lower control arm 1972 Duster
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J-c-c
Well-Known Member
I have yet to hear anyone in over a decade make the case as to removal of the movement you cite that would have any beneficial upsides.
It might seem odd and abnormal and difficult to understand, but in actual use it has no significant negative effect, as long as we are not talking damage from say an accident, etc.
The only time the "slop" enters the picture is when backing up, or wheel is off the ground and if moving, in a vacuum, or the wheel magically is in motion with zero drag/friction.
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@72bluNblu Has lots of experience with this.
@Jim Lusk ’s video covers it pretty well. I clamp the end with the pivot lever together before I weld the boxing plate on the bottom, and then in addition to the boxing plate I add a strap to that end. You want to limit the play, but don’t make it so tight that there’s resistance between the pivot lever and the LCA.
Now, as for the play itself. When suspension is fully assembled and the LCA is loaded, the LCA, pivot lever and pivot all move up and down together, twisting the torsion bar hex end. And the ball joint end of the LCA is constrained by the strut rod.
Under most driving conditions having some slop between the pivot lever/pivot and LCA isn’t likely to be much of an issue, they’re all going to move together. Which is why the factory wasn’t too worried about that slop. I haven’t rebuilt as many LCA’s as Jim by a long shot but pretty much all of them have that play in them.
But under more extreme conditions, you’re going to put more load into the LCA and having that slop there is an opportunity for there to be flex and movement, and if the ball joint moves around the alignment changes and the handling will feel sloppy.
So, the usual “it depends”. If you’re keeping all of the factory rubber bushings, especially at the strut rod, then the movement there will allow the LCA to flex and move quite a bit, which makes the flex in the arm less important. The rubber bushings will give before the loaded LCA will flex.
But if you’re going adjustable strut rods, poly/delrin LCA bushings, wider softer tires etc then removing that flex and slop in the LCA is important.
Now, as for the play itself. When suspension is fully assembled and the LCA is loaded, the LCA, pivot lever and pivot all move up and down together, twisting the torsion bar hex end. And the ball joint end of the LCA is constrained by the strut rod.
Under most driving conditions having some slop between the pivot lever/pivot and LCA isn’t likely to be much of an issue, they’re all going to move together. Which is why the factory wasn’t too worried about that slop. I haven’t rebuilt as many LCA’s as Jim by a long shot but pretty much all of them have that play in them.
But under more extreme conditions, you’re going to put more load into the LCA and having that slop there is an opportunity for there to be flex and movement, and if the ball joint moves around the alignment changes and the handling will feel sloppy.
So, the usual “it depends”. If you’re keeping all of the factory rubber bushings, especially at the strut rod, then the movement there will allow the LCA to flex and move quite a bit, which makes the flex in the arm less important. The rubber bushings will give before the loaded LCA will flex.
But if you’re going adjustable strut rods, poly/delrin LCA bushings, wider softer tires etc then removing that flex and slop in the LCA is important.
J-c-c
Well-Known Member
Please delineate the Slop, movement and flex you are referring to above.
I'm not seeing it, or that it has any appreciable negative effects you note, if any
Do we agree the TB end of the LCA's main task is to transfer rotation/lever arm forces to the TB, and since braking forces (when moving forward) acting thru the LCA are redirected to the rear by the resistance of strut rod, and those forces are reduced by ratio distance of the strut connection to the BJ to the distance of the strut to the TB pivot point, in an opposite direction?
In most situations, if not nearly all, the BJ end of the LCA is being forced/loaded rearwards, the TB end of the LCA is the direct opposite direction with reduced force, by the action of the strut LCA connection being a pivot point.
It's hard to imagine when those forces would ever reverse, and using up any inherent slop in the design, that would effect handling.
Additionally, there has to be slop somewhere in the TB typical Mopar IFS, in that the LCA and the Strut are in conflicting arcs, and suspension bind would result if totally eliminated.
