Howdy folks! I was hoping to learn a bit more about towing with the GL450 and was directed here.. I'm no noobie to forums like this so yes, I did search these topics and found a great deal of information on this topic. Forums are always a great resource especially with "GLE John" around! :-)

So here I am with a '13 GL450, impressed by the towing capacity, but disappointed/concerned about the tongue weight limit on the factory hitch. 600 pounds? Really? Also, the wiring harness for the towing seems like they didn't put the ordinate amount of thought into this per typical Benz engineering (but what do I know?).

Anyway, I'm going to tow a 24 foot "Hyper-Lyght" trailer that could weigh 6K loaded. It has a 545 tongue weight.

I shouldn't use a weight distribution hitch? Should I work on getting the factory hitch reinforced? Should I replace it?

Am I overthinking this?

Thanks all,

MaxCad

 

seems like your trailer and tongue weight are under the stated capacity... what's the problem?

 

Add in the WD hitch and I'm over. Also, I read somewhere that WD hitches were not recommended based on the unibody construction of the GL.

I'll take your response as, "I'm over thinking it." :-)

 

I also remembering reading somewhere that a WD hitch should not be used on unibody either. I’ll see if I can find it. But there are other threads saying that there is no problem.

 

^THIS^

The physics of it would say tongue weight is more about downward loading of the vehicle (ride/sway control), not the hitch fail strength limit. You will be tugging and stoping a 6000 lbd load. No part of the hitch can only take 545 lbs in the vertical, yet take 6000 lbs and more when stoping in the horizontal. The vertical and horizontal forces on the hitch sub parts (welds, braces, bolts) are all getting 6000 lbs and more force on them. Tongue weight is more about the tow vehicle suspension load of the trailer pushing down on the hitch, not the hitch strength. The static downward load on the hitch of 545 lbs will be magnified (leaver'd) when in motion going over say a railroad track and the trailer porpoises and oscillates front to back.Give me a lever long enough and a fulcrum on which to place it, and I shall move the world. Archimedes

To better illustrate the relationship:

https://www.curtmfg.com/types-trailer-hitches

Your loads are well within a Class 3 2x2 Hitch. Now SUV limits (handling, stopping, tugging) will be reached first before hitch strength limits. If a class 3 hitch is bolted to a solid body/frame mount with proper fasteners. Just like the shock towers, don't be fooled by the metal thickness, there is strength in "structural form" to.

 

Well, alright!

I'm still using the WD hitch too. 😁

Thanks!

 

A WD applies a moment (torque) about the hitch ball to transfer load onto the front axle of the towing vehicle. This helps steering performance.

The moment is applied by virtue of the spring bars, and is reacted as a vertical force on the trailer at the spring bar-to-trailer mounting point. It is reacted on the tow vehicle body as a moment at the hitch drawbar attachment point to the body, through the fasteners connecting the drawbar to the body.

The additional moment is what in my view M-B objects to when specifying hitch equipment. The additional moment creates forces and stresses in the rear body structure that M-B may or may not have designed for.

Likely not a strength (yield) issue, unless extreme conditions are experienced, such as max GCW, max tongue load and high speed high severity pothole. For example.

More likely a fatigue issue, in theory. This means the fatigue life (hard to define) of the M-B body structure will be lower with a WD hitch than it otherwise would be. Does it meant the body life decreases from 35 years to 32.334 years? Impossible to say, but automotive engineers with fatigue life calculation software and test labs think about these things.

In short, M-B doesn't recommend it, likely on grounds of fatigue life and secondarily on grounds of yield failure in the hypothetical situation noted above.

 

Time to catch up with posts!

Definitely use a weight distribution hitch to redistribute the weight to the front axle and trailer. A good video I'll have to look up measured the weight put on the front and rear axles of a tow vehicle and it's easy to do especially when people mistakenly think airbags raising the rear does that. Sway control and tongue weight reduction make for a better overall towing experience as others have said. I see more pickup trucks more nose high than my GLE350 and steering along with headlight aim is certainly thrown off and there's no added sway or stability control for them.
Square bar, round bar, brand, and so on are debatable, but check sources online like etrailer.com and towing will only improve as a result.
Cost is what moreover stops people from getting one but with today's roads and drivers, any added safety measures is worth the cost of a WD hitch.

 

John, I've got to say that your posts did a lot of good for me. I got set up this week and did a shakedown cruise rgis morning. Amazing!

Of course the GL is a tank but with the brake controller and the WD hitch working well, it drove like a dream.

Thanks again, sir!