Anyone use PST lower control arm shafts?

[66 Sat]

Well I put them in the same bracket as subframe connectors, solid tie-rod adjusting sleeves, disc brakes, thicker strut rods or any number of other improvements over the factory. Some may be worth more than others (subframe connectors being high on the list of importance), but all might add something. If not, then ok, no harm done, but not "Ugh". They are to all intents and purposes invisible.
This is 60 year old technology, mass produced to a price-point. To think the engineers got it all perfect is naive.

 

[j-c-c-62]

Well I put them in the same bracket as subframe connectors, solid tie-rod adjusting sleeves, disc brakes, thicker strut rods or any number of other improvements over the factory. Some may be worth more than others (subframe connectors being high on the list of importance), but all might add something. If not, then ok, no harm done, but not "Ugh". They are to all intents and purposes invisible.
This is 60 year old technology, mass produced to a price-point. To think the engineers got it all perfect is naive.

Nobody is claiming any engineer got it perfect or ever will.
Likewise, nobody has shown ANY LCA to be lacking design wise in its intended application that a gusset would be an improvement after many millions have been on the road for countless millions of miles. The fact that they saw little change/updates over the years IMO speaks volumes.

 

[RemCharger]

I wonder if they're designed to flex because of the different arcs in the strut rod vs control arm

 

[1KoolBee]

Never.
And without pictures, it's only a claim in all due respect.

Not just a “claim”, I’ve witnessed it more than once. Just because you never have doesn’t mean it never happened. Whether you agree with how I choose to build my car or not is completely irrelevant, I’m boxing my lca’s period.

 

[Kern Dog]

Nobody is claiming any engineer got it perfect or ever will.
Likewise, nobody has shown ANY LCA to be lacking design wise in its intended application that a gusset would be an improvement after many millions have been on the road for countless millions of miles. The fact that they saw little change/updates over the years IMO speaks volumes.

No, Lipshitz...the entire time that these LCAs were in production, tire science was crude, at best.
Torsion bars were skinny, if there was a sway bar, it was small too. Wheels were narrow, shocks were less advanced.
In stock form, a car with all factory equipment probably didn't over stress the LCAs to the point of failure.
Everything has been ratcheted up since then. Bigger torsion bars, sway bars, better shocks, wider wheels and street tires that stick better than many race tires of the 60s and 70s. When you add more tire grip, the car will have more body roll so you add sway bars, bigger torsion bars, stiffer leaf springs to counteract it. If a weak link exists, you'll find it. Any excessive flex is lost motion so why not reinforce what could flex?
Why? Because many of us have driven newer cars that handle great and we want our classics to as well.

 

[j-c-c-62]

I wonder if they're designed to flex because of the different arcs in the strut rod vs control arm

The LCA bushing mostly allows for this this arc conflict.
So far, this discussion counters the basic engineering design process.
Everyone here so far, has a solution, and is desperately trying to offer a reason to justify it after the fact, and so far, zilch. No pics, no failures, but some pretty good stories and digging their heals in.
Even one has gotten predictably "riled" up to resort to name calling.
Any real "flexing" going here in this IFS is with the torsion bar and the OEM brake strut bushing, and to a very minor degree the OEM LCA bushing that is easily overcome by urethane to some degree or by Delrin to a large degree. The LCA is not flexing beyond reason "a".
I'm not telling anybody how to build their cars, I am inquiring to their basis for their choices and subjecting them to a little internet peer review.

Reason "Z" is rather hard to accept for some.

 

[66 Sat]

Read this thread Boxing in LCAs
Post no. 8 some anecdotal evidence for boxing them in.
Has anyone got hard data on subframe connectors? Probably not. Doesn't mean they don't work.
Why such resistance to a cheap easy "upgrade"?

 

[Mopar Miki]

Kern Dog has provided proper background info - many thanks, nice Charger btw

Please just humor jcc, i am not sure if he truly understands where the unibody flexes/suspension flexes.

