That's right, ball joints and tie rod ends. It was part of my design criteria. All components that move or wear are direct unmodified common parts that can be picked up in any automotive supply store. And should be in stock there not special order.
Wops...let me make a correction, that should read "most components". Some of the components for the front end have to be picked up at the dealer.
I have done another design using poly mounts. I like this design better but it doesn't allow for quick bushing replacement unless you have stock on hand. These use universal pivot bushings. I think this is the one I'm going to built onto the cradle I have already made.
The front arm comes out that far to clear the transmission on the other side.
Also notable is that I'm going to design and possibly build an upper control arm to use with the stock slightly modified shock.
While I sympathize with your thoughts that the right commonly used ball joints will be readily available locally...
Spherical bearings are going to be just as easy to find as urethane bushings, both of which will most likely be mail order.
Of the two, I'd pick spherical bearings over urethane any day of the week. The geometry will be more consistent, motion will be quieter, service life will be longer (especially if sealed spherical are used with additional external seals) and replacement will be easier.
Strut suspensions tend to work well when the inner pivots of the control arms are higher than the outer pivots. SLA suspensions tend to work well when the inner pivots of the lower control arms are level to or lower than the outer pivots.
Maybe you can help me locate long life spherical bearings. I know that you have looked into it. As far as I know nobody is guaranteeing more than 10 000 km life. I'm looking for a selection of two bearings, one premium and one economy (or value/$). I have looked around but can't really find any information on the life of the bearings. I know the poly is cheep and lasts a long time between service. What do you have against poly on the inside and spherical bearing on the outside? Should make for a slightly smoother ride, and because the control arm pivots are so far apart it shouldn't affect the toe if it's only on the inside. I found these weld cups that you linked in another thread somewhere, but I'm confused about the brand of bearing to use:
All I know is that the more expensive bearings are usually better, but not necessarily.
About the angle of the lower control arm. For the strut design (pic above) I have 8 to 10 degrees down angle (although it's hard to see in the pic I used), and for the "stage two" with the SLA I found 4 degrees better to use.
Spherical bearing dimensions are pretty standardized, so in theory anyone's bearing could work in those weld cups.
As that thread mentions, there are rod-ends and spherical bearings with integral seals. I will be starting with those and adding external seals for a "double sealed" installation.
Has anyone worked out the geometry points on a stock Fiero to compare with the new changes. I've been wanting to do something like this for a while. Also anyonentice the newer cars have unusual suspension designs with 4 and 5 point link arrangements?
Originally posted by zkhennings: Would that be a modified 88 suspension? Why get rid of the toe link? Doesn't it help with anti squat in addition to toe?
I'm curious about this as well. What's so wrong with the '88 Fiero rear suspension that you'd want to get rid of it?
There is not a whole lot wrong with the 88 rear suspension for everyday enthusiastic driving. In competitive circles, that boat sailed a long time ago but for a few odd balls that are unique in their choice of vehicle.
When you are building your dream car you are only limited by money, skills, talent and what you can get away with from the officials or wife.
The root problem IMO is the one year/one car only rear knuckle with its weany hub bearing. It really sucks when your wheel falls off in a race.
------------------ yellow 88 GT, not stock white 88 notchie, 4 banger
I'm curious about this as well. What's so wrong with the '88 Fiero rear suspension that you'd want to get rid of it?
quote
Originally posted by KurtAKX:
Not enough camber gain
It does pretty darn well either raising the inner pivots or lowering the outers.
quote
Originally posted by ccfiero350: The root problem IMO is the one year/one car only rear knuckle with its weany hub bearing. It really sucks when your wheel falls off in a race.
Totally agree. This is, IMNSHO, the achilles heel of the '88 suspension... very difficult to upgrade wheel bearings.
How much of an improvement would a double wishbone setup, or multilink with two trailing links be over an 88 style MacPherson strut suspension with revised geometry (lowering outer pivots/raising inner)? Due to the high COM of the rear of the Fiero the static roll center can be pretty accurately placed by lowering outer pivots or raising inner pivots of 88 suspension. How stiff of a ride would you need to keep the roll center relatively close to where you want it versus a double trailing link multi link or double wishbone suspension?
I have been trying to decide on which way to go with a rear suspension design (which would be totally custom so knuckles would not be an issue) and use a strut based design or go to a double wishbone/multilink setup
Either one can be made to perform quite well. Ferrari has always used double wishbones, but Porsche still uses strut front ends.
