Dolly sway?

[Skater]

I have a Stehl tow dolly upon which I tow a 1999 Mercury Cougar. The camper is a 1991 Ford Econoline 350-based B190. The issue is that I get sway at 50-55 mph and it gets much worse from there - at higher speeds, I can feel the sway in the camper (a tail-wagging-dog situation).

Here's what I've checked so far:
1. Jacked the dolly up, spun the wheels - they seem about the same - applied brakes (both have the same resistance to spinning) - released brakes (they still spin about the same).
2. Hitch ball is tight.
3. Car is loaded straight on the dolly, as straight as humanly possible.
4. Car does not exhibit any driveability issues or signs of bad wheel bearings or anything like that. Two new tires on rear, rims were recently straightened. Thus I believe the car isn't the problem.
5. Camper handles fine up to 70 mph when not towing (haven't really tried faster for obvious reasons), so I conclude the problem isn't the camper.
6. Wheel straps are tight and checked during every stop.
7. Car is centered on the dolly, again, as much as humanly possible.
8. Dolly tires are inflated to recommended 65 PSI (probably way more than is necessary for that car, though). Car tires are inflated to 32 PSI, which is what's recommended.

Any thoughts? I sent an email to Stehl with this information asking for advice and they haven't responded. I'm sort of desperate for ideas here... Have people had problems like this with other dollies? (Flat towing is not an option for me.)

Thanks.

[Kevin245]

Have you tried towing a different vehicle to see if the problem still exisits? Ideally you'd have a freind with the same make and model but I'd be surprised if there were lots of 9 year old Mercs just wating around for someone to practice towing.

The other things I would check are:

1. Toe in/out and caster/camber of the dolly wheels

[Kevin245]

Originally Posted by Kevin245

Have you tried towing a different vehicle to see if the problem still exisits? Ideally you'd have a freind with the same make and model but I'd be surprised if there were lots of 9 year old Mercs just wating around for someone to practice towing.

The other things I would check are:

1. Toe in/out and caster/camber of the dolly wheels

2. Are there any odd tire wear issues on the Merc? I'd look for some mis-alignment between the rear wheels and frame that could create an offset condition. If seen some vehciles with mis-aligned rear axles that look like they are going doen the road sideways.

3. Check the dolly tongue for any bend, or bow.

[overlander64]

Greetings Skater!

I, too, suspect that you may need to find a shop that does quality four-wheel alignments to check your Mercury out.

Something else occurred to me, is it possible that the placement of the front of the Cougar on the tow dolly is transferring enough weight to the rear axle/tires to overload the tires/rims? I notice that you mention having the rims straightened -- I know that the changing of weight distribution on my Cadillac when towing my Minuet causes the operating characteristics of my straightened/restored rims to produce a slight vibration. It might be worth locating a known good pair of standard steel wheels with tires that could be tried for a comparison (I am wondering if the sidewalls on the Cougar's tires may be flexing excessively causing your problem). I have always flat-towed or used a flatbed, so I am not particularly familiar with the operating characteristics of a tow dolly.

Good luck with your investigation!

Kevin

[dwightdi]

I would check the state of the shocks on the van as well as the toad. Then, I would add 5 psi pressure to all the tires on the van and retest. If the instability speed goes up a few miles, it indicates the side wall and flexibility in the van is the problem. It also may be the distance the ball for the tow dolly is too far back from the back of the van. Look into whether you could modify the drag bar to reduce the distance. It could be that the toad is too heavy for the van in it current state. They have not made B-vans for some time and there might be some wear in the suspension system on the b van.

[easyride]

I think I would be checking tongue weight,too little weight on tongue and it will be all over road.Are you loading the car? That can really throw off tongue weight. Dave

[Skater]

Thanks for all of the suggestions. Here are some responses, in no particular order:

1. The tires on the camper are inflated to 55 psi front, 80 psi rear. The front recommended value is 51 psi; the rear is 80 psi, and that's the max of those tires, so I cannot add more.

2. The shocks on the camper are old and could be in need of replacement (though I don't think they're bouncing like failed shocks would). I've been wondering if they could be causing the problem but I didn't want to bias the answers.

3. The sidewalls on the tires on the Cougar are actually rather stiff - being a sporty car, the tires are rather sporty (they are BF Goodrich Traction T/As). As I think I mentioned above, they are new.

