Dumb question i know, but was playing around with solstice knuckles last night. (for better bearings). I know it has been done before, but is was fun to mock it up. Roughing it in looked like there was going to be a little additional negaitve camber. good. also the ackerman (mind you i am just eyeballing it) looked like it was not quite enough, but then i eyballed the factory knuckle, and the factory ackerman looked all backwards (steering arms angled way in). supposed to be the other way around on a front steer car right. the solstice knuckle was pretty much straight, so averaging between the upper and lower knuckles it appeared to be outboard of the upper and lower ball joint centers. I could not find any discussion about the factory ackerman angles on the 88.
Car and Driver numbers for what ever they are worth
07 Sosltice GXP Skidpad 0.85
88 Formula 0.83
The Fiero was tested on 30 or more year old tire technology, The Solstice on something quite a bit newer.
Ya the Fiero is terrible, should look for a different platform.
Don't compare the Fiero's SLA design to the Solstices modified Double Wishbone design, might look similar but are 2 different designs with different geometry.
Yeah... Stick some semi-slick tyres on a Fiero and the handling can be a bit better, but it's never going to be a modern car. I get hammered on the corners by the Lotus and other more modern cars. It's just that I'm very powerfull and that I can keep up! I've tried lowering the roll center etc..., but it doesn't feel any better? And I can see how the other cars handle, and mine doesn't do that! The Fiero is not a race car, but you can have fun with it!
------------------ "Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero https://youtu.be/hUzOAeyWLfM
The 88 ackerman angle isn't great, but also isn't a constant (varies by cornering loads, tire deflection, as well as front toe adjustment), and there are contradictory theories on what the "best" ackerman should be.
I run almost zero toe in the front and have 235/40/17 front tires and can feel some tire scrubbing in parking lot turns.
The placement (up/down & side to side) is all function of the front suspension design. You can't change it without also changing other parameters (like bump steer). So if you change the location of the steering arms, you likely will be changing the location and/or length of the steering rack to bring bump steer back into something tolerable.
I'm so not a race-car driver, and I barely did SCCA and it was like 30 years ago now and I only did the stuff with the cones in a parking lot in Homestead (I think it was SOLO-1 or something... had to borrow someone's helmet, it was nasty).
But I owned a Solstice back from (late) 2005 to 2009. I modified it so it was honestly pretty quick... header, high-flow cat, better exhaust, intake, etc. The handling was "different." I'd say that the Solstice felt more stable in the rear to the point that, if I started to lose control a little bit in the rear, it was easier to regain control (don't ask why I know this, since this was on public streets when I was more immature). But the Fiero seemed more stable over-all. There was a handling threshold (if you will) that I realized that once I reached that, there was no going back. But in every other category, the Fiero felt more stable, and more... how can I say... the handling was more predictable across all driving situations.
The Solstice... maybe because I was older and a little bit less immature, so I never really pushed it as much... it felt solid, but it never felt as predictable. It drove fantastic, don't get me wrong... it had an excellent balance between great handling and a comfortable ride. It just didn't feel as competent as my 87 Fiero. There were times that at triple digits (again, don't judge me, I was an idiot)... I'd have all four wheels squealing in a turn with my Fiero, and I was right on the edge / pushing that envelope, and as long as I didn't push it too much further, I could really control the car's skid / slide as I made it around that turn.
The Solstice had a more stable back-end, but after 3 years of driving it... at some point the rear end got completely squirrelly. I don't know how to explain it, but the entire back end felt loose. It was still under warranty so I never bothered with it, and my daughter had just been born, so I traded it in for an SUV and I've been driving the speed limit ever since.
Jelly, I am not complaining about the way my 88 handles (just not sure what to do about a loose hub)! i put on sticky tires this summer and did a short autocross course. Got within three seconds of some very pricey porches. I am just an ole guy having fun, but it was a blast. my wife has a sky, and i secretly love the handling of that goofy front-engined car.
Slug, you just cost me some time checking out drag videos. wow. that is some amazing work on that car.
Thanks Guru, you are always expert helpful. The design just looked like it was off from what i had learned, looking for a reality check. I would rather just buy a set of Rodneys hubs, except his no racing clause...
