ahh ok, that will make quite the setup with an end-link sway bar
ahh ok, that will make quite the setup with an end-link sway bar
GOD FREAKING DAMMIT! Hahah no just kidding, that's totally ok with me. Here's the whole album. http://www.pnw-sdac.org/gallery/main.php?g2_itemId=2579 for those that want to look. Also my lower control arm bushings. http://www.pnw-sdac.org/gallery/main.php?g2_itemId=2596.
Turboshad, you referred to some rod ends in your 1st post by abbreviations. I was wondering if you could post the full name so one might be able to search for them via google or any URL's were these type of products could be purchased. My stuff has all been gotten through McMaster Carr and I desire some of the real fancy stuff like you posted and I see on cars like the Ariel Atom and other race cars.
Thanks, and feel free to use my pics whenever.
Originally Posted by turboshad
Hitting bumps is definately a hard one and one I shold look deeper into. Luckily being a macpherson strut there will be no verticle loads transfered into the control arm. I'm not saying you are wrong but where did you get a number of 3-5Gs from? The only extra lateral load that could be experienced over frictional contact would be the vertical, or partially vertical, face of a bump on the tire. Then you are acting against the vehicles forward momentum and it's resistance to change elevation. I would think a number would most easily be figured out in an energy balance equation. Any other ideas?
The sway bar will only put vertical forces into the arm and those will only act between the pickup point of the end link and the spherical bearing which will be quite a small distance. Of course, like you said, I will re-analyse it after the mounting point has been determined. From playing with this model and from my past FEA experience I know the mount won't effect the results of the stuff I am doing now. If anything it should stiffen the structure. As far as the sway bar force, I need to measure the moment arm and then guess at how much it may flex. As far as I know, the bars are just mild steel but if I'm wrong please let me know as it will change the torsional rigidity of the bar. As always I'm up for any educated guessing here too.
I will be doing something similar to what Len Ayala did on his neon. Once I figure out how much longer it needs to be than stock I will model it up and run a simulation on it also.
Picture courtesy of LenAyala
The 3-5G's I got from working with the SAE Formula Hybrid car here at school. We design all the parts to be able to withstand an impact that would equal 3G's without peramanet deformation. I figured that was a pretty good number.
I agree with the mount for the sway bar probably adding strength. I'm interested to see what it's going to do when there is a load on it in cornering becuase not ony are you coung to have the lateral forces on the a-arm ,but also the sway bar will add to the stresses on the thing. Man, that came out all wonky, I'm not sure how to type it! LOL
BTW, I'm taking Vehicle Dynamics right now and my project is to anylize the suspension of my car, so figuring out the roll moments, sway bar forces, ect is part of it!
I hope to be able to get it done and I want to "publish" the information on the forums and such for people to see and use!
How would all those joints hold up to water and salt?
1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS!12.57@104 :O)
1984 Chev Getaway van, 6.2 Diesel with a remote mounted turbo setup burning WMO-For sale.
2003 GSW 2.0L TDI, auto, fully loaded, modified, 360K-wife's.
2004 GSW TDI, 5 speed, fully loaded, modified.
Aurora ignition wires for sale. Link to info
Super60 roller cams or custom/billet cams. Link to info
I have a client who touched the brakes on an empty freeway in his Lexus 430sc. The car turned hard right and hit a barrier. Something broke.I think you should test them on a heavy, high torque car like, I don't know a TC MaseratiI'll buy the first set (OK second set
)AND sign a waiver
He said it had been "making a funny noise when I got on the brakes . . . and I took it to the dealer and they said there was nothing wrong . . . ."
John Laing
"The sole condition which is required in order to succeed in centralizing the supreme power in a democratic community, is to love equality, or to get men to believe you love it. Thus the science of despotism, which was once so complex is simplified, and reduced . . . . to a single principle."
-- Alexis de Tocqueville
"One of the methods used by statists to destroy capitalism consists in establishing controls that tie a given industry hand and foot, making it unable to solve its problems, then declaring that freedom has failed and stronger controls are necessary."
--Ayn Rand
"To evolve, you don't need a Constitution. All you need is a legislature and a ballot box . . . . things will evolve as much as you want. All of these changes can come about democratically; you don't need a Constitution to do that and it's not the function of a Constitution to do that."
-- Justice Antonin Scalia
Phewww.....that was close. Good thing I had my lawyers, which I guess I already admitted I don't have, on standby.
