Towing a Travel Trailer Camper with the ZF 9-Speed Transmission

Wisconsin_Mike · Oct 14, 2024

Most of this information I've already posted, but it's scattered across multiple threads. So please excuse the long post, but I'm just putting my towing experiences together more concisely which will hopefully be easier for anyone else to find in the future.

I'm towing a 2022 Lance 1475. This one:

I installed an Andersen weight distribution hitch, detailed here.

I also detail in that post how I ran my rig across a CAT scale to get my weights. Loaded with the basic camping essentials, my travel trailer weighs 3860 pounds.

After this weigh-in, I added my full-size spare tire using a home-brew spare tire hitch mount. More info on that hitch mount here.

The fabricated mount weighs 30.0 pounds and the mounted spare tire weighs 64.0 pounds for a combined additional 94 pounds added to the rear of the camper. Because of this added rear weight, I was able to pack more into the front storage area without overloading my tongue weight. This includes my Champion dual fuel inverter generator, extra propane tank, and more. I'm sure that adding all this weight brings my total load up into the 4100 - 4200 pound range.

So I have a ZF 9-speed equipped Ridgeline towing a 7' wide travel trailer that weighs about 4200 pounds. Off the top of my head, I'm not exactly sure how tall the trailer box is, but I know that at the topmost protrusions, it's 10' 3" tall. This represents a significant aerodynamic drag as highway speeds increase.

While towing, I by far mostly set the cruise at 65 MPH and set the transmission in Sequential mode, locked into 5th gear using the paddle shifters. If I see a long flat or downhill section, I may shift to 6th. Low hills are no problem for 5th gear. Moderate hills may cause my speed to fall off a little, which I'm fine allowing to avoid shifting and generating more transmission wear and heat. But if the hill is somewhat steep and/or long, then I'll have to downshift into 4th which the Ridgeline has no problem generating enough power in to maintain speed. At 65 MPH in 5th gear the engine runs at almost exactly 3200 RPM.

Mostly out of curiosity, I developed a spreadsheet to figure out engine RPM vs road speed. This RPM-to-Speed and Speed-to-RPM calculator worksheet isn't super-pretty, but it works; and each calculation step is visible so it should be easy for anyone to re-create. Changing the items in yellow including tire size updates the results in green.

I also purchased a ScanGauge III specifically so that I could monitor my transmission temperature. At $270 as of this writing, a ScanGauge III isn't exactly cheap but it works very well. It auto-detects your vehicle and then presents you with a list of known data that it can read. You simply choose from the list what you want to monitor.

The ScanGauge II is the previous generation unit, but can also display otherwise hidden information. At $140 as of this writing, it's certainly a big step less expensive. It requires you to manually enter the correct codes to display Honda-specific data. There is a list of these "X-Gauge" codes here.

Another much less expensive way to monitor the transmission temperature is with a bluetooth OBDII code reader and a phone app. For example, I had good luck with a $30 Veepeak reader coupled with the Car Scanner phone app. You'll likely need to know the custom PID to enter into the Car Scanner app in order to read the Honda-specific transmission temperature. A list of custom PIDs is here.

With any of these OBD port tools you can monitor the transmission temperature, as well as many other obfuscated data points such as VCM status, transmission gear, etc.
Here's an example of my ScanGauge III display:

What I've discovered is that when locked into 5th gear for long distances, the transmission temperature could virtually be used as an outside air thermometer by subtracting 98°F from the trans temp. So if it's 90° outside, the transmission temperature will read 188°. If it's 55° outside, the transmission will read 153°. Downshifting to 4th for a steep hill causes the temp to climb, but shifting back into 5th once again settles the temp back as expected. Upshifting to 6th was... interesting. It seems like 6th may generate more heat than 5th within the transmission, but the lower RPMs offset that. So 6th will run slightly cooler than 5th, but it takes longer for the temp to settle. 5th happens to be 1:1 with 6th and above all being overdrive gears, so maybe there's some truth to that.

These are all very reasonable transmission temperatures. From what I've found on the interwebs (mostly from transmission cooler manufacturers so take this with a grain of salt), at as low as 240°F, varnishes can begin forming in the transmission fluid. So keeping the temps under 240°F is a good idea. An old rule of thumb used to be to expect transmission temps to be approximately 100°F over the outside air temperature. When not towing, my RPMs are significantly lower and my transmission temp is somewhere around 70°F-ish above outside air temps.