Yeah! I like upsetting pricey Porsches as well👍 Turbo Slug thanks you for the complements by the way. And yes, I've tried to get the best out of what I have in terms of suspensions, without going totally nuts and custom made arms, etc...
Interesting what Todd said about feeling secure with his Fiero. I feel the same. I know it's limits and I can push it a bit. My brother in law, who has the pricey Porsches, Corvettes, Jaguars and whatever, was pleasantly supprised when he drove Turbo Slug on a trackday. His only complaint was for the gear shift; but he should remember his old 911's...!? They shifted badly as well. He pushed my car further than I tend to do and he found it to be quick!
Concerning '88s, I've always thought it was strange to narrow down the wheel width at the front? Is the track significantly narrower as well? While the back suspensions of an '88 are better (on paper), it would seem that the front design didn't improve anything? ------------------ "Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero https://youtu.be/hUzOAeyWLfM
[This message has been edited by Frenchrafe (edited 06-27-2024).]
Car and Driver numbers for what ever they are worth
07 Sosltice GXP Skidpad 0.85
88 Formula 0.83
The Fiero was tested on 30 or more year old tire technology, The Solstice on something quite a bit newer.
Ya the Fiero is terrible, should look for a different platform.
Don't compare the Fiero's SLA design to the Solstices modified Double Wishbone design, might look similar but are 2 different designs with different geometry.
The Solstice runs 245 width tires on all 4 corners, vs the 205/215 setup on a Fiero.
I test drove a second year Solstice at a local dealership.
I probably scared the salesman to death.
The test drive was all it took for me to decide to rebuild the suspension in my 86SE.
can speak for the handling of an 88 wish I could upload a video to prove my poin. yellow as much as he prods at my patience is honestly the expert on 88 suspension improvements. I'm more familiar with how he modified his 88 now since I started doing sim software and doing some 3d modeling and mods to the fiero suspension out of boredom and wanting to make use of some newly gained chassis knowledge and found out he's doing extremely well and getting close to the limit of what the control arms and such can hapoint. tldr. yes it ls bad compared to any modern car that someone didn't penny pinch the engineers on but can be made into a real monster with some work
can speak for the handling of an 88 wish I could upload a video to prove my poin. yellow as much as he prods at my patience is honestly the expert on 88 suspension improvements. I'm more familiar with how he modified his 88 now since I started doing sim software and doing some 3d modeling and mods to the fiero suspension out of boredom and wanting to make use of some newly gained chassis knowledge and found out he's doing extremely well and getting close to the limit of what the control arms and such can hapoint. tldr. yes, it ls bad compared to any modern car that someone didn't penny pinch the engineers on but can be made into a real monster with some work
edit: I decided to share the Google drive link. note the fiero is doing ~80 because it is interstate and dodged quickly and perfectly controlled, and this was with bad front bushings https://drive.google.com/fi...Tc/view?usp=drivesdk
Yeah! I like upsetting pricey Porsches as well👍 Turbo Slug thanks you for the complements by the way. And yes, I've tried to get the best out of what I have in terms of suspensions, without going totally nuts and custom made arms, etc...
Interesting what Todd said about feeling secure with his Fiero. I feel the same. I know it's limits and I can push it a bit. My brother in law, who has the pricey Porsches, Corvettes, Jaguars and whatever, was pleasantly supprised when he drove Turbo Slug on a trackday. His only complaint was for the gear shift; but he should remember his old 911's...!? They shifted badly as well. He pushed my car further than I tend to do and he found it to be quick!
Concerning '88s, I've always thought it was strange to narrow down the wheel width at the front? Is the track significantly narrower as well? While the back suspensions of an '88 are better (on paper), it would seem that the front design didn't improve anything?
I'm glad your BIL liked your Fiero. Has he had any experience in mid engined cars?
... Concerning '88s, I've always thought it was strange to narrow down the wheel width at the front? Is the track significantly narrower as well? While the back suspensions of an '88 are better (on paper), it would seem that the front design didn't improve anything?
