So I am planning on making tubular control arms for my 87 fiero, I want them because I can make them more adjustable and I want to use a coil over set up, what materials should I use to make them, I'm an aggressive driver but the car is not going to be jumped or anything to crazy, and how can I tell what length coils overs I need, and what spring rate should I look for

huh.... well i think you are kind of going to be a pioneer here on that. not many people would have any sugg for stuff you plan on building. personally i like aluminum... all over the place. poly bushings and moog joints are a must. sealed wheel bearings are lighter than serviceable units... hence better ride and better handling.
and dont forget your 1.5" anti-sway bar.
look for joints that come out of the half ton pickup trucks for two reasons.
1 they should be much easier to find when they wear out
2 they should be much heavier duty than any lightwheight car versions(longer lasting
its really a personal opinion where exactly you build your specs.
do it your way. if it dont work then start over from scratch.

Honestly, if your asking those questions... You should just buy a set. There are a couple companies that make arms / kits for our cars. Held Motorsports is one of them.

Well i would be using some kind of steel to make it out of, i have a good welder and have a good idea on what i need to do, my plan is to make a jig for the 3 mounting points, and build it around it, i'm not going to do anything revolutionary on the suspension geometry, but i want a good adjustable coil over set up, and maybe be able to dial in a little more caster. I just want to know if there are any experts that can tell me what kind and thickness of steel is best, and my uncle has a lathe so i can get the bushings to fit right and the ball joint to press in right, and i'm a good welder, so i know i can do it, i just need some help selecting the materials. i'm not the type of person to buy something unless i can't economically make it myself.

http://www.cmich.edu/Admiss...ering_Mechanical.htm

Random note, that 49% of central Michigan girls have at least 1 sexually transmitted infection. Just a random fact because you pointed out cmu. I was just wondering if anyone has made them before or if they had a race car and knew a rough guideline on what i had to use.

really, an average engineering education won't get you far as you still won't know what kind of forces to expect. you'd probably need a specialized automotive engineering education for that. So what background do you have? mechanical engineering? Would you be able to calculate the strength/stiffness of a simplified version of the original A-arms?

The upper a-arms are relatively easy as the possible load-cases are limited. Simply make up a design, calculate the forces and stresses and modify until you feel you've got something that will work.
The lower a-arms are a bit more of a pain as the shock and spring connect to it and you can't be certain of the forces.

if I was going to make a set of tubular a-arms, I'd aim for a wall thickness of 2mm and 25mm tubing for the upper. I definitely wouldn't go lower though I might go higher for the diameter. The lower a-arms I would probably look at square tubing of 2mm thickness. I would also run FE analysis on my design in addition to the manual calculation and do my best to compare it to the original A-arm.

edit to add: I definitely would not use aluminium for this in a home-made setup.

[This message has been edited by PerKr (edited 12-16-2010).]

Couldnt we just copy the held control arms?

Russ Fiero has a front cradle fixture for the 84-87 setup and makes his own tubular a-arms:

I Really have no formal engineering background, I've made stuff before for my l67 swap that worked fine, but they were only an engine and alternator mount, obviously it's not going to be under as much stress as suspension. Does anyone know what kind of tubing Russ Fiero uses?

http://www.lssu.edu/program...dy/engineering-mech/

quote Originally posted by darkhorizon: Couldnt we just copy the held control arms?

we could, but do we have any to look at for that purpose? I doubt anyone here would buy a set and then give us the dimensions to make our own cheaper copies

Let me just put it as a simple questin, what materials should I use. I don't doubt at all that I can do it, and I also don't want to just buy them because that ruins the fun, it's about the journey not the destination, I get more pride out of making stuff

quote Originally posted by ckrummy: Let me just put it as a simple questin, what materials should I use. I don't doubt at all that I can do it, and I also don't want to just buy them because that ruins the fun, it's about the journey not the destination, I get more pride out of making stuff

Why not go to the Held site and take a look at the specs it advertise for the control arms Held makes?

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Jim Martin
White '86 GT
California

I would think you need a pipe bender, a drill press... some good bits, a welder and steel

Oh, now I see the problem . . . Held doesn't have a web site, at least not one I can find.

