Suspension question

[Lily747]

Hi everyone,
My name is Alex. I’m supposed to be receiving my 2018 Sprinter 2500 Sportsmobile in July. My question is I want to be able to increase the tongue weight from 500 lbs. to 600 or 700 lbs. I know that Luminess aluminum bumpers have a tongue weight of only 500 lbs., But Im looking to add a 500 lb. motorcycle, a spare tire, and gear box to the back, and I know it will exceed that weight. Does anyone have any suggestions as far as changes/modifications to the springs or overloads? Any ideas would be helpful. Thanks.

[carringb]

I wouldn't do it. That will greatly overload the hitch receiver, and when you see what it's attached to, you'll understand why that's a bad idea. Keep in mind that a 500# motorcycle will effectively load the hitch much higher than 500 pounds of trailer tongue weight, because the load center is so much further back. A standard clearance motorcycle rack is probably about 750# effective hitch load, and probably 1,000 pounds if you went with an extended version to clear the box and tires.

The Aluminess receiver looks stout enough, but it only bolts to the sheetmetal frame using 4-horizontal bolts. It doesn't even look like the frame is sleeved at the bolts. I'd expect those bolts to tear the frame the first trip out, if you load it up that heavy.

[Lily747]

Thank you for your advice, would all steel bumper be my next step or just plan on a DRX 400 about 350 Lbs?

[Fitz]

I have a Sprinter with an Aluminess bumper. I had Aluminess add additional gussets to get the load rating up to 500 lbs. Maybe that is standard now, easy question to ask Kenny.

I’m with carringb above, I think you are asking the Sprinter to do too much. Common practice is to de-rate the load capacity by 50% when adding the extension that is required, thus 250 lbs is the maximum (keep in mind you need to take into account the weight of the spare tire, box and contents also).

I am currently setting my 4wd 2500 Sprinter up to carry my 155 pound Honda CT 70. With the rack components I figure I will be hanging 200 pounds off the back. I have mounted everything but haven’t road tested it yet, that will come when I have a knowledge person willing to follow me and watch everything. The Sprinter suspension has been beefed up with Van Compass springs and shocks and the bumper has been reinforced and with all that I feel I am about at the limit of what I am comfortable with. Anything more and I will use my trailer.

[carringb]

Originally Posted by Lily747

Thank you for your advice, would all steel bumper be my next step or just plan on a DRX 400 about 350 Lbs?

A steel bumper would make the problem worse. The problem isn't the bumper. It's the complete lack of reinforced attachment points on the chassis. You probably could find a fabricator to make a custom frame reinforcement that runs forward of the bumper, but Mercedes doesn't take to well modifications, and they could sometimes warranty hardball.

IMO, even the DRX 400 would be too much, once you add the weight of the rack and factor in the load center. Maybe it would work if you skip the cargo box and tire carrier, and never drive rough roads.

This is all that would be holding on your toys. It's some 7/16" bolts, through double-wall sheetmetal, and no reinforcement to keep the frame from collapsing. I'm surprised they even get a 500# rating out of this.