GMC "Leaf Springs" Why ?

[54blackhornet]

Can someone explain why the more expensive brand went with the POS leafs instead of the smooth riding adjustable coils with trailing arms ? Makes no sence when you consider the option of leafs if you need extra weight capacity ? O well I guess I am stuck with them !
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[Tx Firefighter]

In that era, the GMC still had the image of a work truck. A hard working truck. Chevy's were more civilized. The leaf springs on the GMC played into the utilitarian role better.

There is nothing POS about leaf springs either. They are simple, sturdy, and they work.

[54blackhornet]

You are right "Firefighter"; I was out of line with that comment ! It's not that way now. I guess the wood bed is for work too ? I love my 68 GMC with leafs and wood but wished my 71 had coils...
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[Tx Firefighter]

Originally Posted by 54blackhornet

You are right "Firefighter" was out of line with that comment ! It's not that way now. I guess the wood bed is for work too ? I love my 68 GMC with leafs and wood but wished my 71 had coils...
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I'm out of line with which comment exactly ?

[SS Tim]

There are reasons to like coils and ride quality is at the top. But when it come to load carrying ability leaf springs are hard to beat. The complexity of a coil suspension negates the weight savings of the coils themselves. The loss of inter-leaf friction is a probably the biggest reason for their demise after cost considerations. As are loaded ride height considerations. With a camper on a truck, which at the time was a fast growing market, there is very little to prevent the loaded truck from swaying. This was aggravated by the ever increasing weight and the CG shifting upward and aft on the campers. Shocks alone can provide some stability but the leaf springs friction provide a lot of roll stability that increases fairly linear to load deflection. In fact rear shocks were optional on C30s.
Factor in the cost of two different chassis types plus the wheelbase variations and it is easy to see why leafs became the standard (cheaper) and only rear suspension on the later '73 up trucks.
Wood bed floors were a carryover option from earlier times that worked well for camper mounting (through bolting) but was actually considered a better footing for livestock. It even carried on into the square bodies as well for a number of years as an option on fewer and fewer trucks.

[factorystock]

Originally Posted by SS Tim

With a camper on a truck, which at the time was a fast growing market, there is very little to prevent the loaded truck from swaying. This was aggravated by the ever increasing weight and the CG shifting upward and aft on the campers. Shocks alone can provide some stability but the leaf springs friction provide a lot of roll stability that increases fairly linear to load deflection.

Agreed. The scientific explanation from International which used leafs on all 4 wheels at the time, even on thier 2WDs:

[darush01]

Ive had both and honestly ive never had a 3/4 ton ride as smooth as on my 72 c20 with coils. I still hace good load capacity and it rides like a cadillac
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[factorystock]

Originally Posted by darush01

Ive had both and honestly ive never had a 3/4 ton ride as smooth as on my 72 c20 with coils. I still hace good load capacity and it rides like a cadillac
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I am sure you have the standard 2000 lb coils, which do ride nice. If you had the optional 3000 lb coils on your C 20, the ride would be much more bumpy.

[special-K]

Evidently coils weren't a better idea or trucks wouldn't have gone back to leafs. It was an option on both Chevy and GMC,but all 4wds and one tons have run leafs. People used to buy cars for comfort and trucks for work.

[nobolt]

why is the man "out of line"? it's the truth.....ahhh, hornet you missed an "I" ...LOL

[ETsC10]

Originally Posted by nobolt

why is the man "out of line"? it's the truth.....ahhh, hornet you missed an "I" ...LOL

Fixed the "I"


I love the ride of my '68 C-10 (with it's leaf springs!)
...feels like what it is...a healthy, stable truck.

[GASoline71]

All I can say is if you don't like leaf springs... sell the truck or change the rear spring setup. You ain't stuck with them. There are lots and lots of trucks out there of this vintage with coils.

Gary

[terry b]

Why did you buy it if you don't like it?