But regardless, I am all ears.
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Jim Lusk
Well-Known Member
As stated, I have rebuilt many lower control arms. I have found varying degrees of slop, which I believe MIGHT cause the clunk sometimes heard when turning while backing. I don't have any proof of this, but there's really no reason not to limit the slop. Interestingly enough the LCAs from our GTS convertible are among the least sloppy I have seen. This is a car with around 155,000 miles so it doesn't necessarily seem to be a wear problem, but a manufacturing problem.
J-c-c
Well-Known Member
I agree on all your above points and on face value that seems to dovetail rather well with my shared contention, and as long as everyone is making their own choices well informed, all is good in the world.
Sure, if you’re drawing a force diagram it’s really easy, you have the rotational force at the LCA socket acting on the torsion bar, the suspension input at the lower ball joint and the constraint from the strut rod. Easy, simple, and not the whole story.
Just drawing that diagram assumes the LCA is completely rigid. If you’re just calculating forces that’s a decent assumption, it won’t change the total force numbers and it’s why those assumptions get made for the calculations. But if you’re measuring alignment changes in the suspension while it’s under load it’s a terrible assumption, because the LCA is not absolutely rigid (nothing is, but especially not the factory LCA).
The reality of it is that the LCA flexes forward and backwards. It twists, because it’s dimensional and the suspension forces act at multiple points (ball joint, strut rod mount, sway bar mount, shock mount, pivot socket, torsion bar adjuster). Sure, most of those are short levers but just the car sitting on its wheels is an 800+ lb load on the LCA, forget moving at speed, braking, turning, etc. And a lot of those cancel out, which again, is great in a force diagram. But they’re not point loads, they don’t all line up, and because the LCA has dimensions it means those loads twist and torque that arm. The slop between the socket/pivot and arm will allow the ball joint to move around, the big sloppy rubber strut rod bushing lets the whole assembly shift forward/back, twist, etc. And the better the tire you put up front, the more that happens.
This isn’t my video, but it shows the movement at the strut rod with rubber bushings. If you focus on the head of the strut rod, you can see how much it moves. Well the other end is a solid connection to the LCA, so every movement at the end of the strut rod is coming from movement at the LCA.
Was a lot of that slop between the pivot and LCA body baked in from the factory? I bet a lot of it was. And yeah, with bias ply tires and big soft rubber bushings that’s probably fine, for 1970’s handling. Start improving performance, and therefore suspension loads, and that slop lets the car wallow around and leads to vague steering/suspensions responses.
As far as binding, I have Delrin LCA bushings and adjustable strut rods. If you set the length of the strut rod correctly there’s no binding within the range of travel of the suspension. The different arcs all line up well enough before they diverge that you can tune the binding out and match that up with the suspension travel range, since you’re only talking about ~5” to 5.5” of travel anyway.
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J-c-c
Well-Known Member
You seem to be moving the goal posts to suit your postulation. Stating everything flexes in an engineering sense is only stating the obvious. The LCA's are not flexing in ANY significance, they maybe moving longitudinally slightly on their pivot points. If this nearly 3.5" nearly boxed 11g(?) pseudo I beam LCA is overly flexing in your view, you then must be horrified by the QA1 1.5"(?) tube LCA set-up. In this attached video. you do see movement that the strut is intended/designed to control, and that is mainly under braking. I don't see the significant importance here of this video. What am I missing? The LCA pivot points were never intended to be rigid in more then two axis. The fact remains the strut and the LCA have conflicting arcs which you claim is not a factor because of its insignificance but the slop is significant, without basis, on this thread the slop has been antidotally by another to have only been noted/observed only when backing up. Your contention(?) of the longitudinal LCA slop and LCA flex, real or imagined leading to vague steering responses is still without basis.
