Setting camber/caster (help)

[Mrbill426]

I have found lots of text about cam/caster, and toe specifications and in what order to do each,  but I have not seen any "visuals"  pictures or even video regarding which upper control arm bolts do what and which positions of the eccentrics result in negative or positive results.  Does the front arm bolt do one adjustment and the rear bolt do another?  I do have a factory Chrysler/Plymouth chassis manual and it covers front end height and toe in pretty well but it gives ZERO details on adjusting camber/caster other than to say to set them to spec.    I just need to get the car set up close so I can get it safely and maybe even somewhat "straight" to an alignment shop for fine tuning.

Thanks

[Bullitt-]

I rotated the rear eccentric so the back or the UCA was max inboard * the front so it was max outboard.
Measured caster was about 1.5 degrees.. don't remember the camber # but it was spot on to the service manuals #

Check this article  http://www.allpar.com/history/mopar/front-end-alignment.html

[Mrbill426]

@Bullitt- ok interesting chart and I appreciate the response.  I am thrown  though by the question on it and 4 different picture answers without explanations as to results of each.   Apparently I am getting thick headed in my old age.

I rotated the rear eccentric so the back or the UCA was max inboard * the front so it was max outboard.
Measured caster was about 1.5 degrees.. don't remember the camber # but it was spot on to the service manuals #

Check this article  http://www.allpar.com/history/mopar/front-end-alignment.html

[Bullitt-]

  Most everyone is looking for Maximum positive castor, to achieve this the rear of the UCA needs to move in & the front needs to move out. This causes the upper ball joint to move back creating the +castor.   
Rotating the eccentric of the alignment bolt where the fat is toward you pulls the UCA in. Rotating the eccentric of the alignment bolt where the fat is away from you pushes the UCA out.    #4 in the original diagram is Maximum +castor for the left wheel

[73_Cuda_4_Me]

It helps to picture the cam bracket that the adjusters sit in, so that as the adjuster is turned, the center of the bolt (which is the center of that side of the control arm) moves closer to the center of the vehicle (inside), or farther away from the center of the vehicle (outside).

The bracket holds the outside of the cam in position, so only the bolt centerline changes, changing the centerline of that side of the UCA.

The pictures would be easier to understand first try if they were all in one column, so there is no confusion on inside or outside, but once you understand the way they work, it is clear no matter how they are shown.

[CHL2T]

  Most everyone is looking for Maximum positive castor, to achieve this the rear of the UCA needs to move in & the front needs to move out. This causes the upper ball joint to move back creating the +castor.   
Rotating the eccentric of the alignment bolt where the fat is toward you pulls the UCA in. Rotating the eccentric of the alignment bolt where the fat is away from you pushes the UCA out.    #4 in the original diagram is Maximum +castor for the left wheel

Thanks for this simple diagram and explanation, I need to do this very thing to see if I can stop my new tires from rubbing the bottom edge of the fenders

[Mrbill426]

Thanks everyone, I think I got it.  However... unless I missed it here is Camber a mute point in these adjustments??

[Bullitt-]

The same eccentrics adjust the camber so if not in spec once the castor is set you would need to back off the maximum a little to attain.  Only looking at a smidge of negative camber (top tilted in) like .25 to .5 degrees.. My biggest hurtle was creating a device capable of measuring this.   

[HP2]

Caster and camber are interdependent on a mopar because they are all adjusted with the same eccentrics. Typically you would set them for max positive caster, and then move towards zero or slight negative camber by taking away caster.

Of course you can do the old racer trick and put washers between teh spindle and lower ball joint. This increases negative camber capability so you don'thave to take away caster to get camber.

Also would add that any rear end rake you have will similarly reduce the top numbers of caster/camber you can achieve as you will use up a percentage of adjustment to get into spec.

[Mrbill426]

@HP2 thanks.  From what I have been reading elsewhere people are recommending getting the maximum castor possible when using radial tires (I am) so would that not be sacrificing the "taking away caster" step under normal circumstances.. meaning no racer tricks?

Caster and camber are interdependent on a mopar because they are all adjusted with the same eccentrics. Typically you would set them for max positive caster, and then move towards zero or slight negative camber by taking away caster.

Of course you can do the old racer trick and put washers between teh spindle and lower ball joint. This increases negative camber capability so you don'thave to take away caster to get camber.

Also would add that any rear end rake you have will similarly reduce the top numbers of caster/camber you can achieve as you will use up a percentage of adjustment to get into spec.

[HP2]

Radials will tolerate a broader range of adjustment than bias plys.  This is more related to camber and toe than caster. Camber and toe create create more wear than caster. More positive caster tends to have several benefits - better return to center motion, improved high speed stability, greater camber changes when turning, and a positive for a power steering a mopar, increased steering effort.

Camber is what keeps the tire tread in contact with the ground as the car turns. The softer your springs and the more body roll you have, the more static camber or greater camber gain via upper control arm length, a car will need. Higher spring or sway bar rates that create less body roll will require less camber.

Toe is what takes up the slack in the steering system and angles the tires relative to each other for driving. A slight negative toe reduces scrub while allow the tires to become parallel during driving. It also will contribute to the feel stability. too much toe in will make a car feel unstable, too much will make it feel "darty".  Toe out can also increase corner entry stability and increase ackerman effect, which is the need for more angle on the inside tire compared to the outside tire in a corner. Toe also produces a lot of scrub on the tread face if it is not zero.

For a normal cruiser, positive caster in the 3-5* range is fine. You can couple that with 0-.5* negative camber. More aggressive driving you will want to add more negative camber. Toe would only be enough to get to zero under motion, which is 1/16" or fractions of a degree, depending on tire height.

[Mrbill426]

@HP2 thanks for the info.    I guess I will shoot for as close to the original specs as possible to start with since radials are more tolerant and see how it goes.  What I don't want is odd tire wear attributed to alignment issues, and for the car to go straight down a strait properly crowned road without fighting the wheel.

[tparker]

I learned all this stuff just out of high school and probably a bit rusty on it. Camber is essentially the vertical alignment of a tire from 90 degrees off the road. If the top of the tire leans in our out, that will put more pressure on one edge of the tire and cause wear. Caster has to do with the angle of the of the pivot points. This affects stability and turning. Think sports bike(steep angle) vs a chopper (shallow angle). Also, a shopping cart front wheel has castor behind the center of the wheel. Castor doesn't affect tire wear since it doesn't change any angle off of the rotation direction.

Castor is often not adjustable. I THOUGHT we couldn't do this on the Challenger. So I am learning something here. I worked very briefly at a tire shop doing alignments, but that didn't last long and was 30 years ago. I did my challenger back then and for some reason I have it in my mind I couldn't adjust castor. The eccentric cammed bolts up top move the upper control arm around. I think in a circular position as you rotate the bolt. Turning the bolt would push out the upper control arm or pull it back in thus effecting camber. I am confused how this would adjust castor though. Maybe I am missing something.

Not sure if this adds to the discussion, but thought I'd through it out.

[tparker]

Hi @CHL2T, How do you see alignment giving you clearance? This isn't something I would normally think would give you any extra clearance. Adjusting torsion bars to raise the car up a bit might do it, but there are trade offs.

[Mrbill426]

@tparker it does... come on in, plenty of room for everyone 

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Not sure if this adds to the discussion, but thought I'd through it out.