Weight Dist and 40' DP

Is a WD hitch necessary or required when being towed by a diesel pusher? Probably not but too many variables to have a blanket yes or no answer.

As already mentioned the air bag suspension should sit the same height with or without the tongue weight of the trailer due to the height sensors compensating for the sag. That said, the ride height really doesn't determine weight transfer, merely the height of the hitch upon hooking up the trailer, ie keeping the coach level.

There is still a fulcrum or leverage acting which is at the air bag(s) on the rear suspension. This is the pivot point if you will for the coach, trailer tongue weight plus coach weight behind the rearmost air bag(s). Now a 5 or 6k pound trailer on a 35k pound coach will not make much of a difference but throw a 10k plus pound trailer on the back of that 35k pound coach and it could have an affect on ride quality. This would be more evident in the porpoising affect going down the road. A triple axle trailer would have less of an adverse affect than a tandem axle trailer. A lot of variables come into play.

Personally, I can tell a difference with the use of a WD hitch but then again I am towing quite heavy, and that is even with a tag axle coach. The negative would be that there is an inherent friction or resistance in a WD hitch by design, so when making tight turns there will be some resistance to this turn by the spring bars and/or chains if so equiped working agains one another. It is not much but I thought it worth mentioning.

My theory, and this is only my theory, is that although the air bags are able to compensate rather quickly when going down the road, it is still not fast enough to compensate for the weight transfer and so there is that porpoising affect that comes into play as the tongue weight is magnified being XX distance behind the rearmost air bag. I have even notices this very little with a tag axle coach. Moreso with a single axle rear coach.

Mike.

Hopefully you meant 500 pounds of tongue weight. You coach should be rated for 10000 pound towing with a 1000 pound tongue weight. No need for a WD hitch. I believe they don't recommend WD hitches on DP's because it throws off the leveling system. The air ride system is adjusting itself as you drive. The WD could throw this off.

I weighed a pickup truck and a 27 foot travel trailer on a three axle scale with the weight distribution hitch installed and then weighed it again after loosening the WD hitch.

It had transferred about 300 lb to the front axle from the rear axle on the truck.

"What is Weight Distribution?

Try to think of a Weight Distribution Hitch System as a bridge connecting the towing vehicle and the trailer. It has an adjustable under truss system called spring bars that join the “V” of the trailer to the hitch head and the receiver hitch to evenly distribute the weight.

The head bolts to the shank to ensure proper height and the shank slides into the receiver hitch which is bolted to the towing vehicle. The weight is then more evenly distributed between both axles of the towing vehicle and the trailer itself".

I see nothing wrong and see where a WD would be OK for ANY type trailer towing behind a motorhome. Above is from Reese Hitches. Doug

Ok

Just asking here > What would it hurt if left in place?

Hope the 5000 is NOT the weight rating of the hitch on the MH. You need to weigh your rig loaded up and WD will not do much on a 35,000 lb rig so not needed. Your MH will sit the same without the trailer hooked up... ride height valve controls this.

The air suspension in dp's has a height sensor system and will automatically maintain level. In fact, most of these systems are able to fight against sway in a corner even.

The rear of your coach should sit at exactly the same ht regardless of what it is towing, unless something is wrong with the system, or you are severely overloading it. (I am assuming that a 5000 pound tonque wt is a typo?)

You can adjust the ride ht, but manufacturers have very tight specs of where this should be.

I can't imagine that a 40' DP would need or could even benefit from a WDH. I agree, get rid of it.
Ride height isn't controlled by shocks, it's done with springs and/or airbags. If you think it's low add some air.
You should be able to low your trailer so the tongue weight is around 10%.

You shouldn't need a W/D hitch on a 40' DP.