Dewey316

Of course theirs is properly designed. The lawsuits that would occure if they actualy designed a part that did not last. But, they have a lot of engineer's working on this stuff, its not a few guys in a shop, welding some parts together.

redraif

Have you played any with their new improved design to see how it performs? Just curious!

I got my AJE tubular cross member the other day and well as my new a-arms! Seem solid. Will take some pics tonight to post up some for you all! Have not gotten the coil over conversion kit yet. Called AJE up to check on it. Has not been sent out yet...should be shortly.

Asked about the design of the coil over kit. Said they have a bearing built into the bottom where the height is adjusted, but nothing on the top. Do you think this will be good enough, or should I start checking into a bearing to add to the top as well?

Also he said the max diameter of a strut I can use is 2.25in... I plan to upgrade to better struts with this conversion... any thoughts on what might fit this diameter spec? Tokico... Koni Yellows... Billsteins?

JPrevost

I'm glad you're going with another company although PA's arms would be fine for coil-over.
You only need a thrust bearing on the bottom where the spring nut turns. The top of the spring won't move... only need one bearing .
As for 2.25" struts, I have no clue about that. I bet RTFC would know.

RTFC, college isn't where you just learn knowledge. It might be that way for some but others take a lot more out of it than that. I learned how to apply skills and tools to things I would never have thought. Basic learning of how to do things more efficiently. And as for the modeling software, it's SolidWorks 2003 with COSMOS Works for the FEA. The material is mild steel, the welds were radiuses in the model and 1 solid body. The force was 2000lbs, I didn't sway it and I wouldn't know how too. The FOS is based on the strain and stress. I used 7 gauge for the strap metal and spring perch and basically every from their website. Like was already said, it would take me a LONG time and a lot of $$$ to model a complex stamped steel part. I could possibly try to get the model from a friend within GM but I doubt he can dig it up. Just trust us engineers when we say the stock piece is VERY robust. Unless going to coil-overs I wouldn't change out the a-arms for anything other than some painted stock pieces.
If somebody wants to pay for the modeling of the stock part I'll mesh it and put it through the same test... until them, GM hasn't failed, PA's have... take that to the bank .

MrDude_1

i donno how hard it is to do (im a electrical guy, not mechanical) but could you take your same PA model, remove the center, and apply the weight to the balljoint like the coilover would? i know alot of the force would go through the spindle to the ground, but there's still a lot of force there.. right? plus, it wants to bend under cornering...

is it just a matter of setting angles of force over a location, or is it hard?

83 Crossfire TA

iTrader: (2)

Although I would agree to a large extent that numbers could be fudged slightly this way or the other and show completely different results in these kinds of deals, the fact is that that PA arm isn’t even in the right ballpark.

To be very blunt, I’m betting that your real problem is that someone suggested that the Spohn stuff isn’t really that well designed either, since EVERY time that I’ve said anything about it (as I’ve said multiple times, their stuff is under engineered and overbuilt for the most part, they make up for inappropriate design in places by shear bulk) you’ve gone off.

JPrevost- stick to your guns here… there is no good reason why you should have to do other people’s work for them AND publish it openly. I used to post all sorts of things with all sorts of details on assorted boards and lists, and got fed up with products showing up from list vendors that were EXACTLY what I “published” on some list or board a few months or a year earlier, and I got tired of “I found” posts that literally posted some pics or charts that I posted earlier even in exactly the same format (I’ve seen my pics/drawings in instructions for products…), so I’ve long since quit justifying and responding to “well, lets see what you’ve done” BS from some of the idiots out there.

If you ask me a question I will tell you if it’s right or wrong, I will help you (I get probably a dozen car related what to look at and consider, if you post something blatantly wrong I will correct it, but the kind of thing like what is being asked for here is way out of line.

You may also want to look into a “creative commons” license for more interesting stuff that you post to protect it as your work, it’s sorta like a copy right and patent, but you can define what users can do with it, and it is enforceable. That way you do things like legally allow individuals to use the information for their own projects, but not make any money off of it, require citation/attribution and even put requirements on redistribution of modified versions. My wife (librarian, MLS) has “published” some of my stuff for me under one:
http://creativecommons.org/licenses/by-nc-sa/2.0/

RTFC

You can run all the tests you want. Until I see the same exact test done to another piece for reference your engineering program doesn't mean squat. How do i even know what kind of grade you earned in college and if you even grasped correctly how to run that program?

