Towing with an Audi Q5 3.0L TDI

[waninae39]

read this from ANDy. even a small SUV can pull a 27' AS
https://rvlifemag.com/towing-with-a-...ged-2-0-litre/

[BayouBiker]

It's an interesting article but it seems incomplete. A 27' Airstream is most stable for sway with a 1150-1200 lb tongue weight. But that is well over the Audi guidance designed to avoid oversteer. Reducing tongue weight will induce sway. What justification should lead us to conclude the Audi engineers are wrong and should be ignored? The article doesn't describe how one can be certain these instabilities have been completely addressed for US designed trailers and road conditions.

[jcl]

Originally Posted by BayouBiker

It's an interesting article but it seems incomplete. A 27' Airstream is most stable for sway with a 1150-1200 lb tongue weight. But that is well over the Audi guidance designed to avoid oversteer. Reducing tongue weight will induce sway. What justification should lead us to conclude the Audi engineers are wrong and should be ignored? The article doesn't describe how one can be certain these instabilities have been completely addressed for US designed trailers and road conditions.

The evidence I would look to is that Audi engineers will not have considered weight distribution in their design and initial rating.

I don't see any evidence that the primary consideration of the Audi engineers was oversteer; rather, it seems an unsupported supposition.

Evidence of ability to operate this combination safely would be the several dozen examples of this model that have been set up, tuned, and tested by the author of the article, and his company's demonstrated success in doing this work over the past decades.

Pretty compelling IMO. If it isn't, then one is free to continue towing with a larger heavier truck, and assuming that it is not possible to tow this type of trailer safely with this type of vehicle. But other people who believe that have often changed their mind after visiting CanAm and test driving similar combinations.

[BayouBiker]

Originally Posted by jcl

The evidence I would look to is that Audi engineers will not have considered weight distribution in their design and initial rating.

I don't see any evidence that the primary consideration of the Audi engineers was oversteer; rather, it seems an unsupported supposition.

jcl, I ask these questions repeatedly because I have found previous responses incomplete. Given that any addition of WD tension increases oversteer tendency, if the engineer was ignoring WD and oversteer was not the issue limiting their guidance they would recommend more tongue weight unless there was some other condition limiting tongue weight. the math shows it is not axle weight limit. It is not suspension performance otherwise suspension would require support to exceed limits. It is not a weak hitch, $2 more steel and $5 more on the computerized welder would address that. Engineering practice is to not install a strong auxiliary component if the basic system can't perform, rather it is better for the auxiliary component to be as weak as the primary system. Many good reasons for this engineering principle.

Evidence of ability to operate this combination safely would be the several dozen examples of this model that have been set up, tuned, and tested by the author of the article, and his company's demonstrated success in doing this work over the past decades.

Sure, but the testing and operating parameters presented don't include testing to confirm where dynamic and static instability conditions present themselves. No data was provided to show these instability points occur well beyond the range of expected US road conditions. The SAE handling tests provide an objective but not perfect method to establish if sway or oversteer is likely to exist. The installers don't perform these tests after they have exceeded manufacturers established towing limits.

Pretty compelling IMO. If it isn't, then one is free to continue towing with a larger heavier truck, and assuming that it is not possible to tow this type of trailer safely with this type of vehicle. But other people who believe that have often changed their mind after visiting CanAm and test driving similar combinations.

Opinion is the operative word. I thought you were not a fan of supposition. We can all agree these vehicles tow fantastic within the confines of common road conditions so the phrase "not possible" seems misplaced. Let me suggest risky as a better term because we don't have any direct confirmation that sway and oversteer are well beyond the realm of expected US road conditions when OEM guidance is dismissed. On the other hand we know for a fact the manufacturers test for these conditions and provide guidance with them in mind.

[DewTheDew]

Just an aside; to assume that Audi engineers are somehow oblivious to the US market demands and use of their vehicles is pretty naive. I can assure you they are well aware of the concept of WD hitches and by putting a hitch on the back they have studied the implications of various setups on the safety of their rigs and supplied the documentation that they are comfortable with.

