Setting up a car to maximize the handling potential can be very involved and one of the biggest mistakes made is lowering the car to much, which in the case of the tC is a major issue.

Having a heavy roof is a major impediment in our cars handling but it can be overcome to a large degree with proper suspension setup balanced to acheive the best results within the given fixed parameters of how the car was engineered.


We are working to acheive the best possibly handling yet maintain a resonable ride comfort level, which can be a fairly well balanced outcome. A major issue is spring rates, super stiff is great on a smooth race track, on the street or less that stellar track surface they will cause a loss of traction and of course major discomfort. Another bad result is the transfering of the load into the chassis of the car which will weaken it over time.

A major issue with the tC is a very low roll center results when you drop the car much at all. We have measured this very carefully and ploted it out in 1/2 scale to get a base line of our next round of mods. The low roll center combined with a fairly high center or gravity due to the glass roof creates a rather substantial roll couple. That in turn puts alot of leverage on the suspension when cornering which leads to alot of body roll unless controlled by stiffer springs and stiff sway bars.

The bars and springs can reduce body roll substantially but also the whole combination leads to a great deal of the weight being transfered to the two outside wheels while cornering.

Problem, two wheels are doing the vast majority of the work instead of having four wheels doing a shared amount. This can lead to a substantial loss of grip during the most spirted driving, just when you need it the most.

What can we do about it???

Do not slam the car, though looks cool, it will handle worse, already tested that specifically on our car, far better when up an inch off the bottom on the front ride height setting(tein SS-P coilovers) Rear should be a bit higher than the front, maybe 1/4" to 3/8", this promotes less understeer.

The more you lower the car the lower the roll center becomes. when slammed it is nearly under ground!!!! That is a horrible place to have it, now you have extended the roll couple dramatically, bad news.

Take a look under your car, if you have it droped much at all you will see the inboard ends of the lower control arms sitting closer to the ground than the outboard ends, they should be above them for the best setup, lower is not good, not at all. Severly dropped means severly handicapped handling, no way around it.

Softer springs may be advisable than what come with some coilovers, etc. this can induce a bit more grip around corners but will not solve the roll couple issue. Later on I will look at some of the spring rates for none coilover solutions as well. Two of us here are working on what rates to try next for our Tein SS-P coilovers.

Remove all the weight you can from up high to lower the center of gravity, why we were so serious about getting a CF/Kevlar(could be either one or both materials), we removed 46 lbs up high!

Now we get to the serious side of fixing this issue, either need to modify the outboard ends of the control arms to lower the pivot point of the ball joint (possibly induce a weak spot in the suspension that you do not want to have to worry about)

Or, replace the steering knuckles with modified ones or from another car with a lower ball joint location, somebody here is already researching that for us;)

Another option, may take a combination of the above and this. Raise the inboard pick up points of the lower control arms, another not so easy to do mod since you are now dealing with moddifying the factory suspension pick up points.

We are addressing all areas above and more, dialing in the camber, castor(we added approx 1.5 degrees more postive castor up front), corner balancing, toe settings, etc. etc. Then we have to figure out which settings are best for dry weather, for rain days and in between. We will do whatever it takes to maximize the handling potential of our SM class tC, we have all winter to test and tune for next season. Unfortunately we have rules limitations to follow so cannot do all we would perfer to do but will do all possible within the rule.

If you want to make a slightly porky FWD competitive agains EVO, STI, M3, etc, cars, you have to leave no stone unturned in the quest to get all you can out of the vehicle. FWD can be competitive, 3rd and 4th were won by Civics in our class at the nationals recently. BUT, they are substantially lower in weight than our car.

And, this is not a dedicated autocross only car, it will see as below, drags, road courses, audio comps, and it will be driven to all events.


Rick

 

Rick, move to so-cal so that you can play with my SS+P's please :D

 

Hey, somebody took interest in my thread, sweet!!!!

Try raising them up a bit and resetting your toe in then hit the same corners(autocross is beter) that you did before, it will feel a bit softer, a bit taller, a bit different overall but it will go faster;)

I lived in SD county for most of 22 years while in the US Navy, stayed there 1.5 years after I retired then moved to Shasta Valley but to small for my growing up children so move to the Portland area now so they have more to do. Not going back down there again, to dang expensive and to crowded! I do miss the weather but we have alot more car races up here even though a far shorter season

Come on up and visit, anytime!

Rick

 

I'm sure EVERYone took interest in this thread. Not many of us know what to say though.

Although.. what I said in the other thread about not caring about the outrageous body kits and audio system somewhat applies to here.

