Proper function of an Idler Arm?

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Dusterdenovo

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'73 Duster. I put my steering back together the other day, so put in a new Idler Arm that I had on the shelf from when I bought a front end kit a while back.

After torquing down the Idler Arm bolt to 70 ft.lbs., the Idler Arm is hard to move back and forth, but when I do move it, it goes where I push it and stays there.

I have always thought that an Idler Arm was intended to provide increasing resistance the further away it got from center in either direction, and that it would normally return to the centered position when you "let go" of the steering wheel, to straighten out the wheels after making a turn.

Is this new Idler Arm functioning properly? Have I been confused all these years?

Thanks
 
The purpose is to balance out the Pitman arm as it directs the steering linkage through its travel. Ideally, the Idler and Pitman arms should be the same length.
The tendency to return the steering wheel to center is a matter of proper Caster alignment. The more Caster, the greater the resistance to turning the wheel and the more stable the steering is.
 
It is nothing but a simple parallelogram. It follows the movement "as exactly as possible" to keep the center link located at the idler arm end in exact relationship "as mentioned" with the pitman arm.

IT SHOULD NOT however be terribly difficult to move. If it is, it's either a cheap crap design (I had one) where the bearing/ bushing and the bolt is poorly configured....or you have some hardware missing.
 
Do you guys know if the wheels need to be realigned if you've only changed the idler and pitman arms?
 
You say moderate force. I say that may be too much.
Imagine; if you removed the foam end seals,washed out the grease,and flipped the car on it's side, the weight of the arm should flop it over to the downside. Wheels back on the ground,it should have little to no endplay in the vertical direction.After you grease it up it will no longer flop.The thicker or colder the grease, the harder it will be to turn. Those units are nothing but a smooth center spacer inside a bushing, plus the foam seals.They are also available with a caged needle roller instead of the bushing.
The thing is,any non oem tightness in the design, will prevent the caster/SAI from returning the wheel. This is especially so in the case of tight BJs, but the idler will do it too. And the worst part is that the factory caster spec is zero to negative, so that just leaves the SAI; which I cannot recall how tiny it is anymore, maybe 7 degrees,guessing.Cheap parts used to be the worst. When I was in the front end business, TRW and MOOG were the go-tos. I heard they may no longer be.
 
The purpose is to balance out the Pitman arm as it directs the steering linkage through its travel. Ideally, the Idler and Pitman arms should be the same length.
The tendency to return the steering wheel to center is a matter of proper Caster alignment. The more Caster, the greater the resistance to turning the wheel and the more stable the steering is.
I alway thought it was steering axis inclination that returned the steering to centre on a bodies. Most a bodies normally have almost no caster by design in there alignment setup.
 
It holds one side of the center link up. Period.
 
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