Of course manufacturers put in a factor of safety for everything and there are people who are fine pushing those. Personally I am okay pushing them occasionally but I will not work with a set up that exceeds the published values as a strategy. Same reason I don't put an aftermarket chip in my sports car engine to exceed conditions for which the engineers designed them. Keep in mind that the customers of Can Am and their reports are not a random set; they are people who likely have experience and are inherently interested in making this work and claiming it works.

If they are happy then go for it, but I hope they are not driving next to me!

[waninae39]

if you get up to CANAm, ask Andy to take you for a ride in YOUR TV and one of his AS trailers.

He will show you VERY aggressive lane changes and emergency maneuverers, YOU would have never thought you could do in the TV alone , let with an AS behind .

see here
https://www.canamrv.ca/towing-expertise/videos/

Andy does this to show people how stable the setup is and how much you can push your TV and AS combo.

Most people are VETY conservative, thus don't go push their setup anywhere close to their limits

See if you can find a local dealer that will do the same. I sure that in the USA there are other people like Andy that want you to be safe and want you to understand YOUR setup.

Who knows when you will be in an emergency. But it good to know ahead of time what will happen/not

My 2cents. I get no kickback or compensation form anyone

[BayouBiker]

That's precisely the point, manufacturers test their vehicles to the point of failure so they know with good precision where the safe limit is. They know at what points the setup becomes unstable. Trailer re-sellers and hitch installers do not test to the point of failure. They can tell you what definitely works but they can't tell you what happens if you go even slightly beyond their testing and they can't claim their testing covers the whole range of experiences on US roadways.

What confuses me is how one rationalizes putting much less faith in the manufacturer who does much more extensive tests and has much more to lose if wrong.

[jcl]

Originally Posted by BayouBiker

What confuses me is how one rationalizes putting much less faith in the manufacturer who does much more extensive tests and has much more to lose if wrong.

I trust the manufacturer's tests on the things they test.

It would be crazy to suggest that European automotive engineers are testing their vehicles with WD equipment (which isn't legal there) at the handling limits. Yet you seem to think that they do so, despite no evidence of these tests existing.

It all comes down to understanding that the absence of proof isn't the same as proof of absence.

You look at a capable vehicle with a 3500 lb hitch installed by the manufacturer, and see that as proof that the vehicle can't tow more than 3500 lbs safely. (It may not be able to, with that hitch, given the limitations of the hitch.) I see a vehicle with a 3500 lb hitch receiver, exactly the same as was specified by the product manager, who oversaw the requirement document that was issued to the design team. You see proof of lack of capability. I see lack of proof of capability. Fortunately there are others who can prove out that capability, they just don't work for the product manager who specified that he would pay for a 3500 lb receiver, and nothing more.

[DewTheDew]

Originally Posted by jcl

I trust the manufacturer's tests on the things they test.

It would be crazy to suggest that European automotive engineers are testing their vehicles with WD equipment (which isn't legal there) at the handling limits. Yet you seem to think that they do so, despite no evidence of these tests existing.

It all comes down to understanding that the absence of proof isn't the same as proof of absence.

You look at a capable vehicle with a 3500 lb hitch installed by the manufacturer, and see that as proof that the vehicle can't tow more than 3500 lbs safely. (It may not be able to, with that hitch, given the limitations of the hitch.) I see a vehicle with a 3500 lb hitch receiver, exactly the same as was specified by the product manager, who oversaw the requirement document that was issued to the design team. You see proof of lack of capability. I see lack of proof of capability. Fortunately there are others who can prove out that capability, they just don't work for the product manager who specified that he would pay for a 3500 lb receiver, and nothing more.

Again, why do you think they would ignore testing in the US? Auto manufacturers who sell cars in the US do extensive testing in the US. It is not like the only engineers European manufacturers employ never leave Europe. If they never tested here then they would lack cupholders and their A/C would be horrible.

In fact, some aspects of the vehicles sold here are DIFFERENT than those sold in Europe due to different regulations. You are presuming they sell a vehicle here while ignorant of the US market and that just seems naive. Why would you think that?

[waninae39]

As an engineer for the last 35 years, I have vast experience on how items are designed, testing and labeled by the OEM. I've experienced the Good, Bad and Ugly

Most items have a VERY conservative rating marked on them. Often the marking is market sensitive. This is especially true for consumer items. It is not uncommon for items to be de-rated by 50% before going out with the labels marked up for that market.

