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Old 07-16-2005, 10:21 AM   #21
Denny_A
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Exclamation Re: Towing Cpacity

Here's further info, upon which I will expand following the quote below.

Link to an Acura blurb on the MDX Chassis for 2005:

http://www.hondanews.com/CatID3028?m...53457&mime=asc


Here's the interesting quote, at the very end of the article:

Quote:
TOWING

The ability to haul pop-up campers, medium-sized boats, and recreational vehicle trailers is high on the priority list for many SUV owners. To understand this aspect of the MDX's makeup, MDX engineers polled focus groups and studied survey results that tapped 200,000 households. Their findings offered the insights needed to properly outfit the MDX to surpass the towing expectations of most customers. Engineers learned that roughly one third of the six-cylinder-powered-SUV owners expect to tow something at one time or another. In addition, 18-percent tow more than four times per year. Approximately 10 percent of the miles accumulated on six-cylinder SUVs are with a trailer in tow.

Another notable discovery was that many customers aren't particularly knowledgeable about towing technicalities. Terms like "gross axle weight" may be germane to the engineering process but such language can leave average customers in a state of bewilderment. This realization convinced engineers that customers' interests are best served by load ratings that are both realistic and easy to comprehend. Ultimately, the engineers concluded that a casual or weekend towing capability was most appropriate for MDX. Customer feedback helped set the towing limit at 4500 pounds for boats and 3500 pounds for other types of trailers. A heavier load is acceptable with boats because their pointed bow shapes impose less aerodynamic drag on the towing vehicle than a slab-faced, square-cornered trailer.

Industry practice is to boast a high maximum tow rating, even though some sacrifice of passengers and cargo may be necessary to suitably accommodate such a trailer load - in some cases limiting the vehicle to one passenger to accommodate the maximum specified towing capacity. The Acura MDX's 3500/4500-pound rating is calculated to include up to four passengers and their cargo.

To help ensure that customers will be able to move a maximum-rated load up a grade from rest (such as pulling a loaded boat trailer up a launch ramp), engineers sought out the most challenging entry roads and launch ramps in the country. Through testing, they verified that MDX proficiently handles the 17-degree (31-percent) grades on mountain roads approaching Lake Cumberland in southern Kentucky and the strenuous combination of 15-degree (27-percent) grades and 5280-foot elevation at Lake Tahoe. At sea level, MDX can move a 4500-pound boat and four passengers up an 18-degree (32-percent) slope. A note in the MDX owner's manual suggests reducing gross combined weight two-percent for every 1000 feet of elevation.

In support of safe towing, MDX's tow hitch and other hardware needed for the job are factory engineered for dealer installation. The dealer-installed trailer hitch is a Class III receiver-type design that bolts on with no drilling, cutting, or bumper-cover modifications. An external transmission cooler and a separate power-steering fluid cooler is also included along with a harness to provide electrical power to trailer lights plugs into a connector provided at the rear of the vehicle.
The exact same logic is used for the Honda Pilot, the MDX being the luxury version of a Pilot methinks. I went through this logic when considering a Pilot as a tow vehicle. Not having seen nor heard the magic words "slab-faced, square-cornered trailer", I rejected the Pilot.

Obviously, the TM's are NOT the trailers the MDX engineers had in mind. It is also clear they intended to "dumb down" the towing limits so as not to confuse the normal, less inquisitive owners. Going out on a sturdy limb here, I think a 4090 lb MGW 2720 will be no problem if employing a proper receiver, such as the one in my earlier post, and a suitable WDH.

Caveat Emptor

Denny_A
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Old 07-16-2005, 12:41 PM   #22
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Wow, this is the smoking gun I was looking for. Seems as though our MDX will certainly be adequate for our needs!

To all -- many, many THANKS for all the assistance in this forum! My wife and I are now fully confident about going forward with the purchase of our 2720SL next week, and we hope to be on the road with it by the end of the month!

Since the dealer is based at a Camping World store/service center, I'm going to go ahead and schedule an appointment to have the WDH and brake controller installed before we drive off the lot with the new TM.

Meantime, we'll continue to peruse these forums and learn more. I can't imagine having made the purchase of a TM without tapping the fountain of knowlege of those present here.

See you on the road!