Get the tire to match the weight distribution, get the roll axis inclination to match the centroid axis inclination (or just make the roll axis a few inches lower in front) and you'll be most of the way there. Any rear suspension that gets the roll center high enough in the rear is going to have enough camber gain to make good use of the tires.
I have 215 front with 245 rear tires, stock front springs, softer than stock front bar, 325# rear springs and no rear bar on my '87 GT. It's pretty darn neutral. A modded '88 is going to be similar.
My Formula with rod-end lateral links and Konis is also fairly neutral, but has a slight tendency to slide the rear and a slight tendency to fishtail. That's on stock tire sizes.
My current intentions for my Fiero are to be a weekend driver and a car I can drive hard at the track (semi full welded in cage, full racing seats and 4 point harnesses designed for street use). I currently have 350lb springs in the rear, and I do not know if I would want to go stiffer (currently 2.8, would go stiffer if swapped in a heavier engine) for the road as it is currently pretty harsh (Massachusetts roads). So I guess my hesitation with a strut suspension would be based on how the roll center moves side to side with roll angle. I have seen Blooze's graphs of the roll center movement in the strut based suspension vs his double wishbone suspension and it is significant. I am just unsure if the stiffness of the suspension bearable on the road would allow the car to roll enough that it would make a noticeable handling decrease.
The thing is though I do not know how much this would actually affect the handling in real life so I guess I am asking a theoretical matter of opinion of whether the additional roll center control achievable with double wishbone suspension is worth it.
I would overall like to stay with a strut based suspension in the rear, and knowing that a car can handle with struts (911) is pushing me towards that route, but I simply don't have enough actual experience with knowing how the roll center difference would feel.
And as far as centroid axis inclination is concerned, are the most important points to find the axis between the two centroids located on the wheel center planes? Because that is what I would assume, if there is an accurate way to find them.
Roll center sensitivity is something that's way down the line in terms of importance... Although it is something that should be optimized if you're going to the trouble of building your own suspension.
You're probably 90% of the way there if you have static and dynamic contact pressures equalized front and rear.
Suspension design is less about getting everything perfectly right than it is about not getting anything grossly wrong.
[This message has been edited by Will (edited 02-26-2014).]
A couple weeks ago, Austrian Import (the OP) asked if I would update this thread with the findings from my own project where I'm building an F355 replica with a modified '88 suspension. First a little background for those who haven't checked out my build thread: I started by studying the effects of lowering and widening the stock '88 Fiero suspension and wasn't satisfied with the results. I was inspired by PFF member Datsun1973's design of a 5 link, pushrod system shown at the top of page 9 in this thread and designed my own similar system. PFF'er Zac88GT played a key role running many iterations of my suspension coordinates through his simulation software where I finally honed in on a configuration that lowers and widens the car, and theoretically improves most of the stock '88's handling characteristics.
Here's a summary of the modifications to the rear suspension:
1. Extended the wheelbase 76mm (3.0") to fit the stretched F355 body;
2. Replaced the Chapman strut with two upper lateral links, and a longitudinal coil-over shock absorber on a push rod & bell crank system;
3. Raised the lower lateral link mounts 97 mm (3.8") above stock through a combination of raising the cradle 25 mm (1.0") higher into the chassis and raising the link mounts an additional 72 mm (2.8") on the cradle;
4. Moved the forward inboard lower lateral link mount further outboard by 94mm (3.7"), and the aft inboard lower lateral link mount outboard by 123mm (4.85").
5. Shortened forward lower lateral link by 13mm (0.5") and the aft lower lateral link by 42mm (1.65");
6. Flipped knuckle to address a clearance issue with the new upper lateral link mounts and the inside diameter of the new wheel;
7. Replaced the stock wheels and tires with 18" x 9" et 45 wheels and 265/35/18 tires;
8. The net effect of the above changes increased the track width by 128 mm (5.0") (tire centerline to tire centerline), and increased the overall width of the car by 170 mm (6.7") (tire outer edge to tire outer edge) over stock;
9. Modified the trailing links to accept the new track width, and changed the location of the trailing link mounts on the chassis; and
10. Converted the brakes to 12" vented Corvette rotors.
These are side by side schematics comparing my modified rear chassis to the stock rear chassis:
Side view:
Rear view:
Top view:
And here are a few graphs showing some of the more important characteristics of the new design (pink lines) compared to the stock '88 Fiero suspension (blue lines). It's important to note that the new configuration gives the appearance of an 86mm (3.4") drop when compared to the stock wheel to fender clearance, and yet the suspension still achieves significant improvement in performance in most areas and retains approximately 5.5" of travel.