Items like bridges are typically, road ways etc are 200%-300% under rated. Ie 100Ton bridge can carry 250 ton before it start to show failure. Tires will take a far greater load than marked for short periods without failing.

Auto Vehicles design is similar. look at the same vehicle in Europe, Canada, USA, Australia, S America and China. Between 80-95% of the items are the same. The biggest difference are usually cosmetic ie mirrors, gauges, infotainment and engine options. The chassis is the same, thus the ability is the same given the engine size and load. Yet each of these zones of the world will mark them differently, when in fact they are the same product. ie
- Audi Q5 USA4000 lb rated, Audi Q5 Canada 5000 lb rated
- BMW 530i is not rated to pull any item, hitch will void warranty. The same BMW in Europe, has a 3500lb rating with hitch option from the factory

In the auto industry, engineers are expected to over engineer and cost reduce.
It is expected, that users will add more people and stuff larger loads into and atop the vehicle than expected. They will drive the vehicle faster and harder that is noted in the manual. They will pull loads that were not tested. At the same time, costs must come down. That is a major reason why the chassis around the world have so many common parts. Most OEM now only build a few chassis type ie small medium large and place all there dozens of vehicles on them

Thus take the rate label load as something that is safe. Will the vehicle digitally fail if you go over; NO! What is the 95% percentile for failure, no one will tell you as the OEM will be stuck in courts if they are wrong. Thus these figures are corporate secrets

Thus what some RV dealers do to reinforce an existing OEM vehicle are likely to improve the ride/load but still be within the capability of the OEM vehicle design. Look at these vehicles after a few years and i doubt that you will see mangle frames or distorted elements. This is no different than you adding an addition to the house and beefing up some joints

These are my views as an engineer

[BayouBiker]

Originally Posted by jcl

I trust the manufacturer's tests on the things they test.

It would be crazy to suggest that European automotive engineers are testing their vehicles with WD equipment (which isn't legal there) at the handling limits. Yet you seem to think that they do so, despite no evidence of these tests existing.

I work for a European global company. We use European standards and practices in Europe and American standards and practices in the US. Engineers are flexible that way and I truly can go back and forth. Still re-read my post. I do not assume they test with WD. Oversteer is exacerbated by WD so I am certain the critical points are greatest with no WD and accept the tongue guidance is for zero WD tension.

It all comes down to understanding that the absence of proof isn't the same as proof of absence.

The null hypothesis is that the manufacturer is correct. It is the role of the contrarian who claims their number is wrong to show how it is wrong.

You look at a capable vehicle with a 3500 lb hitch installed by the manufacturer, and see that as proof that the vehicle can't tow more than 3500 lbs safely. (It may not be able to, with that hitch, given the limitations of the hitch.) I see a vehicle with a 3500 lb hitch receiver, exactly the same as was specified by the product manager, who oversaw the requirement document that was issued to the design team. You see proof of lack of capability. I see lack of proof of capability. Fortunately there are others who can prove out that capability, they just don't work for the product manager who specified that he would pay for a 3500 lb receiver, and nothing more.

Your logical error seems to be in assuming the vehicle is capable. Your second error is in assuming the product manager is a fool and does not understand engineering principles. The third is that the engineering team would accept directives from fools.

How does one objectively prove it is capable? Again the null hypothesis is that it is not capable and it is established by OEM testing to the point of failure. So bring forth those hypothetical "others who can prove out that capability". Let them demonstrate with fair precision where the critical points for oversteer and sway exist and have them show they are outside the boundaries of expected US road conditions.

[jcl]

Originally Posted by DewTheDew

Again, why do you think they would ignore testing in the US? Auto manufacturers who sell cars in the US do extensive testing in the US. It is not like the only engineers European manufacturers employ never leave Europe. If they never tested here then they would lack cupholders and their A/C would be horrible.

In fact, some aspects of the vehicles sold here are DIFFERENT than those sold in Europe due to different regulations. You are presuming they sell a vehicle here while ignorant of the US market and that just seems naive. Why would you think that?

They don’t ignore testing in North America. They also don’t often expand the use cases. Which is why none of my BMWs held a Big Gulp (thank god).

