I just picked up what I thought was an older S280 shelter with the mobilizer mounts. KCCLAY and I did the recovery and he mentioned he had a M720 mobilizer that he had got in trade several years ago and if I wanted it, it was mine. Went over today to get it, got the tires and air bags up to stated pressure in the TM hooked it up and left to go home. His place is just off the Hwy and as I was speeding up to merge all of a sudden about 30MPH it started to sway back and forth thinking it would mellow out I kept going, by 40 it was like a drunk baby was driving at 45 I thought it would rip the receiver off the back of my truck. I dumped the speed got below 30 got off the next exit and back to his place. Has anybody else had this problem or is it just me, does this sort of thing not happen with the shelter attached? Tm states 50max highway 15 cross country did they get that backwards?
Shelter is bolted together per the TM btw.
I am going to do another thread on the shelter as that is another bag of worms.
I have an M720 and M1022 and years of experiance with suspension issues.
The problem is the "ALIGNMENT". There are 3 things involved, CASTER, CAMBER, and TOE SET. Toe must be done last. CAMBER has almost no effect on handling.
CASTER will have a dramatic effect on handling, just as you all have been describing.
Now set up your M720 with the load you carry on it. Leveled off and ready to go out on the road.
Wheather it is connected to the truck should make no differance.
You need to make sure the caster angle is negative about 4 degrees. This doesen't sound like much but you can see it with a kittle practice. Less may not be enough. More should be fine. By negative I mean, from the side with the wheel removed as you look at it, the king pin housing should appear to lean toward the rear of the vehicle. This means the top of the pin should be closer to the rear of the trailer than the bottom of the pin.
Probably about an inch.
Some of the finest driving cars on the road have caster angles as high as 11 degrees. That is why when they are going 140mph they feel like they are only going 40mph.
The caster angle is easiest to see on a motorcycle.
Stand about 10 ft to the side of the front wheel and look carefully at the tubes going down from the handlebars to the front wheel axel.
If you follow the direction of those tubes you don't get to the point where the tire touches the road. The tire touches the road several inches behind that axis. By doing this caster causes the tire to want to naturally follow the tire as it travels down the road.
Happy, and safe, travels. Thank you all for your service to our home, the USA.
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