Great info. THANKS
With my 2020 GLS580 I have been using WDH without any hitch. Made a trip from Los Angeles to Albuquerque last month, drove through a severe snow storm with out any issue.
Used the same hitch with 2012 GL 350 for over 40,000 miles.

 

I fail to see the need. As long as the maximum tongue weight (617 lbs) is not exceeded the GLS will self level making it unnecessary. Distribution hitches are for vehicles that don't have self leveling systems. If your tongue weight is higher than the allowed you can't use the GLS.

 

Self levelling has nothing to do with the need for a WDH! A weight distributing hitch moves some of the weight to the front axle so that the loads are properly balanced across the front and rear axles and the trailer. You don't want to put all the weight on the rear of the tow vehicle with heavier loads and also ensure the axle load limits of the tow vehicle are not exceeded. WDH ensures the load is balanced by transferring the weight. Airmatic only levels whatever load it has and does not transfer weight specifically to front or rear axles as needed. To answer your question Mercedes will not give you much help with towing expertise, no German manufacturer will. Europe doesn't allow WDH (for historical political reasons) and Mercedes has a completely different hitch for that region. In North America where WDH is permitted, a hitch that will accept WDH is is used. To get an expert opinion for your question contact Andy Thompson andy@canamrv.ca. Andy has 50 years experience and will give free advice. He has set up hundreds of Mercedes with trailer stabilization and Airmatic and does extensive testing on stabilization and sway with Mercedes and other vehicles.

 

It is all about maintaining the nose down (thus keeping the towing vehicle level) something that the air suspension on the GLS already does ( up to 617lbs) You can also adjust tongue weight by adjusting the cargo distribution in the trailer by placing cargo behind the trailers axle. All a WDH is a trailer height adjuster and a lever to transfer some the weight from the hitch to the frame of the trailer. Contrary to the usual pickup truck with no self leveling, SUVs like the GLS can mitigate the dropping rear end all by themselves, by simply increasing the rear end height and thus counteracting the effects of the additional weight . The reason no one will greenlight a WDH with a self leveling system is that in vehicles with systems like it the antisway system is tied to the self leveling one. Manufacturers don't test how WDH interact with the programming or calibration of their systems thus they will not vouch for their use. They simply give you the designed weight limitations of the vehicle and the rest is up to you. Again the classic WDH is designed for non self leveling vehicles. You can always try one but the consequences (good or bad) are your responsibility!

 

I towed my trailer with Lexus GX470 with self leveling, I had to turned off the self leveling feature because the pump kept running try to level the vehicle.
I don't know much about Mercedes Airmatic system. I am having problem understanding how can self leveling system transfer the weight from rear axel to front, it can certainly level the vehicle.
Even though your vehicle may be level but the rear axel will still carry the hitch weight
I may be wrong, being a chemical engineer this topic is more related to mechanical engineering.
Please continue the dialog I am very much interested being an owner of GLS580 pulling my 23' Airstream.
Cheers

 

A WDH is not a trailer height adjuster. Increasing the rear height with Airmatic levelling does not counteract the extra weight from trailer tongue weight - it just levels. Show us how the anti-sway is linked to the self levelling feature. The antisway uses a brake actuator method on individual wheels to control sway - I have not ever seen a reference to the claim the systems are linked.

 

I'm sorry but I don't agree with your concept of a Weight Distributing Hitch (WDH) at all.
A self-leveling suspension does what it says - levels the vehicle, but does nothing to restore steering control after a load is put on the hitch, which decreases traction of the front axle by levering weight off the front axle.
A WDH's function is to Distribute Weight, restoring traction by restoring weight to the front axle (and some back to the trailer axles.) A WDH has an added benefit of leveling the tow vehicle. They are designed for vehicles with or without self-leveling capabilities.

Relying on a self-leveling system to distribute weight is a misinterpretation of the design and design intent, and is not a safe assumption. Again, it just levels, but does not restore weight to the steering (and primary braking) axle.

I do agree that loading to achieve a reasonable tongue weight is important, but don't shift too much weight rearward, because you need 10 - 15% of the total trailer weight on the hitch to resist sway. I am at 12% on my 6,000# Lance 27 footer. I'm heavier than the hitch rating by 80# but within the rated load capacity, as posted on the Drivers' Door Post.

