A Guide To Towing a 100 Behind an RV

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Nov 14, 2010
San Antonio, TX
Hey Guys,

Many thanks to those of you who've provided input on another thread where I asked for info about towing my 1999 LX470. I'm starting this new thread to provide a "how to" regarding towing a 100 series behind an RV. In the last six weeks, we've rigged the 100 for towing and have pulled it over 2,500 miles. It wasn't completely without problems. In fact, one mistake cost me over $1,000 in repairs! But, that was not due to any deficiency in the 100. That was caused by an aftermarket braking solution we tried (see below).

((((EDIT ON FEB 2, 2015: After 2,500+ miles towing the 100 behind the RV, plus another 1,500 to 2,000 miles driving the 100, today I drained the differentials and transmission. Everything looked perfect.)))))

There has been much discussion about whether or not the 100 can be safely towed flat. Christo, Muddy Bean, and others have done it successfully, as have we. I feel confident that towing a 100 series on all four tires is just fine. Our average speed has been about 70 mph with extended time at 75+. On our first trip (about 1,000 miles round trip), I stopped at 50 miles, 100 miles, 200 miles, etc and checked all the temps with an IR temp gun. No concerns whatsoever.

To tow the 100, we left the transmission in Park, put the transfer case in neutral, and turned the key to Accessory. Each time I check to make sure the steering wheel turns freely.

Accessories Needed

1. Brake Lights, Turn Signals, Running Lights: We did not want to tap into the LX's wiring, so we installed a new set of lights from Roadmaster. It was relatively simple to install. You just run four-flat wiring from the front of the 100 to the back, cut a one inch round hole in the back of the 100's tail lights (do NOT use a paddle bit!!!!!), install the kit's bulbs, and crimp a few wires. Maybe a 2 hour job. The kit's four-flat plug at the front of the 100 simply connects to the RV's wiring harness using a six- or seven-way to four-flat adapter. We also added an additional 12 volt "umbilical" from the RV to the battery on the 100 to keep it charged up. This was already a part of the wiring harness, so we just connected it to the battery and added a 20 amp auto-resetting circuit breaker in-line near the battery to prevent overcharging.



2. Base Plate: We installed a Roadmaster "base plate", kit number 1151-1. It comes with two receiver-type mounts that bolt onto the 100's frame with three bolts. This allows you to connect the 100 to the tow bar on the RV. I don't see how this would work with an aftermarket front bumper. I just kept the stock bumper on the front.


3. Tow Bar: The Roadmaster Sterling All Terrain works perfectly with the base plate above. Note that in the link below you'll see a crossbar on the tow bar. That is not necessary in this setup.


4. Braking System: We're required by law here in Texas to have a braking system on towed vehicles (at least of this size). We looked and looked, and the ONLY option is a braking system that sits in the floor in front of the driver's seat. After extensive research, the Blue Ox Patriot was our choice. None of the air brake systems will work on the 100 brakes. BEWARE! We destroyed our brakes with this system. In short, installation requires that you place the braking system in the floor, attach it to the 100's brake pedal, and push a button on the Patriot to have it initialize. Evidently, it placed just enough pressure on the brake pedal to cause the pads to touch the rotors...or it vibrated forward a fraction of an inch during highway travel, causing the pads to make contact. Regardless, we didn't notice for many miles, and on one of my stops to check everything I had tons of smoke coming from all four brakes. Long story short, they were fried, as was the grease in the front wheel bearings. It was a very expensive problem. I'm trying to get Blue Ox to pay for the repairs. It's a shame that there are no alternatives to this general type of braking system for 100's. With this exception, the 100 is a fantastic "toad" for an RV. I'm still working on a solution to make sure this doesn't happen again.


5. Tire Pressure Monitoring System: Purely optional, but we got the Pressure Pro tire pressure monitoring system. That way, if we have a tire problem on either the RV or the 100, we know it immediately. The 100 is about 45-50 feet behind me when I'm driving the RV, and I wouldn't know it if a tire blew without this system.


I hope you guys find this info helpful!


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Here's a diagram of the base plate(s).