I got the rod ends for free for some work I did for a rod shop but they originally came from Bear Performance Products. The ones I have are the MM seiries which for this application are enough. In reality Bear sells FK rod ends and which are just crossed over to the more popular Aurora numbers to make it easier to order. Unfortunately the ones I got for free were 1/2" because that is what they use for their muscle car suspension arms but because of the different nature of the FWD and macpherson force ratios I think the 1/2" won't be strong enough and I will be using 3/4".
The spherical bearings I bought from HRP World and are the PWB-T series. The W means wide and I chose these because they had a larger angle of deflection and the decent thrust load ratings. In hindsight I could have probably gone with a lighter spherical since at first I was forgeting that no vertical loads besides the sway arm will be going through it though I know I won't ever regret the heavier style.
Aurora has a really good site which gives you almost all the specs you need on their rod ends and spherical bearings and FK Bearings has this really handy cross reference table that gives some different brand options at leas with the rod ends. Through my research I found that Aurora are one of the best bearing manufacturers really only topped by NHBB (New Hampshire Ball Bearings) which seem to get alot of use in the aero industry. Obviously they are also more expensive but if you want the cat's a$$ you're gonna have to pay. NHBB bearings, and aruora for that matter, can be found at Baker Precision Baker also has the specs sheets for the NHBB bearings they sell available since I found it hard to find info on the NHBB site.
SAE projects are great for this kind of thing. I was involved with Formula SAE with my 4th year containing 3 design projects. The first we did a variable runner length and plenum size intake and did back to back dyno testing and then compared it to computer simulation results from GT Power. The second we did the same but with a variable length primary and secondary 4-2-1 header. And then my 2 semester design project was for the suspension. I would be very interested to see your dynamics report when you are done yours.The 3-5G's I got from working with the SAE Formula Hybrid car here at school. We design all the parts to be able to withstand an impact that would equal 3G's without peramanet deformation. I figured that was a pretty good number.
I agree with the mount for the sway bar probably adding strength. I'm interested to see what it's going to do when there is a load on it in cornering becuase not ony are you coung to have the lateral forces on the a-arm ,but also the sway bar will add to the stresses on the thing. Man, that came out all wonky, I'm not sure how to type it! LOL
BTW, I'm taking Vehicle Dynamics right now and my project is to anylize the suspension of my car, so figuring out the roll moments, sway bar forces, ect is part of it!
I hope to be able to get it done and I want to "publish" the information on the forums and such for people to see and use!
In regards to the corner loading, does anyone know the aporximate wheel angle lock to lock on the steering? I did some 45 deg tests but I don't know that the wheels actually turn that far.
They definately aren't as matainance free as the stock stuff. The rod ends will need some periodic attention and can be relubed with some spray lube. (can't rememeber the brand I was recomended to use right now) The Spherical is PTF lined so it is self lubricating but it is still good to give it a clean every so often. There are rod bearing seals that places like Pegasus that you can get and you can also get the ends with greese nipples but since my car is only a summer driver and will rarely even see rain it's not a concern. If it was a year rounder I would look into some of the greesing options.
So I tried a few things today with varying success but the biggest suprise came when I tried using 1.25" .065 wall tubing over the 1". I knew it would improve but I didn't expect this much. The total weight only increased by .75lbs bringing the total to ~5.5lbs. Last night I weighed the stock cast arm and it cam in at 10lb 12oz excepting that it is near the bottom of our scale so I can't garuntee the accuracy. Either way that makes the chromoly version nearly half the weight of the stock. Going to 1.25" over doubled the strength and nearly haved the maximum displacement bringing it down to .019" from .032". I feel much better with this change and I think it is more than worth the extra weight.
Here is a FS graph to compare to the first one.
On this graph I took the new model and overlayed the 1" design so you can see the distortion differences. They are both scaled to 50X but it definately shows how much the 1.25" tube stiffened it up.
Shelgame, I threw the loads on the model at 90 degrees to the acceleration force, so directly to the inside, and there weren't even enough pretty colors to report. The model was quite stiff with only .009" of deflection at the ball joint. And this was done with the 1" tube. I haven't done it with the 1.25" since it obviously isn't a worse case scenario for the design. I did a buckling test with the 1000 psi in the same direction and simulation reported that it would take 95X that much load to buckle the tube when applied in that direction. One other addition I tried on the 1" tube was a gusset in the rear corner which also made little improvement to the system. Without a doubt the tube diameter increase was the most benificial.
for some reason, spherical rod ends look weak to me.
if i were to make custom control arms, id use tapered bearings and races for the pivot points. that way you can seal them and preload them so there is no play and add grease fittings so you can grease them as well. it would need 4 races and bearings per arm but would be able to take the kind of loads that the wheel bearings take. you could even use the same bearings and races as the rear axle. the races would be pressed into the arm, and then the bearings would drop in from either side and the bolt that goes through the k frame and through each pivot point would provide the preload.
outer joint could be a spherical bearing or a standard ball joint.
probably more work than someone would want to do but it would be bomb proof.
