suspension engineering.

[ericjon262]

Preface: This thread is titled suspension engineering not suspension tuning therefore, the idea behind this thread is not optimization of the factory components, but instead, creating a clean sheet design to make a Fiero fly around corners reliably. I am also not an engineer(at least, not by trade or education) so those of you who are, please chime in, those of you who aren't, you're in good company!

I feel the best place to start, is by defining terms, and setting goals.

I feel the need to define terms, because I am still a newb when it comes to suspension dynamics, and the hardest part for me to grasp thus far has been terminology.

Jounce-Upward motion of the wheel relative to the body of the car, the compression of the suspension from it's static position.
Rebound-Downward motion of the car relative to the body of the car, the relaxation of the suspension from it's static position.
Caster-the front to back tilt of the spindle or knuckle relative to a vertical line drawn through the wheel centerline.
Camber-the inward or outward tilt of the wheel relative to a vertical line drawn at the wheel centerline.
Toe-the Pointing of the wheels inward or outward relative to the centerline of the vehicle.
Roll Center-the axis which the front or rear chassis of the vehicle rotates during suspension travel.
Roll axis- The line in between the front and rear roll centers.
Side-view - projection of the physical and constructed aspects of the wheels and suspension onto the longitudinal-vertical plane
End-view -projection of the physical and constructed aspects of the wheels and suspension of one end of a car onto the transverse-vertical plane
Acceleration-the rate of change of velocity. At any point on a trajectory, the magnitude of the acceleration is given by the rate of change of velocity in both magnitude and direction at that point

Recommended reading:
http://www.amazon.com/Tires-Suspension- ... 1560918314

http://www.amazon.com/The-Racing-High-P ... 0768012414

http://www.amazon.com/Tire-Vehicle-Dyna ... 0080970168

http://www.amazon.com/Race-Car-Vehicle- ... GMT2R1S2EZ


Goals:

#1 to make the best use of the tires in the available space. cutting of the sheet metal, including the strut towers, is to be considered acceptable, cutting of the frame rails is not. The engine and transmission cradle, along with the front crossmember, can be completely custom.

#2 is reliability and repair-ability, through the use of off the shelf wear components with no modifications, including but not limited to Wheel bearings, Brake discs, and brake calipers.

The starting point:

I feel the best place to start, is to define the wheel bearing and brake combination to suit goal number 2, as it should be easier to work from the inside out.

Rear bearing options that come to mind:

5x100mm
Stock Fiero
Subaru BRZ or imprezza


5x114.3mm
Pontiac Montana minivan

5x115
GM N body

5x4.75"
4x4 S-10 front wheel bearing. strong, cheap, probably available for a long time.
C6 'vette wheel bearing. strong, 99.99% sure will be available for the foreseeable future. factory proven to >600 hp/600 ft-lb's and 1.15g's @ 3400+ lbs. integral wheel speed sensors.


I'm not above a fabricated knuckle, similar to what CCfiero did



or getting a set of knuckles from/for another car:



My initial questions:
is there any distinct advantage to the 88 fiero rear setup with lateral links and trailing arms, versus a triangulated setup? I guess changes in caster are minimal/negligible through jounce/rebound? I would guess that a triangulated setup would be smaller and lighter than as the 88 fiero setup.

is there a readily available modeling software that can demonstrate how a design will articulate?

Lets get some stuff on paper and make a badass car!

[The Dark Side of Will]

Oh boy...

FIrst of all, read some books. There's a book thread here from WAY back that has some good starting points. There's a book thread at http://www.corner-carvers.com as well.

(What do you mean "triangulated"?)

Terminology:
Side-view - projection of the physical and constructed aspects of the wheels and suspension onto the longitudinal-vertical plane
End-view -projection of the physical and constructed aspects of the wheels and suspension of one end of a car onto the transverse-vertical plane

There are a HUGE number of suspension configurations that have been tried, some of which are very strange, but all of which--no matter how strange they may be--have been tried for specific reasons. Seeing enough of them that you can figure out why a particular one has the features it has requires looking at not only a LOT of suspensions, but a LOT of cars as well.