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On the road...

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Yes and no. Yes, because I wouldn't have had to do all of that to the truck. No, for several reasons. One is that I don't want to be hauling the extra weight of the trailer around. Another is that many of the RV parks/resorts we'll stay in don't have room for me to park the trailer once I've got the truck off of it. Also, it's really fast (as in about 3 minutes) to hook the LX to the RV...much faster than I could get it secured onto a trailer. And unhooking it takes about a minute or less. All told, putting it on a trailer was what I wanted to do for simplicity's sake, but the cons unfortunately outweighed the pros.

A couple of further questions......have you considered a wireless rearview camera setup to both monitor the LC and to check traffic? And, how does a 20 amp circuit breaker prevent overcharging of the LC battery? To prevent that, you need a charge controller, not a CB?
A couple of further questions......have you considered a wireless rearview camera setup to both monitor the LC and to check traffic? And, how does a 20 amp circuit breaker prevent overcharging of the LC battery? To prevent that, you need a charge controller, not a CB?

The RV has a rear view camera already, which helps a lot. Not only can I see the LX fairly well (though not great if the sun is behind me), but it also allows me to see 3 lanes of traffic and know when I can get back over after passing someone.

I wish I could respond to the question about the breaker in a way that made any sense. I really can't though. From what I read on various RV forums, there's a risk of a voltage surge when starting the RV's engine (a 400 hp Cummins with a large alternator) when I have the LX connected. The circuit breaker keeps that from affecting the LX's system...so they say. Since all the old-timers on the RV forums recommend it, I installed one. (Took about five minutes and only a couple of dollars.)
Just tow the rv with the Land Cruiser!

Good idea! But, it's kinda hard to make popcorn and watch satellite TV driving down the highway in a Cruiser. ;)
Here's a towing update. We've towed the LX from San Antonio to Alaska behind the RV over the past several weeks without a single problem. No doubt, these things can be towed with all four tires on the ground. Here's a pic from Haines, AK yesterday.

Wanted to add another update. I followed KMGHMG's original guide except my wiring kit didn't come with a charging wire. Great guide and it worked great! Though I borrowed a 10k lb tow bar.

It was easy to hookup/unhook. Put the tcase in neutral and turn the key to ACC to unlock the wheel and you are good to go. Did a little over 2k miles. I did check to make sure the brakes weren't being applied by the brake setup I was using and it was always fine.

Thanks again to KMGHMG for posting up the guide and info to give me the confidence to do the trip.

This was news to me until about a month ago, but with any automatic simply putting the transmission in neutral may not be sufficient for long tows. In neutral the transmission is still churning inside, but the clutch plates are not engaged. That still leads to a lot of heat build up and without the engine running, there is no fluid pumping/cooling. Google it. Ideally if you want to tow without doing any damage you have to drop both driveshafts. Crazy I know. Not trying to start an argument but it's no joke.
There shall be no churning in the transmission when the T-case is in neutral. You could probably put the transmission in park, if you wanted. :)

This was one of many recommendations to pull the driveshaft for long rows. Tow truck drivers (good ones) even pull drive shafts unless they can get the drive wheels in the air. Do some research and might be surprised what you find. Heck, call a transmission shop and see what they say. For what it's worth, the main center shaft in a transmission (automatic) is always spinning if the driveshaft is connected and the wheels are moving. Only difference is the clutch discs are lot locked together. There is still heat building up. Enough to do damage? Some say yes. Experts say yes. Others say no.
12guns-Please do some better research when it comes to our 100's. Sorry but your information is wrong when it comes to a 100 and transfer cases. If you are flat towing an 88 Oldsmobile then yes you need to pull the driveshaft. However, on our 100's the driveshafts are connected to the transfer case and not the transmission. Once you put the t-case in neutral then the transmission isn't doing anything-that's why we tow with it in Park. Search on here and you will find out this to be true.

And no need for me to call a transmission shop as I used to own one.
Well, that's embarrassing...I never even considered putting the Tcase in N...I was thinking just about the transmission itself. Thanks for clearing that up.

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