Brian
Rod ends come stock on the Ariel Atom. They have an amazing strength depending on the type and size.
no weights on the stocker yet? Our subframe stuff doesnt weigh much I guess. Some rich guy build all tubular subframes for his 3000gt and saved well over 100 pounds.
yeah but the ariel atom weighs nothing. the point that im concerned with is where the threads meet the loop/spherical part. lots of stress risers there.
im sure it would be fine though. im saying it just looks weak and spindly. not actually is weak.
plus im a daily driver kind of guy. rod ends arent daily driver friendly as they usually arent sealed and full of grease like stock parts. you can get seals for them though. i saw them in summit.
Brian
I mentioned above that our scaled wieghed one stock cast arm in at 10lb 12oz. So until someone else comes up with a different number on a more accurate scale that is what I'm calling it.
That is why I had to go with the 3/4" rod ends. Not because the bearing wouldn't take it, but the bending loads at the stud were too much for the 1/2" end.
Really the only thing greased in the stock setup is ball joint. The bushings are just steel on steel which is why the bolts are so hard to get out some times. If you were really concerned you could do PTF lined bearings all around and they would never sieze.
Last edited by turboshad; 02-28-2009 at 01:55 PM.
TurboShad, Have you drawn up a stock arm and overlayed them? I was looking at a pair tonight and they're really clearenced for tire clearance at full lock on the back side. Just looking at your pics I'd be concerned about rubbing when turning. Of course this is just all eyeballing it and no hard #'s. But it did make me curious as to how the shape compares to a stock arm.
He could make the arm like the line overlay in the drawing below to help with the rim clearance. I doubt the 1 1/4" tubing will show too much difference in strength.
Bryan
86 GLHS #161, 2016 Impala
SDAC National Member, SDAC Buckeye Chapter Member
A man has got to know his limitations.....
I don't knwo what happened to ym response, but anyways...
It's looking really nice!
I've also been concerned about that. I am hoping to have the car back in the garage on the next day above freezing. Then I can do some actual on car measurements and make adjustments where needed. I just wanted to get the bulk of the desgning done so when I get the car back it should be a decently quick project.
I may have to do something like black86glhs was pointing out. We will see when I can get under the car with the tape. But I agree that the stuctural integrity shouldn't be hamed too much. But you do what you gotta do, it's all part of the process.
I like it. I think it would be a nice addition to the 16v swap. You know how it works. Make adjustments as needed.
Bryan
86 GLHS #161, 2016 Impala
SDAC National Member, SDAC Buckeye Chapter Member
A man has got to know his limitations.....
Nice to see someone with an ME background. I wasn't the type of person to do well with the complex math involved. Some people get it rather quickly and others like me would have a tutor all the way through college lol.
I think moly steel is a good choice and is just as strong as a forged control arm.. Yes that is right those can't be cast as the deflection after 276k in my mini would of snapped mine by now. Cast isn't very strong in such an application. Just my option but I'm just trying to open up this discussion a bit while we're at it. Not trying to pick word wars hear I've been calling them that too, but with my experience in metal working and light manufacturing I really doubt they actually are indeed cast units so definitely correct me if I am wrong however.
Chromoly is used in the making of a top fuel dragster chassis so I figure that is a good choice from the get go. On the comment with no adjustability for caster at the arm unless using rod ends you could always go with tubular ends that would accept a eccentric bushing and still use the spherical bearings combined with a 9/16" high grade bolt or the factory 14mm unit. Either way its a win-win. I've carried stock control arms before so I can definitely vouch for the weight savings. No matter how you go with this its very interesting and exciting to see more and more people here fabricating suspension pieces and such. After all with a smaller community like ours we definitely need to stick together as well as be self reliant and self motivated in making more options available. When someone says why don't we make this .. well we are they .. and not everyone has a few thousand or hundred thousand lying around to develop and warehouse TM parts so bravo to you sir.. I am definitely impressed with where this is going!
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Depending on the material used, the method used, and the post-processing cast can indeed be very durable. Of course the design also has a lot to do with it.
Think about this, all of the 2.5 cranks out there are cast. They go through MILLIONS of cyclic loadings every year and very few snap. I'm just using this as an example, nothing more.
Oh, and I can tell you from first hand experience just because somebody is an engineer doesn't mean they are a wiz at math!
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