So i am sitting here thinking about my next plan of action as far as doing up a FC chassy starting from the ground up. And i wondered about the suspension design of the FC and how it uses a LCA Front and a swing arm attached to the sub-frame in the rear. While i had no complaints about how my last FC preformed once the new bushings and DTSS eliminator was installed I never thought about how i could make it better over past coilovers.

So here are my questions, Double wish bone /multi-link should be a "superior" design as it allows for better control of each linkage & vertical movement correct? In comparison with the McPherson hub design type that the FC has, would it safe to assume that the car does experience various unwanted and unstable camber changes and side travel during vertical movement? So would it be plausible for myself to convert and engineer a Multi-link Double wish bone suspension design front and rear fitted for the FC3S (for road racing applications) to combat unwanted changes in the geometry of the suspension that i may not be aware of? or Perhaps that the the current design doesn't suffer these issues and maybe building my own LCA and Swing arms made of stronger & lighter materials may suffice? The goal of this thread is explore various applications for road racing / time attack in regards to HUB/ARM/LINK/ in the FC3S and how to address issues that we may not be aware of that exists. (This could apply to your own street car)


Thoughts and opinions, speculations are encouraged! Keep senseless arguments at a minimum please.

-Josh

 

If you want to then go for it. Most people find it more cost effective to just buy an FD...or a Miata. The stock control arms are aluminum so theres not much room for improvement there. I wouldn't underestimate struts in general, some of the fastest time attack cars in the world have struts like EVOs, STi's, BMWs, Porsches.

 

I am not underestimating strut design, and yes i understand that there are various performance cars that utilize this type of suspension. I for one have no issues with the current design for the FC as of yet. I am just bringing this idea up as a discussion, rather than actually considering producing parts for an actual conversion.

 

Correct, the Double-A-arm design is far superior when compared to the FC's suspension. Camber gain is adjustable depending on the geometry of your upper and lower a-arms. Because of our suspension geometry, we are limited as to how low these cars can be. Too low and the car is more roll prone, due to an increased polar moment. A popular band-aid in this case is stiffer springs and sway bars to combat the increased roll.

Is it feasible? If you're planning to put together a "double-wishbone kit", it would be very hard to sell, simply because of the R&D involved -> high prices.

The design would be cool though. If I were you and were designing a similar suspension, I would take it a step further and move the shocks/springs inboard, creating a sort of cantilever/pushrod system, eliminating a good chunk of unsprung weight.

If working with factory designs, creating lighter parts (LCA's, trailing arms) will usually result in less unsprung weight, but the costs involved are varied.


That's all I can type for now, midterms hurt.

 

Im not a real fan of the suspension design myself.
i think a good basis right now would be to copy one of the time attack cars..

for example, the Super Now FC is pretty dam fast right now.. check out some of their suspension setups. Changed lca pivot area


Some trick stuff with them
http://www.supernow.co.jp/diary/diar...ead&y=2004&m=6

 

...i never realized that supernow's Midpipe/resonator looks like a doughnut ...im hungry

 

 

Thanks for the pics saving them now.. How can you get those parts?

 

You mentioned speculation was welcome...

Redesigning the FC to have a radically different suspension system is way too much work, for too little gain, when you consider all other variables you can improve on that are easy to do, including driver training...

A good coil-over setup with the right driver will make a world of difference, though.

 

I've seen front SLA conversions for Mustangs, so its been done.
http://www.griggsracing.com/product_...roducts_id=458

However, unless you are an engineer with access to alot of modeling and manufacturing tools, its going to cost you a fortune and you may as well just buy a FD. I only say this because, while certainly it would be relatively easy to rig up something that looks like it might work, in reality you could easily run into binding or other unintended geometry issues without a proper working model of the system and end up with a slow and ill handling car, but with a mad cool custom suspension.

There are indeed some fast cars with front struts, but they are fast in spite of them. There is no question that a SLA setup is superior in basically every aspect other than cost.

 

If you want to make something for the FC's suspension make roll center correcting ball joints/LCAs so we can fully utilize lowering CG without increasing roll. No one makes them, besides AWR's spacers which do nothing.

 

this said it all imo

it would be very difficult to make your own suspension without significant skills and resources

 

+1 on roll center correctors as well.

 

Non of those parts are anything new. I can call AWR and get all those parts at my house tommorrow. Better parts at that as AWR camber links allow independant adjustment of the rear arms.

All you did was post pics of parts that allow adjustment of the same suspension design that you claim you're not a fan of. Adding those parts doesn't change the design in the least, all they do is allow more adjustment of the same design.

As far as racing goes, driver has more to do with it than anything. A few years ago when I was active in auto-x, the FTD was generally a 13B P-Port in an FB. Yes FB as in solid axle was getting the FTD's going up against corvettes, porsches, FC's, FD, with 2x & 3x the hp and beating the snot out of them.

 

I ran across this suspension buildup thread awhile back:

http://www.ziptied.com/forums/index....2422#msg132422

The OP said he removed the rear sway bar to improve handling, going as far as to grind off it's mounting point on the suspension. Though he never goes into any detail as to what it really does, can anyone ratify or refute his claims?

