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A-arms on an FC?

Old 10-29-05, 05:18 AM
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A-arms on an FC?

Might get moved to suspension but I put it here because I think it will get more of the attention im looking for.

So let me just throw out the idea, I know it isn't cost effective and I know I should find a different car if struts bother me so much. I know I know I know, buy an FD....But im looking for a project, and im interested in becoming a suspension engineer as a career. The knowledge I would learn could very possibly come in handy later. I'm willing and curious to learn how to do this myself.

Anyway... How difficult and expensive would it be to install FD suspension or a custom unequal length double A-arm setup on an FC?

What I have going for me:
+ Plenty of experience working on cars
+ I'm good at and enjoy doing research
+ High standard of workmanship, attention to detail/precision.

What I don't have going for me:
- Not too good at welding, but I intend to take classes

I know the body isn't designed for it and the mounting points would require reinforcement. And after doing research I have found that there are a great many variables in suspension that need to be set right or it wont function properly. I know its a major project. But the fact that somebody hasn't done it before (or have they?) and the fact that I won't something to tune that is smog legal drives my interest.

Last edited by GundamExpo; 10-29-05 at 05:22 AM.
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Old 10-30-05, 01:49 AM
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It would take a lot of custom work. Think about making a whole new rear subframe, or at least extensively modifying the stock one to get the pickup points back further (remember, trailing arm, the pickups are way forward). In the front I suppose you could run some tubes to the shock tower from the subframe and attach the suspension to it. As a bonus you could drop the whole thing out as an assembly. Basically it wouldn't be worth it, just tume it properly with springs, dampers, anti-roll bars, alignment, corner weighting, bushings and such and it'll give you at least 90% as good grip and handling. Porsche 911's use struts, so do BMW's and they are renowned for being good handling, so struts aren't that bad. If you want, run a cantilevered suspension and replace the control arms and such with tubular arms with rod ends instead of the bushings.
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Old 10-30-05, 01:31 AM
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For me Good Handling = Predictable Traction. All the double A-arm suspended cars I have driven have had predictable traction. I can't say that for the strut suspended ones.

Is it possible to get the predictable traction and stability of A-arm suspension in strut suspension with out limiting the travel so much that the car becomes unstreatable? If you can make a car with strut suspension feel as good as one wit wishbones then there isn't a point to this project, But I don't its possible.

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Old 10-30-05, 10:54 PM
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It is easy to get full travel, and unreal predictabilty with the right struts. Any quality shortened race strut, revalved to be more streetable will do the job. My FC ran times 2.5 seconds off a Panos GT2 on a 3 mile course this last weekend, know if I can hang with a semi pro driver in a tube frame big HP purpose built race car, you can get the handling you want with struts. Lots of guys have done a double A Arm an FC. All said it was an improvement, but none suggested it when asked about its value vs effort. Later, Carl
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Old 10-31-05, 01:28 AM
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Carl how does your car do over bumps mid turn?

Do you know if any of these people who have already done the A-arm setup have webpages or are members of this board?