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Jim Martin
White '86 GT
California

copying a known design is one way to go .look at the turbo lsj ecotec swap thread in the construction zone , some great work there .buy Herb Adams book "Chassis engineering " .its the bible for suspension design .i have a held sport front end myself and an RCC rear setup .i dont see it being that hard to duplicate .go on the website "locost usa "and on that site it is the norm to build your own arms and the whole chassis too .most fiero enthusiasts are only doing what they have to do as far as far as fabricating stuff goes .some of the locost guys are off the charts .

quote Originally posted by wftb: my arms are made out of mild steel tubing and if its for an 87 you will need a bender for the main lower tube .i believe they are around 1/8" thickness .i think helds site is now called HT motorsports .i f i was going to do this i would build my own cross member too .

HT Motorsports is now http://www.westshorefabricators.com/

I've built several sets and used several pre-made sets for my rally car. I went back to the stock arms. The tubular bits were more trouble than they were worth. They couldn't hold up to the rigors of rallying I put them through.

Thanks wftb i'm glad someone understands what i'm going for, i'll buy the book and start pricing out some metal, and topher_time i don't think my car will ever be airborne or atleast i hope not, i just want a true coil over set up in the front and i think this is a better solution than modifying the stock control arms. I will look into making a cross member, but i'll see what it's like once i get under the car and start to see what stock it like, and i'm pretty sure i can make a nice set up for way less than $2400. and i do have a tubing bender and all the basic fabrication tools i need. I'll try to make a thread when i decide to start, but my ADOS (attention deficit oh shiny) syndrome might kick in.

the funny thing is if i build another fiero i would not bother with coilovers and tubular arms in the front , just the back .and i would make those myself now for sure .but i have learned that adjusting the rear of the fiero is where more dramatic changes can be made , as long as the front end is solid .i would go with stock front arms with poly .eibach lowering springs in the front and maybe rodneys lowering ball joints if i want lower .a set of koni front shocks and then a version of helds bumpsteer kit in the back with koni coilovers .you can take weight on and off the front with the rear coilovers and they are easier to adjust .if you do build a front setup , open up the upper A arms wide enough to fit the larger bore QA1 shocks in and move the upper perch up as high as you can get it so you wont need drop spindles or lowering ball joints .i had to go with street dreams by ross lowering spindles (and i really like these by the way ) to get the travel and ride height i wanted .have fun....

Yeah that makes sense about the front vs back coil overs, i still haven't decided if i want this car to be a race car or a daily driver, so i want something adjustable so i can lower it if i want and raise it when i need to, like if i live or work at a place that has speed bumps plus it is an easy way to dial in some negative camber in the front for when i do auto cross. I'm still gonna do it, i plan on keeping this car for a very long time and i know i will get bored with it and make them eventually anyway.

A good thick wall mild steel tubing like .120 should be used, seamless is best. The OD should be large enough to provide a good structural foundation for the pivot bushings, something like 1 1/8 thru 1 5/8" diameter.

The lower shock mount needs to be sturdy enough to hold the car up and meet the dynamic demands placed on it. Depending on size and shape 5/16 thru 1/4" plate would be a good choice.

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yellow 88 GT, not stock
white 88 notchie, 4 banger

this is the start of my locost 7 ,have been too busy with the fiero to work on it yet this winter.i did not build these arms but most people do build their own .it has the QA1 shocks i want on my fiero , and they are mounted upside down and are adjustable .uses 86 fiero spindles and a mustang 2 rack .the hardest part of this was finding the perfect spot for the rack so it has 0 bumpsteer through out the travel , something to remember to check if you dont replicate stock angles and ball joint positions .

quote Originally posted by wftb: this is the start of my locost 7 ,have been too busy with the fiero to work on it yet this winter.i did not build these arms but most people do build their own .it has the QA1 shocks i want on my fiero , and they are mounted upside down and are adjustable .uses 86 fiero spindles and a mustang 2 rack .the hardest part of this was finding the perfect spot for the rack so it has 0 bumpsteer through out the travel , something to remember to check if you dont replicate stock angles and ball joint positions .

nice work so far I'm starting to think I will never get around to start building my locost (think I bought the book way back in '96)