Real Fiero Tech

Changing the end-link length to adjust ride height is very easy (in fact Corvettes have this adjustment available from the factory). However, the center hold on the spring dictates both jounce/rebound and roll stiffness.

For example, if the spring is held right at the center, then the jounce rebound rate is "direct" in that the spring displacement (measured as the vertical distance between the "peak" of the spring and its ends) is the same as wheel displacement and roll stiffness is the same as jounce/rebound stiffness.

However, if you split the center hold into two places and separate them laterally...
Then the rate increases because the spring displacement is greater than the wheel displacement.
ALSO, jounce/rebound and roll rates become different. The jounce/rebound is a "first order" deflection in which the spring is bent like a bow. Roll is a "2nd order" deflection in which the spring is bent into an S shape.

In order to be able to dial the spring in for the Fiero, the split center hold lateral separation would need to be adjustable... weight and complexity.

The Dark Side of Will wrote:Changing the end-link length to adjust ride height is very easy (in fact Corvettes have this adjustment available from the factory). However, the center hold on the spring dictates both jounce/rebound and roll stiffness.

For example, if the spring is held right at the center, then the jounce rebound rate is "direct" in that the spring displacement (measured as the vertical distance between the "peak" of the spring and its ends) is the same as wheel displacement and roll stiffness is the same as jounce/rebound stiffness.

However, if you split the center hold into two places and separate them laterally...
Then the rate increases because the spring displacement is greater than the wheel displacement.
ALSO, jounce/rebound and roll rates become different. The jounce/rebound is a "first order" deflection in which the spring is bent like a bow. Roll is a "2nd order" deflection in which the spring is bent into an S shape.

In order to be able to dial the spring in for the Fiero, the split center hold lateral separation would need to be adjustable... weight and complexity.

makes enough sense to me. just spitballing ideas to see if something is feasible.

Lots of things are feasible (Almost anything can be built if you have a welder... just ask Rcheee). Doing the system level trades to figure out what gives the end result the best balance is where the art is.

The Dark Side of Will wrote:Lots of things are feasible (Almost anything can be built if you have a welder... just ask Rcheee). Doing the system level trades to figure out what gives the end result the best balance is where the art is.

I think you know what I meant... smartass.

Lol

There really isn't that much difference between *well executed* solutions. I'd peg the probable weight difference in structure between a coil spring setup and transverse leaf setup at 20-25#. Of course it's possible to make it way heavier than that if you're not careful and use off the shelf linear bearing blocks and overbuild the heck out of it...

Also any way you slice it, using 12+ inch brakes and being lighter than stock on an early car is going to be a legit design challenge. The stock brake may be so tiny as to almost not be there, but that makes them very light. The same goes for the tiny outer CV's and tiny hub bearings. Once 12 or 13 inch brakes, large enough wheel bearings to handle 1g+ cornering loads with 275 tires and large enough outer CV's to handle 300-400 RWHP are in the mix, it's a challenge to make the rest of the system light enough to recover the weight gain, even with 2 piece rotors, aluminum knuckles, aluminum calipers, rod-end links, optimized chassis structure, etc.

I have to shed ~25# from my current system to get back to stock, as I swapped in the A-body large pattern knuckles with HD brakes (which include IRON calipers) and gained 13# (!) of unsprung weight per side.

The Dark Side of Will wrote:A while back I came up with an SLA design based on the '88 rear links,

Just remembered... there's no way a decent outer pivot design will fit inside a 15" wheel; part of the reason I haven't done it yet.

The Dark Side of Will wrote:Lol

There really isn't that much difference between *well executed* solutions. I'd peg the probable weight difference in structure between a coil spring setup and transverse leaf setup at 20-25#. Of course it's possible to make it way heavier than that if you're not careful and use off the shelf linear bearing blocks and overbuild the heck out of it...