I appreciate the input, keep it coming.
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Old 10-31-05, 08:13 AM
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I plan on converting my FC to SLA (short/long arm).
I think the front could be done "fairly" easily if you reuse the stock upright and attach the upper a-arms to one of the strut mounting holes. I've measured and I think a Miata rear coilover would work as a good replacement, and could easily be made to fit the new upper a-arm. The stock lower control arm and steering rack will hopefully be retained... meaning the front subframe would be stock as well.
The rear would need a new rear subframe. Again, I think the stock upright could be reused, and adapt the a-arms/toe link to the original mounting points. There might be a problem with the rear frame rail interfering with the path of the upper a-arm though. We could notch it, but we'll have to see if that compromises too much strength. I'm sure we could reinforce it somehow though.
I've had thoughts that if it worked out well then I might sell them as a kit, but it would be for a RACE only car, since the roll centers and ride height would be setup as such... unless it just happens to turn out that you like your street car to drive like I like my race cars, which is pretty unlikely (spinning death firey crash= liability waiver).
I hope to start the CAD work before the end of the year, and start contruction early next year.
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Old 10-31-05, 10:33 AM
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I've seen an inboard lever style in the rear, but never a Arms. As far as the front it's a matter of building a box off the front frame. Tripoint did it on there FP AX car, but they dom not have any records of the build according to Craig. Other than that I have seen some, ut do not know who owns them. I would track down the Tripoint car and document it. As I said before the FC is already an extremely competent chassis. as far as bumps, I have no control issues at all. even when i go airborn the car does the same thing each time when the car comes down. I am running Ground control advanced designs, which compared to the scope of what you are speaking of would be budget race coilovers. JRZ, and Penske are excellent choices with more adjustability. since I did my hoework, I did not need the range. I set it, and forget it. the car is very good, so I concentrate on my driving. by maintaining the same set up, I always know what the car will do. next year I will start playing with shocks, and alignments. Carl
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Old 10-31-05, 11:00 AM
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Originally Posted by Carl Byck
I've seen an inboard lever style in the rear, but never a Arms. As far as the front it's a matter of building a box off the front frame. Tripoint did it on there FP AX car, but they dom not have any records of the build according to Craig. Other than that I have seen some, ut do not know who owns them. I would track down the Tripoint car and document it. As I said before the FC is already an extremely competent chassis. as far as bumps, I have no control issues at all. even when i go airborn the car does the same thing each time when the car comes down. I am running Ground control advanced designs, which compared to the scope of what you are speaking of would be budget race coilovers. JRZ, and Penske are excellent choices with more adjustability. since I did my hoework, I did not need the range. I set it, and forget it. the car is very good, so I concentrate on my driving. by maintaining the same set up, I always know what the car will do. next year I will start playing with shocks, and alignments. Carl
While speaking with Mark a couple weeks ago during the ALMS weekend at Laguna. That car (FC Solo widebody) was last seen in Atlanta, GA.
Interesting thread! Keep it coming
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Old 11-02-05, 08:10 PM
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So, you wanna do this?

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Old 11-03-05, 02:25 AM
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YES!!! Whose car is that and do you have more pictures?

Edit: is that a dual exhaust setup?

Last edited by GundamExpo; 11-03-05 at 02:28 AM.
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Old 11-03-05, 07:29 AM
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If the FD's geometry works for what you want then I guess that's one way to go. I doubt that'll be the case for me.
What about those two pictures makes you think it's dual exhaust? There's only one pipe and one muffler.
edit: I see what you're looking at now... the other little muffler and dump pipe is from the waste gate.

Last edited by Travis R; 11-03-05 at 07:34 AM.
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Old 11-03-05, 10:48 AM
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Sorry, that's the only 2 pics I have that show it, but that's panspeed's car in japan. I wouldn't reccomend doing that, though. Although you would handle slightly better, the added weight is going to eat up any extra time you would make up.
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Old 11-03-05, 07:00 PM
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Originally Posted by Travis R
If the FD's geometry works for what you want then I guess that's one way to go. I doubt that'll be the case for me.
What about those two pictures makes you think it's dual exhaust? There's only one pipe and one muffler.
edit: I see what you're looking at now... the other little muffler and dump pipe is from the waste gate.
What is disadvantageous about the FDs geometry?
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Old 11-04-05, 07:37 AM
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Nothing in particular, but every geometry is a game of compromises (even F1 suspension). If the original poster is just looking for a challenging project for a street driven car then it could work. But I'm building an autocross car... so if you want me to go into all the stuff about rollcenter migration on heavily lowered cars and all of that I can. It's also illegal for me to change the front crossmember, so that nips it right there.
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Old 11-04-05, 07:46 PM
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Sure id be interested roll center migration and the other reasons you have. I'm looking for a challenging project on a street car, but im also looking to learn something and to have an end product that is fast and phenomenal to drive.

If I don't have the background knowledge I can easily choose the wrong setup and be disappointed with the result.
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