Point made loud and clear that time.

And please don't preach to me what college teaches you, I've been there. I took a few years majoring in CAD design years agoand delved into this realm quite well. I am also probably twice your age and let me be the first to tell you theat lifes experiences far surpase what you think you learn in college.

JPrevost

You sound jealous.
You shouldn't generalize what somebody has and hasn't learned in college. It's your problem if you didn't get much out of it, not mine. Just because you didn't get much from it doesn't mean I didn't... and I wasn't preaching, I was telling you that from my experience, college was worth every penny. In other words you're experiences "mean "squat" to me .
"How do I even know what kind of grade I earned", lol... how's this for grasping how to run the program: I got all A's in CAD classes and was hired by a professor to help teach his class of grad students how to use COSMOS. If that's not proof enough I don't know if there's convincing you. I also worked for National Instruments teaching LabView for a quarter.
Again, show me a GM arm that's failed from "fatigue" and then preach to me how my modeling "means squat." Until then, accept the fact that I was blessed with computer knowledge and in the right place at the right time to learn how to use COSMOS.

RTFC

Regardless how you think I sound, I stand unemotional on the subject. I again still state that facts need to be presented and you are not understanding that.

Show us a comparison to something else or your FEA demo doesn't mean squat to me.

You said it yourself that the part shopuld have failed just by putting the weight of the car onto it- It didn't- to me, your FEA results are obviously flawed by your own admission.

Sorry if I am only stating the obvious, don't take offense.

Lo-tec

I know that FORD's new GT control arms aren't worth a ****. If you read current automotive publications, you would know that they modeled "the **** out of them and they still failed. If you own a GT, I would get your front control arms replaced under the recall . Not to throw gas on the fire, but even the OEM's f*up sometimes. Must have looked really good on that FEA, but just couldn't cut it in the real world .

This is just a good example of "college smarts" meets the REAL WORLD !!

JPrevost

There you go again assuming things about other people. I completely understand what needs to be done but I'm telling you I don't have the time nore the resources to model a stampled sheet metal part.
When I said the part would fail just by putting weight on it I was just emphasizing a point about their design. The FOS showed that the part would hold up but that it would permanently deform under deceleration. Continue to put load on a steel part that's deformed and it will break from fatigue... exactly where my design shows a high concentration of stress.
One more point I need to make to cover all my bases; Nowhere have I said that an FEA designed part is supirior to anything else. My proof is where I stated earlier, before simulation, that the part would fail where it did... my FEA was just proof. To deny FEA as an important and useful tool (when used correctly which hasn't been disproven yet) is just dumb. One control arm on the GT out of how many designed arms that got FEA treatment? Case closed. PA's arm is a terrible design. I'd be ashamed and pull it off the site. If I had the money I'd force their hand only because this part's failure could cause serious injury and/or death... that's how I've helped the community... by putting up substantial evidence that it is unsafe.
Lo-tec, when I said GM a-arm I ment the one found on a thirdgen. I should have been more specific but I rush posted.
Also, the GT isn't a suprise. The person in charge of simulation probably forgot a load or there was a change late in the game. Something had to have changed for the arms to fail. Besides, Ford can easily afford to replace the arms on the GT because of the production numbers. A recall on a single bolt in one of their trucks would cost more! So it wouldn't suprise me if the GT got very little attention in the FEA department just to rush it out the door and into field testing... where it didn't fail or they would have done something about it. Sounds like it was late in the production that the design got altered. If you've got that article could you tell me the source. Or be a nice guy and scan and e-mail it to me. I'd really like to read it.
Just to make some of you happy I will (while on vacation) get a sheet metal arm in SolidWorks. It won't be exact but it'll be close enough to be proof of a stronger design. Give me 2-3 weeks... cause I'm on vacation.
RTFC, I was offended at your generalizations and assumptions. I know you were just playing devils advicate but when I try and help, and then somebody shoots down my help with the word "squat" it tends to strike a nerve. I wouldn't tell you that you can't drive just because I haven't seen you drive, so you're experience "means squat" is something I just wouldn't say. I give people the benifit of the doubt
Have fun guys and for when I get back, could somebody have the gauge metal used on the factory arms? That would save me a step.

