TM lurches forward and back - why?

[Edit - this thread was de-hijacked from another.]

We just picked up our 2720 TM; our TV is a 2008 Toyota Highlander (5000 #). The dealer installed a WDH with torsion/stabilizer (?) bars to keep the TV level. Driving on city streets we experienced severe forward and backward lurching. No brake was engaged. Above 40 mph and on the freeway we did not seem to experience this problem.
Is this normal? Is there any solution to this problem?

Jerry
2008 2720
2008 Toyota Highlander

[Mr. Adventure]

Originally Posted by gerald snell

We just picked up our 2720 TM; our TV is a 2008 Toyota Highlander (5000 #). The dealer installed a WDH with torsion/stabilizer (?) bars to keep the TV level. Driving on city streets we experienced severe forward and backward lurching. No brake was engaged. Above 40 mph and on the freeway we did not seem to experience this problem.
Is this normal? Is there any solution to this problem?

Jerry
2008 2720
2008 Toyota Highlander

I'm guessing here, because I don't have your exact experience. My first thought is that the ride in my Highlander is much stiffer if I put too much load on the weight distributing hitch bars. So my first question is if you measure the front fender to the street before and after hitching, is it less (lower) hitched versus unhitched? (if so, try a little less on the hitch bars and see if the ride improves). However, I would describe the motion as a busier, up and down kind of action in the ride, not "forward and backward lurching."

What kind of hitch to you have?

Two thoughts:

1. experiment with the tension in the WD bars.

2. Experiment with the tire inflation, especially the rear of the Highlander.

With my truck, I run 55 psi when empty and 75 when towing. If I keep it at 55 for towing it "porpoises".

I do not use a WD hitch, because my truck is big enough to not have a use for one. So I can not comment much on the WD bars.

[Bill]

Both Mr Adventure and PopBeavers have given good advice, and I would follow it right away. On the other hand, they both describe an up-and-down motion, and you have described a forward-and-back motion.

Despite the fact that you weren't braking, it sounds to me like a brake problem, rather than hitch/suspension. As if the brakes were momentarily catching/grabbing. Someone who is smarter about brakes than I am can answer the question - could this happen if the brakes are adjusted too tightly?

It is also vaguely possible that it is an electrical problem in the brakes. Try this. Since it is a low speed phenomenon, find a safe place (big empty parking lot) and disconnect the power cable between the tow vehicle and the TM. Now drive the TM down the parking lot in the way that produces the lurch for you. If this fixes the problem, then it is electric-brake-related. What kind of brake controller do you have?

Also, check to make sure that the pin in the breakaway switch is firmly in place.

I had a similar problem when I first got my first TM. It occurred at the moment when I took my foot off the brake pedal, and it occurred only at low speeds. In my case, it turned out to be imperfect release synchronization between the trailer brakes and the tow vehicle brakes. I doubt that this is the problem you are experiencing, but it sure sounds like the same result.

Bill

sounds like a problem i once had,the bars might be too heavy 1000lb bars on a 300to 400lb tongue weight doesnt allow no flex on your bars. thats why the right bars need to be used. alot of dealers put on what they have in stock. 2nd back off on the bar tension, good luck, keep us posted.

[Mr. Adventure]

Morning thoughts:
Fore and aft motion can only be brake related. I posted another thread once where I accomplished this by improperly failing to adjust my Prodigy brake controller. But you said you weren't braking when this was going on.

Excessive up and down motion in the front seat, where you really feel the trailer wheels hitting every bump, is easily arranged by cranking the WDH bars too tight. Of course, it's normal for the ride to be a little stiffer when towing, even when you have it right.

I'm also a fan of reading the tire sidewalls and inflating them to the max number. In my case, that's 44psi vs the 30psi recommended on the door post. This also makes the ride a little stiffer, but it's the way to have the least flex in the tire, get better tire durability, have better vehicle stability, carry the maximum load, and get better gas mileage.

[Bill]

Glad you agree. We should be able to pin this down quite quickly.

Bill

This is a long shot but make sure you have the right size ball on your hitch. Especially if you are getting a clunking sound when the TM lurches.

I had the exact same problem and it resolved completely when I inflated the TM tires to the proper level. I was sure it was brakes or hitch but an experienced voice told me to make sure the tires were inflated properly and he was right.

Thank you for all of your comments and suggestions!!!
As clarification, I have a 5000 # WDH with 800 # Pro Eagle bars.
I will check the tire pressure of the TV, and raise it to the max as indicated on the sidewall of the tire.
I shall also contact the TM dealer about the possible lack of synchronization between the TV and TM brakes.

An additional factor is that I also purchased a Honda 3000 si generator (wgt 134 #) which is carried on the back of the trailer in a Tow Rite basket carrier, which fits into the hitch receiver at the rear of the TM. Could this addition have an effect on the rided? I aked my wife, and she also described it a forward/back lurching motion....
We plan to go to Campland in San Diego in September and will not need the generator there. We'll try to notice if we have the same problem without the generator/basket attached.

Jerry Snell
2008 TM
2008 Toyota Highlander
5000 # WDH/800 # bars