Originally Posted by dnebout
Not sure what the problem is other than a light front end. Is it also that the leaf pack will be overloaded? If so, can't you use a thicker leaf pack or air bags?
The chassis is designed with specific weight restrictions on the front and rear axles, that is determined by the springs as well as the axle itself. That is the axle and springs are designed to handle a specific load range. Build it too sturdy and you waste money and the ride will be rough. Build it too light and you will have warranty issues and field failures.
You have a W20 chassis has a front axle that is rated for 7,500 lbs and a back axle that is rated for 13,500 lbs. Add the two together, you get 21,000 lbs, which is where the 20,700 lbs GVWR (maximum the coach can weigh) comes from.
When the RV is designed the manufacturer chooses a chassis wheel base that will distribute the weight of the vehicle over both axles. Of course this also depends on the interior layout of the RV. One of the techniques is to choose a wheel base that will place the rear axle under a balance point so the the rear overhang can reduce the weight on the front axle. Its a balancing game.
Typically the frame is not long enough to extend all the way to the end of the rear overhang, so the frame rails are extended to support the box and to have somewhere to mount the trailer hitch. This extension will be designed to handle the installed trailer hitch and the weight of the box. This is why the trailer hitch on the gas Class A RV's have a 500 lb tongue/ 5,000 lb toad limit.
To make this more real lets use your RV specs. The distance between the axles is 228", the distance from the rear axle to the hitch is 116. This is basically a 51% ratio.
If we add 1,500 lbs to the trailer hitch, the frame extension will need to be substantially beefed up (note that this adds weight). So now the additional weight is 1,700 lbs. Using the RV specs if 1,700 lbs is added to the hitch, the front axle will be unloaded by 49% of 1,700 lbs or 833 lbs.
This is not too bad, but the load on the rear axle will increase by 1,700 lbs plus the 833 lbs that shifted towards the rear from the front axle, or 2,533 lbs.
I couldn't find the base weight of the Allegro 32B for 2004, but for 2005 the base weight (weight with no fuel, water, waste, passengers, cargo, nothing) is 17,000 lbs. This leaves 20,700 - 17,000 lbs, or 3,000 lbs of stuff.
It is a sad truth that most gas RV's (I would suggest upwards of 90%) are loaded to a weight that exceeds their GVWR as they sit in front of your house ready for a trip. A full tank of gas weighs 546 lbs, 25 gallons of water is 200 lbs, clothes, tools, toys, people, etc.
The questions are;
- How will the lifetime of the rear axle be affected by adding 2,500 lbs over its rating?
- Will the reduced weight of 800 lbs on the front axle affect the steering?
- How much will it cost to reinforce the frame extension to the hitch, and can you find someone that is willing to do the work?
- How much would it cost for a custom trailer for the bike and boat?
- Will the weight of the bike, boat and trailer exceed the 5,000 lb tow limit of the 32B (hitch capacity)?
You should weigh your RV as it is ready for a trip and measure how much weight is already on the front and rear axles.
I know I am over weight on my RV, but I have measured it and am comfortable with it. The alternative was to switch to a pusher diesel and I can't afford it.