On the street, I would much rather drive an 88, than an earlier car. But one of the old school Fiero autocrossers - his name escapes me - found that the most responsive (best turn-in) combination was an earlier front suspension (he had an 85) with an 88 rear cradle swapped in. He also ran a 4.9/Isuzu combination. Some of you may remember him. Haven't seen him post for years. He also ran the Cadero Usenet group. (Dating myself, here.)
Originally posted by Frenchrafe: Concerning '88s, I've always thought it was strange to narrow down the wheel width at the front? Is the track significantly narrower as well? While the back suspensions of an '88 are better (on paper), it would seem that the front design didn't improve anything?
88s have a wider front track than previous years.
The front suspension is a Huge improvement over the earlier, maybe a bigger improvement than the rear. Gone is the brutal harshness, no longer are you fighting the car, you are driving it. Anyone that's drivin them ' in anger' know you have to put way more effort into the steering than the reward it gives, the 88 is ' point and shoot' with way more smoothness and feel. You know what I mean, driving hard in earlier car's you do something with the steering wheel and then you see what it's doing where-as an 88, it's instantaneous, plus that steering wheel isn't fighting back.
On the street, I would much rather drive an 88, than an earlier car. But one of the old school Fiero autocrossers - his name escapes me - found that the most responsive (best turn-in) combination was an earlier front suspension (he had an 85) with an 88 rear cradle swapped in. He also ran a 4.9/Isuzu combination. Some of you may remember him. Haven't seen him post for years. He also ran the Cadero Usenet group. (Dating myself, here.)
Ya and there was never any proof he autocrossed a proper 88 on a regular basis, just spouted thou art holy on his particular setup.
can speak for the handling of an 88 wish I could upload a video to prove my poin. yellow as much as he prods at my patience is honestly the expert on 88 suspension improvements. I'm more familiar with how he modified his 88 now since I started doing sim software and doing some 3d modeling and mods to the fiero suspension out of boredom and wanting to make use of some newly gained chassis knowledge and found out he's doing extremely well and getting close to the limit of what the control arms and such can hapoint. tldr. yes it ls bad compared to any modern car that someone didn't penny pinch the engineers on but can be made into a real monster with some work
Hello Since Carter mentioned me, allow me to introduce my self. I started life as a car guy and became an engineer, designer and scientist. Retireist. After spending 20 years restoring driving and racing British Sports Cars, Sweetie and I decided to try something more modern, maybe mid engine. Lets see .... Lotus, Ferrari, Lamborghini, Maserati, Toyota, Pontiac ..... Hummmm ...
We bought an 86 SE. We where bitterly disappointed. I felt "numb", the controls felt disassociated. The car rolled lite a boat. Wow.... but it made a restoration project and a great show car. We were learning a whole new thing.
I learned that the 88-was a better chassis design so I bought a 88 Base Coup. Nothing on it that didn't make it go. Yellow started as an red 5 speed iron duke. The first look on jack stands had me almost drooling. Sweetie was nodding a big smile. "This thing has potential." My experience taught me to recognize good design when I see it.
My next post on this thread will continue as ...... This is chassis 101. It may be elementary for some but not all. So please stand by. It's time for the debate.
Ya and there was never any proof he autocrossed a proper 88 on a regular basis, just spouted thou art holy on his particular setup.
No argument from me. I owned an 85 GT that I bought new, in 85. It became a PITA to drive. So much so that when I traded it in, in 88, I wouldn't even consider a Fiero (for several reasons, but the 85's steering was waaaay up there. At that point I didn't care how improved the 88 was.) Ended up with a Firebird Formula until '97 or so. Then I got back into Fieros. Haven't been without at least one (nearly all 88s) since then.
[This message has been edited by Raydar (edited 06-28-2024).]
This may be elementary for some but not all. Please bear with me and hopefully enjoy. Here are the basic concepts that define how a chassis behaves when outside forces are applied to it. Fortunately the laws of physics don’t break so we’ll have a dependable starting point.
Chassis 101
Ackerman is the principal that the inside steering tire will follow a shorter radius than the outside steering tire. Projected axel centerlines will meet at the same point.
Roll axis is the line between the center of mass at the front axle center line mid-point, to the center of mass at the rear axle center line mid-point.