I was looking for a real car rather than a show car. I'm sure many of the cars were fast but the kits did not have any aerodynamic reasoning to them and the audio systems did not have any consideration for load distribution. What I wanted to see was a car that was well engineered and took into consideration all the things you've talked about. More than anything, I wanted to know what was done to the car and why. For the most part, the only thing done was a replaced body kit and perhaps a few bolt-on mods.

I wanted to hear about urethane mounts and custom suspension tuning and stuff that tuneers would do.

However, not having done any of this myself, I can't really add anyhing useful except for,

"Awesome write up. thumbs up! So I guess the S-techs are NOT good for handling? I guess that makes sense since people were reporting that the s-techs actually handled worse than h-techs. The drop you're talking about seems to be on par with the drop that the TRD springs give - guess they did some thinking too!"

:D

 

Glad you understand buddy, not enough do but at least we have some pretty savvy members here, smart enough to not want a clone of a million other cars that look just like it and sound like crap, lol!

I see very few body kits I can stand to look at, most are just plain goofy and anti-performance.

I seldom go to shows and when I do I scan around for the very few, if any, real cars and am so happy to see some once in awhile. A big show I was at one time had a really sweet rally based Subaru that was actually rallied, impectable build quality, had a comp sound system that was excellent as well, very impressive to say the least.

Thanks for the compliments, just trying to help others understand what a real car can be.

TRD sometimes uses progressive springs so not always the best way to go but still better than slammed.

I like more cars pretty low personally and really liked the look of ours most of the way down(the Tein coilovers really do not go super low, which is fine by me) but when I calculated the roll center it was time to raise it up a bit and I actually like the look better now.

About time to sign off, good night!
Rick

 

Bump!

Hey, I'll bet we're all pretty damn curious about any progress you guys have made.

This suspension business means a lot more to a lot of people than power so:
-Have you found the ideal spring rate yet?
-Any progress on finding a solution to the control arms?
-Found those better ball joints?

I know it's not quite winter yet but surely it's possible that leaps and bounds be made before then?

 

The reason for not having my coils all the way down was that I felt that my car did not handle right. Glad to see that my instincts still work
Awesome post Rick, can't wait till you find the right coilover settings for street/track!

 

Ah finally someone who wants what i do...exepct is a lot more knowledgeble then me. When I got this car i had one thing in mind make it perform as best that i could make it in both autocross and drag. I was at first not going to go any springs just shocks and struts lately though ive been thinking about trd springs since they dont lower that much and i imagined woudl work good with the trd shocks. If there is a better way to go please enlighten me iam new to car mods i researched quite a lot but alot of info is just for looks not perfromance.

Oh and this is offtopic but you mentioned a sound system in the subaru before...I am going to replace the headunit with some other pioneer one and i also was thinking about getting a sub something that can give me a little more base while not adding substantial weight to my car that might hurt performance. Is there anything out there that i should consider? I know we have the bazooka but is that any good?

 

If you wanted a sports car, perhaps you should have bought one. Not sure if all the time and effort are worth it..... It's a $17K car.

 

Here is another perspective to consider, a car is far more than just transportation or even just a fun way to get around for many of us. It can be many things, to me it is more meaningful to take a decent platform and make it into something far more capable than it was originally.

Anybody can buy a fast car, I could of bought an Evo, STI, M3, etc, and with a couple of simply bolt on mods have one hell of a fast car. Or I could buy a Z06 and do the same thing, nothing challenging in it, not much thought needed(unless going really all out), anybody can just do that.

But, to take something and make it into what I want it to be, against pretty stiff odds of success(i.e. autocross competitively against such cars as mentioned above), to me that is rewarding and enough of a reason to invest alot of time and money into it. Even when I know full well it costs more in the end, money is not the point, just going fast is not the point, those things are to easy.

One more thing, do you know how many people you see driving around in such cars that even know how to really drive them anywhere near thier potential? Not enough I can gaurantee, they just know how to make money or get it from mom and dad and buy fast toys.

Not dissing those that do understand and can drive and chose to buy and modify and some race their cars, not in the least, I am glad they do and wish them all the best at doing so I just like a bit more of a challenge and chose to do things a different way.

Then again, I have been around quite some time, the only way to get such a car in my younger days was to make one from something less, at least in the economy I grew up in, there were not many ways to make that kind of money to buy a Tii (which is a snail by todays standards) let alone a Ferarri, Cobra, etc, just not many choices unless you consider muscle cars and they have never appealed to me personally though I respect those that love them.