In terms of analysis, there are three basic classes of indepedent suspension:
Single arm (Swing axle, semi-trailing arm, trailing arm)(Morgan sliding pillar is analyzed like a swing axle in side view and parallel dual arm in end-view)
Strut
Dual arm (Short-long or SLA, equal arm, parallel, non parallel, etc.)

If you don't think understanding how to analyze a semi-trailing arm suspension is important, read this at times heated discussion of the 2015 S550 Mustang rear suspension:
http://forums.corner-carvers.com/showth ... 44&page=34
(Thread starts with suspension pics here: http://forums.corner-carvers.com/showthread.php?t=46744 and more here: http://forums.corner-carvers.com/showpo ... tcount=420 )

The integral link is a concept that BMW and Ferrari have been using for about 10 years. It allows good ride quality, good anti-squat. The lower arm is analyzed in side view like a semi-trailing arm, but the integral link allows the suspension to avoid the camber and toe problems of the semi-trailing arm, and is analyzed in end-view like a short-long A-arm.



Can you make heads or tails of it? Why would it be good or bad for a Fiero to have something like this? Why could a Fiero *NOT* have something like this? (Hint: What was Gordon Murray's definition of the automotive problem?)

Check out these pics:
http://forums.corner-carvers.com/showthread.php?t=44187 and
http://www.fiero.com/forum/Forum3/HTML/000089.html





These two probably do the best job of showing the rear suspension on the Fiero GTU silhouette car.
Check out pics of the original Ford GT-40 suspension, the Lamboghini Aventador suspension
Check out Elephant Racing for very good suspension tours of a variety of Porsche models
Check out photos and descriptions of the NSX suspension
Check out descriptions of the McLaren F1 suspension and how Gordon Murray achieve both good ride and good handling from it.
Caster is meaningless on the rear and camber doesn't have an h.



So....

Where do you think we should start?

[ericjon262]

Oh boy...

lol...

FIrst of all, read some books. There's a book thread here from WAY back that has some good starting points. There's a book thread at http://www.corner-carvers.com as well.

I'm currently trying to figure out how to get a logon on CC, I only have a Gmail account and will not let you on without a legit email address. I didn't see the book thread, but I'm still looking, I did find a link to some SAE publications that seem like they could be interesting.
http://topics.sae.org/chassis/pubs/
RFT book thread here:
http://realfierotech.com/phpBB/viewtopi ... 808&start=

(What do you mean "triangulated"?)

triangulate seems like a poor word choice. but I was meaning to have the links attach to the knuckle at an angle as opposed to square, that way they can absorb forces sided to side, and front to back instead of just side to side.

Terminology:
Side-view - projection of the physical and constructed aspects of the wheels and suspension onto the longitudinal-vertical plane
End-view -projection of the physical and constructed aspects of the wheels and suspension of one end of a car onto the transverse-vertical plane

added to first post, thanks.

There are a HUGE number of suspension configurations that have been tried, some of which are very strange, but all of which--no matter how strange they may be--have been tried for specific reasons. Seeing enough of them that you can figure out why a particular one has the features it has requires looking at not only a LOT of suspensions, but a LOT of cars as well.

In terms of analysis, there are three basic classes of indepedent suspension:
Single arm (Swing axle, semi-trailing arm, trailing arm)(Morgan sliding pillar is analyzed like a swing axle in side view and parallel dual arm in end-view)
Strut
Dual arm (Short-long or SLA, equal arm, parallel, non parallel, etc.)

If you don't think understanding how to analyze a semi-trailing arm suspension is important, read this at times heated discussion of the 2015 S550 Mustang rear suspension:
http://forums.corner-carvers.com/showth ... 44&page=34
(Thread starts with suspension pics here: http://forums.corner-carvers.com/showthread.php?t=46744 and more here: http://forums.corner-carvers.com/showpo ... tcount=420 )

The integral link is a concept that BMW and Ferrari have been using for about 10 years. It allows good ride quality, good anti-squat. The lower arm is analyzed in side view like a semi-trailing arm, but the integral link allows the suspension to avoid the camber and toe problems of the semi-trailing arm, and is analyzed in end-view like a short-long A-arm.

the integral link is new to me, I've never seen anything quite like it. I'm going to try to find an animation of it articulating so I might better see how it works. do you have any other similar images of it? the more I look at it, the more I think I'm understanding what's going on. kinda neat, complicated though.