Here's a little schematic showing the how to interpret the above graph at 6 degrees roll:
And finally, a short video demonstrating the new design as it travels through it's range of movement.
For the diehards, the discussion, graphs, analyses and drawings of each of the four designs I considered before finalizing on this approach can be found in my build thread starting here: www.fiero.nl/forum/Forum3/HTML/000116-13.html
I've read your posts, and I understand what you've done and why you've done it.
It's very nice work.
There's one thing I can't figure out after watching the video- how did you operate the floor jack in the video so smoothly, without stopping between strokes?
Originally posted by KurtAKX: ...how did you operate the floor jack in the video so smoothly, without stopping between strokes?
A good magician never reveals his tricks.
OK, so I'm not a good magician: I videoed the suspension on the down stroke only (which is easy to get a fluid motion), then simply played back the same video in reverse.
OK, so I'm not a good magician: I videoed the suspension on the down stroke only (which is easy to get a fluid motion), then simply played back the same video in reverse.
Wow I was wondering the same thing, I thought you might have one of the pedals on your jack that will lift it like halfway in one push (when unloaded)
Just a bump .If anyone is interested , I have built and installed an SLA rear suspension in my 86 GT .(look in construction zone) Not tested yet but I hope to bounce it around the backyard soon .
thread is called " ecotec swap" .I am not great with computers , have no idea how to post a link .The new suspension stuff is on the last couple of pages .
I have tested the new suspension in the backyard and I am happy so far .But we are back in to winter again so no pavement runs till early April if the weather cooperates .I will see if I can post a link here .Most of the work on the rear suspension is in the last 3 pages //www.fiero.nl/forum/Forum3/HTML/000029.html
[This message has been edited by wftb (edited 02-26-2016).]
Why is it that engineers have to constantly change things? Granted this can be improved on, but why? I don't see model T people trying to improve their handling. I can see trying but they are 30 years old, they were designed to work and still have a trunk, why should you have to lose the trunk? I like the trunk in my Fiero, I need the trunk in my Fiero, I want my dam trunk in my Fiero so I will not be even looking at this thread again.
Sorry not a fan of this disposable society we have become, everything must be improved constantly to keep some engineer at work. The next newest idea is not always a good idea or may even work. look how often the technology changes those peace's of technology are just plain disposable in a year or sometimes less.
These cars have lasted 30 years and drive fine even today, have a great crash rating. sorry not a fan.
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
The model T is the most modified car in history , and there are lots of modified suspension examples . I am building my car to have fun at the track . If you like a stock fiero that is fine but threads like this are not going to be to your liking .And I still have the upper half of my trunk .And my golf clubs fit in quite nicely .
Why is it that engineers have to constantly change things? Granted this can be improved on, but why? I don't see model T people trying to improve their handling. I can see trying but they are 30 years old, they were designed to work and still have a trunk, why should you have to lose the trunk? I like the trunk in my Fiero, I need the trunk in my Fiero, I want my dam trunk in my Fiero so I will not be even looking at this thread again.
Sorry not a fan of this disposable society we have become, everything must be improved constantly to keep some engineer at work. The next newest idea is not always a good idea or may even work. look how often the technology changes those peace's of technology are just plain disposable in a year or sometimes less.
These cars have lasted 30 years and drive fine even today, have a great crash rating. sorry not a fan.
Steve
why do engine swaps? all they do is make the car faster, does it need to go faster?
Why is it that engineers have to constantly change things? Granted this can be improved on, but why? I don't see model T people trying to improve their handling. I can see trying but they are 30 years old, they were designed to work and still have a trunk, why should you have to lose the trunk? I like the trunk in my Fiero, I need the trunk in my Fiero, I want my dam trunk in my Fiero so I will not be even looking at this thread again.
Sorry not a fan of this disposable society we have become, everything must be improved constantly to keep some engineer at work. The next newest idea is not always a good idea or may even work. look how often the technology changes those peace's of technology are just plain disposable in a year or sometimes less.
