I just completed a 200 mile round trip with my new 13' Trillium towed by a 2000 Subaru Outback rated at 2000#. The trip up was fine. I kept it about 50mph in an attempt to save gas and to build some experience with the rig.

However, on the trip back, the rig developed a 'jerking' motion fwd and back. It seemed to be caused by bumpy pavement, but not always. I also kept it at 50mph.

I thought of everything from bad clutch, loose axle on the Trill, misbalanced loading, etc.

Any experience with this motion out there?

were you using cruise control? if so, that can do that.

"jerking' motion fwd and back"

Loose hitch ball?...Tighten nut quickly! (250 foot pounds torque)

Loose hitch in receiver?

Hitch ball too high? Trailer should be level or slightly down at hitch.

Yeah, on I-5 south...... Where were you at when this occured, or was it all the time? Larry

was your fresh water tank full?

There are some sections of I-95 in the Carolinas where I just go crazy from the trailer motion. It starts to cycle and even if I slow down to the minimum of 40mph it's still practically unbearable. It's an up/down sort of bobbing that really goes right through the whole rig.

On that same picee in a car (when not towing), you don't even feel it. I wondered if it was something to do with my rig, then one time caught sight of another truck and utility trailer on that stretch of road that was doing the exact same thing.

So it's possible it was the road and not your set-up.

Raya

On certain concrete roads with my trailer and tow set up an uncomfortable motion as they cross the expansion strips. Usually speeding up or slowing down a skosh solves the problem for me.

There are sections of I-5 in Washington state that can produce a similar motion in my truck/trailer combo. It usually is an up and down motion as we go over the expansion joints in the concrete. Speed changes don't seem to have much effect. I just try to ignore it until it passes. BUT at times it's all I can do to tolerate it!!!!!!!

Exactly, Paul. That's how it is for me too. Just an "up-down-up-down-up-down" as if you were a high-speed inchworm. Slowing down doesn't change it for me on that particular stretch either. Just makes any bobbing less likely to break something. I despise that stretch of road. But with just the car - I can hardly notice it.

Edited to add: In all of the 2800 miles I towed home with the Boler, I had none of that motion. Even at 65+ mph and/or in crosswinds. For me it's only on that one weird stretch of road. It could be trailer balance if you're NOT one one of those stretches.

Roger, et al …
First – confirm that you have adequate tongue weight. US experts seem to say 'at least 10 percent' of the gross weight of the trailer should be on the hitch. I agree more with those who suggest that 12 to 15 percent is a better target.

As you would expect that up and down jerking motion is amplified by the weight of the trailer in relation to the tow vehicle. It makes sense that a light tow vehicle would feel the effect of the movements from a heaver trailer.

The older concrete highways with tar strips almost caused me to stop traveling when towing my Scamp 19' 5vr. Then I starting using a Shocker Air Hitch and could forget the Scamp was there while driving over most any surface. Now that I tow a Casita 17' with the same tow vehicle, the Shocker is probably not necessary but since I have it – I use it. It is a little pricey and probably not for everybody but if you really want to isolate the trailer from the tow vehicle – it does work. (Disclaimer: I have no interest in Shocker other than as a satisfied customer.)
Click to view attachmentClick to view attachment
Don

Thanks everyone for your input. It WAS on I-5 from Mt Vernon South. It did start on Hwy 20 from Deception Pass Park on Whidbey Island. After I exited the freeway, I purposely took a steep hill and the clutch pulled fine.

I was using the cruise. I will try not.

I thought of concrete expansion strips also, but the road was asphalt. But on second thought wasn't that asphalt laid over concrete? Also another possiblility.

We stopped at the Everett rest stop. I picked up the hitch (and car) and got no looseness or clicking like I would if something was not tight.

Fresh water tank was empty.

Hitch ball at height specified by Trillium. (16")

Again, thanks again for your contribution. I have several things to try if it happens again.

hehe... it was most likely the cruise and heavy trailer light car combo. I'm 99% sure in your owners manual it says not to tow with the cruise on and also not in 5th gear for a manual. thats what it says for my 99 Toyota Tacoma and its rated at 5500 lbs towing and those 2 things will cause it to act funny when towing on my rig.

I think the "don't tow in overdrive" is strictly about not straining the transmission or (maybe) differential. I tow in overdrive sometimes (carefully, when not "asking anything" of the drivetrain), and there is no difference in how the trailer handles. Only in how I'm loading the transmission of my car.

Raya

Towing in OD is something that's somewhat different with different transmissions, so word-of-mouth is not always a good guide -- Read your Owner's Manual.

However, all the experts agree that if your transmission is 'hunting' or changing back and forth between two gears (ANY two gears, not just OD), it's time to force a change to the lower gear.

The only time I have experienced a back-and-forth (not up and down) jerking is when I was having a bad bearing start to seize up on the axle spindle.

I didn't mean to imply that no vehicles should tow in overdrive, if that was how it sounded. Sorry. My particular vehicle doesn't recommend it, and I know many don't; but I still don't think that if you DO tow in overdrive it will change the towing characteristics of the trailer. I just don't see them as related in that way.

Raya

OD shouldn't have any effect on the trailer, just on the tow vehicle -- Reportedly, there are some transmissions that do different things in OD than they do in the other gears, while to other transmissions OD is just another, higher, gear.

It is a stick.

Good idea. Will look at owner's manual.

(If all else fails, read the directions)

Pete,

What happen? Did it actually seized up? Damage?

Frederic

It rode up on the spindle shoulder where the seal rides and welded itself there and on the spindle badly enough that I eventually replaced the axle. Most of it had disintegrated. Expensive lesson about bearing packing -- The opposite wheel had water contamination in the grease, so I presume that's what was caused the failure of the first set.

Hi: Roger C H... Check the adjustment of the coupler lock down clamp. If not properly tight, it will allow the ball to slop back and forth in the coupler, with braking/accelleration. If it is too tight it can wratchet its self loose after some miles towing/turning, and if too loose it will slop back& forth. You can have a surge brake installed as a coupler to eliminate the action/reaction!!!
Alf S. North shore of Lake Erie

I have not had any problem since except occasionally and in a few places. It does seem to be connected to the road. Anyway, thanks for all your input. I have more miles experience now and even that seems to help. LOL

I haven't read this entire topic and maybe this has been addressed. But it's easy to forget you have six wheels (or more) now on the pavement. Every bump or pothole that hits the front tug tires will in turn hit the back tires, then the tow tires. You'll feel every one of those through the seat of your pants and through the peddles of the tug. Only some of this discomfort can be minimized by proper tire pressure, etc.