http://www.motoiq.com/magazine_artic...-your-car.aspx

One of THE BEST articles on (what I believe to be a horrible, stupid fad) but also will give the basic user a very good explanation on your suspension and can easily be applied to the tC. Pay much note to page 2, and page 3.

The basis car for the article is a Sentra SE-R, however the tC uses an extremely similar suspension setup, and aside from specific measurements, you can adjust these easily.

Notables:

 

Stancing? What's that? I don't think that's a real word. Plus, I don't really think those who do this thing you call "stancing" to increase handling. They probably dont care.



Sent from Somewhere using Something.

 

I apologize "Super Performance". Shall I retitle it "stanced? illest? horribly offset wheels?" just for you? :palmface:

Edit: forgot to mention if you happen to be smart enough to READ, you'll get a great understanding of how suspension actually works, and the amount of travel even allowed after a simple spring swap. But I forgot ScionLife doesn't like FACTUAL data to help modding.

 

I've tried explaining this to people tons of times on here, and you get the typical "i beat 350z' in the twisties on my stechs all the time" or "i highly doubt the amazing engineers at (insert ricer supplier company here) would have made these if they dont perform well" .... Those people may as well say "I am the typical clueless tuner customer that these companies get rich off of". But they already believe that they know it all and wont listen. Effects of over lowering on camber curves, travel, etc mean nothing to most. And what even those that kind of care dont get is that an over lowered car is not fixed even if you run uber stiff springs. Geometry is still thrown off.

If you go to a true autosports forum, this stuff is common knowledge, bit most on here just care about how low they can slam it, even if that means making it handle worse than stock, so most if this is lost on them.

And there is a ton more to it. For example, since higher rear spring rates on this car tend to sacrifice ride comfort more, some lowering springs run barely higher rates in the rear, or worse, lower. With the wishbone setup in the rear having a much lower motion ratio than the macstrut front setup, plus the nature of how a nose heavy fwd handles, the rear rates should be much higher. There is a lot more to it than most care about. I can understand not everyone is trying to build a winning setup, but people should at least try to understand what they are doing to the parts of the car that make the difference if you have to make a sudden manuever.

 

Well stated Engifineer and Spicy Mchaggiz True suspension modification needs to be well thought out because one change makes a difference.

All we(Members with actual autosports/mechanical experience) can do is pass on the correct knowledge hoping people will read it and understand it and not do something be cause it's the new trend.

 

Subscribing because I want to know more.

Can someone explain the following to me, and I hope I am not off topic.

The Scion TC weight distribution is 58.5 Front and 41.5 rear (this may be off, but from what I have read, those are the "avg" conclusion of weight distribution.

The Scion TC Stock spring rates are 150 Front / 245 Rear (I think that is some what correct).

As stated above "With the wishbone setup in the rear having a much lower motion ratio than the macstrut front setup, plus the nature of how a nose heavy fwd handles, the rear rates should be much higher"

so my questions:
1. why does companies sell BC/Tien/Whatever coilovers with spring rates of 10K front and 7K rear?

2. If the weight of the car is 60f/40r, should the stiffer springs be in the front or the rear?

3. If you were buying custom coilovers, what spring rates would you use for the front/rear and why?

Thank you all for sharing your knowledge. Reason I ask is because I want to start modifying my suspension, and I want to do it right, and make it fully functional and I want the car to feel comfortable, not annoying. My current suspension set up is TRD struts with TRD springs, Rear TRD sway bar, stock wheels, no other modification.

 

^Stance(GR+) does 7K front and 9K rear, B&G(RS2) does 6K front and 8K rear. JIC and Function Form if I recall do 8K front and rear as some others. Can't generalize all adjustable coilovers with one set rate. They also can give you a setup of your choosing if available most times no charge. Why some other companies do some off rate combos IDK.

