the brackets.

Nope, I am well aware of the overload spring and what it is used for. I am referring to the flat leaf spring that is located right above the axle but below all of the other leafs!
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[bedsled71]

that is also an overload spring. its used so the other springs dont de-arch after time and with heavy loads.. all stock leafs have them. yours just happeneds to come with a secondary overload leaf

[502ss]

Originally Posted by bedsled71

that is also an overload spring. its used so the other springs dont de-arch after time and with heavy loads.. all stock leafs have them. yours just happeneds to come with a secondary overload leaf

Ok, so then I can remove it? I have no intention to use the truck for anything other then towing my boat (800 lbs tongue weight) with the lowering components the axle would hit the bump stops before the leafs even came close to de arching. My main concern is if removing it would effect it's weight capacity. Meaning right now the truck sags 1" when I hook the boat up. I want to make sure that removing that spring doesn't cause the truck to sag any more then 1"
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[502ss]

ttt
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[bedsled71]

I think that itmioght cause it to sag alittle more but im really not sure. hopefully someone else could chime in... i know it will lower it alittle because its about 1/2 inch thick.. it will also not ride as stiff without it... looks like you have 5-6 other springs anyways.. i say just do it!

[blown240]

I had the same setup on a Ford truck I used to have. I removed that leaf and it made no difference when there was no load. Under load though the truck sagged more. Its an overload spring.

[N2TRUX]

If you aren't going to do an axle flip, removing that leaf will lower the truck the thickness of the leaf. It will reduce your towing capacity, but that doesn't seem to be a concern. If it were me, I would remove a few more leafs, and add an air bag. That would improve the ride, and allow you to tow with no concerns.

[502ss]

Originally Posted by N2TRUX

If you aren't going to do an axle flip, removing that leaf will lower the truck the thickness of the leaf. It will reduce your towing capacity, but that doesn't seem to be a concern. If it were me, I would remove a few more leafs, and add an air bag. That would improve the ride, and allow you to tow with no concerns.

Yup, both overload and two additional leafs are gone! I plan to add a bag assist kit.




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[N2TRUX]

That should do it...

[SCOTI]

Originally Posted by 502ss

Yup, both overload and two additional leafs are gone! I plan to add a bag assist kit.

So 6 leafs total now?

[502ss]

Originally Posted by SCOTI

So 6 leafs total now?

yes, 6 leafs

[sparkydog]

I just removed the bottom (overload) leaf off the chassis of my project truck (the pic in my avatar). This chassis is a stock '96 GM 2WD X-cab 1/2t and had the same bottom overload leaf setup as 502SS pictures.

I expected my rear body to drop and it didn't. I measured before and after from the ground to the top of the arc of my fender opening and same-same 35.25". Go figure....?

I even went out and drove around for awhile and rechecked bolts etc and still no drop. The total weight of my truck is virtually identical to the stock GM. I am at 4080# curb with 1/2 tank gas and my rear axle is taking 1550# of this.

My only explanation is that the overload leaf (which is almost flat) maybe was de-arching the springs above it and now they are freed up and that canceled out the hoped-for drop of 3/4"??

Anybody got ideas why nothing changed?

[502ss]

Originally Posted by sparkydog

I just removed the bottom (overload) leaf off the chassis of my project truck (the pic in my avatar). This chassis is a stock '96 GM 2WD X-cab 1/2t and had the same bottom overload leaf setup as 502SS pictures.

I expected my rear body to drop and it didn't. I measured before and after from the ground to the top of the arc of my fender opening and same-same 35.25". Go figure....?

I even went out and drove around for awhile and rechecked bolts etc and still no drop. The total weight of my truck is virtually identical to the stock GM. I am at 4080# curb with 1/2 tank gas and my rear axle is taking 1550# of this.

My only explanation is that the overload leaf (which is almost flat) maybe was de-arching the springs above it and now they are freed up and that canceled out the hoped-for drop of 3/4"??

Anybody got ideas why nothing changed?

I am not surprised by no change in height. Remember what you removed was an overload spring. This spring only becomes active when carrying a lot of weight. I achieved a 3/4" drop just by removing the overload spring because I also had a large spacer that I was able to remove at the same time. I also achieved some additional lowering by removing 2 of the actual arched leafs.
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[sparkydog]

Originally Posted by 502ss

I am not surprised by no change in height. Remember what you removed was an overload spring. This spring only becomes active when carrying a lot of weight. I achieved a 3/4" drop just by removing the overload spring because I also had a large spacer that I was able to remove at the same time. I also achieved some additional lowering by removing 2 of the actual arched leafs.
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I thought your original question was if you take that spring out shouldn't the rear drop by the thickness of that spring? And I thought the answer was: "Yes".

And that is what I did - took out those spring leafs and expected the rear to drop. But it didn't.

[sparkydog]

Just realized my shocks are coil-overs. I thinking their coils are pushing the rear up and keeping it at the same height. I'm going to unhook them and see what happens to the stance.

[JAMESCHURCH13]

Does anyone know the out come of this? I also have an 87 Dually and would like to know what happened.

[sparkydog]

If your question was directed at my issue instead of the OP's then the answer is that once I took out the coil-overs then I got the drop I expected. The removal of the overload leaf dropped the rear by the thickness of the leaf.

[JAMESCHURCH13]

Awesome. Thanks. Does it still ride like a tank?
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