Rick

 

Someone who understand hehe. Now as for question anyone know anythign about subs?

 

Subs? that belongs in another area, kind of busy right now but I have a pretty good handle on car audio;)

That will have to wait for another time, got to get to work, I am a slave driver of myself, lol!

Rick

 

Awsome write up deffinatly agree about the tC being a better challenge, more fun. I was looking at a tC or a new si, but the si is fugly, and tC has better potential, it just hasent been unlocked yet, give it time. Wont be slamming my tC now, oh well. lol.

 

Great write up -- please keep 'em coming

 

why woud u have the rear ride height higher than the front...

if you put it this way. if the front is lower, you are putting more weight on the fronts, and when you are braking, you are putting even more weight ot the front. and if you turn slightly, you will fish tail and cause oversteer.

how i see it is that our cars have a heave front so you want the front to be a little higher than the rear so when you floor step on teh gas through a turn all the weight will go towards the rear and it will create a better balance. same with the aspect of braking. if you shift the weight to the rear and when you brake, it will transfer to the front. you shoud always try to have a 50/50 weight distribution.

and thats also another reason why weh ave stiffer spring rates in teh rear. the rear end of the car points the car in the direction that we go in. if we are to take weight off the rear tires, the tires will lose traction and in turn not turnin the car in teh right direction or mayb over turning it because there is less weight in the rear making it to oeasy to turn.

yes i have experienced oversteer in our car. its quite simple. going fast, heavy braking, and turn, the car wil oversteer a little. but then again i have TEIN S.TECH springs. it lowers teh car 2.4"F and 2.0"R. transfers to much weight to the front.

this setting is good driving uphill but on a downhill section, it puts to much weight ot the front, over using the front tires and thus loss of traction over time

 

By lowering the front end, yea, you put more weight towards the front when braking. But on the converse, by setting the two springs equal to eachother in drop, while accelerating or turning, you'll get some ugly understeer. Dropping the front by a little more than the back will get you some oversteer or perhaps neutral handling characteristics.

Of course, fishtailing is never a good thing but in order to win an autoX you gotta get that rear end to rotate a little or else you'll lose too much speed to clear a corner. Well, maybe not rotate per se but with a proper set up you'll get the right amount of oversteer without compromising vehicular stability.

That's why the rear should not be higher than the front by any more than half an inch.



And we're still waiting on those optimal drop heights!

You know.. a friendly reminder.. that we want information.. i dunno.. NOW.

:D

But.. Is testing being done to find the optimal drop height before the revised suspension arms? Most of us aren't going to be messing around with the pivot joints and control arms that much, if at all, so having the data after those modifications won't tell many of us very much other than that the RAAMaudio car is uber. We want uber cars too :D

 

Mostly you have it fairly well figured out and I for one until recently would of agreed more than I do now. I am doing intense studying of FWD suspension design and handling and learning about a few things that I was unaware of.

The ideal front to rear weight distribution for FWD is 60/40 (generally speaking) If you do not have enough weight you do not have enough traction to power out of the turns, to much and you start losing traction, a delicate balance indeed.

Left to right is great to have balanced but not as critical as crossweights.

Springs, sways and shocks all play critical rolls in the amount of weight transfer and when it transfers(shocks and driving style)

Part of your problems with over steer is caused by severly degraded suspension geometry caused by how low your car is.

This is due to the extreme lowering of the roll center which increases the roll couple(that heavy roof has alot more negative effect on a lowered car)

You need weight transfer well controlled and taking care of the front end is done with the rear tuning mainly, as you mentioned but it gets a bit trickier than that.

I am obviously speaking in gross generalities here because I am reading books that take chapters and charts to explain all this in a level I have never gone to before.

Your springs may be an issue and maybe not as far as weight transfer for and aft problems, what are the rates??

Your heavy braking if done abruptly will cause much of the handling issues as well, smooth is fast and safer too.

Ok, enough for now, I have so much more work to do figuring this car out that I cannot be of much help to anybody yet but we are going to find the real level of grip this car is truely capable of and will pass on as much as I learn to our fellow tCers

All this is but a scratch on the surface of what we are going through, sure is fun though!!!!!

Rick

 

Sounds like a classic situation of "the more you learn...the more you realize how much more you need to learn". Lots of head scratching and adjustmnets are on the way...fun and tedious at the same time.

 

You nailed it buddy, whewwwwww!!! But, I have done alot of things in my life and am bored with many of them so a challenge is like new blood in my viens, love it

Rick

 

Well... Damn.



Just... Damn.