These cars have lasted 30 years and drive fine even today, have a great crash rating. sorry not a fan.
Steve
Because some people have higher expectations and standards than you do?
Why is it that engineers have to constantly change things? Granted this can be improved on, but why? I don't see model T people trying to improve their handling. I can see trying but they are 30 years old, they were designed to work and still have a trunk, why should you have to lose the trunk? I like the trunk in my Fiero, I need the trunk in my Fiero, I want my dam trunk in my Fiero so I will not be even looking at this thread again.
Sorry not a fan of this disposable society we have become, everything must be improved constantly to keep some engineer at work. The next newest idea is not always a good idea or may even work. look how often the technology changes those peace's of technology are just plain disposable in a year or sometimes less.
These cars have lasted 30 years and drive fine even today, have a great crash rating. sorry not a fan.
Steve
Because they're engineers.
They're never right the 1st.... 2nd.... 3rd..... 10th time.
My god, did I just agree with you?!?!
[This message has been edited by Thunderstruck GT (edited 02-26-2016).]
Why is it that engineers have to constantly change things?
Sorry not a fan of this disposable society we have become, everything must be improved constantly to keep some engineer at work. The next newest idea is not always a good idea or may even work. look how often the technology changes those peace's of technology are just plain disposable in a year or sometimes less.
Steve
As an engineer (automotive electrical), I have to take offense to your statement. While true that engineers are trying to improve upon the last generation of an item, it is typically NOT engineers driving that change. It is the marketing and sales teams that drive things into obsolescence and the purchasing public that "needs' to have the latest item to one up their neighbor.
-off soap box-
(that might be the Patron speaking)
Bob
[This message has been edited by RCR (edited 02-26-2016).]
As another automotive Engineer (also electrical), at least with wiring harness, the changes typically are driven by the other groups, or management trying to save money by cutting costs.
70% other groups making changes (improved parts, new supplier, cost reduction, etc.) 25% management wanting to cut costs of the parts 5% me wanting to tweak the design to improve it (like moving splices so they're in an easily accessible part of the car, and mirrored between the two sides, like the doors).
Most Engineers have also never worked on a car, and they wonder why I want to make stuff easier to service. I spent an hour a month ago showing another Engineer what each part of a car was because he wanted to learn.
As another automotive Engineer (also electrical), at least with wiring harness, the changes typically are driven by the other groups, or management trying to save money by cutting costs.
70% other groups making changes (improved parts, new supplier, cost reduction, etc.) 25% management wanting to cut costs of the parts 5% me wanting to tweak the design to improve it (like moving splices so they're in an easily accessible part of the car, and mirrored between the two sides, like the doors).
Most Engineers have also never worked on a car, and they wonder why I want to make stuff easier to service. I spent an hour a month ago showing another Engineer what each part of a car was because he wanted to learn.
Oh I know all of that, problem is there are to many chiefs and not enough Indians. And I appreciate when someone wants to learn what they are doing that was never taught in school, like WTF moron thought it was a good idea to put the gas line filter under a car, lower than the gas tank so that anytime you change the filter you get soaked in gas? Who's fkn bright idea was that? Not only that they have used that stupid set up on everything from Fiero's to Suburban's and everything in between for decades.
I liked when an engineer came down to the floor and said,
"It worked on paper" or "The computer said it works"
Well the dam holes in the dam doors don't match up with the carrots on the doorpad, You make it work.
You change the dam gas filter, on the ground and get gasoline all over you.
You change the rear load floor heater core without disconnecting the AC lines in a suburban.
You are right for the most part these engineers I speak of are the ones who haven't got a clue about how a car works or how much extra work they make a car owner or mechanic do because their design is not ergonomically right. Because no one talks to anyone else.
Get off your high chair and take a walk down into the shop, climb that bridge, try to repair a part on a car that is covered by plastic covers that take longer to take off than the part you have to replace.
No one talks to anyone else, not even the other engineers who are working on a related part.
Want to really learn just how fkd up the automotive world is read, read
Bob Lutz Car Guys VS Bean counters.
One hand doesn't know what the other is doing, and it shows in how something's are designed. And in some cases it is guys sitting right next to each other in front of a computer designing, Or department heads to other department heads about how this will work with that.