- Mark
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Old 07-16-2005, 04:07 PM   #23
Denny_A
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Default One last iteration........

....regarding aerodynamic drag. Did a little normalized analysis on drag equivalents; re "slab, standard travel trailers" vs. a TM under tow.

Drag = Cd*q*A, where Cd = drag coeff, q = dynamic pressure and A = frontal parasite area.

Since Cd and q are fixed, when comparing any two objects, one needs only look at the ratio of drag to area. So, if D(TM) (Trailmanor) is compared to D(FT) (full size trailer), then the percent difference in drag is the ratio of frontal areas.

Long story, short result: Found frontal area of an 8.5'x7.6' (FT) and 5.9x7.6' (TM). Subtracted 1 foot of ground clearance from the height of each to account for limited drag there. Finally determined the frontal area of the MDX (approx., from specs) and reduced 20% to account for MDX sloping sides.

Subtracted the MDX area from each trailer. Finally divided A(FT) by A(TM).

RESULT: Drag of the full-size, slab front trailer was 3.5 times that of the TrailManor!

Allowing for approximations and other unknown factors, the drag of a full height trailer of identical width is at least 3 times greater than that of a TrailManor. I would even bet the TM's drag will be less than that experienced when towing a 4500 lb boat and trailer combo.

Happy TrailManoring

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Old 07-16-2005, 04:23 PM   #24
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Yep: Denny put both the icing and the ice cream on the cake with the Acura web site find.

I was hoping RMRay would sign back in to answer your question about the proper spring bars to get with your WDH. He has a 2720SL and is our resident expert on WDH's as well as many other subjects. I think he is using 750lb bars but hopefully someone will correct me if I'm wrong. Others are using up to 1,000lb bars on truck-based SUV's and pickups but you'll probably want to stay below that with the MDX. We recently moved from a 400lb Draw-Tite to a 600lb Equal-I-Zer for our (350-400lb tongue weight) TM2619 but the 400 D-T was adeqate for the light loads we carried when towing with the Odyssey.

My wife's eyes lit up when I told her she can now take more stuff along so I may live to regret revealing the WDH change.
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Old 07-16-2005, 07:56 PM   #25
Denny_A
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Quote:
Originally Posted by fcatwo
Yep: Denny put both the icing and the ice cream on the cake with the Acura web site find.

I was hoping RMRay would sign back in to answer your question about the proper spring bars to get with your WDH. He has a 2720SL and is our resident expert on WDH's as well as many other subjects. I think he is using 750lb bars but hopefully someone will correct me if I'm wrong. .....snip.....
I used 750 lb bars on my 2720SL. worked just fine!!!


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Old 07-16-2005, 09:20 PM   #26
RockyMtnRay
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Default 750

I'm using 750 lb bars with 5 links dropped. I also travel "heavy"...I have two extra wooden cabinets in the trailer and carry both a microwave and the TM overhead cabinet in the front of the trailer while underway. I suspect my tongue weight is around 600 lbs or more.
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I use my TM as a base camp for hiking, kayaking, mountain biking, and climbing Colorado's 14ers


The Trailer: 2002 TM Model 2720SL ( Mods: Solar Panels (170 Watts), Dual T-105 Batteries, Electric Tongue Jack, Side AC, Programmable Thermostat, Doran TP Monitor System)

The Tow Vehicle: 2003 Toyota Tundra V8 SR5 4X4 w/Tow Package (Towing & Performance Mods: JBA Headers, Gibson Muffler, 4.30 gears, Michelin LTX M/S Tires, Prodigy Brake Controller, Transmission Temperature Gauge)


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Old 07-17-2005, 08:16 AM   #27
Bill
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I am under the impression that the rating of the spring bars is related to how much upward force the bar is CAPABLE of producing. There is nothing to say that you must actually use all of the available force. In other words, you pick up only the number of chain links needed to set the weight distribution properly. And you don't pick up any more, even though the bars are capable of it.

The process for determining the needed number of links is described in the Reference Library - TM Info You Won't Find Anywhere Else.

Of course, if you have 300 pound spring bars and need to pick up 400 pounds, you are out of luck. Underspec'ed bars won't work, so you should choose bars that are a little stronger than you think you need, rather than a little weaker.

