Quote:
|
Originally Posted by ddnavar
Has anyone considered the changes in aerodynamics and not the weight distribution? Don't know if a bike would change the aerodynamics that much, but I know the faster I go over a certain speed, the more sway I have on my 3124ks.
Of course that certain speed is 75 mph -- as fast as I dare go.
I live in Colorado and constantly go up and down I-70 with my 6 cyl 2000 4-runner and can get speed downhill very easily.... 35-40 mph uphill on the 7% grades.
I have air shocks "100 psi when towing" and no sway bar or equalizer hitch. May consider buying the equilzer hitch. http://www.trailmanorowners.com/foru...ote=1&p=16323#
New Eyecrazy |
The reason you have sway isn't aerodynamics, it's mostly because you're unwisely using air shocks to level your 4-Runner and partly because a 3124KS is just too long a trailer for your 4-Runner.
The air shocks are masking a fairly severe front/rear loading on your 4-Runner's suspension...and that's where most of your sway is coming from. When you hookup a trailer with a heavy hitch weight like the 3124KS (probably around 600 lbs), you're not only pushing the rear end down, you're also causing the front end to rise through a teeter-totter effect with the rear axle as the fulcrum. Because 200 to 300 lbs of weight was taken off the front end, your front tires have much less control over the vehicle and much less ability to fight transients coming from the trailer. The net effect is you get sway. The 2000 4-Runner is a short (105 inch) wheelbase vehicle that's barely long enough to control a 24 foot trailer; raising its front suspension is making a bad situation a lot worse.
Then when you raised the rear suspension with the air shocks to make the 4-Runner level, both ends are now actually
higher than stock. That makes a dangerous situation even worse...much worse. Reason: on the rear axle of your vehicle is a Brake Proportioning Valve. Its purpose is to limit the amount of brake pressure on the rear brakes when the vehicle is lightly loaded (to prevent lockup) and to enable more rear braking when the vehicle is loaded (rear suspension compressed). By raising the rear of the 4-Runner to level it with the too-high front, you've basically closed this valve and your rear brakes are doing virtually no braking...your front brakes are doing almost the braking. And worse, those front brakes are trying to brake tires that only have about 80% of their normal friction because the front end has been unweighted.
The bottom line is air shocks are downright dangerous and should be banned from the market.
AIR SHOCKS SHOULD NEVER BE USED TO LEVEL A TOW VEHICLE.
You can solve all this by simply getting a weight distributing hitch. Then, instead of the front suspension being unweighted, it will be additonally weighted with about a third of the hitch weight. So instead of removing about 200 lbs from the front, you'll be adding 200 lbs. That additional 400 lbs on the front will make a huge improvement in your ability to steer and your sway problems will very likely mostly disappear. The sway may not entirely disappear because your trailer is simply too long for your 4-Runner to fully control.
And even better, because both the front and rear suspension on the 4-Runner are being equally compressed, the Brake Proportioning Valve will be opened more, thus enabling your rear brakes to actually contribute to the overall braking effort.
As is, your rig is so marginally controlled that I shudder at the thought of having to share a Colorado highway with you.