First towed test... shaky ...!

[kannonvaggon]

Well, we finally got our new motorcoach on the road after the first set of mods and prep and such.

We had the Blue-Ox baseplate installed at the coach dealership since they have two bays that just do towbars and such. They took ALL day with two men to get it done. We went with the internal lighting and diode system with a weatherproof electrical umbilical plug just below the license plate bracket on the grill. Seems to work just fine.
They had to cut a bit more on the front bottom grill than I would have liked but it still looks fine. The way the grill fits up to the baseplate ya have to leave just a bit of extra room for clearance on the safety cable hooks . Not a problem.

Now for the good stuff....

Hooked up the Cabrio easily, after we added an 8" drop receiver that weighs about 30lbs. It looked like I could get by with a 2" drop but after I pulled up and the coach came up to ride height I found it was quite a bit higher than expected back there. The 8" drop made it just about 1 inch higher than the Smart pins. OK.

Wiring worked perfectly and all lamps functioned.

Put the Smart in neutral, turn the key to the left. Dash lights went dark. Car rolled freely and steering wheel was tested to be unlocked full throw each direction. Fine.

Pulled out in a straight line.... car went into a violent headshake side to side. Stopped and restarted twice... didn't go away. Dealer tech got all excited and ran to get on the phone to Blue-Ox. I asked for a couple bungee cords. I got one long one.
The tech came back and said Blue-Ox told him to use a bungee laced around the center of the wheel and hooked to both door handles... ??

I installed the bungee with a couple wraps around the center of the wheel bottom and hooked to each side of the seat rail frame.

Pulled out again. NO shake at all. Went around the block making a couple tight turns. NO shake. Tracked straight and true. Headed out on the highway and drove almost 300 miles home in heavy rain. No problems... except the Smart was pretty grungy when we got it home from the splashing highway sludge. Things were MUCH cleaner when the Smart rode in the back of the garage coach like a proper princess.... Oh well it's just gonna have to get over it.

I can see the car plainly in my rear camera. Other than that I can't see or feel it in any way. I can't tell any difference in handling or performance or braking or anything at all. It's just back there somewhere. I can catch a brief glimpse of the tail of the Smart if in a tight turn. I was watching it pretty closely in the camera to make sure it didn't start acting goofy but it never did.

It just needed a rubber band, of course....

Heading out again today. It's storming again right now so I'm gonna try and wait it out and then hook up and head west for a few days then next week will head towards the great white north for a while on the shake-down cruise of the new coach. The Smart got the shakes... but settled down fine once the bungee was installed.

[pmolink]

The bungees can do double duty as power to the front wheels for better handling in snow and ice.

[bcope01]

I'm surprised you got the "wobble" pulling straight forward. First I've heard of that. A couple of times I got the wobble on hard right turns from a stop at very slow speeds. No wobble otherwise. Haven't used a bungee yet, but have one ready if needed.

[Alan_Hepburn]

The wobble seems to be related to many factors - including the length of the connecting hardware. My original setup was a Blue Ox 8" drop receiver to the Blue Ox tow bar. It would only wobble if the steering wheel was off-center at the start, or I was starting by turning the motorhome. But then I added a dual receiver setup between the motorhome and the 8" drop receiver so I could mount my bike rack back there. That moved the tow bar about 10" farther back - the smart would wobble at the drop of a hat. the solution: bungee cords from the driver's seat frame to the steering wheel - no more wobble!

[fortow]

If the car is straight behind the motorhome, and the car's steering wheel is centered, and you don't turn immediately - then there will be no wobbles.

You don't need the bungee chord.
It only will happen under those conditions and on starting from a stop. When you hook it up just make sure it's not angled relative to the motorhome and that the steering wheel is centered.

If you install wider front tires that will reduce the liklihood of this happening as well.

Alan's comment about it having a tendency to wobble more when the dual receiver was installed may indicate that if the connection to the tow bar is not stable, that is if there is play in the connection to the motorhome, then the wobbles might be more likely. If there is play, then the greater distance to the motorhome will permit more lateral movement which will affect tracking.

[chieftmc]

OR...............you could use one or these: Smart Trailer USA-Smart Trailer Center and solve the whole problem

[fortow]

Originally Posted by chieftmc

OR...............you could use one or these: Smart Trailer USA-Smart Trailer Center and solve the whole problem

No, not really - or practically.

I gave it some thought before buying the tow bar and towing the car 4 wheels down - but that thought didn't last too long. The smart was purchased specifically because it could be towed 4 wheels down.

If you tow it on a trailer you then have three vehicles to contend with instead of just two. It also makes life a little more difficult in campgrounds. I don't want to find a place to store a trailer, the car, and the motorhome. It also increases the towed weight.

I've towed the smart many thousands of miles. It only wobbled once when it was first hooked up - since then there has been no problem because I learned what not to do. Hooking up and unhooking is quick and easy. There's no reason to be towing this car on a trailer.

[kannonvaggon]

I think the PRIMARY trigger for the steering wobble is : caster angle...

I might be way off , yet again, but when ya think about it we know that adding a bit of caster can often stabilize a "shaky" front end or make it drive with more stability without a decrease in turn-in performance , etc...
The engineers set these things up with a particular caster and camber setting for a GIVEN ride height and WEIGHT on a particular tire and wheel size.

I THINK that maybe some Smarts are maybe within spec but might be on the ragged edge of it for instance. If ya add 45lb plus to the front end weight it MIGHT not do anything good and MIGHT require the front end alignment, caster and camber angles to be rechecked and MIGHT need maybe a hair more caster angle to allow the Smart to track easily when towed. Not all Smarts are exactly the same for sure.

I towed out to a RV park near Starved Rock in Illinois yesterday. Pulled straight ahead and started to get a head shake. Installed the bungee again and all was well again.
BUT.... I think I'll have the front end checked out and maybe add an additional 1.5 degrees or so of caster angle to see if that makes things work well without the bungee.
If we keep using the bungee system I have a sneaking feeling that we may see some abnormal tire wear and/ or suspension component wear over time when towing.

I dunno.

Watcha think?

The car tows just fine with the rubber band, but I would prefer it to do so without it.

When we mount the motorcycle lift on the rear of the coach, there will be an extension of around 24" behind the existing receiver drop point. We want to tow off the center of the three receivers on the chassis frame rather than off the frame of the lift.
Probably doesn't matter much with the Smart. We may have enough clearance under the lift to not need the long extension, but I don't know for sure yet. We'll see.

We'll be heading for the great white north this next week , dragging the Smart behind the behemoth like a dirty sack of potatoes...

[Bumbee]

bumby towed like a champ. no bungee, but i don't have power steering.

[kegrv]

Ihad to use bungee strap but had to use in past pulling small car.