Edit: I did see the lack of something maybe in the video. If as claimed the LCA was flexing and or rotating, the strut rod that is rigidity attached to it, and is approx. 16" long, would visually significantly amplify any rotational flexing of the long axis of LCA, as would be seen on the rubber mounted bolted end of the strut rod. I saw no detectable movement vertically nor bending of the strut rod nor unexplained distortion of the rubber bushing. Most movement seen was reaction to the braking action firstly and then normal compression/rebound action. Adding a temporary telltale brake light indicator in the video would help in future recording to distinguish suspension inputs.
Edit: I did see the lack of something maybe in the video. If as claimed the LCA was flexing and or rotating, the strut rod that is rigidity attached to it, and is approx. 16" long, would visually significantly amplify any rotational flexing of the long axis of LCA, as would be seen on the rubber mounted bolted end of the strut rod. I saw no detectable movement vertically nor bending of the strut rod nor unexplained distortion of the rubber bushing. Most movement seen was reaction to the braking action firstly and then normal compression/rebound action. Adding a temporary telltale brake light indicator in the video would help in future recording to distinguish suspension inputs.
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With the rain, the track's gonna be slick
Oh, this baby loves the slop. Loves it, eats it up. Eats the slop. Born in the slop. His father was a mudder.
His father was a mudder?
So was his mother
His mother was a mudder?
Oh, this baby loves the slop. Loves it, eats it up. Eats the slop. Born in the slop. His father was a mudder.
His father was a mudder?
So was his mother
His mother was a mudder?
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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On the street, it is a non-issue. and is actually required during braking, to prevent a bound-up situation.
just send it!
just send it!
Moving the goal posts? Yeah, no. Still just talking about the slop in the LCA and why it's relevant.
My point in bringing up all of the different forces acting on the LCA was not to highlight the fact that there is flex in the LCA structure, because of course everything flexes. My point was rather that the SLOP in the LCA, which you say isn't important, is in fact an issue because the LCA is constantly subjected to loads that don't just act rotationally at the pivot point. Which means that the slop that's highlighted in Jim Lusk's video between the torsion bar socket, pivot arm and the halves of the LCA is in fact an issue. Because if those forces can flex the LCA, they can cause the LCA to move around in all of that slop. They can even spread the halves of the LCA which will allow the LCA to move about on the socket/arm. And if they can do that (they can), then the slop between the halves and the socket is an issue that should be corrected. You want the LCA to just pivot about the socket like it would in a simple force diagram, and any movement of the LCA around the socket will create alignment changes that you don't need. But doing that means the LCA has to be able to resist the forces that act in different directions, which it won't do if it's sloppy at the socket end.
I included the video only because it shows that even on a simple drive around the block (which is what was happening in the video), there is significant forward/backward movement of the LCA, even just under very boring driving situations. Maybe that wasn't news to you, but it isn't something that a lot of people understand. And because the video shows that the LCA does in fact move around forward/back it further highlights that in the real world you don't just have a simple rotational force at the socket. The video was an attempt by another member to locate a different issue, it's not mine (as I stated).
The diverging arcs of the strut rod and LCA are important, but only in that you need to make sure that the LCA and strut rod are not binding within the range of travel of the suspension (which is easily done even with delrin LCA bushings and adjustable strut rods). This is where you didn't follow at all. The arcs of the strut rod and LCA overlap well enough in the range of travel, and the ~5" to ~5.5" of suspension travel most of these cars have from the factory is a relatively small section of the total arcs created by the LCA and by the strut rod. You try to equate that relatively large suspension travel to the relatively small amount of slop/flex in the LCA, but those are completely different things. The suspension travel is a lot larger, but that distance is small compared to the diverging arcs. The slop and flex is much smaller than that, but it results in movement in the ball joint, which means caster and camber changes that are not built into the suspension geometry. That slop is small, but it results in variable changes in the geometry that are reactive to changes in load, which is what creates vague handling. The changes that occur on the defined arcs are what we plot out as camber gain, bump steer, etc, and because they're created by defined geometry that isn't variable we can plot it, evaluate it, and correct it if necessary. You can't do that with the changes you get from slop.