[54blackhornet]

I ment to say I was out of line, not "Firefighter" Sorry all ! I myself have a C-20 with coils and it drives way better then my 1/2 tons with leafs ! I would have thought leafs would have been stock on both lines ? Must have cost more to equip one with coils when new ? Again just wish my 71 I just got had coils so I would have a little more latitude in upgrading future...Sorry for getting you all upset, never would want to do that...
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[Tx Firefighter]

Originally Posted by 54blackhornet

I ment to say I was out of line, not "Firefighter" Sorry all ! I myself have a C-20 with coils and it drives way better then my 1/2 tons with leafs ! I would have thought leafs would have been stock on both lines ? Must have cost more to equip one with coils when new ? Again just wish my 71 I just got had coils so I would have a little more latitude in upgrading future...Sorry for getting you all upset, never would want to do that...
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No problem. I see you're posting from a phone or something and stuff like that is easy to do. It's all good.
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[terry b]

Didnt all chevy truck's come stock with rear coil's and leaf's were a extra cost option?

[darush01]

I cant complain about comfort or load capacity in my c20 with coils, i guess its all about the driver ive had 1900 lbs in the bed a 4600 on a trailer and never bottomed out rubbed wheel wells or swayed but i was raised to haul my dad had me driving an olf 2 ton truck through his junkyard at age 10 and my c20 with coils has handled everything ive put in it
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[bobs409]

Originally Posted by darush01

I cant complain about comfort or load capacity in my c20 with coils, i guess its all about the driver ive had 1900 lbs in the bed a 4600 on a trailer and never bottomed out rubbed wheel wells or swayed but i was raised to haul my dad had me driving an olf 2 ton truck through his junkyard at age 10 and my c20 with coils has handled everything ive put in it
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Whatever the reason, I agree that the coils are nicer. I have a 3/4 ton and it rides fantastic and still hauls the freight. I had more weight on than I should have on an occasion or two and it didn't complain at all.

On the other hand, I remember my 69 Blazer 4X4 that rode like a tank! Hated the harsh ride it had due to leaf springs.

[bollybib]

Not ever having owned a full size truck, I learned about coil vs. leaf ride quality during my research before I bought one. Because I would be using it in light duty service (more like a car with a lot of stroage capacity, really), I specifically wanted rear coils for the better ride quality. I rejected a few trucks I really liked only because they had leafs.

I got what I wanted. I like the ride and I have no need for any rear end modification.

[68gmsee]

My old 69 was coil and it sure drove smooth. My 68 GMC is springs and even though it's not as smooth, I like it. A lot simpler and cheaper.

I knew the rancher that had it before me. He used it for hauling fence posts and other ranch work. It was a simple thing for him to add additional springs for this type of work. When I got bought it, I didn't need them, so it was a simple job for me to remove the additional springs. I have them available if I ever need them but I doubt it. Still hauls a good load.

I believe that cost and simplicity -along with suspension advances -may be a big factor in GM's decision.

[factorystock]

Ground clearance is another reason for leaf springs. Coil trailing arms can get stuck on large rocks off road.

[skillet]

Originally Posted by 68gmsee

My old 69 was coil and it sure drove smooth. My 68 GMC is springs and even though it's not as smooth, I like it. A lot simpler and cheaper.

I knew the rancher that had it before me. He used it for hauling fence posts and other ranch work. It was a simple thing for him to add additional springs for this type of work. When I got bought it, I didn't need them, so it was a simple job for me to remove the additional springs. I have them available if I ever need them but I doubt it. Still hauls a good load.

I believe that cost and simplicity -along with suspension advances -may be a big factor in GM's decision.

Are you talking about helper springs from the 67-72 era or something else? Reason I'm asking, I have a '69 with leafs and was looking for something like his solution for my truck. Thanks very much.

[darush01]

Oh and the wood bed was rotted out so i have a peice if steel and a bed liner down for now
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[stsalvage]

Boy all you need to do is find one of the board members near you that has a junk 1960-72 1/2 or 3/3 ton and swap out the coil springs for the leaf springs.the problem comes around about the 12 bolt rear ends with the locator bar post But i've heard that all you need to do is change the axles in the 6 lug rear ends and use them as your rear end

All of the trucks can be eather one leaf or coil where the ladder bars are they have the holes to bolt it back up

[special-K]

Yes,the wood floor is for work,just like it is in all the pre-67 Fleetsides,Stepsides,flatbeds,dry goods vans,and a heap of utility trailers. Guys with '73-ups do 4-link/bag suspension and get the best ride and capacity all in one. It's not that complicated. A lot of guys with coils do it,too. With anything,it's always esiest to buy it the way you wanted it already.