LCA stiffening plates

[Rbob]

For the restoration guys, does adding LCA reinforcement plates hurt the value - not an accepted practice?

[Burdar]

It's debatable if those plates do anything anyway.  For a stock restoration I'd leave them off.  It's more important that there isn't excessive play between the LCA and the torsion bar socket.  Some were built very sloppily.  I added a small strap to the back of the LCA to take out some of this slop.  It's less noticeable then the reinforcement plates but it's still not stock.  I've heard of people cutting the lower bump stop plate loose, tightening the torsion bar socket by squeezing the LCA halves together, then welding the plate back solid.

[HP2]

The plates are very obvious, so they could be a detractant to the restoration crowd.  If you wanted to look more factory, the TA/AAR arms had a smallish, one inch long strap tucked up and welded inside the arm that performed the same function.  However, unless you are also adding a large diameter anti-sway bar that is going to be severely leveraging the arms, they aren't going to make a lot of difference to the overall feel of the car.

[Rbob]

I need to look at these tomorrow for that 1" strap, I did not know that.

The LCA's are pretty tight so what you say makes sense so I will not use the plates.

Thanks guys!

[dodj]

It's debatable if those plates do anything anyway. 

Pretty sure they do next to nothing as far as "stiffening". 

[FSHTAIL]

Beware of your LCA bolt adjusting block when tightening/re-welding to get rid of the slop,
you're limited by how much you can tighten them up if you use aftermarket that sometimes aren't as narrow as the stockers.
I learned the hard way, I welded the braces on but went only as tight as those blocks and shes still sloppy.

If I had used the factory ones, I could have tightened things up substantially tighter using those.   
Mine were from PST...

[MOPAR MITCH]

I've inspected the factory Posey/Gurney race cars... they don't have their LCAs welded with any plates or mods that I can see... perhaps their vintage rules didn't allow such mods back then.    I've recently added the stiffeners to my LCAs... will be driving/racing soon and will try to notice any difference, but its been ~5 years since i was last on a road course/competition AX track.

[7212Mopar]

Factory control arms are made out of two stamped piece of sheet metal and riveted together and bridged at the top with the bump stop plate. Most have a lot of play at the TB socket and pivot shaft. The LCAs is also use to put torsion load on the TBs. Just look at how rigid other manufacturers make their control arms and you would think it does not hurt to stiffen ours by additional boxing it with a plate at the bottom. I agree it is not for those that needs or wants to keep the stock look. I did it on mine because I wanted to get the best handling out of the factory setup.

[dodj]

I did it on mine because I wanted to get the best handling out of the factory setup.

A good goal, but I don't think those plates accomplish anything noticeable. They don't add any rigidity. Just weight.

[FSHTAIL]

There is less torsional twist with the braces on it, somebody did some sort of a 5-foot pipe fatigue test..   
stock versus braced and it was more than significant.

I did it on mine because I wanted to get the best handling out of the factory setup.

A good goal, but I don't think those plates accomplish anything noticeable. They don't add any rigidity. Just weight.

[7212Mopar]

Lets think about this some more. The pivot pins is held to k frame in a taper hole fairly rigid. The pin is pressed into the LCA bushing that flex. More so with rubber bushing and to a lesser degree with poly bushing. The other end is to the torsion bar cantilevered off the cross member. The strut rod is just restraining the LCA forth and after movement. I would think there is a lot of load at the LCA bushing and that location flex a lot. The slop at the LCA torsion arm pivot would amplify the movement especially when loading the torsion bar under suspension travel. If front sway bar comes into the picture, more load on the control arm and the bushing.

[FSHTAIL]

You got it!

Lets think about this some more. The pivot pins is held to k frame in a taper hole fairly rigid. The pin is pressed into the LCA bushing that flex. More so with rubber bushing and to a lesser degree with poly bushing. The other end is to the torsion bar cantilevered off the cross member. The strut rod is just restraining the LCA forth and after movement. I would think there is a lot of load at the LCA bushing and that location flex a lot. The slop at the LCA torsion arm pivot would amplify the movement especially when loading the torsion bar under suspension travel. If front sway bar comes into the picture, more load on the control arm and the bushing.

[dodj]

There is less torsional twist with the braces on it, somebody did some sort of a 5-foot pipe fatigue test..   
stock versus braced and it was more than significant.

But I can't envision how the LCA would ever see twisting from the ball joint end like in that type of test. The LCA needs to be very rigid in the vertical plane. The mopar LCA is like two 'C' beams riveted together. Much stronger than single piece designs. The welded on "stiffening" plate does very little in this regard. Where it would have any effect is in the horizontal. A force from the front pushing the wheel rearward the plate would resist the two "C" beams from moving relative to each other. But, unless your strut rods are loose, mopar already designed in the fix for that kind of movement. So does the plate do much? I don't think so. Does it hurt? No.
Like mentioned before, unless it was against the rules, the factory trans am cars didn't feel doing anything to the LCA's would help.