I have purchased several books and eBooks from RVbookstore.com, but I can’t find the answer to my burning question. In your eBook The Complete Guide to Dinghy Towing you say to never back up a motorhome when pulling a dinghy. My question is: You see many motorhomes pulling boats. If you can’t back up a toad, how do boaters back up to launch their boats? --Jim Walker
Dear Jim,
The reason you can back a boat trailer, but not a dinghy (car or other vehicle), is that the boat trailer doesn't have a set of steering front wheels.
A while back an engineer at Blue Ox experimented backing several towed vehicles. The results weren't good. One person would drive the motorhome and another would attempt to steer the front wheels of the toad. The problem was, in every test, the front wheels would unexpectedly turn drastically to one side making the steering wheel violently spin out of control. If a person has their hands or arm caught in the steering wheel the results could be a broken finger, hand or arm. Even when they attempted to back straight back the wheels would turn, and it was with other manufacturers tow bars too. You should never attempt to back a toad!
Here is how the engineer explained it:
"The reason this happens is not the tow bar but rather the caster angle in the front end of the towed vehicle. Caster is the forward tilt of the steering axis versus vertical. It provides steering stability, steering returnability and cornering ease. In reverse, the caster angle makes the wheels want to turn around the other direction like "casters" on your office chair or shopping cart. We all know they can't turn all the way around on a car, but they will turn off to the side as far as the steering mechanism will let them.
This is virtually undetectable from the driver's seat in the motorhome making this a very scary situation. If you continue to back up, after the wheels have turned, the tires "scrub" or slide sideways causing damage to the tires. Other things caused by this are; severe stress to the steering components, suspension and towing system components."
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Finally, an explanation that makes sense! Thank you.
ReplyDeleteWith your explantion in mind, would it then be possible to back up a car on a towing dolly provided the front wheels are the ones up on the dolly?
ReplyDeleteYes, backing a car on a dolly is doable; I've done it with no unusual behavior.
ReplyDeleteI wonder if you can carefully pull the mororhome back by starting the tow vehicle and pulling the motorhome back eith the tow vehicle (dinghy)? The motorhome would have to be in neutral (running) and someone steering it following the tow vehicle backwards. ????
ReplyDeletePeggy,
ReplyDeleteI would not recommend trying to back a tow dolly either. When you attempt to back up the tow dolly will turn but the vehicle on the dolly will try to stay in a straight line. The results are the tow dolly fender hitting and damaging the side of the vehicle on the dolly.
Mark Polk
Having been a semi truck driver I have backed with my toad many times. It is very tricky and you have to be very careful. It can only be done in a straight line and you must go very slowly to control the straight line. Using the mirrors and the rearview camera and someone outside watching. If you get off line even by an inch or so you must stop and pull forward to correct. But I have backed well over 100 feet using my method. Easier than unhooking but not easy. SLOW is the key word. Slight adjustments to the motorhome steering wheel can keep the toad going straight. Not for everyone.
ReplyDeleteI have successfully backed up my motorhome and toad short distances by turning the ignition to off and removing the key, therefore locking the steering column but I do it very carefully and only attempt when absolutely necessary.
ReplyDeleteI have hears (not seen) people who have pulled the RV back a bit, with the toad.....but it was in a straight line, for short distances....on flat ground!
ReplyDeleteI had always figured it had more to do with the 4 wheels on the ground (in addition to the steering), as it's pretty tough to back a four wheel wagon too.
I think it has to do with the fact that trailers with 4 wheels have the wheels in the center next to each other but cats have a wheel at each corner.
ReplyDeleteIf you can back a 4 wheel hay wagon you can back dinghy with no problem. I mean really back a 4 wheel wagon at a 90 degree angle & not have to pull the farm tractor forward. Do it all the time. Farm boys vs City boys
ReplyDeleteWith a four wheel wagon you are steering the front wheels even when backing. With a tow dolly you are also steering the dolly, But you can't turn much before reaching the limit of the steering as the rear wheels try to keep going straight and the geometry between the four wheels gets out of alignment. With a car four down, the tow bar is pushing (or pulling) on the frame and the front wheels steer themselves. Even going forward, there are a few cars with steering geometry such that the wheels will "flip", particularly in a sharp turn, that is one reason not all cars are approved for towing on all four.
ReplyDeleteWe used the M&G Tow System (no longer in production) with our 2002 Lazy Daze Class C, towing a 2004 Honda CR-V, for several years. We were able to back up in both a straight line or a curve. Check it out:
ReplyDelete