Front LCA Design

[LS1 240Z]

I was thinking.. could the front LCA be combined with the TC rod to make some sort of a arm? A lot of people make their own LCAs.. and then also TC rods.. what if the TC rod didnt bolt to the LCA but was welded to or part of it. having adjustable ends where it connects to the body at the LCA and at the TC rod.. would this present any issues i am overlooking?

[kyle]

The angle between the LCA and TC rod will change slightly with the adjustment of those parts. Having bolts there allows a small range of attachment.

 

Really, though, why make them one piece anyway? What does it help?

[JMortensen]

There were pics recently of someone who had installed RX7 front LCA's in a Z. They look very similar to Porsche 944 LCAs, by the way. Just in case you're looking for donors...

 

The advantage to that style arm is that you can gain tire clearance by shaping the arm differently than an arm + a rod. I would imagine that the single piece arm is stiffer too, especially an aluminum arm. I do remember that I could really feel the difference between an aluminum arm and a steel arm on a 944, and that was just driving around on the street.

 

The disadvantage is that you either have to adjust caster at the top of the strut (no room in a Z) or by moving the LCA rear pivot side to side (extremely limited room). So if you're going to do this and you want more caster than stock I'd suggest you design it in by placing the arm further forward.

[olie05]

There were pics recently of someone who had installed RX7 front LCA's in a Z. They look very similar to Porsche 944 LCAs, by the way. Just in case you're looking for donors...

 

The advantage to that style arm is that you can gain tire clearance by shaping the arm differently than an arm + a rod. I would imagine that the single piece arm is stiffer too, especially an aluminum arm. I do remember that I could really feel the difference between an aluminum arm and a steel arm on a 944, and that was just driving around on the street.

 

The disadvantage is that you either have to adjust caster at the top of the strut (no room in a Z) or by moving the LCA rear pivot side to side (extremely limited room). So if you're going to do this and you want more caster than stock I'd suggest you design it in by placing the arm further forward.

 

The 951/944s2 front control arms (aluminum) have a caster adjustment at the rear part, something like an eccentric bushing that rotates it about the main pivot point, moving the ball joint end forward relative to the car. Also of note on the 944 steel vs. aluminum arms, the aluminum ones are at least half the weight of the steel ones.

 

If you are getting a donor control arm, you might as well get the donor strut and hub. This way you get their camber adjustment (slotted holes where the hub bolts to the strut) rather than being stuck with one single setting.