Also any way you slice it, using 12+ inch brakes and being lighter than stock on an early car is going to be a legit design challenge. The stock brake may be so tiny as to almost not be there, but that makes them very light. The same goes for the tiny outer CV's and tiny hub bearings. Once 12 or 13 inch brakes, large enough wheel bearings to handle 1g+ cornering loads with 275 tires and large enough outer CV's to handle 300-400 RWHP are in the mix, it's a challenge to make the rest of the system light enough to recover the weight gain, even with 2 piece rotors, aluminum knuckles, aluminum calipers, rod-end links, optimized chassis structure, etc.

I have to shed ~25# from my current system to get back to stock, as I swapped in the A-body large pattern knuckles with HD brakes (which include IRON calipers) and gained 13# (!) of unsprung weight per side.

There are some places that, IMO, it's ok to have the extra weight. brakes serve a purpose, and a very important one I might add. I'm ok with them being a little heavier. same goes for the bearings and axles, less breakage is a good thing, I like my wheels/tires to stay on the vehicle thanks...

I remember someone on OE running the entire corvette rear suspension, but that was a longitudinal setup without an engine and trans in the way. Could the corvette rear knuckles be adapted easily for our use? from what I can see, C6 knuckles look a little tall, but they offer alot to us, bolt on brake options, wheel bearings, axles, aluminum construction.

I saw something else that might be an option, how about solstice/sky parts. looking at pictures, the rear suspension parts look like they might fit with some custom cradle work...



still needs an upper control arm mount, but I think that could be done easy enough.

That being said I don't know how much of an aftermarket following those have, or parts interchange, has to be better than a fiero though... also, I'm just assuming a sky or solstice has a halfway decent suspension compared to a fiero...

Doing a little more research on the solstice parts, Wheelbase, and track width are very close to the fiero (as expected) this is looking a little more promising than I thought. anyone driven a solstice or sky? what did you think?

Chase Race wrote:

whipped wrote:It's interesting that they have a "mock tubular" (welded stamped halves?) a-arm, instead of the old fashioned stamped steel pieces...

If you're talking about the Solstice parts, they're cast aluminum.

And rear tie rods or not, that suspension works, and works well.

http://realfierotech.com/phpBB/viewtopi ... 252#p83252

Doug Chase thinks highly of the Solstice suspension.

It's been discussed before... There was a discussion, I *think* on Old Europe, in which it was determined that swapping the Solstice suspension could work well if the UCA's were swapped left for right to match the Fiero's frame rail angle in that area. If you look at the graphic you posted, the UCA pivots are biased toward the front of the car. That would work better in a Fiero biased toward the rear.

HOWEVER, any front-heavy or even 50/50 car is going to have braking capacity seriously biased to the front. Fieros, Corvairs, Porsches, Ferraris and mid- or rear-engine cars with rear weight bias like brake setups that are much closer to "square".

The Dark Side of Will wrote:

Chase Race wrote:

whipped wrote:It's interesting that they have a "mock tubular" (welded stamped halves?) a-arm, instead of the old fashioned stamped steel pieces...

If you're talking about the Solstice parts, they're cast aluminum.

And rear tie rods or not, that suspension works, and works well.

http://realfierotech.com/phpBB/viewtopi ... 252#p83252

Doug Chase thinks highly of the Solstice suspension.

It's been discussed before... There was a discussion, I *think* on Old Europe, in which it was determined that swapping the Solstice suspension could work well if the UCA's were swapped left for right to match the Fiero's frame rail angle in that area. If you look at the graphic you posted, the UCA pivots are biased toward the front of the car. That would work better in a Fiero biased toward the rear.

HOWEVER, any front-heavy or even 50/50 car is going to have braking capacity seriously biased to the front. Fieros, Corvairs, Porsches, Ferraris and mid- or rear-engine cars with rear weight bias like brake setups that are much closer to "square".

I feel like the brakes issue could be corrected easy enough. matching the frame rail angle could be harder though, because the shock passes through the UCA. of coarse, both control arms could be swapped...

Rickaddy88GT has the Solstice/Sky suspension sitting around and mocked it up with is LS4 swap/cradle.


