Boxing in LCAs

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harrisonm

harrisonm

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I have seen the LCA boxing kits, and I was wondering what results it would yield for mostly street driving. I see NO auto crossing in my future, but I wonder If I would notice a difference if I tended to drive just a bit aggressively around traffic circles. BTW, 69 Barracuda Fastback, 340, 4 speed, Hotchkiss Front swaybar.
 
It will limit lower control arm deflection. It will make the suspension do its part more then the parts flexing. Will it make a seat of the pants noticeable difference? Prob not but combined with stiffer tortion bars, sway bars, etc it's a good part to add with other upgrades
 
Cheap enough to do so why not ?
Might make a difference when you hit that unseen pothole by minimizing deflection ?
 
What the plates do is resist deflection by adding shear strength. Looking at it like I do from a construction background, a wall frame is stiffened tremendously when it has plywood sheathing nailed to it. The plywood adds a huge amount of torsional resistance.
Here is a simpler way of looking at it all: The chassis and frame all have some degree of flex that occurs under stress. The less flex, the better the car will handle. These were designed around 6 inch wide bias ply tires so back then, the chassis probably never saw as much force put into it as we are able to deliver with todays tires.
Some upgrades like this are cheap and easy to do and lay the foundation for upgrades in the future.
Backing up a bit....
A solid platform is a great way to ensure that everything bolted to it works to its potential. What I mean is, if you put in bigger torsion bars, sway bars, better shocks and wide-sticky tires, they will not work their best if the chassis is still stock as built when new. The chassis/frame acts as another "spring" in the system, as the suspension goes up and down the frame is moving too. Subframe connectors, torque boxes, Monte Carlo braces, radiator yoke supports, a welded K member...All of these things work together so that the suspension is connected to a solid foundation.
With my 70 Charger, I took a stock K member and welded all the seams fully. The steering box mounts on all of our cars had open voids that allow the steering box to flex and move around. This only gets worse with wider tires and hard use. I made metal pieces to fill in the voids so that the steering box stays in place. I made my own frame connectors and torque boxes and welded them in. It was a pretty cheap upgrade that really gave the car a solid feel.

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This is a 1973-76 A body V8 k member. Even the 67-72 K members have similar condition around the steering box mounting pad. Open voids and even mediocre welds where there IS metal.

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Here is one that has been modified with additional gussets and more welds.

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I did these mods for my brother in laws 72 Duster, my 70 Charger and a project car that I sold 2 years ago.
If you have access to a welder, it as a fairly easy upgrade.
 
I folded a lca on a light curb hit years ago. It bent right around the tension strut.
They'll be done on all my cars now.
 
For what its worth... The aftermarket plates with oval holes are sexy but aren't absolutely req'd. Just a couple of pieces of flat bar welded across will do the same thing ( probably not capture as much dirt and gravel either ). Place them clear of the adjust bolt.
 
I too had my K-member seams all welded and reinforced. I took pictures of it after I had it out and sand blasted. It looked like swiss cheese. Couldn't hardly believe how much weld WASN'T there. Welded reinforcement plates to the lca's and welded in frame connectors. I couldn't believe how much more solid the car felt afterwards. My Dart had so much body flex in it that changing a front tire would prevent you from almost opening the door on that side with the car jacked up. No longer an issue. Like was said in the other posts, its a fairly cheap upgrade to do but well worth it.
 
harrisonm said:
I have seen the LCA boxing kits, and I was wondering what results it would yield for mostly street driving. I see NO auto crossing in my future, but I wonder If I would notice a difference if I tended to drive just a bit aggressively around traffic circles. BTW, 69 Barracuda Fastback, 340, 4 speed, Hotchkiss Front swaybar.
Click to expand...

The weld on plates help, but the weak point on the lower control arms is the cast iron portion that the lower ball joint fits into. It's riveted between the two halves.
 
RedFish said:
For what its worth... The aftermarket plates with oval holes are sexy but aren't absolutely req'd. Just a couple of pieces of flat bar welded across will do the same thing ( probably not capture as much dirt and gravel either ). Place them clear of the adjust bolt.
Click to expand...
you at least need the hole in the middle for the torsion bar adjustment bolt dont forget that! lol

EDIT**** i need to teach myself to read better! you said to clear the adjustment bolt my bad lol
 
jbc426 said:
The weld on plates help, but the weak point on the lower control arms is the cast iron portion that the lower ball joint fits into. It's riveted between the two halves.
Click to expand...

That cast iron portion also has a hole in it where the strut rod passes through. It does seem the weld-on plates could bolster that portion a bit.
 
Normal driver, I wouldn't spend the time to do this.

The more "solid" the lower control arm is, the more energy gets transferred into other parts when it takes a hit in an accident. There is likely some structural design failure limits in that part so energy gets dissipated. When you box them, the design failure points are changed.
 
Most commonly seen fault is the 2 halves spreading apart. Allows the torsion pivot to wobble around more. Draw them back together and tie them with any little something to hold them in place can't hurt. Those aftermarket plates would make them more structurally rigid.
A accident that bent only one half would still lead to replacing the entire arm anyway.
 
I look at it this way if you have the front end apart and you are taking the time to clean and paint the arms. Why not stiffen them up. More then like the two halves have spread apart in the last 40 years and this is a sure fix to solve your problem. Yes you can weld strip of sheet metal across but for the time, effort and for aesthetics I would lean towards a pre fabbed set. We sell a pair for $32 and free shipping within the US.

Thanks
James
 
Thanks for all the comments. I am going to pull the suspension soon for a rebuild. I was planning to use PST so as to support a FABO vendor. I rebuild the front end about 10 years ago using cheap China parts because I was on a tight budget. So the front end will be apart, and I will be powder coating everything. I will be contacting you soon, James.
 
First job needs to be to reduce the play between the LCA and torsion bar socket. Here is a video showing my method.

 
RedFish said:
For what its worth... The aftermarket plates with oval holes are sexy but aren't absolutely req'd. Just a couple of pieces of flat bar welded across will do the same thing ( probably not capture as much dirt and gravel either ). Place them clear of the adjust bolt.
Click to expand...
I agree w/ this post. But I was going to fab my own plates, that were actually more like strips of 1/8" . not as heavy, liter than store bought, but enough to keep them from spreading . Ended up w/ an aftermarket front end, which I modified a little, so it all moot to me now...
 
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