My thinking is based on a long career in engineering, including leading an engineering team for automotive product development and validation (fuel systems supplier) for products used in both Europe and North America.

The reason that Euro SUV manufacturers don’t cater to the US towing market is because the vast majority of their customers don’t care. More specifically, the US marketing arms of those manufacturers don’t care. So there is little or no reason for the design engineers to care.

When Porsche North America wanted to tow an AS 27, they didn’t call their own engineers in Europe. They called North American towing experts, who promptly set them up. Think about that.

[jcl]

Originally Posted by BayouBiker

I work for a European global company. We use European standards and practices in Europe and American standards and practices in the US. Engineers are flexible that way and I truly can go back and forth. Still re-read my post. I do not assume they test with WD. Oversteer is exacerbated by WD so I am certain the critical points are greatest with no WD and accept the tongue guidance is for zero WD tension.

So we agree that they aren’t testing with WD. Great. They don’t appear to have adopted your style of using commonly accepted North American practices, in this case the use of WD for heavier NA trailers.

Originally Posted by BayouBiker

The null hypothesis is that the manufacturer is correct. It is the role of the contrarian who claims their number is wrong to show how it is wrong.

We aren’t up to that yet. They can’t be right or wrong if they haven’t considered the use case. They are simply MIA on this. It is generally accepted that properly used, WD can enable the safe towing of a larger and heavier trailer. You are taking the contrarian position. Burden of proof is on you. Your oversteer concern has not been shown to be relevant. It is just noise at this point.

Originally Posted by BayouBiker

Your logical error seems to be in assuming the vehicle is capable. Your second error is in assuming the product manager is a fool and does not understand engineering principles. The third is that the engineering team would accept directives from fools.

How does one objectively prove it is capable? Again the null hypothesis is that it is not capable and it is established by OEM testing to the point of failure. So bring forth those hypothetical "others who can prove out that capability". Let them demonstrate with fair precision where the critical points for oversteer and sway exist and have them show they are outside the boundaries of expected US road conditions.

I never assumed the vehicle was capable. I just didn’t jump to the conclusion that it wasn’t, as you did. The capability has often been well demonstrated by others, BTW. One way of evaluating the capability of any specific vehicle is to look at the different tow ratings in different markets. It can be enlightening.

The product manager isn’t assumed to be a fool. If he or she doesn’t see a marketing benefit to a higher tow rating, he or she would be negligent in requesting one and wasting his or her employer’s money. It starts with market opportunity, not engineering. That is often frustrating to engineers, who think that it starts and ends with engineering, and their engineering principles.

Capability is validated by testing. But we agreed above that the manufacturer doesn’t test with WD. So we will have to drop your reference to OEM testing, and rely on the testing of those who may not be OEMs.

And given that the acknowledged experts aren’t in the US, could we start referring to North America and not the US?

[BayouBiker]

Originally Posted by jcl

So we agree that they aren’t testing with WD. Great. They don’t appear to have adopted your style of using commonly accepted North American practices, in this case the use of WD for heavier NA trailers.

No, it was another unsupported claim you pretend to detest but commonly use that was the basis for using that hypothetical. But it is not a bad hypothetical since oversteer is least with no WD and will become more significant as more WD tension is added so tongue weight guidance based on oversteer is highest with zero tension.

We aren’t up to that yet. They can’t be right or wrong if they haven’t considered the use case. They are simply MIA on this. It is generally accepted that properly used, WD can enable the safe towing of a larger and heavier trailer. You are taking the contrarian position. Burden of proof is on you. Your oversteer concern has not been shown to be relevant. It is just noise at this point.

It is established that WD increases oversteer. This is the null hypothesis that has been tested and modeled and retested. My only task is to ask if the installer can assure the customer there is no oversteer or sway instability for the overloaded airstream set-up for expected road conditions. The installer must either test the combination or show that instability was not an issue at the OEM limits and by extension using established modeling show they remain a non-issue. Trouble is OEM testing at the limits use a trailer design with much lower inertial moment than Airstreams. This makes the installer's task, on overladed set-ups using Airstreams, much more difficult. We shouldn't be surprised to learn the installers don't perform the tests for stability.

I note with some disappointment, but not much surprise, that my direct questions generally go unanswered.