Can you make heads or tails of it? Why would it be good or bad for a Fiero to have something like this? Why could a Fiero *NOT* have something like this? (Hint: What was Gordon Murray's definition of the automotive problem?)

by the looks of it, it wouldn't fit under the Fiero body with a typical transverse engine/transmission layout. some longitudinal swaps like engineman's Audi 4.2 V8 might be able to make use of it. Seems like any other problems could be tuned out with changing spring rate or shock valving. one thing that I don't like about that particular design, is that even with extensive use of aluminum, it looks very bulky and heavy. Mustangs are also, typically more front heavy, whereas fiero's are typically more rear heavy. which would play into how much articulation the suspension will undergo during a maneuver.

Packaging is part of the reason I really like Blooze's rear suspension setup, only thing I would do different, would be to bring the coilover and bell crank closer to the lower frame rail to make it more compact.

Check out these pics:
http://forums.corner-carvers.com/showthread.php?t=44187 and
http://www.fiero.com/forum/Forum3/HTML/000089.html





These two probably do the best job of showing the rear suspension on the Fiero GTU silhouette car.
Check out pics of the original Ford GT-40 suspension, the Lamboghini Aventador suspension
Check out Elephant Racing for very good suspension tours of a variety of Porsche models
Check out photos and descriptions of the NSX suspension
Check out descriptions of the McLaren F1 suspension and how Gordon Murray achieve both good ride and good handling from it.

I'll check them out, can't see any pics on CC's yet until I can find a way to get a logon.

Caster is meaningless on the rear and camber doesn't have an h.

I take it caster is meaningless because there is no active steering on the rear?

I can't spell/

So....

Where do you think we should start?

My starting point, more reading, lots more...

design starting point, I feel should be the wheels and tires, they will define what can be done for the bearings and brakes. from there, we can design the knuckles and cradle.

I did find some freeware that might be helpful:

http://www.susprog.com/index.htm

[Emc209i]

For what it's worth, I almost started this thread a month ago but decided against it, so I'm right there with you Eric. Like most things mechanical, the concepts really aren't that hard to understand with enough seat time. What is hard is finding people who aren't information snobs and don't want you to catch up to them in understanding of systems. I think reading published works is the best way to lay a ground foundation for where to begin (as Will so kindly pointed out) and sort out all of the bullshit so you can build on that foundation with opinion and anecdotal extras.

I have yet to lay my foundation, so I planned to stay out of this thread until I read up, but I'm getting ready to spend some nights in the library reading, so I'll be along to chat with you soon. I've had all of the books for a while, just haven't had the interest to delve into them yet, I've been focusing on engine dynamics.

Will, since you're big on Murray, I'm sure you read his interview talking about how the NSX inspired the McLaren. I personally think the NSX is floaty, so it was interesting to think that he derived the hard riding McLaren from it.

[FieroWanaBe1]

My recommendation here is to start at the source of the problem, and not focus on the path.
The problem we face is accelerating a mass of a certain dimension package across a paved surface.
Definitions:
Acceleration is the rate of change of velocity. At any point on a trajectory, the magnitude of the acceleration is given by the rate of change of velocity in both magnitude and direction at that point
We analyze this situation with Newton's second law.
simplified to F=ma, or Force = mass * acceleration

Our goal is to, with the same input achieve a higher rate of velocity change of our vehicular mass by way of a direction shift.
Truly the only object from the vehicle that translates force to the road surface are the tires.

Tires have outputs that are very particular to their inputs. The more you understand the relationship of your
tires to the traction surface, the better you can optimize the entire system to react the way you see fit.

Everything else that is popular for the "tuning" or "performance" community is done with the best intention to optimize the force input-output relationship

Don't take this as a cop-out or elitist view. But you will not understand fully the problems of the designer/engineer until you fully understand the problem. You cannot control tires to do what you want them to if you don't understand their reactions, just like you wont have sex with your partner without the right inputs. You cant truly control what you don't understand, the rest is just getting lucky.