The QA1 LCA is also more rigid than the factory LCA's, so your claim there is false. Although this is obvious if you actually have seen both of them side by side or run them on your car, it was actually tested by Mopar Action in the April 2011 copy. This was actually when CAP was still making the arms, before QA1 bought them out and improved the design (they're stronger now). Mopar Action tested the factory LCA supported at the load points, the rivets popped at 2,800 psi. The CAP arm didn't fail until 7,700 psi (must not have had bad welds that CAP became known for), when it still failed in bending. From the article...
Regardless, this isn't just "postulation" on my behalf. I certainly didn't come up with the idea to box and strap the factory LCA's, that was done by the guys that were circuit racing these cars decades ago. Probably the most telling fact though is that Chrysler redesigned the control arms on the later cars, starting in '73 on the B-body cars and continuing from there on the later cars that were heavier and got factory radial tires.. The LCA's on those cars are not halves connected by rivets like on the A's, and their construction surrounds the torsion bar socket/pivot so the slop between the socket and the LCA is greatly reduced.
A Chrysler "kit car"- notice the large strap on the LCA tying the halves together
The later B-body LCA - no rivets, no halves, socket/pivot captured completely by the LCA to reduce slop
So, do what you like. Doesn't hurt my feelings if you leave the slop in the LCA's on your car alone. But, having driven Mopars with factory LCA's, boxed and strapped factory LCA's with the slop removed, and the improved QA1 LCA's, well, the handling is more responsive and less vague than the unmodified factory stuff was. So, I'm going to keep boxing and strapping the factory LCA's if I use factory LCA's at all.
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J-c-c
Well-Known Member
So when was the last time you EVER heard of an OEM mopar LCA failing by popped rivets of the literally millions out there for over 6 decades of use?
Why is nobody marketing LCA high strength bolts as a weakest link rivet upgrade?
You haven't because the test loads are never achieved under ANY driving conditions that we here face. The reason being the real world loads are mostly limited by a torsion bar rated in the 200lbs/in and travel can't exceed approx 5 in with a preload of less than 1000lbs, hitting wheel destroying potholes or banked concrete retaining walls excluded. IF the LCA is flexing, and as agreed to earlier they ALL do, upping the TB rate ever so slightly completely offsets that minute flex.
I am skeptical of the CAP reported test results above anyway, as to what the complete test conditions were or if the test was skewed to achieve the results reported.
I have not seen the QA1/OEM LCA side by side. I have QA1 at PRI and in press releases. I find the claim unsupported and likely misleading and inconsequential anyway as to the "flexing" concern. My initial impression at PRI was how frail compared to OEM they might be but couldn't decide why they were not up to the task.
I completely disagree the LCA TB pivot points is to suppose the prevent LCA movement F to R, that is the sole task of the strut. If it was the LCA bolted single shear pivot point is a very poor engineering design with now even more tasks.
You note "small" in your ball joint movement concerns. You fail to quantify that. When you do you might want to mention how relative that movement is to those running say 40 aspect and up sidewalls. Not sure what OEM "slop" camber reduction method has been shared here anyway short of aftermarket replacement.
The lack of concern of conflicting arcs you voice, albeit minor, is mainly because the dreaded "slop" allows it.
The Kit cars were designed to reduce owner maintenance costs and improve reliability on Sat night wheel to wheel grudge rubbing and racing. That hardly applies to our uses.
The later B LCA pictured IMO seems to be actually a weaker design than the earlier design and its main success from a corporate standpoint, it was an easier/cheaper item to mass produce in quantity with a lot less parts and labor, and any "dreaded" slop reduction was simply a byproduct of the process. I may be wrong. You are welcome to prove me wrong.
However, since this newer design is fundamentally loaded much different than the older version, it really should not be included in this discussion.
