Rear coils and alignment

[ThreeQuarter]

When I assembled my '68 C10 coil rear suspension I bolted the axle to the control arms last, after loosely connecting the panhard/track/locating bar. With the suspension hanging, I noticed I had to pull both trailing arms a couple of inches to the driver's left to get them to line up with the axle. No big deal I thought, because when I get more weight on the rear the panhard will shift everything back into line.

Now that I have the rear end resting on the ground and everything torqued, I can tell the springs are still not happy where they're sitting. The bottom of both springs are skewed to the driver's left. Even if I bottom out the suspension, there isn't enough lateral movement in the panhard to make the springs look vertical. I made sure all four spring ends rested on the trailing arm/frame, and I aligned the clamp's notch with the spring end. Original panhard, trailing arms, axle, frame...new springs.

So...I'm thinking it's the way the springs are made--the way the ends sit on the trailing arms & frame when they're clamped down that makes them want to not sit plumb. Maybe I can loosen the top & bottom spring clamps an spin the springs to find their sweet spot?

Anybody have similar experiences with new springs? Mine are HD C10 springs.

[ratty69]

I would also like to know. I've got a similar problem, and came to the conclusion that the track bar should have been designed at least 1" shorter to allow adjustment to the correct length.

[old51sedan]

You didn't say as to whether you lower your truck, if you did you may need to do some adjustments. I just lowered my 69 with 4" drop springs. In doing so I installed a shim under each axle to maintain the same level of the driveshaft. Also went to a new adjustable panhard bare and a new shock reloacating kit.

[ratty69]

Originally Posted by old51sedan

You didn't say as to whether you lower your truck...

Good catch. Just noticed that the OP didn't say, and he's using the original track bar.

Mine is lowered 4" with hd coils, long adjustable bar, and shock relocators and still doesn't line up. But not as bad as his.

[ThreeQuarter]

New springs are factory height HD C10 springs with the two-stage (progressive?) coils. They’re made a little different than the original springs—the originals had the tight section of coils in the middle while the Eaton ones are at one end.

With everything being factory spec, I’m thinking this should bolt up and align well, but I might be missing something. I’ll loosen the coils this afternoon and rotate them to see if the they might be happier when they’re oriented differently.

[LH Lead-Foot]

I did not use "Variable Rate" springs on my 67, but with the photos showing the bottom spring perch position are different from side to side. I would loosen them to see what happens when you rotate one or both.

I don't believe the panhard bar is the issue. Just un-bolt one end, then push & wiggle the frame a little bit. I don't think you will see any difference.

I have installed hundreds of springs either for replacement or required due to other work, but they had pre-formed pockets to sit in. These truck don't. The mounts are where they end up when you tighten them down. Give it a try.

[ThreeQuarter]

Looks like the springs have a preference about how they sit on the trailing arms. I rotated mine and found the sweet spot before I clamped them back down. Still not perfectly neutral but much better than they were.

[68 P.O.S.]

That’s just how it is. Only thing you can do is rotate the springs as you said, then center the rear end and connect the panhard bar. Or, if you have the cashola, put a 4-link in there lol.