RE-Spring 2500 HD

[jtdalrymple]

I am considering have the rear leafs re-sprung. The truck is a 2003 2500HD extended cab short bed. I purchased the truck new and it currently has 104,000 miles. The spring stack now rides on the bottom helper leaf constantly, loaded or not. Most of the miles have been loaded, towing RV trailers. The first was a 32 foot 5th wheel. Now it is a 27' Airstream.

The ride continues to get rougher. Thanks in advance for any input.

[DmaxMaverick]

A re-spring isn't your only option. They can be re-arced for less than 1/2 the cost of replacement, and can be an improvement over the original in new condition. Or, you can install airbags for a similar cost. If your tongue weight isn't significant (long springs able to handle the weight in an emergency with a failed airbag), you can remove the high-load leaf with airbags. Airbags are most beneficial because they can be adjusted as needed, and "on the fly" if you install the compressor/controller. I have this and love it. It also eliminated the need for a rear sway bar (L/R bags are independent, not connected).

"Helper" springs are good for heavy loading, but don't improve unloaded ride quality/comfort, and most often make it worse.

[jtdalrymple]

Thanks for the thought. I do have the Firestone ride-rite system installed, with an onboard compressor. I installed it while we still towed the 5th wheel. As you mentioned, they work great for heavier loads.

The Airstream has a tongue weight of around 700#s, and I do use a weight distributing hitch but mostly for the anti-sway features of the dual cam. The truck can handle that much weight very easily. I don't remember the springs compressing down to the helper leaf when I first switched from the 5th wheel.

I mostly want to know if others had seen the springs settle and compress over time as I have.

Regards,

Jeff

[DmaxMaverick]

I have seen spring sag on other brands, and previous GM's, but haven't noticed it on the late models (2001+). I'm sure it's happening, but I haven't noticed any obvious sagging, or just didn't look. Springs settling after new is normal, and expected. However, they shouldn't allow the primary stack to settle onto the heavy load leaf, unloaded. That's excessive, and suggests a failed leaf stack. Your previous 5th wheel towing conditions sound similar to mine over the life of my truck, with a typical pin weight now around 2K. My previous 5'er was lighter on the pin, and I towed for 5 years with no airbags, and no unloaded spring sag. Now, if I dump the airbags completely, I still have no noticeable sag. Running normal, the electronic airbag controller keeps a minimum of 5 PSI at all times.

Since you have airbags, it should be as simple as adding a little air pressure to offset your current spring sag. Getting the springs off of the high load leaf goes a long way to soften the ride. The high load leaf shouldn't be engaged without a significant load over the axle.

What pressure do you keep on the bags, unloaded? A minimum air pressure should be maintained on the bags at all times, under any condition, to prevent premature airbag failure.

Another thing to consider is the condition of the front suspension. Settled, or sagging, torsion bars not only caused the front to sag, but the rear will settle lower, proportionally. In your case, using a WD hitch, you could have a condition of front sag, rather than the rear, or both. This is easy to correct, by simply increasing the torsion bar preload setting. A turn or two of the torsion bar cam adjusters (while the front suspension is unloaded and fully extended) should be all that's needed in an extreme situation. Also, if the front suspension "bump stops" have failed (and likely are), this also effects the suspension geometry. With an OEM setup, correctly adjusted, the bump stops should be slightly compressed while unloaded, as they are included in the suspension load. They are not only "stops", but actually considered part of the load bearing package, according to GM. If yours have failed, they should be replaced before continuing any further diagnosis.

[87max]

I was told by a friend that did springs for a living that in the long run your better off to add a leaf or get a new pack as re arching typically doesn't last without a change in the reason why they sagged to begin with. If the ride is to harsh by adding air to your bags when empty how about adding a block?