Still nobody has yet quantified the downsides of the dreaded "slop" in real world use. IMO, you and others have drank the marketing koolaid on a problem, that in realty has not yet been proven to or may not exist.
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Jim Lusk
Well-Known Member
No marketing koolaid here. Independent of any aftermarket companies efforts and without seeing what others have done I found extreme slop in some arms I was rebuilding. Upon further investigation of those arms I discovered that they were basically put together in a haphazard manner. In reducing the slop the arms felt better. Again, I don't have any improvement numbers, but cannot see any reason to not tighten the arms up.
Now this is moving the goal posts. It doesn't matter that you've never heard of the rivets failing, they are in fact the most obvious failure point for the factory LCA. And it shouldn't be surprising to you that in a destructive test that the rivets failed first. Where else would the factory LCA fail? You think it will buckle before the rivets fail? Nah. Maybe the cast section that's riveted in, but it would be between that and the rivets. So it makes perfect sense.
I have in fact heard of the rivets failing, although the cases I know of were accidents so it's not of great importance. Still, we were discussing slop weren't we? Not strength? Goal posts moved.
First, factory torsion bar loads were in the 90-120 lb/in range. Second, 300+ lb/in bars have become pretty common for pro-touring style cars with large and sticky front tires. I run 300 lb/in bars. Third, the load is not limited by the torsion bar, because if the suspension bottoms out the load can be MUCH higher. And pot holes can pretty easily bottom the suspension. Even mine, with 300 lb/in bars. On a street car it's a bad assumption to think the highest load will be the total applied by the torsion bar.
Finally, increasing the torsion bar rate will not "offset" the flex or slop in the LCA. It will in fact increase it, because the load on the LCA can be higher. Better tires put more force into the suspension, larger torsion bars resist that, and the LCA's in the middle.
The test was conducted by Richard Ehrenberg at Mopar Action. The LCA's were put in a 10 ton press, supported at the pivot points, and placed under load until they failed. They have 2 major loading locations (excluding the struts and sway bar), and a 2 point destructive test is ridiculously simple. I don't agree with Ehrenberg on a lot of things, but even he shouldn't screw up a 2 point destructive test being an SAE guy.
Do you have any test results to show otherwise? I bet not.
Well, I have seen the QA1 and OEM LCA's side by side. For that matter, I've seen the later 73+ B body LCA's next to the A-body LCA's too, and I wouldn't put money on the A-body LCA's against either of the other two.
Ehrenberg agreed that the QA1 LCA's "look kinda spindly" (his words!) but the DOM tubing they're constructed of is tougher stuff than the factory LCA's. Either way, basing your opinion on what things look like vs. how they actually hold up in a destructive test is wrongheaded. You asked for evidence, I supplied it. You don't like it, come up with your own evidence. And still, this isn't the slop discussion, you're just wrong about the quip you threw in about the QA1 LCA's. If anything, they're stronger than the CAP version, QA1 has improved the design. I've have the CAP version too, so, I've compared those as well.
Well, how much slop is in the LCA's in the video? An 1/8"? More? That's small, but it's not insignificant when you're talking about caster change. Or toe change, if the LCA's move forward the toe angle changes too.
Comparing that slop amount to the deflection of the tires is a false comparison too. You get both of them, not one or the other, and they add up. You can eliminate the slop from the LCA, you can't do much about the tire deflection other than running better tires.
Removing the slop is easy, if you watch Jim's video. You can eliminate ALL of the slop at the socket end of the LCA with a plate and a strap.
The arcs of the strut rod and LCA are not "conflicting", they're diverging. That's an important distinction. And no, the "slop" does nothing for the diverging arcs of the LCA's and strut rods on my car. As I've already mentioned, I run QA1 LCA's that have no slop like the factory LCA's, as well as delrin LCA bushings, and adjustable strut rods (heims, no bushings). So, no slop, still diverging arcs, and I've tuned the length of the strut rods and checked for binding throughout the suspension travel range on my car. There is no binding in the range of travel, which is why I don't worry about the diverging arcs. They overlap well enough so there isn't binding in the range of travel I use (~5").