Camber is the angle of the radial plane of a tire to the road surface. Looking from the rear to the front along the roll axis; a smaller angle on the inboard side of the tire radial plane than on the outboard side is Negative Camber. Positive is the opposite. Zero camber is when it’s perpendicular to the road.
Toe angle is the angle of the tire radial plane relative to the roll axis looking from the top down. The roll axis would appear as a line. Toe- in is when the tire radial planes relative to the roll axis converges forward of the chassis. Toe out is the opposite. Zero toe is when the tire radial plane is parallel to the roll axis.
Bump steer refers to toe angle change caused by up (bump) and down (droop) movement of the outboard end of the control arms.
Tire contact patch is the “foot print” the tire bears on the road surface.
Scrub radius describes the circular path the center of the contact patch takes, when steering input is entered. Zero scrub radius means; the center of the contact patch is the center of rotation when steering is input. An important design parameter, rarely discussed.
There are a few others I’ll save for later.
The ideal scenario for an optimal chassis is to meet all dynamic outside forces with equal and opposite ones. And no more. Unnecessary opposite force cost contact patch friction.
The 88 chassis is a dream for an engineer car guy who’s favorite car thing is chassis. Why?
Let’s see …. First off, clearly it was the work of an engineering studio dedicated to building an actual mid-engine sports car . No, lotus wasn’t involved, but they appear to be working out of the same book. Especially at the front.
Clearly the early cars were never intended to be true sports cars. Their suspension geometry is actually worse than an MGB. Of course the MGB is a pretty nice 70 year old sports car chassis. We know that the front is from a Chevy Chevette and the rear is a backwards Citation. Brilliant on a budget …. but not a sports car.
I agree with Carter, I really like the 88 chassis as a starting point to a very serious Sports Car. I'll continue this if anybody's interested.
This may be elementary for some but not all. Please bear with me and hopefully enjoy. Here are the basic concepts that define how a chassis behaves when outside forces are applied to it. Fortunately the laws of physics don’t break so we’ll have a dependable starting point.
Chassis 101
Ackerman is the principal that the inside steering tire will follow a shorter radius than the outside steering tire. Projected axel centerlines will meet at the same point.
Roll axis is the line between the center of mass at the front axle center line mid-point, to the center of mass at the rear axle center line mid-point.
Camber is the angle of the radial plane of a tire to the road surface. Looking from the rear to the front along the roll axis; a smaller angle on the inboard side of the tire radial plane than on the outboard side is Negative Camber. Positive is the opposite. Zero camber is when it’s perpendicular to the road.
Toe angle is the angle of the tire radial plane relative to the roll axis looking from the top down. The roll axis would appear as a line. Toe- in is when the tire radial planes relative to the roll axis converges forward of the chassis. Toe out is the opposite. Zero toe is when the tire radial plane is parallel to the roll axis.
Bump steer refers to toe angle change caused by up (bump) and down (droop) movement of the outboard end of the control arms.
Tire contact patch is the “foot print” the tire bears on the road surface.
Scrub radius describes the circular path the center of the contact patch takes, when steering input is entered. Zero scrub radius means; the center of the contact patch is the center of rotation when steering is input. An important design parameter, rarely discussed.
There are a few others I’ll save for later.
The ideal scenario for an optimal chassis is to meet all dynamic outside forces with equal and opposite ones. And no more. Unnecessary opposite force cost contact patch friction.
The 88 chassis is a dream for an engineer car guy who’s favorite car thing is chassis. Why?
Let’s see …. First off, clearly it was the work of an engineering studio dedicated to building an actual mid-engine sports car . No, lotus wasn’t involved, but they appear to be working out of the same book. Especially at the front.
Clearly the early cars were never intended to be true sports cars. Their suspension geometry is actually worse than an MGB. Of course the MGB is a pretty nice 70 year old sports car chassis. We know that the front is from a Chevy Chevette and the rear is a backwards Citation. Brilliant on a budget …. but not a sports car.
I agree with Carter, I really like the 88 chassis as a starting point to a very serious Sports Car. I'll continue this if anybody's interested.