 

Think of a teetertotter. if you push one side down the other comes up aka weight transfer. If you jack up the side you pushed down despite keeping the same weight on it the other side comes down. Comprende? The bags compensate the additional weight on the body and transfer it to the rear axle. Presto the car is even again! Physics 101.

 

Your teeter totter is a great example, but you are looking at the situation from the wrong perspective.
The perspective to use is the amount of weight that is removed when you drop a load on the hitch ball. Think of it as a teeter totter but move the fulcrum so it approximates the location of a rear axle. If you place a load on the end, it exerts an upward force on the other end. Now pretend that it's a tow vehicle - you have just removed weight, and traction, from the front (steering, braking) axle. You have less control.
Now take your teeter totter and raise it up so the hitch end is at the original height - like a self-leveling suspension. You have not restored any weight to the front axle and you have still compromised your handling.

Watch this video to help understand. There are many similar videos and tutorials online, comparing self-leveling suspensions to WDH, and the conclusion is, as you say, physics (equal and opposite forces). The WDH is needed because the leveling suspension (or air bags in the video) don't restore control as well as a WDH. In other (longer) videos the numbers may indicate that a leveling suspension may make the reduction in front end loading worse if used alone. Check them out!

Again, the critical concept is that "being level" does not restore the reduction in steering control at all, but a WDH does.

 

I was looking at my hitch from the underside and noticed that there are specs. for Wt. Distrib. hitch. Mine is a Canadian model which is the same hitch as the US model but we may have a different label on Canadian ones. It specifies a lower WD rating at 7500lbs. Mercedes would appear to have much more information on these "North American" hitches that is not shared correctly with the employees answering questions. I think much of the confusion is that there are 2 totally different hitches available globally and answers are given for the wrong hitch sometimes. My owners manual (Canada/US version) goes into great detail on towing hitch use and features pages 271 -278 all reference the wrong hitch and nothing at all written about the North American hitch provided. Interesting they do not say anything about trailer back up assist which is not on the North American models. Do others have trailer hitch info. in their manual for the North American hitch? No wonder MB employees and customers are confused!

Wt. Distrib. spec. for Mercedes GLS

 

I tried scanning the QR code but my camera can't get at it . Anyone tried it and see what you get? Also doesn't the "i" mean there is info. in the manual?

 

Thats the exact information from the manual. It does not address weight distribution hitches!
If you go to any weight distribution hitch manufacturer they all say the same thing.....Their products are not for vehicles with self leveling systems unless the vehicle manufactures say so! Which of course almost none does.
Furthermore, you are correct, european WDH are entirely different animals than NA ones.

 

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C4004 - Do you own an X167 GLS?

 

A 580. Not much towing besides a 16 foot boat and the occasional U haul.

 

Does your hitch have the same label as mine showing weight distribution - max trailer weight 7500 lbs, and weight carrying - max trailer weight 7715 lbs.? Also can you get the QR code to work and if yes what does it reference? I can't get a good angle with my phone to get the QR code to register.

 

Here's my AMG GLE53 US hitch label. I tried a new QR reader and it just shows "ACPS 10066744 / A1673102500" instead of a link. Try your QR reader on my photo.

Notice that the 600# tongue weight is exactly 8% of the allowable trailer weight, which has been the convention for years, with Euro tow vehicles. Euro trailers are designed to be pulled by sedans, and the axles are in the middle to provide low tongue weights. This is based on history from Andy Thompson at Can-Am over the years, and the WDH politics directed against US products.

For a few years, Porsche and Range Rover went to 10% on their hitch ratings (and my '14 ML350 diesel) but it looks like the 8% is back. Maybe the Euro trailer and WDH politics are ramping up again?

Anyway, because of all this confusion, including the lack of GCVWR (combined GVW with trailer) rating, I just go by payload second, and gross axle ratings (GAWR) first. I can load to 12% of my Lance 6,000# gross weight with lots of axle margin, and this has been great for the ML's. Hope to find the same in the 53.

 

The alleged "WDH politics directed against US products" narrated by Can Am might just be an old wives tale. Chatted with a guy from England that used weight distribution hitch on his trailer that had electric brake -- Had never heard of this "law". You can also buy a weight distribution hitch on Amazon in many European countries.

IMO, the hitch on Mercedes is overbuilt and capable of handling 10% of weight of a 7500# trailer. Again, IMO, the 8% limit is due to rear suspension. Independent suspension is designed with ride comfort in mind and carrying a heavy tongue weight may result in wear and tear. The shock absorbers on GLS can be replaced at around $1500 a piece. So, wear and tear could be pretty costly.