Unfortunately, fuel economy while towing this camper (like any solid walled camper) is pretty poor.
I've been keeping good track of my fuel economy all summer. NOT towing, I've averaged 27.1 MPG via hand calculations (not the dash indicated values) over the course of over 4,000 miles in the last few months. For reference, over the same fill-ups, the dash indicated an average of 28.0 MPG. So my hand calculation is 0.9 MPG lower than the dash display (3.2% lower). I'll admit that I've been specifically trying to get good fuel economy while conducting a range test, so this average might be slightly better than I'd get just driving normally.
On my recent camping trip, I averaged 10.7 MPG over the course of about 1500 miles when towing for the entire tank. For reference, over the same fill-ups, the dash indicated an average of 11.1 MPG. My hand calculation was 0.4 MPG lower than the dash display (3.6% lower - so about the same percentage). Obviously driving at 65 MPH into a headwind produced the worst fuel economy (my worst was 9.3 MPG). But driving on country roads at generally 60 MPH with slowdowns for occasional small towns would increase my fuel economy up to around 13 MPG.

My ScanGauge has an editable field it uses to accurize the fuel economy displays. Through trial and error, I have it set to -3%, which checks out according to this data.

I've now towed that camper for almost 5,000 miles this summer and am happy to report that the Ridgeline does a very good job towing, as long as the expectations are reasonable. I've experienced no problems with the transmission running too hot. Actually, the hottest I saw the transmission get on my whole camping trip was while I was NOT towing. I was driving slowly up steep switchbacks in the Black Hills and saw the transmission temperature peak briefly at almost 210°F when the outside air temperature was in the low 90s. Clearly speed helps to get more air through the factory transmission cooler and driving slowly at higher RPMs generates more heat.

Xrayguy75 · Oct 15, 2024

Thanks for the in-depth report, much appreciated! I don’t plan to pull a camper with my RTL, but it’s good to know it’s possible.

I had an unexpected maintenance issue come up with my side by side 2 weeks ago and had to make two 180 mile round trip journeys to have it serviced. Overall I was very pleased with how well the RL handled the job. Towing the empty 6.5x12’ 750# utility trailer was a breeze. I tried different speeds with pulling the trailer, 60-70 mph using Sequential mode mostly in 7-8th gear, gas mileage was about 20 over 180 miles. With the 1850# side by side on the trailer, I kept my speed at 60-65 and never went above 7th gear on the mostly flat ground. MPG on the first trip was 16 and on the return trip 14.5, all hand calculated. I don’t have a scanning tool to monitor transmission temps; I may get one but I don’t plan on having to do much towing. As I said, this was an unexpected trip that I don’t plan on doing again. With the machine on the trailer you know it’s back there, but the truck didn’t labor at all pulling it. My old 5.3 V8 GMC did pull that load somewhat easier and got the same mileage. I do take a once a year hunting trip in November which will be my biggest hauling challenge. I figure to have around 4000# in gear, generator, side by side and trailer. This is a 120 mile round trip on back highways and country roads. I plan to use 5-6 gear for this journey.

I think the RL is plenty capable, but I do wish the towing capacity was between 6-7000#, if for nothing more than a little extra peace of mind.

Allen_Labradragon · Oct 18, 2024

Be careful what you wish for. There are always engineering trade-offs. If Honda built the mid-size unibody to tow 7,000# then something(s) else would be affected. Handling, payload, performance, whatever. IMO the current Ridge is at a sweet spot, and improving on it with G3 will be challenging (other than some obvious, easy not major things like adding tow hooks and skid plates).

BlueRidgeBlackEdition · Oct 16, 2024

Hi Mike

Thanks for a very helpful and interresting article. The links you provided were particularly appreciated and the information about the trans was really useful.

I am just learning about towing, I haven't actually done it yet but I intend to, with probably something similar to your set up above.

Could you tell us about your trailer brakes set up, please? Like I said, I'm new to this, so please feel free to be as simplistic as you can

I found a wiring harness in my glovebox when the RL was delivered which I believe is for electric trailer brakes. I also got got the OEM towing kit with the RL - hitch, etc.