Having said all that, I should point out that there is one potential problem with grossly overspec'ed bars like mine. Occasionally you will need to cross a wide swale or drainage ditch by driving down into it and up the other side. When you do so, there will come a moment when the tow vehicle has passed the lowest point and is angled up the other side - but the trailer is still on the downslope. At this moment, there is a substantial angle between the axis of the tow vehicle and the axis of the trailer. In this situation, the spring bars should "spring" - that is, bend upward to maintain something like the original tension on the chains. With overly-hefty bars bars like mine, the spring is too stiff - the bars won't bend, and so the tension increases. With a sturdy box-beam frame such as my Explorer has, this is no problem. However, on vehicles with a less-strong frame, I suppose this might result in the frame-bending problem mentioned above.

The best answer is choose spring bars that are matched to the tongue weight, with a little reserve. I suspect that Ray's choice of 750 pound bars is just about ideal. As he has laid out in previous posts, 500-pound bars are just a bit too light for most loaded TMs.

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Old 07-22-2005, 07:49 PM   #28
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Follow-up:

We pulled the trigger and took delivery of our new '06 2720SL last Thursday! I had to special order a Reese round-bar WDH (750 lb bars), because the Camping World didn't have that hitch in stock ... but we DID get the Prodigy brake controller installed and towed it home.

The MDX performed terrific on the maiden voyage. There was a little bit of "dip" at the tongue/hitch connection, which I hope will be corrected when the WDH gets installed in a week or so. The RPMs never got about 3000, even when gunning the gas to accelerate onto the interstate. Most of the time, the needle was between 1900-2200 RPM. However, it DID seem to shift between 4th and 5th gear quite a bit; since I don't have the "overdrive off" button that a lot of big SUVs have, should I drive with it in D4, instead of D5????

The Prodigy controller made it seem as though the TM wasn't even there. Braking distances weren't any longer than what I was used to before hitching up the TM, and it rode quite smoothly.

Once the WDH comes in, we're getting it installed, adjusted, and then we're off to do some camping! THANKS again for all the insight!

- Mark
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Old 07-22-2005, 10:48 PM   #29
Denny_A
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Quote:
Originally Posted by radiojon
Follow-up:

We pulled the trigger and took delivery of our new '06 2720SL last Thursday! ......snip............

The MDX performed terrific on the maiden voyage. ...snip.... The RPMs never got about 3000, even when gunning the gas to accelerate onto the interstate. Most of the time, the needle was between 1900-2200 RPM. However, it DID seem to shift between 4th and 5th gear quite a bit; since I don't have the "overdrive off" button that a lot of big SUVs have, should I drive with it in D4, instead of D5???? ..........snip.......

- Mark
Mark,

Re hunting between 4th & 5th gears. I'll just direct you to the following thread, which has some useful insights:

http://www.trailmanorowners.com/foru...sion+overdrive

When I had a Honda Odyssey (3500 lb tow limit) I shifted from 5th to 4th whenever the conditions wer right for a downshift - i.e., I would try to catch it before the transmission started hunting (unlocking, thereby raising the xmssion fluid temp).

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Old 07-25-2005, 05:51 PM   #30
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Default Problem with WDH -- please help!

Okay, so I take the brand-new 2720SL back to Camping World today to have the Reese 750-lb. WDH installed that I had special-ordered from them last week. I came back an hour after dropping it off, and the guys there say the WDH can't be installed on a TrailManor because of my swing-around tongue. They called over to the TM dealer (on the same grounds), who didn't know of anyone who had a WDH on their TM and couldn't recommend a type of WDH to install. Camping World's only suggestion was to install air shocks on the MDX, which I really DON'T want to do.

I'm led to believe that both the TM dealer and the Camping World folks aren't nearly as knowledgeable about their own products as those on these boards, so I'm back to referring to help here.

Dejected, I drove it back home without a WDH and here I sit. I *MUST* have a WDH installed -- my TV (the MDX) really does dip down at the tongue without one, especially since my wife has spent the past 3 days filling it with the "camping essentials" (as she puts it) and added some weight to it.

Now what? I really wanted to take this thing out camping, instead of continuing to look at it in the driveway.

Any suggestions? Should I find a different place to install a WDH? I *CAN* install a WDH on a 2720 SL with swing-around tongue, correct???

- Mark
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