Rear Suspension Sag While Hauling/Towing

They do make carriers with a higher weight load. Discount ramps is where I actually bought my Rage Carrier from

https://www.discountramps.com/hitch...-mRpAGImjr6VjNr6LQbtmZOozjLODcUAaAhIaEALw_wcB

They also make a hydraulic hitch carrier .

https://mojomotosport.com/products/...DwPQ9s5qlOGE8G4GbStZOKBUci2dbq8UaAnaYEALw_wcB

 

Even at 400 lbs, the bike cantilevered off the hitch will in effect be more like 7-800 lbs.

Its acting like a lever on the truck with the rear axle as the pivot point. Essentially, a torque.

Making a guess at the distance from the rear axle to the bike of 4 feet. The 400 lbs on a 4 foot lever is 1600 ft lbs of torque being applied.........lifting the front end........ Yes, the rear axle is supporting the 800 lbs of the ATV and the bike.

You are close to being overloaded.

 

If you're going to haul both without a trailer figure out how to load the ATV like the image below, close the tailgate and lose the hitch extension that is causing a shaitload of leverage (thereby having the dirtbike closer to the tailgate.) This'll move the weight forward.

You'll probably still need one of the following to prevent a saggy ass:

AAL, sumo springs, airbags OR a new leaf.

 

Actually reviewing the OP's picture.....I think my guesstimate of 4' behind the rear axle is very conservative.

Probably 5' or more. So, the applied torque to the frame of the truck will be 2000 ftlb or more.

Yeah, you need a trailer that would fit both the ATV and the bike. Unload that torque on the frame. A small 4x8 trailer from the local Big Box store is not terribly expensive. Plus you'll be removing stress from the truck.

FWIW, road bumps will intensify the lever action from the bike. Wouldn't take much to produce an momentary torque in the 3000 ft lb realm.

 

I had relatively new tsb springs and a 200lb cap dropped it almost 2 inches to the point the leafs were slightly negative. I’d get new HD springs or airbags if you don’t want to sacrifice the unloaded ride. I’ve heard a lot of off-roaders run air bags on here without many issues.

I do agree a trailer would be better but storing/maintaining can be a pain and will limit where you can go loaded up.