Thanks & best wishes

Siouxsie

Wisconsin_Mike · Oct 16, 2024

Many pickup trucks (like the Ridgeline) come with some form of tow package. In our case all new Ridgelines come equipped with a hitch, 7-pin trailer wiring connector, and come pre-wired for a trailer brake controller to be added. That pigtail that is included in the glove box has the appropriate connector pre-terminated on one end to plug into the Ridgeline. The other end is bare wires and is intended to connect to your trailer brake controller. The connector in the Ridgeline is tucked way up under the dash, kind of in front of your left knee if you were sitting in the driver seat. It's tucked up pretty high and some people have a difficult time locating it, but it's up there.

There are a lot of good trailer brake controllers available. It seems like most new ones use a 3-axis accelerometer coupled with the braking indicator wire to determine if you're braking and the rate at which you're slowing down. Back in the day, a trailer brake controller actually had to interface somehow with the vehicle to determine how much effort to apply to the trailer brakes. So you'd have to mechanically link the vehicle brake pedal with a linkage into the brake controller, so it "knew" how hard you were pushing on the brake pedal. Today, newer brake controllers just measure the acceleration rate (negative acceleration = slowing down) and applies the trailer brakes proportionally. The advantage of using the 3-axis accelerometer is that it's much easier to install the brake controller. The disadvantage is that the brake controller can sometimes be fooled into over-braking by measuring it's own braking and stacking more braking on top. That likely means that the braking proportion needs to be dialed down slightly. Also, because the controller is measuring the vehicle accelerations, it must be mounted securely. Any play or vibration in the controller will lead to erratic operation.

I did some reading and settled on the REDARC Tow Pro Liberty trailer brake controller. What I liked about it is that the brake controller can be mounted anywhere and the user interface (the knob and LED indicator) is all that needs to be brought out. I thought that this could lead to a cleaner installation, with only the knob visible. Plus, REDARC has a separate wiring harness specifically for the Ridgeline. So I didn't need to wire up any custom wiring harness using the supplied Ridgeline wiring harness that was in the glove box. Instead the REDARC wiring harness had the appropriate ends to both plug into the Ridgeline and the REDARC trailer brake controller. So the wiring portion was truly a snap. Just plug one end into the Ridgeline and plug the other end into the REDARC controller. Done.

I detail all the parts I ordered and include pictures of my mounted knob in this thread:

https://www.ridgelineownersclub.com/posts/3378781/

I would not necessarily recommend mounting the knob where I did. I put mine here:

It fits and works great and I'm very happy with where it's mounted, but you better measure 5 times before cutting once because you really only get one shot at getting it right. If you have an available blank plate in the switch panel in front of your left knee, that's an ideal location. Oops, I see you have a Black Edition. So you won't have any available switch blockoff plates.

Unfortunately I don't have a very good picture of what's behind the dash on that side. This is the best picture I can find from when I was tinkering on defeating the auto-idle-stop, but before installing the trailer brake controller:

Here's the same picture, but to be more clear I drew roughly where I had to drill a hole for the knob in the dash panel, and then a much bigger hole in the plastic behind the dash for the knob assembly to pass through from behind.

That dash panel pops off pretty easily. Just start at the left side plate and pop that off first. That's the hardest part because it's flush fitting. You can use a plastic spudger pry tool to get under it and pop it away from the dash. Once it's off, then grab the dash from the bottom lip and pull gently forward on the left side and it'll release. No screws anywhere. Just clips that release straight toward the driver. That's as far as I disassembled it while I mounted things up.

Otherwise I know people have mounted the knob inside the cubby under the HVAC controls. I prefer it on the left side, away from any passenger wondering what THAT knob does.

BlueRidgeBlackEdition · Oct 18, 2024

Thanks Mike for a very helpful, interesting and informative post. Enhanced with great photos.

I learnt a lot reading that. I assumed that contemporary trailer barkes worked akin to how they did in the fashion you described from 'back in the day'.

Once I've got my head around most of that stuff, next is learning the nature of the trailer brakes themselves.