Torsion bars were skinny, if there was a sway bar, it was small too. Wheels were narrow, shocks were less advanced.
In stock form, a car with all factory equipment probably didn't over stress the LCAs to the point of failure.
Everything has been ratcheted up since then. Bigger torsion bars, sway bars, better shocks, wider wheels and street tires that stick better than many race tires of the 60s and 70s. When you add more tire grip, the car will have more body roll so you add sway bars, bigger torsion bars, stiffer leaf springs to counteract it. If a weak link exists, you'll find it. Any excessive flex is lost motion so why not reinforce what could flex?
Why? Because many of us have driven newer cars that handle great and we want our classics to as well.

 

[1KoolBee]

Read this thread Boxing in LCAs
Post no. 8 some anecdotal evidence for boxing them in.
Has anyone got hard data on subframe connectors? Probably not. Doesn't mean they don't work.
Why such resistance to a cheap easy "upgrade"?

Thanks for that, and so member JOS51700 points out in his post:


“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.”

That’s all the “engineering” I need to know in this case.

Remember, the Ark was built by amateurs, the Titanic was built by “Professionals”.

And I am an Engineer by the way, so I understand the discipline well.

Meanwhile it took me less time to weld the braces on than we wasted here debating whether or not to do it.

I don’t need to do a FEA for every decision I make on building this car! And I sure don’t need a committee for approval! Thanks everyone who responded to the original question.

 

[j-c-c-62]

Thanks for that, and so member JOS51700 points out in his post:


“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.”

That’s all the “engineering” I need to know in this case.

Remember, the Ark was built by amateurs, the Titanic was built by “Professionals”.

And I am an Engineer by the way, so I understand the discipline well.

Meanwhile it took me less time to weld the braces on than we wasted here debating whether or not to do it.

I don’t need to do a FEA for every decision I make on building this car! And I sure don’t need a committee for approval! Thanks everyone who responded to the original question

"in that proper engineering normally requires the discovery of a problem and defining the problem. an analysis of all the possible solutions that fix that problem, a rational decision on the best solution, and then defining precisely the chosen solution before implementation."

The difference between understanding and practicing evidently escapes you, BTW.

 

[66 Sat]

Not agreed.

proper engineering normally requires the discovery of a problem - flexing LCA potentially causing wayward handling or damage under impact
and defining the problem - 2 halves of LCA not linked along full length. an analysis of all the possible solutions that fix that problem - join 2 halves of LCA along full length
, a rational decision on the best solution - use a flat piece of metal to join, leaving access hole for torsion bar adjuster
, and then defining precisely the chosen solution before implementation - buy some pre-made joiners from PST and weld on while you are in process of rebuilding your LCAs"

 

[j-c-c-62]

Not agreed.

Too bad you cannot detail your disagreement.

proper engineering normally requires the discovery of a problem - flexing LCA potentially causing wayward handling or damage under impact

Discovery? You got any proof of said LCA Flexing and/or this flexing causing wayward handling??
Damage under impact? So, tell me again, what is the problem discovered here, flexing or damage?

and defining the problem - 2 halves of LCA not linked along full length. an analysis of all the possible solutions that fix that problem - join 2 halves of LCA along full length

All possible solutions for the two? problems mentioned, has only one solution?

, a rational decision on the best solution - use a flat piece of metal to join, leaving access hole for torsion bar adjuster

On what rational basis is the thickness of the gusset decided, beyond Monkey See Monkey do

, and then defining precisely the chosen solution before implementation - buy some pre-made joiners from PST and weld on while you are in process of rebuilding your LCAs"

Or Not

 

[1KoolBee]

By the time you get done trying to over analyze an obvious problem and share your professional opinion, I’ll have the front end back together. News flash : nobody gives a **** about your opinion!

 

[71RRHI]

I look at it this way. There is no down side to boxing the LCA. If an engineer can't see any benefit to welding the stiffing plates, The same engineer can not show any adverse affects of welding the stiffing plates.

 

[j-c-c-62]

I look at it this way. There is no down side to boxing the LCA. If an engineer can't see any benefit to welding the stiffing plates, The same engineer can not show any adverse affects of welding the stiffing plates.