Hahah... you certainly have the narcissism going in the previous post, but I definitely appreciate this response, lots of good info in here. For my own personal goals... I largely don't even know where to start, but getting everything properly replaced and restored is the first goal. When I have to start putting the front suspension bolts back in, I'll make sure I read up more on this so I don't upset camber and caster.
[This message has been edited by 82-T/A [At Work] (edited 06-29-2024).]
Todd, why do you almost always copy/quote the entire post that you're responding to? Text is bad enough, but you also include images when they're present. Not trying to give you a bad time, but all it does is necessitate a whole lot of extra scrolling for everyone over duplicated material when reading the thread.
Todd, why do you almost always copy/quote the entire post that you're responding to? Text is bad enough, but you also include images when they're present. Not trying to give you a bad time, but all it does is necessitate a whole lot of extra scrolling for everyone over duplicated material when reading the thread.
I only quote an image if I'm referencing that specifically in my response (at least within the past couple of years).
But it's OK to quote the message itself (just the text)... sometimes I abbreviate it, but the unwritten rule is only about quoting images unnecessarily.
I only quote an image if I'm referencing that specifically in my response (at least within the past couple of years).
I won't do it here... but I'll demonstrate to you that this is simply untrue. I don't think you realize how often you just quote everything for no practical purpose.
quote
Originally posted by 82-T/A [At Work]:
...but the unwritten rule is only about quoting images unnecessarily.
I don't know what "rule" you're referring to, but it's just common sense not to quote a whole lot of text for no reason... especially when you're responding immediately below the post you've quoted in full.
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[This message has been edited by Patrick (edited 06-29-2024).]
Thanks for asking. This is my favorite car subject and I enjoy sharing it.
We often hear the term handling used interchangeably with the term cornering. They are related but separate. Cornering forces can be measured in the lab. Handling is something a driver “feels”. This will first be about “cornering”.
A chassis is 4 tire contact patches bearing the cars mass; Ideally, equally distributed over the 4 contact patches. The Fiero is already close to that. And, almost all of the mass is inside the wheelbase. That leads to low polar moment of inertia ... and makes the physics much easier.
Step one in tuning a chassis; the 88 only requires tuning and not a redesign like the early cars; is to make it able to roll perfectly straight with the least possible resistance. All 4 tire radial planes need to be parallel to each other and to the roll axis. Ideally they will stay that way regardless of bump or droop movements. If there is zero toe angle change over about 4” off travel between bump and droop, it can be called zero bump steer. (for all practical purposes) The 88 front end is there already.
If tires are steering in slightly different directions at every undulation, their just scrubbing rubber from their contact patches fighting each other. That’s lost energy that needs to be made up with more power. If feels uncomfortable too.
I could not find any discussion about the factory ackerman angles on the 88.[/QUOTE]
You won't find any because "Akerman" is not and angle. Ackerman is the principal that the inside steering tire will follow a shorter radius than the outside steering tire. Projected axel centerlines will meet at the same point.
Originally posted by Raydar: But one of the old school Fiero autocrossers - his name escapes me - found that the most responsive (best turn-in) combination was an earlier front suspension (he had an 85) with an 88 rear cradle swapped in. He also ran a 4.9/Isuzu combination. Some of you may remember him. Haven't seen him post for years. He also ran the Cadero Usenet group. (Dating myself, here.)
i remember him. He was from Oklahoma City if i remember correctly. He had raced his Fiero extensively with a Quad Four and then built a car with the 4.9 engine that he said was superior. i also remember his advocacy of the earlier front end with the 88 rear cradle swapped in. He almost convinced me to do likewise.
quote
Originally posted by Yellow-88: I'll continue this if anybody's interested.
And Yellow - keep it up. i am listening
------------------ Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.
Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.
I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 3800SC, 4-wheel drifts are fun!
So now that we have a chassis that can roll perfectly straight and can absorb surface irregularities without scuffing any of its contact patches. We can introduce some forces to it. Call them simply; the forces that cause roll angle change.
By projecting the roll axis, it forms a plane perpendicular to the road surface plane, virtually dividing the chassis into left and right side. Any variation from perpendicular is roll angle.