4. The wheels on the car were straightened due to an incident with Baltimore area roads. The sway problem was visible before they were straightened. I don't have another set of wheels to try.

5. The rear struts on the car are old (91,000 miles), and I believe are coming due for replacement; however, again, this has been happening a while.

6. The car was aligned about 10,000 miles ago for other reasons; I don't drive it that much (about 6,000 miles/year).

7. I am not loading anything into the car; however it is FWD so pretty much all of the weight is sitting on the dolly.

8. The ball on the B-van is within inches of the bumper - I do not have any sort of extended hitch.

9. I don't believe the angle of the car would be transferring too much weight to the rear - I have the same wheels and tires, with the same inflation pressure, so I can't see how I'd be overloading the rear wheels in any way. Moreover, the front wheels of the car are right over the "axle" of the dolly (if it had one).

I really appreciate the suggestions. I'll try to tow my other car, an '04 Chevy Impala, to see if I still get sway, but I really would prefer to have the Cougar working on the dolly, since that's the car I prefer to take on vacations. And to CougarFest.

Thanks.
--RJ

[picture]

Skater,
As you probably know, the Stehl Tow Dolly has no provisions for wheel alignment. My Stehl TD wore out tires at the rate of 1 tire every 1,000 miles. NO help from Stehl after numerous emails and phone calls. Also, no help from the dealership where I bought the TD (Motorhome Specialist in Alvarado, TX). Anyway, you HAVE to align the TD. It is a somewhat painful process, and you may have to find a shop that does frame bending. If you would like details on aligning the TD, please contact me.

Picture

spwrona-tx@hoodcounty.com

[Skater]

First, some more background information for this thread - I was able to test the other car on the dolly, and it swayed, too. This indicates that the car being towed is not the problem.

Also, I got new shocks on the camper, and the situation is better than it was. I still get some sway, but now I feel safer at higher speeds (not that I go faster as a result). It definitely doesn't feel as sloppy as it used to.

Originally Posted by picture

Skater,
As you probably know, the Stehl Tow Dolly has no provisions for wheel alignment. My Stehl TD wore out tires at the rate of 1 tire every 1,000 miles. NO help from Stehl after numerous emails and phone calls. Also, no help from the dealership where I bought the TD (Motorhome Specialist in Alvarado, TX). Anyway, you HAVE to align the TD. It is a somewhat painful process, and you may have to find a shop that does frame bending. If you would like details on aligning the TD, please contact me.

Picture

spwrona-tx@hoodcounty.com

Wow. I'm not going through tires like you were, fortunately. I'll drop you an email, but if you could please post the info here it might help someone else out, too.

I'm glad to hear I'm not the only one that Stehl has ignored. I'm definitely never buying another Stehl dolly again.

I really feel like some of the sway is simply the wind from the van pushing the back of the car around, similar to how it feels when a truck pulls in front of you.

[Chaplain Kent]

I used a tow dolly for a very short time with my 280 turbo diesel. What I experienced was the same thing you describe. You essentially are pulling a trailer with very poor weight distribution. This can be corrected by changing your hitch to attach equalizers, and cams to distribute your weight better and control sway. We sold the Mazda and bought a Saturn which towed four wheel down and had no more problems.
Good luck to you.

[flagwaver]

I have the same problem with my tow dolly wearing the tires out in a short time and with very few miles. In fact, I sold my first tow dolly because it had the same problem and bought one that had only been used once for a 600 mile tow and it did the same thing. I assumed I was loading the car in a manner that was inconsistent with the way the tow dolly was built. However, after replacing the tires and finding the wheel bearings on the tow dolly somewhat loose, I thought I had the problem licked. My next trip after only 1500 miles I found the tires were almost down to the cords. I had a tire shop turn the tires around and used them for another 1500 miles. I haven't used my tow dolly since. I am now preparing to go on another adventure and want to use my tow dolly. I have found a local alignment guy that thinks he can accurately check the alignment on the tow dolly. I will report back to this fourm on what he finds.

[Mikethefixit]

I dont have a tow dolly but You guys may find the reason they ware out the tires is Improper toe- in or cast and camber. Im not a tire or alignment person but I think if you would load up your dolly and take it to an alignment shop and have it looked at they will find its an alignment problem