Sharp Tugging on Towed

Healeyman wrote:
Just bought a new RV and am pulling the same Miata towed.

Because my new 30 ft. RV has about 3 ft. more overhang than my previous 22 ft. RV, while going over a series of bumps or especially RR tracks, the towed will experience a violent pulling and pushing as the back of the RV bounces up and down and the angle of the tow bar changes and that suddenly changes the distance between the RV and the towed.
.....

Whenever there is a change in the road height (train tracks, dip in the road, transition into a driveway, etc.) you will feel the toad. That part is normal.

What caught my eye is your use of the word: violent. It reads like you're towing the car with a tow strap.

Look at your tow bar. Are both arms on the towbar locking when fully extended. They both need to lock. If not, the car will roll a few inches (develop slack) into the towbar when you brake or go through road changes, and you'll feel a strong tug against the towbar when the MH accelerates and the towbar arm (or arms) extend to pull the car.

I can only tell you what I believe to be the cause. All I can think of now would be do the most you can to dampen bouncing on the rear springs. It's new, new shocks, but are they HD and/or adjustable like Bilstein or Koni? Maybe install a full air-ride rear suspension? I can't guarantee success with either.

I'm not overjoyed with how Ford chassis like to wander on the road, and I'd like more cab room. Still, Ford allows more wheelbase stretch than GM does. I wonder if the coach/chassis combination you chose is limited in wheelbase by the GM chassis.

Another school of thought is that the interior designers place a certain rear bedroom design above what the overhang does to handling on the road. They need the wheel wells out of the way.

Letting form govern function is common but shouldn't be allowed. We've had a member trade a coach in because of issues involving overhang.

Go get your old Four Winns back! well...I don't know what else to say.

Now to the issue. Just how much extension is behind the chassis frame, and how is it constructed and connected to the frame? Depending on the construction of the chassis extension, can it be re-enforced if that is the problem. And I don't know if that will help, and there is a awfully lot of overhang there!!! That has become something about some motorhomes, including gas powered Class A's, that I really dislike!

Shock absorbing receiver

The upper portion is the shock absorber. Perhaps you could replace the bottom portion with your tow bar stinger.

Good Luck
Eric

I think all you can do is to go DEAD SLOW over those bumps. Crawl up and crawl down.

imgoin4it wrote:
I do not think it will solve all the problem as you describe, but I would get a "hitch tightner". Blue ox as well as others sell them and they take all the "play" out of the tow bar / receiver connection. I have a drop receiver so I have 2 connections and the two tighteners make a world of difference.

In looking at half a dozen "Hitch Tighteners" it appears as if they are made to eliminate the see-saw up & down rocking, on the hitch pin, of the tow-bar tongue within the hitch receiver tube.

I am using two hitch pins through my receiver tube so that there already is no up-down movement.

I don't see how a hitch tightener will remove the violent Pull-Push of the tow bar on the towed car.

It seems to me that only a front-back motion snubber will do that and it appears as if no one has ever built one.

I guess that I'll be the first....

Tim

j-d wrote:
Just looking at the picture, that coach looks like it has a very long rear overhang with respect to wheelbase/overall length. I can see where it'd really whip on the towbar. Result would be coach trying to jerk the toad up and ahead, or shove it back and down.

j-d,

Isn't THAT exactly what I said in my original post???

The question is HOW does one fix or stop that?

Tim

Just looking at the picture, that coach looks like it has a very long rear overhang with respect to wheelbase/overall length. I can see where it'd really whip on the towbar. Result would be coach trying to jerk the toad up and ahead, or shove it back and down.

I do not think it will solve all the problem as you describe, but I would get a "hitch tightner". Blue ox as well as others sell them and they take all the "play" out of the tow bar / receiver connection. I have a drop receiver so I have 2 connections and the two tighteners make a world of difference.

I feel the tugging when pulling my truck, particularly on dips in the road. This is why I frequently inspect my tow bar, hitch, and base plate connections, and slow down for rough roads. A single incident can take loads beyond what was considered in the design of towing systems, especially mountings for towing brackets or base plates.

Also why I won't pull a vehicle precious to me, and why many manufacturers recommend against recreational towing when there are no transmission lubrication issues: towing is hard on the vehicle being towed.

I don't think the change from your previous rig means the forces are necessarily more, just that you feel it more with the change in length. I think it is good that you now feel it. I cringe at the common expression "I don't even feel it back there." The towed vehicle is back there, and things can be happening that you really want to know about. Did you ever see the picture of the Explorer SportTrac that was towed in Park, aluminum wheels ground flat until the vehicle was resting on the brake disks?