The big thing to keep in mind is that from the outer edge of the lower flange on the 88 cradle to the outer edge of the tire is about 17.5" if you plan to keep the tires under the stock body panels. In the picture the above it looks like the wheel flange is considerably further out than that and the upper a-arms are almost touching the engine (which is 1-2" from the frame rail and its about 2" thick), so the upper a-arm are probably too long to pull everything back under a stock bodied fiero.

Now with a widebody, custom cradle (wider) and some fab work to the lower frame rails to mount the a-arms it might be a pretty good setup.

fieroguru wrote:Rickaddy88GT has the Solstice/Sky suspension sitting around and mocked it up with is LS4 swap/cradle.
http://i152.photobucket.com/albums/s162 ... Medium.jpg

The big thing to keep in mind is that from the outer edge of the lower flange on the 88 cradle to the outer edge of the tire is about 17.5" if you plan to keep the tires under the stock body panels. In the picture the above it looks like the wheel flange is considerably further out than that and the upper a-arms are almost touching the engine (which is 1-2" from the frame rail and its about 2" thick), so the upper a-arm are probably too long to pull everything back under a stock bodied fiero.

Now with a widebody, custom cradle (wider) and some fab work to the lower frame rails to mount the a-arms it might be a pretty good setup.

That's the discussion I was referring to... Note from the graphic above that's the left side of the Solstice suspension on the right side of the Fiero.

The upshot is that each design is based on the packaging constraints of everything else in the immediate area. If you change everything else in the immediate area, then it becomes more difficult to reuse engineering elsewhere.

Eventually, you come to the point at which it's better to make a clean sheet design with the RIGHT compromises than it is to try to hack something into place that wasn't designed to be there.

Or if you want solstice suspension you just buy a solstice

I don't particularly want a solstice suspension, I want to make my car turn better, preferably using off the shelf components.

Retune your definition of "shelf components" to be standard rod ends, standard wheel bearings, standard outer CV's instead of standard control arms and knuckles and you'll be good to go.

The Dark Side of Will wrote:Retune your definition of "shelf components" to be standard rod ends, standard wheel bearings, standard outer CV's instead of standard control arms and knuckles and you'll be good to go.

lol, fair enough.

ericjon262 wrote:I don't particularly want a solstice suspension, I want to make my car turn better, preferably using off the shelf components.

You don't need a custom cradle. Just do this and this and get the front and rear Konis from here. Use 325 to 375 lb/in springs for the rear, and WCF's 400# lowering springs in the front. Install polyurethane bushings in the front control arms and rear trailing link. Set your front caster to the maximum amount possible with the stock control arms, and slot the mounts if needed to get at least 1.5 deg of camber. Ditch the rear swaybar. You will need an 800# spring up front if you want to be able to run the stock rear swaybar with the stock front swaybar.

Series8217 wrote:

ericjon262 wrote:I don't particularly want a solstice suspension, I want to make my car turn better, preferably using off the shelf components.

You don't need a custom cradle. Just do this and this and get the front and rear Konis from here. Use 325 to 375 lb/in springs for the rear, and WCF's 400# lowering springs in the front. Install polyurethane bushings in the front control arms and rear trailing link. Set your front caster to the maximum amount possible with the stock control arms, and slot the mounts if needed to get at least 1.5 deg of camber. Ditch the rear swaybar. You will need an 800# spring up front if you want to be able to run the stock rear swaybar with the stock front swaybar.

that would be the easiest option...

The Dark Side of Will wrote: What I'm intending to do with The Mule is to build two crossmembers, one forward and one rear. The rear would bolt directly to the current cradle attachment points, but would have to be triangulated forward and aft along the frame rails. It would have a pair of powertrain mounts projecting foward, similar to the control arm or cradle bushings that Guru used to mount his LS4 powertrain. The crossmember powertrain mounts would be set up with corresponding brackets on the engine such that the engine could be dropped straight down without removing the crossmember.

I've been thinking about this, and would a N* even have enough room to drop out the bottom like that? it seems to me like the powertrain would be too wide. a V6 might be able to.