My recommendation is starting with Race Car Vehicle Dynamics, the status qou on the topic, though some information has been decidedly shown incomplete. (available on the internet)

The High Performance Tire is a very good book explaining the big picture problem to non-engineers (this book is inexpensive)
and
Tire and Vehicle Dynamics by Hans Pacejka, this is the standard for most modern tire models. (people have summarized the model over the web)

Once you have a basic understanding on tires, keeping in mind the reactions differ from a mild street tire to a racing slick.
You can look at how they can be put in our package, and how its limits define the tires reaction.

By focusing on the problem first, and not the solution, we can understand why so many solutions have succeeded or failed in the past, and can learn more from them than we could by just following industry trends. (and trust me this is a very real issue in the engineering field.)

[ericjon262]

For what it's worth, I almost started this thread a month ago but decided against it, so I'm right there with you Eric. Like most things mechanical, the concepts really aren't that hard to understand with enough seat time. What is hard is finding people who aren't information snobs and don't want you to catch up to them in understanding of systems. I think reading published works is the best way to lay a ground foundation for where to begin (as Will so kindly pointed out) and sort out all of the bullshit so you can build on that foundation with opinion and anecdotal extras.

I have yet to lay my foundation, so I planned to stay out of this thread until I read up, but I'm getting ready to spend some nights in the library reading, so I'll be along to chat with you soon. I've had all of the books for a while, just haven't had the interest to delve into them yet, I've been focusing on engine dynamics.

I'm also working on a foundation, I'm going to order up several of the books mentioned here and in the RFT book thread shortly.

My recommendation here is to start at the source of the problem, and not focus on the path.
The problem we face is accelerating a mass of a certain dimension package across a paved surface.
Definitions:
Acceleration is the rate of change of velocity. At any point on a trajectory, the magnitude of the acceleration is given by the rate of change of velocity in both magnitude and direction at that point
We analyze this situation with Newton's second law.
simplified to F=ma, or Force = mass * acceleration

Our goal is to, with the same input achieve a higher rate of velocity change of our vehicular mass by way of a direction shift.
Truly the only object from the vehicle that translates force to the road surface are the tires.

Tires have outputs that are very particular to their inputs. The more you understand the relationship of your
tires to the traction surface, the better you can optimize the entire system to react the way you see fit.

Everything else that is popular for the "tuning" or "performance" community is done with the best intention to optimize the force input-output relationship

Don't take this as a cop-out or elitist view. But you will not understand fully the problems of the designer/engineer until you fully understand the problem. You cannot control tires to do what you want them to if you don't understand their reactions, just like you wont have sex with your partner without the right inputs. You cant truly control what you don't understand, the rest is just getting lucky.

My recommendation is starting with Race Car Vehicle Dynamics, the status qou on the topic, though some information has been decidedly shown incomplete. (available on the internet)

The High Performance Tire is a very good book explaining the big picture problem to non-engineers (this book is inexpensive)
and
Tire and Vehicle Dynamics by Hans Pacejka, this is the standard for most modern tire models. (people have summarized the model over the web)

Once you have a basic understanding on tires, keeping in mind the reactions differ from a mild street tire to a racing slick.
You can look at how they can be put in our package, and how its limits define the tires reaction.

By focusing on the problem first, and not the solution, we can understand why so many solutions have succeeded or failed in the past, and can learn more from them than we could by just following industry trends. (and trust me this is a very real issue in the engineering field.)

This all makes sense, if there's no problem, there is no solution (unless you're a chemist, but we won't go there...)

is this "High Performance Tire"?

http://www.amazon.com/The-Racing-High-P ... 0768012414

the other two were easy to find.

http://www.amazon.com/Tire-Vehicle-Dyna ... 0080970168

http://www.amazon.com/Race-Car-Vehicle- ... GMT2R1S2EZ

[The Dark Side of Will]

Truly the only object from the vehicle that translates force to the road surface are the tires.

I need to fall back on my schtick from every time this topic comes up on Old Europe...

Any discussion of suspension that does not begin and end with tires is a waste of time.

EVERYTHING done to the suspension in the name of performance is done to make the best possible use of the tires.

Tires Suspension and Handling by Dixon is another good text.