That is classic logic, glad you shared it and not me.

BTW, never understood I needed to show any adverse reasons in the first place. A waste of time.
So far, my takeaway with promoted modification, anyone who does the modification truly does not understand the forces at play, and is only following the crowd, and is not a credible source for chassis improvements.

Kinda of like saying red pants makes one run faster, so everyone should wear red pants, and implying I need to prove the adversity in wearing red pants?

 

[1KoolBee]

So at what velocity and impact angle did you simulate the expected impact forces? Then what forces did you come up with? What were the failure modes and effects? Fact is , you didn’t. This is just an exercise in you attempting to prove you’re smarter than everyone else, and successfully proving the exact opposite! You believe there have been no failures because you haven’t witnessed them, yet I have and in the post above, another enthusiast shared his own experience, but apparently you can’t read.

 

[Don selleck]

I'm welding mine, have new bushings greaseable pivot shaft etc. from P.S.I. I will be pressing then together slightly to take up a small amount of slop in the torsion bar socket, then adding the stiffening plate. Not a whole lot of movement but some, maybe an 1/8" or so. That was my reason for adding these. And gaining some strength, bonus.

 

[j-c-c-62]

So at what velocity and impact angle did you simulate the expected impact forces? Then what forces did you come up with? What were the failure modes and effects? Fact is , you didn’t. This is just an exercise in you attempting to prove you’re smarter than everyone else, and successfully proving the exact opposite! You believe there have been no failures because you haven’t witnessed them, yet I have and in the post above, another enthusiast shared his own experience, but apparently you can’t read.

So, the problem you discovered that needs correcting with the LCA is impact forces with the wheel/tire hitting something, that you have no pictures of the damage, and that Mopar was not concerned with for the nearly 19 years with the basic LCA was being used for many millions of miles that required any upgrade for Mopar to correct?
I have never said nor believe there are no failures, I question the circumstances of those "failures" and how an added gusset discussed is supposed to affect those "failures".
BTW, since you brought it up, do you have a problem with somebody maybe more knowledgeable than you are, or are you the smartest guy in the room?
Also, reading is I agree important, but comprehending is a bit more. Quote your "enthusiast" and I will address.

 

[j-c-c-62]

I'm welding mine, have new bushings greaseable pivot shaft etc. from P.S.I. I will be pressing then together slightly to take up a small amount of slop in the torsion bar socket, then adding the stiffening plate. Not a whole lot of movement but some, maybe an 1/8" or so. That was my reason for adding these. And gaining some strength, bonus.

You know the OEM rubber Strut bushing is designed to freely allow each wheel's lower BJ to move longitudinally nearly 3/8" in normal operation?

Inform us why you are not making the gussets out of 1/4" material and making them even stronger.

 

[Kern Dog]

By the time you get done trying to over analyze an obvious problem and share your professional opinion, I’ll have the front end back together. News flash : nobody gives a **** about your opinion!

Guys, THIS is his signature trait....He loves to piss on chassis modifications that people do to their cars. This exact same bullshit was his standard practice at the Moparts site. He thinks that his "education" puts his opinion well above everyone else.
Yeah? Well I have known some educated people, including engineers that have had some incredibly stupid ideas that are supported by their calculations.
If you have no common sense, no amount of higher learning will make you smart. There are intelligent engineers and dipshits with degrees.
Regarding the last sentence from JCC in the above post...
As a carpenter, I knew that 3/8" plywood provided adequate shear strength in walls and that even doubling the thickness to 3/4" would be a matter of diminishing gains. The same applies to gussets in structural metal framework.
If you don't have a front sway bar and don't drive aggressively, the gussets may be dead weight but even then, so what? What is it hurting? You can advise people against it based on your opinion that it is a waste of time but your responses read as if you have some personal interest in what others do to their cars.
It may be right that these modifications have no actual value. Who has a chassis jig and high speed measuring equipment to monitor the flex and movement? If the car feels more solid and responsive after the changes, who has the right to bitch about it?