Thank you, best

Siouxsie

geezee60 · Oct 18, 2024

I have towed this rig for 35k miles over the last 3 summers, all over the US and Southern Canada (Banff and Lake Superior) numerous mountain ranges, etc. Its got wood-less construction, a welded all aluminum frame so its dry weight is just 3300 lbs, including a slide out. Now you must still be careful not to go crazy with tongue weight as all the storage is fwd. We worked hard to get it to a bit under 500lbs including the addition of the rear trunk and the relocation of one of the two LP tanks back there, along with lots of other 'heavy stuff. I do not have a WDH nor do I think I need one. Generally I run 'S' mode 7th gear 65mph on highways. No issues, get 13-14mpg at this speed. Push it to 70 and you'll get 8-9 mpg.... Not recommended. The sweet spot with a trailer this size is really around 55-60 mph, the truck is loafing along but this is not feasible on an interstate. 'S' mode paddle shifting is the deal maker IMHO... Works fantastic. Mountain climbs, 4th gear, coasting descents not requiring engine braking , 8th or even 9th. I DIY change my ATF and rear diff far more frequently than spec'd , done it 3X in 52k total miles already($100 material cost/change). I did also replace the stock tires with XL rated Yokohama Geolandars 255mm width and run them at 40psi when towing. Work great.

geezee60 · Oct 18, 2024

For a RL to tow 7000 lbs right off you'd need a larger engine or add turbo(s) which I do NOT want, much more suspension, which would possibly wreck its excellent road handling characteristics, and probably re-engineer the frame and body components for more stiffness (maybe). The tranny is probably also not up to the task. Honda has a rather poor history of redesigned upsized trannys going back to 2000 with the ODY.....Granted a Honda V-8 would be mouth watering......! They could retain the midsize RL and simply 'scale it up' to a full size, model also, like Nissan does with its full size/V-8 platform. IDK how much market there is for another full size though, and I wonder longer term how much appeal the full size behemouths will have when gas creeps up to 5 bucks a gallon. My RL is pretty dang close to the size of my '72 F-100 anyway- except for the 8' long bed. I fail to see why Honda has not marketed a sport-compact pickup based on the excellent 2.4l CRV engine/drivetrain. No NOT CVT, thank you. Maybe even a manual tranny option. Its been decades since that market was exploited and the Ford Maverick seems to be selling like hotcakes.

geezee60 · Oct 18, 2024

Siouxsie etrailer has been one of my favorite go-tos for these things, like the Tekonsha electric brake controller which as already posted, plugs (With appropriate adapter) into the connector already residing in the RL up under dash/steering wheel. ITs a must for trailers over 3000 lbs- and is the law as well. As I've posted elsewhere, I use 'S' mode almost exclusively in my '20 RTL-E when towing. Smaller trailers, no issues whatsoever just count on longer stopping distances. For my rather heavy trailer I did upgrade to 'XL' tires, a higher load rating than the stock ones.

Bmac51 · Oct 24, 2024

Evening all, I have been towing various campers for 35+years. Largest was a 23' with no slides and weight of 4400 pounds unloaded pulled by a 2017 Ford Expedition. I bought a Coachmen Clipper Express 12.0 this year to haul out west. It is a small trailer with a listed weight before loading up of 2400 pounds. My Ridgeline is a 2022 Black Edition, and I have to admit I think it is the sharpest looking truck around, receive lots of compliments from my fellow Ford and Chevy truck driving friends. Long story short the month-long trip out west fell through, but as compensation I just spent 3 weeks toodling around Northern Michigan and Michigan's Upper Peninsula. My impression was that the Ridgeline was working harder than it should have been for the size and weight of the trailer. On the flats you wouldn't know that you were towing anything but hit an incline and the trailer made itself known. I experimented with S mode but frankly did not care for it, I was probably bouncing from 5 to 6 to 7 to 6 to 5 to 4 more than the rest of you trying to maintain revs. Lest you think I do not know how to manage a stick I have a 5 speed Saab that I run around in and have been driving sticks since I was 16, I am 73 by the way. My average mileage while towing I thought was good at 14.1 mpg and I typically kept it between 60 and 65 where appropriate although there were many stretches where the speed limit was 55. My feeling is that Honda needs to get serious about the Ridgeline and towing; that being said they may have but I have not checked the newer models. Having the Ridgeline wired for the brake controller yet putting the wiring in an almost impossible location to find is ridiculous, spend a few extra dollars and integrate a brake controller. My last 2 TV's had a tow mode and I did not have to muck about with the paddle shifters, just slip it in tow mode and off you go. I really like everything about the Ridgeline (well except for the NAV system which is another story not really related to towing) but did not care for it as a tow vehicle when compared to my last two vehicles. So that leads me to the question of do I keep it? Or look at the other mid-size trucks like the Ranger or the Colorado? Just not sure at this point.