The first thing to do for a clean sheet design is pick the tires. Series8217 has demonstrated that 275/35-18's work very well and only rub a little bit with his spring rates and alignment settings. I'm cautiously optimistic that 285/30-18's could work as well.
For tires that wide, the camber behavior of the suspension is extremely important.
Also, when the wheels get wide, packaging becomes very important. Pushing the hub flanges out to have more space for control arms compresses the brake components, reduces caliper clearance and results in very high wheels offsets. C5's use 18x9.5-65 rear wheels... 65mm offset. ( http://www.corvette-web-central.com/C5C ... heels.html )

One thing I'd love to see from Series8217's car is three point tire temperature data.

Blooze is building a classic "5 link" suspension. It's similar to what Mercedes started using with the 190E and BMW started building with the E90 3 series.
The 5 link has dual trailing arms, a lower transverse link, an upper camber link and a toe link. As you can see looking at the Mustang suspensions above and Porsche 996/997 suspension, the toe link can basically go anywhere.

You noted that the Mustang suspension looks heavy. Independent suspension almost always has less unsprung weight than a solid axle. However, it's difficult for manufacturers to get total vehicle weight lower with independent suspension. The integral link Ferrari/BMW/Mustang design puts both bending and twisting loads into the lower control arm, making it a large heavy part.
A 5 link system (or any design that loads links in tension/compression only and does not have links loaded in bending) will have much lighter links comparatively.

[FieroWanaBe1]

All those are the books I'm talking about.
I forget Carrol Smiths books, they are a really good basis for sound construction techniques, even if the cars he refers to where the pinnacle of technology 40 years ago, they don't differ enough to be irrelevant by any means.

http://farnorthracing.com/tech.html takes a good approach to explain his approach. It may not be seen as ideal for all, but is a great way to look at how things can be handled.

Right on with Will.

He isn't being elitist, he is telling the truth.

Needless complexity of push-rod actuation, rocker arms, multi-link, and adjustablity are merely eye-candy for the uninformed if you have no actual idea why they are there. Add as much complexity as you can, the only real input will always come from one person : the driver. That person needs to be confident that his inputs will result in a controlled output, and that they are the same every time.

I'm sure everyone has taken a gander at Bloozeberry's build on Old Europe. Although i don't agree with all his decision making, he made the point to become at least half informed, and use fair arguments for many of his decisions. The back and fourth discussions there could be worth while to look into, just filter through all the jaw-jacking and awestruck praise.

"Tuning" is a huge part of the package, and carefully selecting rates and variables to match the constraints of our system means so much more than it's given credit. A matched system of the current configuration has much more potential for a good "feeling" car than a complex conglomeration of parts that are poorly thought out. I would point to Steven's approach for inspiration on that.

So with that and all this in mind Ill say; a top down approach can keep everything thrown in discussions around from seeming over-whelming.

[The Dark Side of Will]

(What do you mean "triangulated"?)

triangulate seems like a poor word choice. but I was meaning to have the links attach to the knuckle at an angle as opposed to square, that way they can absorb forces sided to side, and front to back instead of just side to side.

One of the beautiful things about the '88 Fiero suspension and the 5 link suspension I mentioned above as far as analysis goes is that the loads are very well segregated. The lateral links carry lateral loads and are easily analyzed in end view, while the longitudinal links carry longitudinal loads and are easily analyzed in side view. Angling links confuses what should be a simple, elegant design.

by the looks of it, it wouldn't fit under the Fiero body with a typical transverse engine/transmission layout. some longitudinal swaps like engineman's Audi 4.2 V8 might be able to make use of it. Seems like any other problems could be tuned out with changing spring rate or shock valving. one thing that I don't like about that particular design, is that even with extensive use of aluminum, it looks very bulky and heavy. Mustangs are also, typically more front heavy, whereas fiero's are typically more rear heavy. which would play into how much articulation the suspension will undergo during a maneuver.

Packaging is part of the reason I really like Blooze's rear suspension setup, only thing I would do different, would be to bring the coilover and bell crank closer to the lower frame rail to make it more compact.

