1999 Suburban 2500 and 31' Bunkhouse - Shocks

[stevegriffin]

I have recently purchased a 31' bunkhouse (8800lb GVWR) and am pulling it with a 1999 Suburban 2500. I have anti sway bars hitch etc. I am getting a bit of porpoising when riding down an interstate when going over bumps. Aside from that it tows great. I just bought the Surburban and the previous owner did not replace the shocks, so it's unclear how old they are.

Advice from the airstream dealer service guru was to replace the shocks and to insure the tires on the Suburban are LT type with the thick sidewalls indicated by the higher air pressure capability (80lbs). The tires meet those specs.

The local Chevy dealer suspension guru suggested seeking advice from others with similar setups to see what has worked, rather than experimenting with various shocks.

Thanks in advance for passing on your towing wisdom, so I avoid having to build up a lot of trial and error experiences.

[HowieE]

gas or diesel?

You need to determine the rear spring pack code. The codes are on he inside of the glove compartment door.

This site should help.

RPO Codes.com- GM option codes,GM rpo codes,General Motors options

There is little you can do to reduce porpoising while using a bar type sway control as the resonant frequency of the bars is often about the same as the plate separations in the road while going 60 mph.

I had this problem with my Excursion and 34 ft trailer. The install of an Andersen hitch solved the problem. The difference is the use of urethane as the damping material.

[stevegriffin]

It is gas.

I am not familiar with pack codes, but looking at the site it would seem to tell me about how the car came from the factory. Would the rear spring pack code tell me what shock to buy w/r the shock's match to the car's design parameters?

Disappointing to hear about the sway control. Wish I had looked into anti sway more fully - being a newbie I took the dealer's recommendation at face value.

In backing with the bar type anti sway I can already see how the chain approach is superior.

Thanks

[HowieE]

No the spring pack will not address the shocks.
If you need shocks, and i am not saying that is the case without checking them, Bilstein is the only shock I will use. Most of the common named brands are useless out of the box.

I have not checked but i think the 2500 can come with anyone of 3 different spring packs. A quick way to tell if you have the 1 ton set is the truck will most likely have 5 marker lights across above the windshield. The 1 tons should not porpoise, just too stiff. My 97 had 1 tons.
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