RTFC

My appologise, wasn't trying to offend anyone, just stating that "I" needed more facts to make credit to the FEA report.

Since you bring up my driving as an example, let me take this opportunity to boast alittle- yes I can drive. I just took out 9 local TGO members with V8's in my little underpoweered V6. I didn't just beat them, I humiliated them. The closest one was 3.9 seconds behind on a 60-70sec range lap course. Thank you for allowing me to waste everyones time.

Mike's (Reddrocket)in car run showing the course.
He was closest to me with a best of 67.214
71.620 Run - In Car

Dean's Runs AKA RTFC
Best of 63.324 (I never walk course beforehand either I went out full blast guessing)
First
Second
Third

Yes I can drive, be assured of that. This is just the wifes car I was playing in that day.

83 Crossfire TA

iTrader: (2)

Dude, don’t you have an aerospace engineering degree? OTOH, I think that in a lot of ways we both have seen the difference between what works and what should work...

Anyway, I believe that there is a problem with whatever ford is using to do that modeling… there are recalls for assorted bits and pieces in the front control arm, strut and spring assemblies all across their line right now. It looks like it’s so common that they’re not even replacing the parts now on most of the car lines but installing safety devices. I know that my mother’s Taurus just went through their recall procedure where they installed a shield between the front suspension and the tire so if/when it fails it doesn’t take out the tire and cause a major accident. Now that’s AFU.

83 Crossfire TA

iTrader: (2)

If you want I can get you just about anything you want about them, I have a few sets of extra ones sitting on the garage floor…

Dewey316

Check your tech sources. The problem with the arms was in the manufacturing, not design. The contractor actualy building those parts, made a change to the casting process without consulting Ford. That is the reason Ford is now going with a forged arm, that is being done by a diffrent contractor. Ford has some serious QA issues right now, the seat-belt issues really point that out, along with the fact that a faulty casting on their arms went un-noticed. But, also notice that Ford recalled ALL of their flag ship cars, when 1 of the test mules (driven and likely abused by Reporters and such) devoloped a crack, the arm did not even fail on that car.

Lo-tec

The article was in the June 05 Car and Driver. I found it, and if you want I can scan it. It doesn't go into much detail, and Dewey316 is right, it is a manufacturing issue. Just throwing it out as food for thought, the OE's screw up all the time.

I would think you could compare apples to apples by building a heavy duty jig to mount a control arm, put some strain gauges on it, and load it in a hydraulic press and measure the actual deflection under load. Like 83 Crossfire, I have an extra set of stockers in the garage floating around. Get a couple different aftermarket arms, and it might make an interesting project for an engineering major.

BMmonteSS

What Dewey said is true, I read it in my SAE mag. This is where the OEM engineers get their news.

CrazyHawaiian

Well I'd like to say thanks to you guys for making us aware that certain products out there are not safe. Alot of people on these forums use up alot of their own personal time to help spread knowledge, and with no payback other than this: Thank you guys!! I really appreciate it, and honestly, its one of the things that makes this the best tech forum I know of.

Bottom line for me, I'm sticking with stock A-Arms forever.

bjm323

Question for redraif, When did you originally purchase those a-arms from PA?

LT1guy

iTrader: (1)

I think she bought them around Feb of last year; we installed them near the end of March, just before the STARS show.

3.8TransAM

This whole arguement only proves one thing.

College isnt anything without sense and practicality to back it up.

Backyard engineering isnt any better unless someone has the grasp and common sense to actually realize how the parts work.

The only true way to do this, is to have the people with the degrees and simulations design and build it, and then have actual techs go thru the design and beat it to death.

