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Old 06-29-2003, 10:50 AM   #9
Join Date: Feb 2003
Posts: 68

Hi Bill -- --

In my opinion -- You're considering the wrong approach --- changing the air bags. Follow along --

You've a 3 - axle tractor .. ment to carry 25,000 (appx.) pounds on the Holland hitch -- To gross 34,000 on the drives. In towing a 5th wheel RV -- You may reach 4,000 pounds pin weight. Obviously -- the rear suspension -- is rated far in excess and the ride of the 5th wheel will be "Stiff".

This is what I recommend -- 1st off a "Ping-tank" will do you no good at present.

The first thing you need to do is loose one drive. This will eliminate 2 - air bags and cut your rear rating in half. If yo need more softening -- Try this ......

If you've an adjustable pin box on the 5th wheel -- pull the 4 bolts and lower the pin box one hole -- 2". To compensate -- do this .....

Slide under the rear of the Tractor and adjust the ride height control rod as it mounts to the lower frame that supports the bags -- You'll want to shorten the rod 2" to compensate for the pin box. What this does -- is to lower the air pressure in the 2 - air bags as it adjusts the frame lower to the ground. Keep in mind also the shocks -- If you've stiff aftermarket shocks -- this also works against you. Need more softening .. ..

Then -- You may want to consider either an Air Hitch -- Or an air pin box.

As to a ping tank -- This is using a typical 7 gallon air tank purchased at Walmart -- and adpting it to the 2-rear air bags. The tank is made for high pressure and low volume. For our purpose we need to change this to low pressure -- high volume. Considering pressure -- no change needed -- just use as rated. For high volume -- we need to add several more paths from the air bags to the tank. Easiest way -- is more "T's" in the crossover air line connecting the 2-bags. How many -- I don't know --- as I dropped the ping tank idea -- as my Tractor had one on it -- so I've towed with my Tractor both ways. It made no difference. Need more -- --

If you've a sliding 5th wheel -- slide it full back -- as you will use this "lever" to your advantage. Like using a length of pipe on a breaker bar. Need more ......

Some folks bolt steel plate as far rearward on the frame as possible. Need more ......

Have a steel bed made with storage boxes.

I've incorporated the above suggestions -- into the development of mine -- with the exception of a bed. If you'd like to view -- click here:

A lot of geometry is involved to attain as close to a perfect setup as possible.

Have you weighed you setup combined/bobtail -- as this is the starting point to evaluate.

Here is a link to where I've posted my weights:

In closing -- the additions/alterations I've done to mine -- now afford me -- with a rear entertainment center -- never having to remove anything from the enclosed glass cabnets. Here's a link to the interior of mine:

Hope this has provided some insight -- in your question of softening up the ride for your 5th wheel .......

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