Gordon Murray said that the automotive problem is fundamentally one of packaging.
A Fiero is a rare case in the world of high performances cars because of its transverse mid-engine design. This is one reason I put aside thoughts of adapting a high performance suspension from another car to the Fiero. There isn't anything else with the similar packaging compromises to make the design trades remotely close to what we'd want in the Fiero. The Fiero rear frame rails are much further apart than the Solstice's or Corvette's, for example, in order to fit the transverse driveline. This means that the upper link has to be either very short or very high... neither of which lend themselves to good geometry.

I take it caster is meaningless because there is no active steering on the rear?

Right.

I feel should be the wheels and tires, they will define what can be done for the bearings and brakes. from there, we can design the knuckles and cradle.

Everything interacts... as I mentioned above, looking for longer links pushes the hub flanges out, which leads to high offset wheels, flat brakes and peculiarities in caliper clearance to the wheels.

That's in interesting looking software package.

[The Dark Side of Will]

"Tuning" is a huge part of the package, and carefully selecting rates and variables to match the constraints of our system means so much more than it's given credit. A matched system of the current configuration has much more potential for a good "feeling" car than a complex conglomeration of parts that are poorly thought out. I would point to Steven's approach for inspiration on that.

Starting with good geometry makes tuning easy. I generally call calibrating a suspension "setup" and calibrating an engine "tuning".

In BMW front ends (and struts in general) when the car is lowered, the roll center drops much more than the body. This dramatically increases the roll moment that a given lateral g load puts on the body.
The semi-trailing arm suspension in the back of an E30 has good camber behavior, but terrible toe behavior.

Between these two problems, BMW tuners have ended up with the maxim "The best way for it to work is not to let it work" and have to use extremely stiff setups in order to get fast lap times and good driver confidence.

If the cars didn't have these particular idiosyncrasies, then setting them up would be much easier.

A familiar example of setup being complicated by poor trades in the basic design is the Fiero. GM shipped most Fieros with square tire fitments. GM shipped V6 '88's with a slight tire and wheel width stagger. However, the car works best with a LARGE stagger. People who try to setup Fieros with square tire fitments actually end up fighting the tires and have to use a lot of bar to move cornering loads around the car. These cars can handle well up to the limit, but end up touchy and easy to spin because the setup is working against the natural tendency of the tires.

[The Dark Side of Will]

Will, since you're big on Murray, I'm sure you read his interview talking about how the NSX inspired the McLaren. I personally think the NSX is floaty, so it was interesting to think that he derived the hard riding McLaren from it.

Gordon had a really pure idea and the resources to bring it to fruition with very few compromises.

I haven't driven an NSX, and I probably will never drive a McLaren.
My impression was more that Murray admired the daily driver usability of the NSX. One of my favorite lines is that he set the climate control and then didn't touch it for 7 years.
Murray did do many interesting things in the F1 for ride quality, like the biaxial bushings he went on and on about.
However, the F1 has WAY more grip than the NSX and is capable of MUCH higher speeds, so it simply needs to have a stiffer suspension in order not to have bad behavior at the edge of its performance envelope.

Radial acceleration = V^2/R. The squared dependence on speed means that even for a large R, the large V dominates. That means that at very high speeds, a very small course change results in a large lateral acceleration. This acceleration comes on so quickly that the suspension (specifically the dampers) have to be very stiff in order to maintain control of body motion at high speed.

The NSX's control arms are works of art... They're like spider webs of aluminum. The "compliance pivot" is a very interesting feature, and may contribute to floaty front end feelings under hard braking. There are aftermarket kits that disable the compliance pivot by simply clamping it to the frame rail... I would like to try a link that connects the two compliance pivots to each other. That way, the car retains the good points of the compliance pivot, but for braking loads, the link takes the load instead of the compliance pivot bushings.


Also:
Photos of Ferrari 308 suspension:

http://www.ferrarilife.com/forums/proje ... arted.html

Simple design, good capabilities.

[ericjon262]

All those are the books I'm talking about.
I forget Carrol Smiths books, they are a really good basis for sound construction techniques, even if the cars he refers to where the pinnacle of technology 40 years ago, they don't differ enough to be irrelevant by any means.

http://farnorthracing.com/tech.html takes a good approach to explain his approach. It may not be seen as ideal for all, but is a great way to look at how things can be handled.

