Too much tongue weight

[Dog Hauler]

I have a 2014 Mercedes GL350. The owner's manual states that maximum tongue weight is 600# and I struggle mightily to stay within that limit. I could easily get to 900 or 1000# tongue weight if I just packed stuff in the most convenient places. At the very least, I know that excessive tongue weight can cause the trailer to be a handful, especially in crosswinds or when passing/being passed by trucks. And if there is enough tongue weight, it can cause the front end of the TV to be light which can affect handling and stability.

Nothing is stated in the manual about that limit increasing with use of a weight distributing hitch. In fact, the manual fails to mention use of a weight distributing hitch at all. I asked my dealer about it and the service guy said that I shouldn't use a weight distributing hitch on my GL because of the way the factory hitch is attached to the unibody. I don't know if that's true or not.

The service guy also said that use of a WD hitch will increase the distance between the ball and the end of the receiver so much that it will be outside of factory specs. I know there is, indeed, a factory spec on the distance between the end of the receiver and the ball. All WD hitches I've seen would exceed that distance.

Is there anything I can do so that exceeding the factory specs on tongue weight (perhaps by a lot) won't adversely affect towing or my TV? Thanks for any advice.

BTW, I searched this forum and found discussion about tongue weight but nothing that addressed my situation. If I missed it, I apologize in advance.

[idroba]

Give these people a call, they know more about the subject than anyone else. From what I understand they also will talk with you about it.

Can-Am RV Centre | #1 Airstream Dealer in Customer Satisfaction Worldwide | Your Full-Service RV Dealer

[switz]

When I arrived at the CanAm location in October of 2013 in my Mercedes 2007 ML320 CDI for a hitch modification and with parts from from my Hensley Arrow weightb distribution hitch, they cut about four or five inches off the car side of the stinger and drilled a new hitching pin hole bringing the locking pins location so close to the rear bumper that the Hensley wrench could not fit over the locking nuts. I used a Harbor Freight 21" crescent wrench after that.

There was no issue with the 1,150 pound tongue weight of the empty 2013 25FB International Serenity (new on the dealership lot increasing to 1,175 pounds camping ready with same scale). The Airstream literature listed 833 pounds as the tongue weight. The air suspension worked well. The engine had no issues in the mountains out of Palm Springs on I-10 headed for Phoenix (down shifted manually to 5th maintaining 2200 rpm at 55 mph).

Note that the higher than literature tongue weight reflected that we added a single 155 watt solar panel on the roof, both rear and street side awnings and the Hensley hitch head before taking delivery of the trailer. There was only partial water in the fresh water tank and no gray or black tank contents, the two stock 30 pound propane tanks were full and there was a spare tire installed by the factory under the hitch "A" frame.

The rig was legal weight wise getting it home with nothing else in the car, but the Mercedes was overloaded weight wise (both the front axle rating and GVWR were exceeded) camping ready with both me and the wife and about 40 pounds in the rear of the car. That discovery resulted in a different tow vehicle.

Below my avatar, click on "images" to see a photo of the hitch reinforcement done at CanAm in London, Ontario, Canada.

[andreasduess]

First off, a GL350 is a very different beast to a ML320. You have ample payload to deal with your trailer.

The weight distribution advice is partly correct, your hitch should be strengthened before adding weight distribution to the mix. There are many, many happy 350 drivers out there, loving the vehicle for towing.

As others have said, give CanAm RV a call.

[JustSomeGuy]

Another vote for calling Can AM. They set up my 2012 Chrysler Town & Country minivan for towing my 25' Airstream. Yes, I know they're far away, but many people have found it worth it to go across the country.

Incidentally, I recently rented a 6x12' Uhaul trailer, towing with the above mentioned minivan. I recall it saying to avoid trailer sway, load heavy things closer to the front (I interpret that as being closer to the hitch). Did so, towing a load of furniture across the country, in the trailer and in the back of the van. No problems at all, except that, even with the weight distribution kit I have, the front still sits up a bit high and the back a bit low, causing the low beam headlight to shine upward. During night driving I had lots of people flashing their high beams at me thinking I had forgotten to dim mine. Same thing happened when towing the Airstream.

[Ohiobrits]

Can-Am in addition to doing the hitch mod to strengthen for WD also will move the batteries to the rear for FB AS's. They relocate them under the dinette (with the inverter if you have one). This will reduce tongue weight about 150 to 200 lbs depending on what batteries you pick. You would need new sealed batteries for this, the stock lead acids are not to be used inside the coach. Assume about $750 to do this yourself or probably $1200 for Can-Am. The spare can also be removed. Suggested Can-Am mod is to upgrade the the Michelin LT 16" tires which are much more robust then the Goodyear Marathons which are 15". Many AS's until recently ran without a spare. I completed the battery move to the rear, upgraded to the 16" Michelins and also carry a full size spare for my TV under the dinette and got my tongue weight down from 900 (factory delivered with second AC, wrap around awnings and inverter) to 650. Check out my post on "FB move batteries to the rear". I'd probably not reduce it this much unless you plan on a Hensley or PP, since this will be 10% tongue weight or lower. I'm running with a ProPride now at 780 tongue (scale measured, about 640 with WD applied).

On hitch mods, is it required? Maybe, maybe not. I'd take advice from Can-Am, they will almost certainly say yes. I had a local custom exhaust shop do mine. I had them drop the rear muffler also, not really needed on the diesel.