Quote:
Originally Posted by Dean
As I figure it, there are to ways to adjust what we commonly refer to as Camber.
1. Adjust the angle of the axle relative to the strut at the base by use of camber bolts, etc.
2. Adjust the angle of the strut itself by use of camber plates.
I am trying to figure out the pros and cons of each from a geometry perspective.
Obviously camber plates are easiest to adjust, and the combination can be used to optimize tire clearance issues, but what are the basic geometry considerations to each.
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- (Spindle/strut adjustment): I would say this is the most decoupled camber adjustment. Adjusting the spindle/hub relative to the base of the strut will have the least effects on the front view geometry. SAI will stay the same. Instant center locations & roll center height will change a bit as the strut body angle changes. As that spindle/strut body angle increases (so the strut body itself swings closer to vertical) you will get some more side loading on the strut & possibly more wear/play in the shaft bushings over time.
- (Camber plate adjustment): Has multiple side effects on SAI, instant center locations & roll center height. It's also way easier to adjust than #1. If you're just using it for fine adjustments at the track (within ~2-3*) it shouldn't have noticeable bad effects.
- (Lower control arm): If you have adjustment in your LCA chassis pivot (like with an eccentric), or an adjustable length LCA, you can also adjust camber by pushing the lower balljoint in or out. This will also affect SAI, but probably won't change the instant centers & RCH much if the LCA is near horizontal. With an eccentric I believe it would also affect bumpsteer a bit since the pivot center would rise & fall a little as you adjusted camber.
Off the top of my head I don't believe any of them have a large effect on bumpsteer. If you change caster with caster/camber plates though it will, since the tie rod height changes as the spindle tilts back/forth.
For practicality reasons, I would keep the camber plates roughly centered in their range of adjustment and use #1 & #3 as your gross adjustments in the shop to get the camber close to where you want it. Then use the camber plates as your fine adjustment for final alignment & at-the-track adjustment. You don't want to have to monkey with #1 at the track if you can avoid it.
SAI has noticeable bad effects on dynamic camber when the wheels are steered, but it's a more important consideration during design of the suspension than when the suspension's already been built and you're just trying to align the car. Making sure you have enough range of adjustment in your camber plates is more important IMO than trying to absolutely mimimze the SAI by keeping your upper strut bearings as far outboard as you can get them. You never know when you're going to want/need to make a camber change in either direction.