Says you. They had to handle well and hold up to much higher loads than most street cars, plus deal with "rubbing is racing". They also used much larger torsion bars and better tires, so, their construction and durability would be well used on a pro-touring car with better tires and larger torsion bars.
Seems to be? You haven't seen them in person either have you? They're heavier than the A-body LCA's. And they lack the rivets, which are the strength limiting factory on the A-body design. And they don't have the cast section to support the ball joint, which can also fracture. Sorry, the later B-body LCA's are tougher stuff.
As for loaded differently, no, they aren't. They're loaded at the ball joint, the torsion bar pivot, the strut rod, and the sway bar, EXACTLY like the A-body LCA's.
Marketing cool aid? Ok. The QA1 LCA's are lighter than stockers, by about 8 lbs. Less unsprung weight. They also increase the suspension travel, because their height profile is lower. That's why I run them, lowered the car without losing suspension travel. Their construction that eliminates the slop between the LCA and the pivot is a nice bonus. I didn't care that they were stronger, but, yeah, they are.
Why don't you show that the slop between the torsion bar socket/pivot and LCA at the K frame end isn't translated directly into slop in the path of the ball joint? Because movement at the ball joint end of the LCA will result in irregular changes in caster, camber, and toe. All of which can result in poor handling, especially if they're not consistent changes. And since the ball joint is at one end, and the pivot is at the other, it seems pretty logical that a bunch of slop between the torsion bar socket/pivot would translate directly into slop in the path of the ball joint.
J-c-c
Well-Known Member
You brought up the rivets failing in a test first as an example of something, not me
I picked 200 as an average everyone could relate to. If we are designing for pot holes as a necessity, address failed rims and low aspect tires in your first concerns not LCA.
First, I don't accept your premise the LCA is flexing in the first place and you have yet to make the case it is or proved it, This discussion is becoming silly and redundant, and yes it will, as any greater forces in the LCA pivot will tend to keep any slop pinpointed by up to the least force applied (preload when tire is off the ground)
Dude, everything fails, Everyone knows that, Big deal, Show me real world failures first.
Cross section trumps material here all day long. Maybe I should be having this discussion with Ehrenberg?
So what axis the slop is found is pertinent here. You don't seem to ever address this. Radially or longitude?
You mixing issues here. Pay attention. the LCA movement F/R that effects toe controlled by the strut, not the LCA Pivot point, There must be slop to prevent bind from conflicting arcs, The LCA pivot point on a single shear pivot is not designed or intended to prevent F/R angles changes of the LCA. Its movement to any measurable degree is the control of the strut design, not the pivot point slop. Why am I repeating myself here?
Because normally problems are solved first by addressing the lowest hanging fruit, and concern about a .5Deg(?) of caster change is very little bang for buck in the big pictyure even if it is accumulative.
Explain the distinction here that matters, regardless, bind is still the result to be avoided.
Yes it does.
Antidotally, slop is why you have no bind, discovered because there is no moving part of any amount that does not have "slop"
Sorry pro touring is no Sat Night "rubbing is racing" or even close.
Ypou state the below newer mopar LCA are "heavier" and stronger "unsprung weight concerns tossed aside and all?
Doesn't matter, its a rather different design ans shopuld not be included here.
A paper tiger argument, in that they don't fail in real world use, and as it seems they are the weak link in the design, the rest of the LCA assembly is as robust as needed evidently.
Are you certain they are cast vs forged? Regardless, ever seen/heard of one "fracturing"?
More empty claims.
To be clear we are not talking about the later B LCA as in 73 up?, The pictured stamped LCA I would be hard pressed to believe it has greater strength that the slop LCA in the original conversation.
I will only agree to at this time that the stamped LCA pictured is much cheaper to manufacture.