I've wondered for years why us dealer techs always got the short end of the straw when **** poor parts were designed and installed in cars. We could literally see a new modle and blurt out, thats going to go, I give that 10k miles and the scary part is, we are usually right. We would fix things the non factory way just so we wouldnt have to keep doing the same annoying job over and over again. Did they ever bother to fix them. Unless a direct safety defect(like as in happen asap and injure driver or others) they dont waste their time. This isnt only OEM's, its aftermarket part manufacturers too, just like we are saying here.(I could go on for hours over crappy OEM designs)

As far as RTFC and PRevost go, I can vouch for Prevost being a pretty smart cookie, doesnt mean we agree on anything(sometimes we do sometimes we dont), but he is capable and does end up applying things he designs and comes up with on his car in the real world.

RTFC has a very capable car using only a v6. That speaks something of itself. He is definitely knowledgeable and has obviously studied designs as well as what his own car wanted and was telling him to get where he is at. Both devoted time effort and $$$ to what they did, and both succeeded, one started on the engineering path, the other a decent understanding of suspension in the first place.

They got to the same place, just have taken two seperate paths.

And just for grins and giggles, I dont road race seriously, more for fun, same with drag racing. I do both and I enjoy it enough to keep going. The one thing never mentioned by anyone here and something I feel is missing. By looking at the design of the PA control arm I wouldnt run it. It doesnt look right to me in the forst place nor robust enough to take the abuse.

My two cents
Jeremy

Justins86bird

I think this thread has been discussed enough.

My little friend is getting antsy ->

Justins86bird

I was PM'd by someone who would like to add some on-topic, usefull info to this thread. We'll give it one more try

JPrevost

It would be nice to have the $$ to just go and buy various aftermarket arms just to thrash and trash but in the "REAL WORLD" people pay to have this done to THEIR arms vs what they're trying to improve. Example; PA racing paying me or some other engineer to go and test their parts using displacement gauges, FEA, and till distruction. Worst case scenario's etc... but again, the company USUALLY pays for this. An engineering major doesn't work for free. If anything, an engineering major for a project would design his OWN arms (like I did) and then build and test. That's of course in my reality, not sure about yours .
It would be rather hard to replicate the extream forces seen on an a-arm in a controlled environment and that is where FEA comes in hand. I can sit here and design a part, test it within a few minutes it'll tell me my FOS depending on the study (yield, static, ultimate, fatigue, etc.) that is why this is so powerful. Not because it can simulate the real world, but that it can simulate an ideal world giving you the ultimate control. Right now my part has a weak spot in 1 area. 10 minutes clicking away and finding a reasonable fix or brace and the weak spot moves to an area of less concern. Using FEA I can twist, bend, push, squeeze, heat, press, and torque any surface I want making for short work of critical suspension part design. It saves lives, time, money, and materials... what isn't good about it? Where as it used to take 10 guys with 10 drawing boards 10 weeks with 10 fabricators with 10 parts variations to test a single part it now takes 2 guys, 1 computer, 1 powerful software package, 1 fabricator, and 1 part and 1 week to get to the same result.
I wish PA would accept responsibility and contact the other owners of their defective and grossly under-engineered parts.
Since I didn't have any LCA's to take with me on vacation and the sheet metal modeling would have taken me forever to complete I instead spent my time making some strong designs. PA's arm weighs between 7 and 8 lbs, I got mine to have a minFOS of 1.8 in a non-critical area of the perch support and an average FOS of 8.6 in the bending welded surfaces that contact the outside rails. My design was 8.7 lbs . Then I did a robust design that used thickermaterial and very few cuts and came up with a 13 lb arm that had a minFOS 3.6! All this was done using mild steel and testing for yield strength. The ultimate strength FOS would be higher but at ultimate means breaking completely, yield means deforming permanently but not breaking (like bending a paperclip).
I can go into great lengths and step you through my testing procedure but it might bore you to death. Take my word for it, the original PA arms are VERY unsafe and I wouldn't trust my car even sitting on them let alone driving down the street.
My design uses box steel inplace of the round for stronger bending strength at a slight sacrifice in weight. Does anybody have any forces they want me to simulate? Be specific like 1500lbs, torque about the perch plane, etc. It takes only a few minutes to run on my desktop.
Now if Justin wants to close it, go for it, I'm done here. I feel I got my point across and hope it's enough to whip the aftermarket back into shape.

cali92RS

Actually, an engineer doesnt work for free, but an engineering major does, in our case.
As our class senior project, we had to design a launch vehicle with a 10kg payload to orbit in LEO (low earth orbit). We did the structures, aerodynamics, avionics, and proplusion work while a friend of our professor, who owns his own launch vehicle company, used all of our work for himself and cashed in.
Crooked a$$ thieving bastard.