Introducing roll angle transfers weight to the side with the smallest angle. Because gravity is involved, the contact patches on that side now carry a higher percentage of the chassis weight. Roll should transfer weight to front and rear contact patches equally. A properly sized roll bar does that. Things get tricky real fast when one divides the chassis into sprung and un-sprung weight. Now it becomes suspension … suspended with springs and levers. Gravity gets involved.
At this point the fancy physics and math leads to a simple result. Roll causes weight transfer and that compress a spring that balances the load. The equal and opposite forces thing. It also moves the control arm toward bump in the process. It doesn’t cause bump steer because we” set” that in step one. But what happens to the camber angles?
A well designed Double A arm Suspension system will compensate for camber change caused by roll angle. Zero camber at maximum roll angle is ideal. That’s when springs can no longer balance the transferred load, so the over loaded contact patches reach their limit of adhesion. Adding extra negative camber to compensate may help with high aspect ratio, 60 plus series tires, because they may distort enough to actually keep a full contact foot print. Low profile tires want to be at zero camber for maximum contact … always. Naturally my pitch for the 88. Somebody already thought all that stuff out.
We haven't entered any steering inputs yet so Please stand by.
A thought; If any of you 3D Cad guys with scanners what to model the 88 front end, that would be wicked cool. I'm a pioneer dinosaur in the Cad Modeling field. Carter, wanna take a shot at it?
I could not find any discussion about the factory ackerman angles on the 88.
You won't find any because "Akerman" is not and angle. Ackerman is the principal that the inside steering tire will follow a shorter radius than the outside steering tire. Projected axel centerlines will meet at the same point.
Exactly this 'Ackerman angle' is a made up term for someone wh0 doesn't understand the basic of steering geometry. what a messed up world we now live in.
This can be a great conversation, start with Steering axis inclination, see how that effects things and work from there. No, this isn't your answer, but will set you into the right direction of knowledge
[This message has been edited by jelly2m8 (edited 06-30-2024).]
Originally posted by jelly2m8: Exactly this 'Ackerman angle' is a made up term for someone wh0 doesn't understand the basic of steering geometry. what a messed up world we now live in.
This can be a great conversation, start with Steering axis inclination, see how that effects things and work from there. No, this isn't your answer, but will set you into the right direction of knowledge
Hi.
To continue ... now that we have a virtual chassis with a suspension system it's time for more terms and concepts. First we need to revisit my description of "roll axis". In the first ultra simple chassis model with no suspension, I described roll axes as a line between the front and rear centers of mass. With the suspension system added that line runs between the front "roll center" and the rear "roll center". Roll Centers are points in space created by the "geometry" of the suspension system; that's the parts that actually locate and move the components of the chassis. "Steering axis Inclination" is just one of the concepts that determine the location of "roll centers". I'll continue a discussion of that after my "Sunday Afternoon Blues" jam session. Yes ... knowledge is powerful.
It’s called suspension geometry because it’s all angles and arcs. It's theoretical lines drawn in two dimensions. It’s all about figuring out how to keep the tire contact patches in complete contact with the road while the suspended part of the chassis is being affected by dynamic outside forces. Tell you what... You young CAD guys have no idea how beautiful the modeling software has become. Chevy Chevette suspension was probably drawn with T squares and triangles, on paper, figured out with slide rules. I give them credit. (Does anyone still have your first slide rule?)
Google suspension geometry / images and you’ll see that there are a lot of ways to design a double A- arm suspension, all with the same goal. Compensate for camber change and bump steer caused by roll angle. It’s in the geometry design drawings were you see terms like steering axes inclination, instant center and roll center. In a nut shell some designs are better than others but, all designs are specific to a purpose. The 88 front end was designed specifically for a sports car.
The roll center is a point in space about which the sprung mass of the chassis rotates as presented in two dimensional geometry. Its location is determined by the designer’s choice of control arm configuration. The roll center is dynamic in that it moves relative to the degree of longitudinal roll. Where it’s located and how dynamic it is, is part of what separates one design from another. There is a front and a rear roll center so connecting them establishes the roll axes for that particular suspension geometry front rear combination.