GCSteve · Oct 31, 2024

The midsize trucks are so small feeling inside, I could never go back. S mode is the tow mode for the RL. On my 10,000 mile trip this summer pulling my 4k tailer I mostly used manual in 4th or 5th and sometimes 3rd on a mountain pass. The huge mountains needed to let it rev but the RL did great and I didn’t feel cramped or worry about the reliability at all. I did go about 50mph up the Eisenhower tunnel in Colorado. When I upgrade my trailer in a few years I will need a full size though.

Wisconsin_Mike · Oct 31, 2024

FIVE separate times while on my week-long vacation to the Badlands and the Black Hills of South Dakota, someone stopped to chat about my Ridgeline pulling my camper. Twice while I was getting gas at a truck stop someone at another pump walked over to chat. Once at the Badlands and twice at our campsite in the Black Hills someone driving along stopped right in front of my truck to ask questions.

Every single time, one of the questions they would ask was about the fuel economy when towing vs when not towing. 2 or 3 of the people seemed disheartened when I told them that I was lucky to get 12 MPG while towing. My average on that trip while 100% towing was 10.9 MPG. The others seemed to expect that kind of mileage.

Otherwise one person seemed truly shocked that the truck they were looking at was a Ridgeline. Another person said that they knew Honda had redesigned the Ridgeline but didn't realize it looked this good.

fdeno · Oct 31, 2024

I know I'm an old codger but remember back in the 60s in Norfolk when sailors would get transferred from VA to CA and the wives would follow them after the house sold and the kids were out of school.

Young woman with two small kids loaded up the beat-up station wagon with a Bubba trailer hitch and towed the entire family's goods across the US in a rented trailer before cell phones and without AAA. I serviced more than a few of those vehicles before these road warriors started out on the trip.

And yet, they made it, maybe with some adventures along the way and the world did not end.

murrayjestin7 · Nov 22, 2024

There are always engineering trade-offs. If Honda built the mid-size unibody to tow 7,000# then something(s) else would be affected. Handling, payload, performance, whatever.

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klhutch52 · Nov 25, 2024

I don't have nearly the accumulated mileage or data as Wisconsin Mike but my limited experience with towing a Rockwood GeoPro 20FBS matches his pretty well. I'm 72 and have never towed anything before so I guess old dogs can learn new tricks! The trailer has a GVWR of 4400#, CAT says we run 4200# as we load it. We have a 2024 RTL, the Rockwood is also a 2024. I put in a Curt Triflex Next which is a proportional brake controller with a three axis accelerometer as the name suggests. Curt makes a custom cable for the Ridgeline. I found it easier to connect to the Ridgeline socket by pulling the instrument panel trim partially off. We have an E2 WDH and the CAT scales say it is necessary to correct an overloaded rear axle. Tongue weight is just a few pounds over too. I plan to switch to a Lithium battery next season to fix that. I'm quite happy with the combination so far. The Ridgeline is nice to drive around town at home and it's so much more fun than our old class C was when it comes to driving around to see the sights from a campground.

Wisconsin_Mike · Nov 25, 2024

klhutch52 said:
the CAT scales say it is necessary to correct an overloaded rear axle. Tongue weight is just a few pounds over too.

I had really good luck lightening my trailer tongue by installing an aftermarket trailer hitch on the back of my camper. This hitch alone added 65 pounds to the back of the camper which helped lighten the tongue. You can read about that here:

https://www.ridgelineownersclub.com/posts/3406234/

Then I fabricated a full size spare tire hitch mount to connect to that added hitch. This added 94 pounds to the back of the camper. You can read about that here:

https://www.ridgelineownersclub.com/posts/3409889/

After these changes I was free to add more gear to the camper front storage compartment, still be under the max tongue weight, and have a properly balanced trailer.

Towing a Travel Trailer Camper with the ZF 9-Speed Transmission

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