 

Tein coilovers for the first gen are the other way around. They are 10k rear and 7k front

The motion ratio plays into how much spring rate you need, not just the weight. If the exact same suspension setup were used in the front and the rear, then yes, technically you would need more spring in the front. However, that is not the case. The rear motion ratio is much lower than the front. Front is going to be over .9 and rear is a bit over .5 from the design used (I plan to do some physcial measurements to back this up to more accuracy, but this is what you will hear from a lot of others that have done the math and what you can see from some quick measurements) What this means is that the connection point of the rear spring/damper is closer to being centered between the hub and the control arm bushing. On the front, the damper is connected very close to the hub. So think of how the force of the wheel is applied to the spring. If the force at the wheel is applied right at the strut (closer to how the front is designed) then it is almost a direct function of weight applied at the spring, if that makes sense. On the rear, there is more leverage applied to the spring, since there is more distance from the wheel to the spring. Thus, to support an equivalent amount of weight, you need more spring to account for this. It is actually a lot more spring needed, even though there is less weight back there.

This, and the fact that running more roll resistance in the rear on a fwd helps it rotate better and not push as bad, means your rear springs should be stiffer (which is how the stock springs are designed).

For something that will be driven on the street and using a fairly stiff rear sway, 400F/600R is probably about as stiff as you would want to endure. Maybe even less rate on the front than that. On the track, some are running 600F/900R, but you would not want to use that on the street. Those measurements are in pounds/inch. Compare to the Tein SSP, which are 392F/559R and you see that is pretty close to a decent setup.

Things to consider with the Tein coilovers is that although the are a pretty decent coilover for out the box on the tC, japanese springs tend to not be as consistent on rates and the dampers will not be dead on or linear. So simply running a higher quality spring (like hypercoils) and a better quality damper (koni or higher quality) will provide even better results with the same rates. I plan on putting something together similar to that in the near future on this car.

Now, if we did all the perfect math, there would still be some swapping out of rates upon doing empirical testing since driving styles, application, etc will always make for some further tuning, if you really wanted to get all you could out of it.

There are some great books out there by people like Carol Smith and others that you can read and learn even more about setup and getting more out of the cars handling.

Now, the numbers above are good for a tC dropped at about 1.5 inches or less, which is the sweet spot really. Below that and camber curves begin causing you more issues than what you gain by dropping the CG. But even putting that aside, look at Stechs. They drop the tc around 2 inches, yet only run rates of about 202/336. Very little travel and too soft of a spring regardless of the geometry of the suspension.

 

And honestly, for handling and daily driving, if I werent autoxing it, I would have probably stayed with TRD springs and rear sway. That is a great mix of lowering, handling and still keeping it comfortable on the street. The SSPs get a bit harsh every day, but they work better for autox than a softer setup.

 

I do thank you for the great information above, and the explanation. Thanks. And sorry for novice questions.

Ultimately, I feel that the TRD springs travel way to much, or maybe my issue is that struts are going bad, they are getting bouncier, and they travel way more than what they did when I first got them. My car has 95K and i think I bought them when my car had 30K. I drive my car everywhere and on harsh roads here in Philly. I think its bad when I have 18x7.5 rims, offset 45, and I’m rubin on the fender when I take bumps…

I have BC coilovers on my SE-R, I only dropped the car about 1.5" all around, so I can keep it comfortable on the roads, plus I have a nismo front lip that makes it a bit lower so I don’t want nor I like to be slam, I have 7K springs front and rear, and the car feels great, I think it has a bit of a wave effect due to the same spring rates both front and back, but as a daily driver to go to the store and back it feels way better than my Tc, and still stiff enough that when I hit a pot hole it adjusts quickly, yet does not feel like the strut is going to go through the car.

I like BC coil overs. I like the adjustability, the design and the simplicity to raise and lower the car and the ability to change the dampening setting.

I was looking at this post: https://www.scionlife.com/forums/showthread.php?t=211109&highlight=BC+coilover

this is what sparked all this conversation and I guess my confusion: on the thread they state that "The standard spring rates for the BR system for the TC is 10k front 7k rear" and yup they will do custom set ups. My SE-R was set up my 2J-Racing out of Atlanta, they specialize in SE-R and racing, and they set everything for me, custom valves, the spring rates to something that would be comfortable for a daily driver, and they even set up the height for me, since they have a B15U body at their shop.