Just read a good bit of that site, I was glad to see that many of the concepts contained on it, were how I thought they worked.

Right on with Will.

He isn't being elitist, he is telling the truth.

I apologize if I implied anyone was being elitist, I enjoy the back and forth question and answer sessions, because they allow both sides to analyze the other's thought process.

Needless complexity of push-rod actuation, rocker arms, multi-link, and adjustablity are merely eye-candy for the uninformed if you have no actual idea why they are there. Add as much complexity as you can, the only real input will always come from one person : the driver. That person needs to be confident that his inputs will result in a controlled output, and that they are the same every time.

outside of packaging or ease of adjustment, I don't see a huge benefit to pushrods and rockers. they make a system heavier and more complex, but they allow for springs and shocks to be moved completely out of the wheel well where they could interfere with the wheel.

I'm sure everyone has taken a gander at Bloozeberry's build on Old Europe. Although i don't agree with all his decision making, he made the point to become at least half informed, and use fair arguments for many of his decisions. The back and fourth discussions there could be worth while to look into, just filter through all the jaw-jacking and awestruck praise.

having seen the pictures of Blooze's setup, I like it, it's interesting, but, without reading the specifics in detail, I can't tell you how much gain he made through his design. I can say, that I would have mounted the rocker much lower, closer to the frame, so the shock could ride just above the frame rail, but that would just be to make packaging other hardware easier.

"Tuning" is a huge part of the package, and carefully selecting rates and variables to match the constraints of our system means so much more than it's given credit. A matched system of the current configuration has much more potential for a good "feeling" car than a complex conglomeration of parts that are poorly thought out. I would point to Steven's approach for inspiration on that.

Agreed, the preface of the thread wasn't meant to imply the design wouldn't be tuned, it was more to mean this thread aims to create a entirely new design.

So with that and all this in mind Ill say; a top down approach can keep everything thrown in discussions around from seeming over-whelming.

makes enough sense. so what are our goals?

My goals: learn and build something cool
Will: I've seen him mention 285's under the back of a Fiero more than once....
FieroWanabe1:
EMC209i:

[ericjon262]

One of the beautiful things about the '88 Fiero suspension and the 5 link suspension I mentioned above as far as analysis goes is that the loads are very well segregated. The lateral links carry lateral loads and are easily analyzed in end view, while the longitudinal links carry longitudinal loads and are easily analyzed in side view. Angling links confuses what should be a simple, elegant design.

Makes sense, because it is no longer analyzed on single plains. cool.

Gordon Murray said that the automotive problem is fundamentally one of packaging.
A Fiero is a rare case in the world of high performances cars because of its transverse mid-engine design. This is one reason I put aside thoughts of adapting a high performance suspension from another car to the Fiero. There isn't anything else with the similar packaging compromises to make the design trades remotely close to what we'd want in the Fiero. The Fiero rear frame rails are much further apart than the Solstice's or Corvette's, for example, in order to fit the transverse driveline. This means that the upper link has to be either very short or very high... neither of which lend themselves to good geometry.

I have some ideas floating around, but I need to figure out the design software first. along with making a rough outline of the Fiero frame rail.

Everything interacts... as I mentioned above, looking for longer links pushes the hub flanges out, which leads to high offset wheels, flat brakes and peculiarities in caliper clearance to the wheels.

That's in interesting looking software package.

Subarus (at least my buddies 06 WRX) used very low offset brakes, off the shelf parts may not be too far off.

[FieroWanaBe1]

My goals: learn and build something cool
Will: I've seen him mention 285's under the back of a Fiero more than once....
FieroWanabe1:
EMC209i:

FieroWanaBe1:
My goals are to get 315s in my rear, but I do currently have an V8Archie wide-body kit. I don't want to limit myself the stock body width, and I want the components to be able to handle the loads of the 315 tires.
I work beyond slow though, who knows if Ill ever get to it.