And you maintain they are far stronger? LOL You are really reaching now.
When did that enter the picture?
I never said I could and I can't. But I can make the case, it's rare, its insignificant, and not pertinent in any application our cars will encounter.
If this is just an exercise in feel good, count me out.
And where your beliefs are different than mine. Quantify the changes of caster, camber, and toe and under what conditions, that concern you and we will continue the discussion.
Based on the actual results of the "slop" and your definition of "directly" and "consistent", this is the crux of our disagreement, skipping all the intermediate marketing koolaid in the middle.
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J-c-c
Well-Known Member
Jim , I have no real bone to pick with your upgrades, mainly because you are making no unsubstantiated claims here.
Additionally you bringing back to life some severely beaten on or haphazardly built LCA's has no downside as you allude to.
Those calling this mod the holy grail without qualification gets my attention.
Hi AJ,
Are you able to explain to a simpleton (me), what bind is being prevented especially during braking? Or what bind would be happening if it's easier. I saw the video posted above, and for a seemingly slow drive ( that clip appears to be someone simply turning into a driveway and coming to a stop) I was surprised at the amount of fore/aft movement. How much more would one expect if they were "pushing" their car, or even out in todays insane traffic?
We have 50+ years of materials technology since these systems were new. It seems to me that the designs of the day had to have been a compromise made to cost, and that the average car buyer was going to compare any cars ride to that of a Cadillac. Todays consumers certainly aren't "smarter" about car technology, but as a whole are used to better handling vehicles. I see fore/aft movement and can't help to think that with todays traffic habits, even that little movement adds that nanosecond to your reaction time. We are talking about a day when comparisons are made between the "speed" of lightbulbs, (LED vs incandescent).
Is there a way to create a mounting point that allows the movement needed, yet prevent the binding you mention, and simultaneously improve braking and/or safety as a whole?
All I seem to grasp right now is that the strut should prevent (most?) fore/aft movement of the LCA, and has to be able to rotate up/dn at its mounting point so the LCA can swing up/dn around its mounting point (the dreaded "slop" zone in the rest of the conversation). Can you catch me up so I might be able to follow the rest of this? I'm not understanding why some fore/aft movement is required.
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J-c-c
Well-Known Member
It's a fair question. One thing I believed overlooked here, is most hard braking is or should be done in a straight line. In that case any suspension issues caused by lack of strut control of the LCA are fairly symmetrical with a proper set-up and do not affect ultimate braking or stability. meaning, it matters little in a straight line. Now of course as any turning occurs/increases while braking that outcome can change.
Understand on your nanosecond of movement, nobody has defined when that movement might ever occur/occurs, except maybe when backing out of the driveway or sliding backwards in a skid at 50mph.
This of course is assuming the front wheels always have some rolling/aero/braking/etc drag on them which keeps the dreaded slop always closed to one side. There are no normal forces present acting the other direction. The slop here does not define a loose rattling condition, the LCA pivot point is ALWAYS under load.
Your original question asking for an explanation on a "bound up situation" is worthy and also shared by me.
Understand on your nanosecond of movement, nobody has defined when that movement might ever occur/occurs, except maybe when backing out of the driveway or sliding backwards in a skid at 50mph.
This of course is assuming the front wheels always have some rolling/aero/braking/etc drag on them which keeps the dreaded slop always closed to one side. There are no normal forces present acting the other direction. The slop here does not define a loose rattling condition, the LCA pivot point is ALWAYS under load.
Your original question asking for an explanation on a "bound up situation" is worthy and also shared by me.
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I'm not getting involved with the debate, but I do want to make a recommendation. If you decide to add the gussets, make sure your socket will still fit inside the control arm so you can tighten the bump stop nut. Don't ask me how I know this can happen...
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I'm a streeter. I am Not a racer. My comments always pertain to being a streeter, unless specifically stated otherwise. I've been driving A-bodies since 1970, and occasionally wondered about that slop.
