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Old 01-28-2016, 11:39 AM   #57
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I wanted to clear up a few things. I work for Audi and tow a 25FB with a 2015 Q7 TDI. The 2017 Q7, which is a complete redesign top to bottom, has a label on the hitch listing 770 lbs weight carrying and 770 lbs weight distributing with a max trailer weight of 7700 lbs. I studied the hitch reinforcement issue closely but decided that route was not necessary for my 2015. After towing the 25FB all summer I removed the bumper cover on the 2015 and I and our Shop Foreman inspected every inch of the hitch. We even removed the hitch and inspected the bolts and mounting points. No evidence of stress or cracks was found. After talking with an Audi Engineer I believe that they purposely underrated the hitch on the 2015 (662 lbs/6600 lbs) and earlier models. Interestingly both hitches have the same part number!
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Old 01-28-2016, 12:13 PM   #58
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Great to hear. I question the need to "reinforce" the factory hitches if the TT is well within the hitch specs.

The Treg hitch specs have also gone up close to those of the 2017 Q7.
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Old 01-28-2016, 12:27 PM   #59
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Thanks for this clarification.

I am not an engineering, so can be ignorant in this topic. The fact that OE Mercedes hitch kit includes those 2 support arms does not mean for me that other German SUV have less stout hitch setup. Those support arms can be part of the chassis, can't they? In fact, I recall that BMW X5 E53 (2 generations back) had some kind of inserts as part of the hitch kit (similar concept to GL I guess, but the inserts were shorter). E70 (the next generations) does not have the inserts and I believe that they increased the towing capacity for E70 vs. E53. My guess is that there is some kind of reinforcement built in the chassis.

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Originally Posted by rostam View Post
The 2 support arms are part of the OEM hitch kit. Note that buying/installing a hitch and the associated electronics could cost around $2k (if you are retrofitting it). The factory tow package option is a steal at $550.
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Old 01-28-2016, 12:37 PM   #60
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We tow our 2015 23D International Serenity with our existing 2007 Mercedes ML320 CDI diesel using a Hensley Arrow hitch. The car went to CanAm in October 2012 to have the factory receiver reinforced (it had been rewelded earlier in a recall). See photo in "Images" under my avatar. They also modified the Hendley stinger by taking about 5" off the car side and a slight downward bend to preload the weight distribution arms.
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Old 01-28-2016, 01:16 PM   #61
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Audi Q7, Treg, Cayenne and Audi Q5 also use an OEM trailer hitch set up that utilizes rails inserted into the structural parts of the vehicle. In the case of the VW Audi Porch products, the support are not as long as the Merc but they are welded onto the trailer hitch and not bolted.



I had the factory hitch reinforced to eliminate flex that may occur due to the drop of the hitch receiver and increase my piece of mind when towing. My hitch reinforcement was done by Can-Am in London Ontario.
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Old 01-28-2016, 01:34 PM   #62
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Quote:
Originally Posted by bono View Post
Thanks for this clarification.

I am not an engineering, so can be ignorant in this topic. The fact that OE Mercedes hitch kit includes those 2 support arms does not mean for me that other German SUV have less stout hitch setup. Those support arms can be part of the chassis, can't they? In fact, I recall that BMW X5 E53 (2 generations back) had some kind of inserts as part of the hitch kit (similar concept to GL I guess, but the inserts were shorter). E70 (the next generations) does not have the inserts and I believe that they increased the towing capacity for E70 vs. E53. My guess is that there is some kind of reinforcement built in the chassis.
I am definitely not saying that Touareg's hitch connection to unibody is NOT stout -- I'm saying the Mercedes hitch unibody connection is more stout due to 2 large support arms. I'm not an engineer either, but that's just simple physics.

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Originally Posted by KSA63 View Post
Audi Q7, Treg, Cayenne and Audi Q5 also use an OEM trailer hitch set up that utilizes rails inserted into the structural parts of the vehicle. In the case of the VW Audi Porch products, the support are not as long as the Merc but they are welded onto the trailer hitch and not bolted.



I had the factory hitch reinforced to eliminate flex that may occur due to the drop of the hitch receiver and increase my piece of mind when towing. My hitch reinforcement was done by Can-Am in London Ontario.
I believe that's a Q5 hitch (not a Q7). Current Touareg/Q7/Cayenne's hitch does not have the bars. Hitch is only connected to unibody via 8 bolts.
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Old 01-28-2016, 01:44 PM   #63
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Great T/C/Q hitch & towing info guys!

And the last pic of the Audi hitch explains why there are 2 bumper bars in the Porsche parts catalogs - 1 for without hitch & another with hitch!

So apparently if retrofitting the Cayenne's hitch tow option, we should be buying both the bumper bar & hitch parts for the correct installation!

cactus - FYI - Andy T. had said on my other topic thread asking about issues with Cayenne S's for towing, that he didn't feel that I'd need to reinforce for our 1960 Avion T20, since it's only about 3-3500 lbs. wet & loaded - & even if it went to 4-4500-ish (vintage AS & kin are much lighter than todays' TTs).