 

Thank you for the pic. I see yours is bilingual French and English too. I thought you would have different label because only Canada requires these. I do not recall my 2014 ML Bluetec hitch label but towed it fully loaded 7000 lbs for many miles without any trouble or excessive wear except tires which was another story. I see the label has a 7.5 inch requirement for the ball to the pin hole that has never been discussed before that I know of. Exceeding that length could reduce the weight carrying capacity of the hitch. None of these things are in the owners manual.

Towing trailers in Europe is very different with lower average weights and sizes. Andy from Canam has told me the background on WDH in Europe and it goes back to the "early days of towing" but there may be changes since then. Enforcement of legal tow hitches and trailer brakes is likely as rare in Europe as it is in North America so any individual can add or change equipment and not be challenged. I am a Canam customer and have known them for many years and trust their 50 plus years of towing experience. I chose 3 different Mercedes to buy for towing with input from Andy at Canam.

 

AFAIK Electric Brakes are legal since 2012 in the UK. You can buy anything on Amazon - that does not mean the country it is used in doesn't allow it to be sold if it is not permitted to be used in that country.

 

Yes, things have changed in Europe since the "early days," which probably means around 2012-15. That's when a couple of Euro companies entered into the WDH fray with actual WDH's, and the ban on WDH's was lifted/ignored. But the earlier mid-single-axle configurations with minimal tongue weight was real, as was (is) E.U. protectionism.
If you watch the past few years' Tour de France, you finally see "caravans" with dual axles, large enough for more than a weekend's jaunt, parked along the Tour. Even pickups pulling them! But if you watch episodes of Top Gear (British car show) you'll see the lightweight construction as you see them destroying the cheap Caravans of the times.

I agree that M-B hitches are capable of handling 10% of trailer weight, or 12% for that matter. I haven't decided if I need to do a Can-Am hitch reinforcement - I'll measure the hitch deflection when I get the WDH set up. In the past, pickups except the 2014+ Rams had more deflection than a M-B (another Can-Am RV video and print article on Hitch Hints). I verified with a friend's F150 compared with our former ML diesel.
I don't think independent suspensions are limited in capacity by being "independent" - look at the GAWR - it's right up there with the body on frame, solid axle SUV's. That's why I pay less attention to the 8% than any other metric. The extreme example would be a railroad car - independent suspension with coil springs!

 

Exactly the same. Im in the US.

 

Following on from this discussion, what are people’s insights into tow bar down force.
I see the factory fitted (both 50mm hitch version and the electric foldable versions), both state 280kg downforce. But it seems if they are locally fitted (I.e, even the same bar, but not factory fitted), then this seems to drop to 140kg downforce.

is this correct ? Is it to do with “increased towing capacity 557” being present ?

In the process of specing a new GLS and downforce is really important to me and I want to get this correct. If this means ordering the factory fitted version to get the 280kg, then so be it.

Really keen to hear what people know about this please.

 

Are you able to order from the factory either hitch? I don't think you can do better than the ones installed at the factory. Your profile does not indicate the country you are from so it is hard to say without knowing if you can use a weight distributing hitch WDH. We use WDH with the 2 inch (50MM) receiver in North America to help distribute some of the tongue weight to the trailer and tow vehicle and get a take higher limit than 280kg.

 

Fair question, we are in New Zealand and have the option to factory install the electric fold down style (all in one, none removable European style). If we do, it comes with “Increased Towing Capacity 557”. This has the 280kg downforce rating.

I can get the MB 50mm hitch style installed by the local dealer (installation is all approved by MB as well). However I am told if this is locally installed, the downforce rating reduces to 140kg. However no one can tell me why this is reduced, I wonder if the extra 557 is the key here ?? In NZ, I cannot order 557 by itself, and I cannot factory order the 50mm hitch style.

In Australia, I notice they can factory order the 50mm hitch, and it comes with 557 and has the 280kg downforce. Which adds to why I wonder if 557 is the key here. Does anyone know what 557 actually does ?

Even though the electric version is really tidy (and actually slightly cheaper), I like the flexibility that the 50mm hitch style offers. But I don’t like the 140kg downforce. I would rather have the higher capacity and accept the fixed bar style, than go with the lower downforce.