 

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/remove-rear-swaybar-better-handling-817785/

that's not really what this threads about But yeah, a lot of guys do it. read the above thread.

 

A proper three link and watts link combo on a solid axle could prove to be a solid design.

I am designing that same setup for a friends, 70 chevelle right now. With that said some of theses muscle car guys a re pulling over a lateral G with tubular control arms and solid axles.

 

You can ask Howard Coleman about his RX3 when he was racing back in the 80's

 

The rear suspension is more solid, cancels out the DTSS steer, changes the front pick up point on the lca. I think its worth mentioning..

I dunno why people always gotta try to out-prove each other "oh you can get the AWR parts been out forever" who cares? i was just posting what they where running which works really well for them.

 

If you want an SLA suspension, then buy an FD. The Mustang SLA conversions are $3500+ and that is the cheapest one. I tihnk it woudl be too cost prohibitive to do in an FC.

The R&D would be better served in making a new front K member with improved geometry.

You can get the car pretty dialed in with the OEM suspension architecture. There really is no need to reinvent the wheel on this one, unless cost is no object.

 

Typically i would agree with you, but for this application i am going to disagree with you. Although you are right, The cost of creating such a system would not be reasonable especially when working with a Cantilever system. Nor it may not be worth the time spent needed to research, map, draw out and design a suspension that geometrically works and fits without binding. BUT the gains i believe could be substantially large at it allows for better use of dialing in Camber, Caster, Toe, Acceleration to toe-in, Vertical Acceleration changes, energy displacement, caster braking loads, turn in angle, also addresses unsprung weight, etc.. When all these items are tuned, i would assume that they shave off far more time off the lap times, vs a good coilover setup and driver ability. With that said i believe that.. A Skilled driver can push the car to and beyond its limits, but the car may not push the driver to his limits.

Hypertek, thnx for the pics

hmmm a Roll center correction ball joints.....interesting you mentioned that KhanArtisT because several years ago i was on a mission to find roll center correction ball joints but ended up using AWR roll center blocks which did nothing for me as well. Good thing i am a little less ignorant vs then..(well i hope rofl)

Hecubus84, eliminating Rear sway sounds kinda sketchy, although i can see how the driver feels like its more responsive. Possibly something worth researching.

I wish i could do thermal load graphs to show how the FC suspension stresses. It would be nice to actually see where energy & load travel through the body of the car and how it dissipates.

 

You're missing the point, you're not changing the actual design of the suspension in the least. All you're doing is adding adjustability. It's not about "out proving" someone, it's about making concise, helpful, on topic posts which your's was not. Your post was, look at the shiny purple JDM parts that a japanese tuner is using.

Now, to stay on topic-
Re-Engineering a suspension is not an easy feat. If you want double A-arms, think about all the geometry that's involved and all the added mounting points and parts. Is it better, yes - but by how much? Decent questions to ask when trying to gauge whether something like this is worth the rewards would be
Whats the highest Lateral G that an FD can attain?
Whats the highest Lateral G that an FC can attain using the same size/brand/model tires that the FD got? (using FC/FD as the power, weight and ditribution are about the same)
Is that difference worth all the work and coin? Probably not considering the lateral g's that an R-comp equipped FC can get.

Maybe this is your little toy experiment where the cost vs benefits have absolutely nothing to do with it and you just want to see if you can do it. If that's the case, by all means, go for it. But if this is for a street/mild track car where time and cost are a factor, I don't see the gains being worth the expense, mainly becuase the expense will be so high.

 

that's what I thought until I read the thread I posted earlier...

but that thread alone made me rethink it. I'm definitely going to give it a try this spring when auto-x starts up again.

 

Its not a matter of changing vehicles for the sole purpose of wanting SLA suspension or any other system found in other performance cars. If it was i would have bought a different car and this thread would have never opened to begin with.

The Front K member does sound like it has been neglected, but i am just making assumptions. Thnx for the direction change.

and i agree with you that the OEM suspension can be dialed in very well.

For anyone If you didnt read my original post, this thread is to EXPLORE THE APPLICATIONS FOR FC3S.

So what have we gathered thus far;

1. Cost for R&D and Production = Fail ...that was an obvious reasoning to begin with.
2. Large gains vs minimal gains is only reasonably debatable when there's data to compare
3. OEM design is relatively sufficient
4. Center of Gravity and Roll center IS still an issue that has not been addressed.
5. Rear sway bar elimination changes the tire ground contact (good or bad is debatable)
6. Supernow & AWR make products to allow for a range of adjustments that the OEM design does not allow.
7. DTSS is fail (also debatable)
8. Cantilever system may be favored over SLA (debatable)
9. Unwanted changes in tire movement and how to prevent them still needs to be discussed.
10. Ideas in improving the design structure of the subframe and K member.


Moar XD

 

For the sake of this thread, lets say that all of us are a racing team board, and are discussing that the prospective FC is our own teams demo car, and is a dedicated track car, out to achieve the goal of .53'000 seconds on Tsukuba also ONLY discussing suspension in this meeting.