So I think it depends upon how heavy the TT is.

Also, as noted above, a large drop or rise from the receiver may also impart more of an angular load on the hitch, so that too may be a foctor in deciding to reinforce.

PS - I think that MBZ G-range hitch reciever set-up is well thought out, but I'm not sure if the smaller mid-sized M-line (& whatever they've renamed it to now) is the same or similar design. The one shown would help transfer the WD torque load forward in the unibody very well though.

The mod with the drag strut type extension which CanAm does operates under the same concept of getting the forces moved up forward at the rear axle area, from what I've seen.

PSS - To clarify, my earlier comment about the Euro hitches being the same was in reference to their hitch OEM suppliers being that group noted above - not that they were all necessarily the same design. That said, I'd talked to an early M-320 owner who said his hitch was almost the same design as in the Touareg & Cayenne, but I don't know how similar nor if it changed to the type posted above for the G-series.

Cheers!
Tom
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Old 01-28-2016, 01:47 PM   #64
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I am not trying to negate what you are saying. I am just wondering whether other German SUVs have some kind of support arms built into chassis. If not, I agree that GL hitch looks very stout. I am even more happier about this as most likely GL will be my next TV. Just waiting for BMW X7 to be launched in two years. If I do not like it, GL will replace X5.
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Old 01-28-2016, 01:49 PM   #65
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Any idea whether the 2017 Touareg will be longer like the Q7?
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Old 01-28-2016, 03:27 PM   #66
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As long as we're guessing about stoutness of w.d. hitch mounting, and why Mercedes GL has no advisory not to use a w.d. hitch and VW does, I'll guess VW Touareg does not need the extra length of the retrofit OEM hitch. And Touareg's w.d. hitch advisory is because they are built in Europe where w.d. hitches are illegal, GL is built in America where they are legal.

My other concern though, would be twisting of the crossbar on any vehicle hitch from the vertical lift of a w.d. hitch combined with dynamic loads. This twisting as well as the side attachment has been addressed with a reinforcing steel bar welded to the receiver and forward under the vehicle. Probably good insurance against both issues.
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Old 01-28-2016, 04:12 PM   #67
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Quote:
I believe that's a Q5 hitch (not a Q7). Current Touareg/Q7/Cayenne's hitch does not have the bars. Hitch is only connected to unibody via 8 bolts.
You are correct, when I researched the purchase of my Q5 OEM hitch I guess I convinced myself that the hitches were the same across the VW SUV fleet, I was wrong. That said, the Touareg hitch looks pretty darn solid.

Also, I DO understand that you are not saying that it isn't.

Cheers,
Kevin
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Old 01-28-2016, 04:13 PM   #68
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Originally Posted by dkottum View Post
As long as we're guessing about stoutness of w.d. hitch mounting, and why Mercedes GL has no advisory not to use a w.d. hitch and VW does, I'll guess VW Touareg does not need the extra length of the retrofit OEM hitch. And Touareg's w.d. hitch advisory is because they are built in Europe where w.d. hitches are illegal, GL is built in America where they are legal.

My other concern though, would be twisting of the crossbar on any vehicle hitch from the vertical lift of a w.d. hitch combined with dynamic loads. This twisting as well as the side attachment has been addressed with a reinforcing steel bar welded to the receiver and forward under the vehicle. Probably good insurance against both issues.
I don't think the country of origin has anything to do with WDH being allowed or not. BMW X5 is built in America, and it advises against using WDHs.

There was a thread a while back, where the issues with the hitch reinforcement was discussed in detail. The gist of it was that welding a bar between the hitch (which is attached to the unibody, and cannot move) and the axle carrier (which is not attached to the unibody, and can move freely) does not make any sense.
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Old 01-28-2016, 04:26 PM   #69
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Quote:
Originally Posted by bono View Post
Thanks for this clarification.

I am not an engineering, so can be ignorant in this topic. The fact that OE Mercedes hitch kit includes those 2 support arms does not mean for me that other German SUV have less stout hitch setup. Those support arms can be part of the chassis, can't they? In fact, I recall that BMW X5 E53 (2 generations back) had some kind of inserts as part of the hitch kit (similar concept to GL I guess, but the inserts were shorter). E70 (the next generations) does not have the inserts and I believe that they increased the towing capacity for E70 vs. E53. My guess is that there is some kind of reinforcement built in the chassis.
The E53 platform (2000-2006) included similar inserts installed into formed rails in the rear of the unibody, and they were bolted in more than one plane. The E70 (2000 onwards) does not have similar inserts, but the unibody is different as well. They didn't increase the towing capacity to my knowledge. I don't think we can conclude that the E70 OE hitch is as strong as the E53 is, we simply don't know. Perhaps they simply reduced the safety factor, given that they don't allow additional tongue weight with WD in any case. Certainly the E53 was overbuilt, but nicely so.

Jeff
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Old 01-28-2016, 04:36 PM   #70
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I might be wrong, but I thought the E53 was rated to 6,000 LBS (and 5,300 LBS with smaller engines) where E70 is rated to 7,700 LBS (except for the US where they say 6,000 LBS).
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