Increasing Front Suspension Caster (Upper Front Control Arm Modification)

@panterror posted:

Anyone happen to know what material was used on the factory a-arms. Is it a mild steel or carbon steel such as 4130?

K

Mild steel is 1018 and 1020 or higher. Pertaining to the % of Carbon in the (Iron) Absorbing Oxygen and Creating Steel.

4130 is 'Chrome-Moly'. (banned for Roll Cages by Race Sanctioning Bodies, as 'IT' Does Not Bend, Easily, before the Welds Snap). As is My Understanding.

To Increase the +Positive 'Caster Angle' the (Front) TOP/Upper Ball Joint is Moved REARward. This puts the TOP Ball Joint farther to the Rear in Relation to the Tire 'Contact Patch' to the Road Surface. It Does Increase the 'Centering Effect' of the Wheels, and Increases the Steering Effort.

MJ

I have my arms out and am interested in possibly adding caster however my arms look different than the ones pictured above. Mine do not have that “S” shape to them. Did the earlier cars come with more caster?

Those a-arms are from a '71 car.  They do not have more caster.

John

That's interesting, I've never seen those before. If the rearmost arm of the a-arm is in line with the mounting point then unless the suspension mounting points are different on early cars the upper ball joint would have to be farther rearward. Are the lower a-arms different as well moving the lower rearward? if so that would suggest you could increase caster on an early car by changing to later lower a-arms.

First off thanks for the info. This forum is and has been the greatest thing since sliced bread! Everyone is helpful and very respectful to different directions that people go with this particular car.

I thought about modifying the upper but your theory on the lower maybe different intrigues me. I can’t imagine why they would have changed the pickup points but who knows. Here’s a couple picks of my lowers hopefully someone can notice if there is a difference or not

The upper front a-arms on the '71 Panteras did not have a bend in the a-arm's rear channel. Factory caster is minimal at best, and there isn't any space for caster shims.

According to the orange parts book, there is a First Series (w/o adjustable caster) and a Second Series (w/adjustable caster). The front lower a-arms are listed as being the same.

Regarding the upper a-arms, I would have to either measure the spacing on the '71's upper frame mounts and compare that measurement to that of a '72 (which I don't have available to measure), or measure the a-arm. I suspect that there is a difference.

John

Turns out I have pair of what look to be early a-arms, I'll do a side by side comparison later in the week, when I can get to them, but I'm starting to think the straight arm in relation to the bushing mount is at a different angle on the early ones, so the ball joint lands in the same place.