[Emc209i]

I basically want to replace all of the rickety old shit GM endowed a 140bhp commuter car with. It's classic GM, and I hate it. I want an '88 front sub frame with tubular arm suspension but much beefier and completely replaceable hubs, and I'll probably move up to 5x120 bolt pattern front and rear if I can. Power steering up front. The rear is already converted to tri-link, and I've always run a high performance 245 back there and the back end moves well enough for me for street use. If I come across an easy way to upgrade the rear I might consider it, but for now its ok. I do however want to use a larger axle, so I'm going to have to do something about the rear knuckles eventually. I plan on snapping a lot of axles otherwise.

This picture has been saved on my desktop for months. I look at it often.



Anyone who thinks I plan to track my car after all of the detail work I've done is crazy. So I just want something pretty to look at. Call it piece of mind.

[FieroWanaBe1]

I apologize if I implied anyone was being elitist, I enjoy the back and forth question and answer sessions, because they allow both sides to analyze the other's thought process.

I don't think you gave that impression, but some people at some other forums seem to think that is an avoidance type of answer.

outside of packaging or ease of adjustment, I don't see a huge benefit to pushrods and rockers. they make a system heavier and more complex, but they allow for springs and shocks to be moved completely out of the wheel well where they could interfere with the wheel.

The big benefit that would make it worth while on a full fender car, to me, is more room inside the fender, and a low hood line (for the front of a car), and it allows for a rising rate motion ratio, and that can be a big deal (if both axles can benefit).

[The Dark Side of Will]

I basically want to replace all of the rickety old shit GM endowed a 140bhp commuter car with. It's classic GM, and I hate it.

Purely bolt-in won't work, but one of the things I'm avoiding is doing much metal work to a 1980's GM car that was built with the intention of being a cheap semi-disposable econobox.

For the amount of effort that Blooz is putting into his replica, he could have A) *bought* a 348 or B) built a GTM or other kit car that already has a reasonably sophisticated chassis.
I totally get the joy of making, but I'd rather make a one off original than a one off copy, and I'd rather make a production line than either of those.

This picture has been saved on my desktop for months. I look at it often.



Anyone who thinks I plan to track my car after all of the detail work I've done is crazy. So I just want something pretty to look at. Call it piece of mind.

What build or thread is that from?

[Series8217]

What build or thread is that from?

CCFiero on Old Europe: http://www.fiero.com/forum/Forum3/HTML/0 ... .html#p256 (the suspension build starts here)

It uses the following parts:

- HHP adjustable swaybar, which I think is just a bar from Speedway Engineering (Sylmar, CA) with the appropriate arms and mounts for an 88 Fiero
- SPC upper control arm (with 20-deg upper ball joint plate and bolt in GM metric ball joint)
- Vue hub in Solstice knuckle
- ZL1 Corvette rack with Rickady88GT's adapter bracket and tie rod adapters
- bump steer adjusters with rod end toe links
- 95-04 Mustang Cobra brake rotors
- 2010 Mustang GT brake calipers
- Fabricated lower control arm --- probably from RCC or Held, but I'm not sure

Overall the thread is a very good read.

He also fabricated some neat rear uprights. See the link.

[The Dark Side of Will]

What build or thread is that from?

CCFiero on Old Europe: http://www.fiero.com/forum/Forum3/HTML/0 ... .html#p256 (the suspension build starts here)

It uses the following parts:

- HHP adjustable swaybar, which I think is just a bar from Speedway Engineering (Sylmar, CA) with the appropriate arms and mounts for an 88 Fiero
- SPC upper control arm (with 20-deg upper ball joint plate and bolt in GM metric ball joint)
- Vue hub in Solstice knuckle
- ZL1 Corvette rack with Rickady88GT's adapter bracket and tie rod adapters
- bump steer adjusters with rod end toe links
- 95-04 Mustang Cobra brake rotors
- 2010 Mustang GT brake calipers
- Fabricated lower control arm --- probably from RCC or Held, but I'm not sure

Overall the thread is a very good read.

He also fabricated some neat rear uprights. See the link.

Ahh... ok. The LSJ swap thread. I was thinking of the "CopperTop" thread where the guy basically turned his Fiero into a tube frame car.
I was mostly curious about what knuckle it used.

[FieroWanaBe1]

I find the Elise rear suspension beautifully simple. (and a transverse engine does fit between it)