truck is not sitting level - need help diagnosing

[hpp]

Hi everyone. I could your help diagnosing a problem with my C10. On level ground, the truck doesn’t sit level and I’m trying to figure out why.

• 77 C10 short bed
• stock suspension – no lift or drop
• factory control arms with coil springs
• Rear leaf springs have 4 leafs
• Front and rear bushings on leaf springs are good
  
• I assume the springs are factory specs
• no accidents - frame looks good
• cab mount bushings are in good shape

Measurements from ground to top of wheel openings:

Front left 32-1/2” Front right 32”

Back left 32-1/4” Rear right 31-3/8”

The front left is high and the rear right is very low. When measuring left vs right side of the rear bumper, the right is > 1” lower. Clearly visible by eye.

I would like to correct/level the truck’s stance, but I’m not sure of what’s causing this.

Some more data points:

1. I put a 1-1/2” piece of lumber (2x8) under the rear right tire and this leveled the truck completely.

2. I put two jack stands under the rear frame rails near the bumper. This leveled the rear, of course. This leveled the front also.

3. I moved the jack stands to the front of the frame rails right in front of the sway bar brackets. The front was level and the rear was not level. Right side was low about 1/2” when measured to the top of the rear wheel wells.

My hunch is that the right rear spring is weaker. Is it possible that one spring went bad? From my experience, I’ve seen springs sag but usually in a uniform way.

Could what looks to be a straight frame have a twist?

Thoughts? I would appreciate any and all advice. Thank you.

 

[Curt]

Tires?Yes,springs wear,so do the bushings.Loose,wore out body mounts.

It would be hard to diagnosis not seeing it in person.Almost impossible without pictures of every single component

 

[78C10BigTen]

Possible the frame may have a twist... the lower rear side may have had a heavy item in the bed for a very extended amount of time that weakened that leaf spring. Possibility? plus pics of the truck, the stance and as stated above the parts you suspect.

 

[gotyourgoat]

First off, welcome!

Pictures always help btw.

Is the truck empty? Single or dual tank?

Ever been wrecked or disassembled? Maybe in keeping the panel gaps uniform something got shifted or over/under shimmed along the way.

 

[Shorty81]

Welcome from the Buckeye State.

 

[82sbshortbed]

Why worry about 1/4" one way or 1/2" the other? I think you'd be hard pressed to find one of these old trucks that sits perfectly level. But, I'm not that picky about it. Lol

My old machine shop boss used to be real picky about that kinda ****. When I was running pvc for the air system everything had to be level and perfectly done or it drove him nuts. Lol

 

[Keith Seymore]

They didn't sit level when new.

Add some shims to square it up.

K

 

[PeteJr]

My '83 sits lower on the driver's side. My theory is the gas tank and (usually just) the driver on that side for 37-38 years has weakened the springs on that side.
But, a lot of them sit like that as was already stated.
It's on my list of things to address.

 

[C10MixMaster]

I took my rear leaf springs apart and swapped leaves from side to side, alternating leaves with more of a curve with those with less of a curve . This took away most of the lean.

 

[hpp]

Thanks for your replies. Answers to your questions here:

• Tire pressure is good.
• Visual inspection of leaf spring bushings is good. Pictures attached of right leaf spring bushings.
  
• Body mount bushings good.
• Previous owner did a restoration approx 15-20 years ago. Maybe 10K miles since. That's why bushings look new-ish still. Used for fun since, not as a work truck, so no heavy loads.
  
• Single gas tank on right side.
• Visually speaking, the frame is very straight. I would be surprised if it was ever bent/damaged. I don't know how to check for twist.
  
• By the time you get to the back bumper (which is spare to end of frame rails and rear bed, there is more than an inch - see the picture. In the pic, there is a level across the bumper with a rock under one side. Shows diff from true level. I'm not that picky either I've had the truck for 6 years and this is the first time I'm looking into this.

Any additional thoughts are appreciated. I may end up ordering new leaf springs... not sure yet.
(BTW, this is a great forum - I have found a lot of great info since getting my C10)

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[Danderson]

Have you measured from the ground to the bottom of the frame rail on each side, both front and back?

 

[Juggernaut]

Have you checked for a broken leaf? Look for a crack in one of the leaves at the spring center pin between the u-bolts

 

[AuroraGirl]

My '83 sits lower on the driver's side. My theory is the gas tank and (usually just) the driver on that side for 37-38 years has weakened the springs on that side.
But, a lot of them sit like that as was already stated.
It's on my list of things to address.

i would say yes primarily when you consider dual tank trucks or pre 83 or whenver they switched to the driver side as primary tank. before that the gas would be pass side

 

[HOTFOOT]

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Have you checked for a broken leaf? Look for a crack in one of the leaves at the spring center pin between the u-bolts

A lot has happened in almost 40 years, here’s my top 2 on one side

 

[Dave M]

Park it on level ground, jack the rear right under the chassis rail, not the axle, up until you have even measurement with the opposite side. See how it looks then. sounds like the rear leafs need resetting, one has sagged more than the other Take them to a spring works.