Up to this point, this chassis is still rolling in a straight line. The “forces that cause roll” are not from cornering forces, they're from rolling on a tilted surface. I think we can call it "simulated" Lateral G force. ( ?? )
Before we add steering forces into our virtual chassis, there’s one more important concept that involves “steering axis inclination” geometry. That is Scrub Radius.
If you draw a line between the upper and lower ball joints and project it through the road surface plane, you have defined the “steering axis”. Ideally, its “inclination” will pass directly through the center of the tire contact patch. That would be zero scrub radius. It "feels" really, really nice, if you can do it. We'll visit it later.
So …. It’s able to roll perfectly straight on bumpy undulated surfaces that are sometimes tilted to pretty steep angles that are still bumpy and undulated and still continue to roll straight. OK. It’s time to see how it corners. We need another force.
If you’re waiting to hear about how to build the ultimate 88 Fiero, stay tuned. I think it’s extremely important to understand why you do something, way before you do it.
Well, the goal was to use better hubs. Yes, i am toying with solstice knuckles. Also c5 knuckles. My solstice knuckles had been machined for c5 hubs. Maybe 5x120 wheels are a good choice? Anyway, The steering geometry refresh is just what i needed. I keep trying to get greedy with camber gain. Raising the upper ball joints too high.
Well, the goal was to use better hubs. Yes, i am toying with solstice knuckles. Also c5 knuckles. My solstice knuckles had been machined for c5 hubs. Maybe 5x120 wheels are a good choice? Anyway, The steering geometry refresh is just what i needed. I keep trying to get greedy with camber gain. Raising the upper ball joints too high.
I imagine that you mean the sealed wheel bearing / hub unit that bolts into the cast iron "knuckle". Better meaning more meaty? If I may ask, why?
You aren't the only one looking for more camber gain, meaning negative camber. That may be a hang over from the days of tall floppy tires. It's also a natural thing to do as bipedal creatures. We tend to angle our legs against the outside of a turn, or brace against steep down will. In a car, the goal is keeping your footprint as flat on the ground as possible .... always.
So our suspended chassis is able to roll perfectly straight on bumpy undulated surfaces that are sometimes tilted and are still bumpy and undulated and still continue to roll straight. OK. It’s time to see how it corners. To do that, we need a new term. Slip Angle.
Our test track is a straight line with a section that is banked, like a banked corner but straight. It is mildly undulated with an occasional bump as its surface.
As our chassis travels onto the banked section, its roll angle increases, transferring weight. A well designed suspension system adjusts camber angle to compensate for camber change. Zero camber always. That is tire radial plane perpendicular to the road surface plane.
As our chassis travels into steeper and steeper banking along the straight line, at some point the tire contact patches begin to “slip”. They are responding to (“G-Force”) pushing them beyond their limit of “absolute” adhesion. If we hold the bank angle (roll angle) steady, keep traveling and trace the line that the contact patches make relative to the straight line, we’ll see an angle forming. The higher the chassis longitudinal roll angle, the higher the contact patch Slip Angle. The chassis is still following the straight line because its roll axis is parallel to the straight line. It’s slipping sideways, away from the straight line.
So …. How do we get this thing off of a straight line?
I heard WRX 2004ish front knuckles are similar to 88 rear knuckles...
It would be the rear, not the front. The 88 rear uses a tri-link suspension with 2 lateral and 1 trailing links per side. There is no lower ball joint, which is what is used in 99% of front knuckles to enable turning. The rear WRX knuckle is also a tri-link design, but offsets and angles are different, which will make retrofitting one to a Fiero more of a challenging than most are willing to undertake.
I owned an 87 and 88 Fiero GT at the same time. Easy win for the 88. Sold the 87.
I also owned the 88, which had the suspension modified (Konis + sway bars front and rear) and had a 300 bhp turbo engine at the same time as I owned (and still own) my 09 Solstice GXP coupe with 375 bhp (yes, also somewhat modified) and with nonstock sway bars and shock/springs) so I can confirm that the Solstice is a better handling car but the Fiero done the way I had it was no slouch either, and was head and shoulders ahead of the pre-88 Fieros, and was possibly the equal of the GXP in dead stock form before I improved it.