Same thing for a master's thesis. Free R&D for either a company or university.

BTW...this is why I dont buy that argument that college doesnt teach you practical sense and application in the real world. Every engineering program I know requires, to graduate, a senior project where you transfer knowledge you learned studying, from books and professors, into practical, real world solutions.

Guest

College didnt teach me that if the stock part doesnt have a history of failure that there is nothing wrong with it, learned that way before then. The only thing useful you would get out of testing a stock piece with the program is if you are using the correct input variables for loading. If you were to make an accurate model of the factory arm and used the same loading and it failed miserably then you have a point and someone needs to look at their input data. Now if you dont trust the program, better not ride in any airplanes or go into any newer tall buildings because they use these programs for design.

I havent seen a non-rusted out GM LCA fail. I've heard of some cracking, and I have had quite a few in my hand with the area at the ball joint worn out.

The problem IMO with the aftermarket designs isnt in the materials used, or maybe even the manufacturing, but in the design. The factory part doesnt rely on welds to carry load. The aftermarket arms I have seen have all failed at the welds, whether the weld itself failed or the metal near the weld that was affected during the welding process. Where is the weld on the factory piece? There isnt one. The same failure point on the factory arm would require a fairly sizable bearing failure. Something tells me that isnt going to happen. I had some firsthand experience with this, *GASP* in college *GASP* while doing load testing on pre-fabricated sections of a steel bridge in the college lab. Funny that the analysis program showed exactly the results obtained in the lab.

How about that whole Ford GT fiasco? They moved to a billet part.

Funny you mention that Ken. A bridge I designed for senior project is in construction, no changes. A friend was working on a project doing a traffic analysis study, information that the city took and is using for future improvements.

I can still get some strain gages and other stuff I need, maybe I should run some real world tests for Dean

l98-tpi-guy

Now that's the kind of disclaimer I like to see...

BTW: Thanks JPrevost.

RTFC

Dean runs his own real world tests Or do you not remember Chris? I handed you your *** the other day in AutoX.

Lo-tec

For my senior "project" I did FEA on a radar dome that my professor was "convienently" getting paid to do research for by the military.

Again, a couple of donations from a couple of vendors, some computer analysis, and some real world testing of said donations would make an interesting senior project for the right gearhead engineering major. The testing won't be "exactly" the same as the all the loads on the arms while say autocrossing, but it would be easy enough to load it as the car sits, and crank up the static load and measure how much each arm deflects, etc etc etc.

JPrevost

You got had just like every other dufus that kissed up to the professors for better grades . My senior project was designing the cooling system for our FSAE team. It had no fans so no electrical draw and it didn't get over 210 degrees on the track at competition in some serious heat! Nobody profited from that project except myself. I got Visteon to donate a couple heat exchangers which I then modified and performed tests on. Pure no profit project like the rest of my team (that were seniors). So I don't believe for one minute that you HAD to design something FOR a professor. You always have the option to do your own project unless you lack the creativity.

KiLLJ0Y

iTrader: (1)

BMmonteSS

I didn't have much of a choice for my senior design project either, I started SAE on campus and started a mini-baja team, just so I could have something cool to work on. The contacts I made on that team led me to the full time job I have now. Great experience I couldn't have gotten anywhere else. Ohh and JP the ohio state guys were top notch, they helped us alot.

redraif

Still waiting to get the final details worked out with PA on my reimbursment. Hopefully I will get an answer in the next few days! Will let all know how it goes!

Guest

You did? I wasnt racing against you.

Justins86bird

<--he brought a friend!