Here's my Opinion;
>As the body moves up and down relative to the road, and/or the center of the spindle moves up and down on the changing wheel-radius, the Lower ball joint and it's LCA, are moving simultaneously in many directions; including; forwards/backwards, in/out, and up/down.
IMO, if you restrict the fore/aft movement of the in-board end of the LCA, you simply create a point of bind. and now the LCA wants to twist and so then you decide to tie the two sides together, and create even more bind.
If the strut was not there, so that the LCA could only move vertically, then sure, weld away. But since our Mopes are not Chevys, the strut has to be there. And since the the strut is only the right length at exactly one point in suspension travel, and that point walks around a bit; the LCA is constantly push-pulling on that inner pivot.
Now;
>Under braking, the body moves forward relative to the LBJ. If the strut wasn't there, obviously the LCA would be severely damaged. As it is, in stock form, the strut is pulled rearwards to the limit of it's travel in the "rubber" bushing.
>I have done hundreds of alignments on these A-bodies, and I can tell you that, it is a rare car that can maintain a minimum of caster/camber/toe change, with changes in jounce and/or rebound; And during turning, as the weight transfers, things can be moving in opposite directions. Throw simultaneous braking into the mix, and those LBJs and all alignment specs, are moving all over the place.
So then
>IMO, some so-called slop, for a streeter, has to be there, to allow for all this monkey-motion, and to provide a decent lifespan for all the normal-wear parts.
> I drive the crap outta my car, on potholed streets of every kind of surface, but speeds rarely exceed say 40 mph. In practice, on the street, this slop, has never been an issue for me. Those doggone sandy corners in spring, now those can be tricky. and I can tell you first hand that cops don't like it when I drift around a pair of silos on a huge gravel-lot, at full steering lock, with man-passengers giggling like little schoolgirls. Boy I'll tell ya, I gave those sloppy LCAs a good work out that day!
These are my opinions; based on 50plus years of running A-bodies on the street.
Here's my Opinion;
>As the body moves up and down relative to the road, and/or the center of the spindle moves up and down on the changing wheel-radius, the Lower ball joint and it's LCA, are moving simultaneously in many directions; including; forwards/backwards, in/out, and up/down.
IMO, if you restrict the fore/aft movement of the in-board end of the LCA, you simply create a point of bind. and now the LCA wants to twist and so then you decide to tie the two sides together, and create even more bind.
If the strut was not there, so that the LCA could only move vertically, then sure, weld away. But since our Mopes are not Chevys, the strut has to be there. And since the the strut is only the right length at exactly one point in suspension travel, and that point walks around a bit; the LCA is constantly push-pulling on that inner pivot.
Now;
>Under braking, the body moves forward relative to the LBJ. If the strut wasn't there, obviously the LCA would be severely damaged. As it is, in stock form, the strut is pulled rearwards to the limit of it's travel in the "rubber" bushing.
>I have done hundreds of alignments on these A-bodies, and I can tell you that, it is a rare car that can maintain a minimum of caster/camber/toe change, with changes in jounce and/or rebound; And during turning, as the weight transfers, things can be moving in opposite directions. Throw simultaneous braking into the mix, and those LBJs and all alignment specs, are moving all over the place.
So then
>IMO, some so-called slop, for a streeter, has to be there, to allow for all this monkey-motion, and to provide a decent lifespan for all the normal-wear parts.
> I drive the crap outta my car, on potholed streets of every kind of surface, but speeds rarely exceed say 40 mph. In practice, on the street, this slop, has never been an issue for me. Those doggone sandy corners in spring, now those can be tricky. and I can tell you first hand that cops don't like it when I drift around a pair of silos on a huge gravel-lot, at full steering lock, with man-passengers giggling like little schoolgirls. Boy I'll tell ya, I gave those sloppy LCAs a good work out that day!
These are my opinions; based on 50plus years of running A-bodies on the street.
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