Don't fully understand tubular control arms

[Magntik]

so I'm still trying to figure which arms to go with and they all seem to have the "slugs" for caster adjustment(?)

So I don't understand how they work exactly. I read some other posts and it seems these are a good thing, they let you add positive caster( I think that was it) but here's my confusion, and I hope some one can explain this to me...

1. Do I need positive caster for 95% street driving?
2. Can I use these arms without adding caster?
3. I'm figuring the way the slugs are installed in the cross shafts, determines how much is added? But which way does what?

Do these arms come with instructions explaining some of this so you know before you bolt everything together?

[MrQuick]

1. Do I need positive caster for 95% street driving? no but it makes it nicer when you have it.
2. Can I use these arms without adding caster? You need at least a stock caster number and the slugs make it adjustable.
3. I'm figuring the way the slugs are installed in the cross shafts, determines how much is added? But which way does what? The slugs have off set holes that moves the upper arm back or forward to tilt the spindle back or forward. The slugs help avoid a large shim pack.


I'd rather use a lower control arm that increases the caster cause it moves the tire away from the rear of the wheel well. You might lose tire clearance with the adjustment on the upper arm.

[dipren443]

FYI, DSE, Hotchkis, and SPC lowers add positive caster.

[Magntik]

The slugs have off set holes that moves the upper arm back or forward to tilt the spindle back or forward. The slugs help avoid a large shim pack.




one more set of newbie questions...

1. Are the slugs marked?
2. How do I know which way moving the arm does what?
3. Do I want the spindle tilted back for more caster or forward?

Thanks for the info.

Jeremy

[dipren443]

one more set of newbie questions...

1. Are the slugs marked?
2. How do I know which way moving the arm does what?
3. Do I want the spindle tilted back for more caster or forward?

Thanks for the info.

Jeremy

Jeremy,

I am going to suggest that you read some basic alignment tech. Educating yourself now will help you in the long run. You can keep asking many of these simple questions on here and slowly make headway, but if you do some basic reading, you will be steps ahead of the game.

http://www.ozebiz.com.au/racetech/theory/align.html

http://www.familycar.com/alignment.htm

[LSx_88_Ciera]

The best way to explain what caster does is with the car not moving turn the wheels from full lock left to right or vise versa and notice that one side of the car lifts up this gives you better stability in a straight line and return to center. The farther you move the top of the steering knuckle/spindle towards the rear the more positive the caster. Caster is a non wear alignment angle and the best angle to use to compensate for road crown. Typically with manual steering you want between .5 & 1° of positive caster and with power steering you want 3 - 5° of positive caster. The more positive camber you have the more force is required to turn the wheel. The only other effect caster has is that if you have excessive positive caster it can cause the ride to become more harsh.
You should never have negative caster for an example of the effect of negative caster go in reverse at a decent speed and turn the wheel a little bit (CAUTION) and feel the force that is created that makes the wheels want to turn further instead of returning to center.

[Magntik]

Thanks for the info, but I think I may not have been real clear on what I was asking.

I am wanting to know more about the upper arms and slugs themselves and how to know what way to install them, and what that does for me. I"m trying to educate myself more on the arms and less on the alignment.

In my city I only know of 1 guy that will align my car. The big box places say their machines can't do it. And the guy I go to is great but sets the specs to what I give him, and I want to make sure when I take the car to him, install on new arms was done right.

[dipren443]

Thanks for the info, but I think I may not have been real clear on what I was asking.

I am wanting to know more about the upper arms and slugs themselves and how to know what way to install them, and what that does for me. I"m trying to educate myself more on the arms and less on the alignment.

In my city I only know of 1 guy that will align my car. The big box places say their machines can't do it. And the guy I go to is great but sets the specs to what I give him, and I want to make sure when I take the car to him, install on new arms was done right.

We are trying to be as helpful as possible. If we spell everything out for you, then what have you learned? Think about where the slugs go... Lets draw a straight line running through the middle of the car front to rear...

Depending upon which slugs you install, this will install the control arms closer to the front or closer to the rear of the vehicle with respect to that line. The further to the rear, the more POSITIVE caster. The closer to the the front, the less POSITIVE caster.

Three scenarios:

Front - Spindle Orientation - Rear

F - l (Zero caster) - R

F - \ (Negative) - R

F - / (Positive caster) - R


The manufacturer of the control arms shall provide recommended alignment specs.

[exwestracer]

If the thick part of the slug is facing out (toward the tire), it will push that mount OUT. If the the thick side is facing the engine, it will pull that mount IN. So for more positive caster, you would install the front slug thick side out, and the rear slug thick side in.

Both installed thick side out will give neutral caster and more positive camber. Both with thick side facing engine will give neutral caster and more negative camber.

Since this is the only adjustment your alignment guy has to play with, he will probably have to move them around to change anything anyway...right?

[MrQuick]

If the thick part of the slug is facing out (toward the tire), it will push that mount OUT. If the the thick side is facing the engine, it will pull that mount IN. So for more positive caster, you would install the front slug thick side out, and the rear slug thick side in.

Both installed thick side out will give neutral caster and more positive camber. Both with thick side facing engine will give neutral caster and more negative camber.

Since this is the only adjustment your alignment guy has to play with, he will probably have to move them around to change anything anyway...right?
The inserts (slugs) I assume he is talking about are the same thickness. The hole location is the only difference. Moves the upper arm forwards or back.

https://static1.pt-content.com/images/noimg.gif https://static1.pt-content.com/images/noimg.gif

[Tom Welch]

SC&C-------> sponsor--------> good info------> lather, rinse, repeat.

[exwestracer]

The inserts (slugs) I assume he is talking about are the same thickness. The hole location is the only difference. Moves the upper arm forwards or back.

https://static1.pt-content.com/images/noimg.gif https://static1.pt-content.com/images/noimg.gif

WHOOPS! My bad... Sounded like he was referring to offset bushings on the pivots...

I guess a picture IS worth a thousand words...:idea:

In that case, holes to the front of the car is + caster.