I want to pull the plug on the BC coilovers but it seems as if 10Kfront/7Krear may be to stiff up front, or not the right set up.

What do you guys recommend?

How would a 7Kfront/8krear feel on the Tc?

Thanks again! and i'm going to go to Amazon and pick up those books!

 

Hey! You are a 100 percent correct; I should not generalize all companies and assume they are all running higher spring rates up front. As you just demonstrated this is not the case. Sorry for my general statement.

 

Good read. Now I understand my suspension more.

But how do sway/strut bars add in? Do they just tighten everything up and keep everything from rolling?

 

A sway bar works by applyng a percentage of the spring compression coming from the outside wheel in a corner to the inside spring. So, in a right hand corner, your car is trying to roll or lean to the left. This compresses the springs on the left. A rear sway bar, for example, applies some of this force upwards on the right hand spring. This means that the body rolls less. The stiffer the sway the higher percentage of the force is applied from one side to the other.

There are drawbacks though as well in trying to perform all body roll correction via sways. For one, you are effectively lifting up on the inside wheel more. This sacrifices some grip. In addition, if you do it on the driven wheels, you create inside wheel spin when trying to power out of corners.

Since you reduce suspension independence with sways, the car may behave more erratically over bumpy surfaces as well.

On the other hand, running stiff enough springs to not need sways would be impractical, so they are a necessary evil for any car that doesnt have a perfectly ideal suspension design (aka practically every vehicle, including race cars :p ).

I do not recommend running a stiffer front sway on the tc due to the corner exit issues. Plus, stiffer rear bar in relation to the front helps reduce understeer, which is a nose heavy fwd's curse. You have to remember though that a ton of rear bar can make the car prone to snap oversteer as well. It is all about finding the right setup for your needs.

 

what would be your idea spring rate set up for a Tc?

 

Depends on what I was doing with it. Mostly track/autox setup that you are trying to milk all the performance out of, or street car that you want to handle better, but not at the expense of shaking the fillings out of your teeth?

 

street car that I want to handle better but not at the expense of shaking the fillings out of my teeth!

 

Great write up and and good read, but you have to understand the people that are "stancing" their cars don't do it to autox or race. They do it just to go to shows and car meets so they can circle jerk with a bunch of other guys that do the same thing. (I never liked going to car meets late at night just to stand in the cold with a bunch of guys)

As for me I have s-techs to lower my car just for looks, I don't think I'll ever compete with or take the tc to any track events and like you've said I'll never push it hard enough to feel that my handling has gotten worse. All in all I think you guys that really have an understanding about suspension will always scratch your head and wonder why do they do this and the other side will always snap back with "I don't care, more low, hella flush, stance nation yo!"

 

Hey, nothing wrong with being circle jerked in the cold...

But seriously, thanks for the explanation. Granted...I am on the bandwagon...even participated with previous set ups. But it is nice to understand that which I am destroying

 

NYNCTC your welcome to come to Philly and help me destroy my set up!

Well said Andrew, when I read your post it reminded me of Apes in the wild huddle together picking fleas of each other's backs lol and I can understand why that does not interest you, but its in our nature to just hang together.. like idiots at 2am, in the cold looking at the same car for 3 hours...its who we are...we hunt together, we travel together, we are all brothers sharing a common interest...Cars, yet our own personality aids in the decisions we make, some may go with the hellaflush, low, daily scraping, and others will go with a usable, performing vehicle...

but I think this is great and as NYNCTC stated, at least now we can all understand what we are doing to the cars even if its causing destruction or increasing the performance of the car.

I still need advice on my set up, so I am still waiting for the experts to chime in before I purchase more parts.

 

While it's true they like to run around to parking lots and hard park, they do still need to understand what this does to their car, and the effects of it. I've seen plenty of "stanced" cars thinking they can whip around corners because they have super wide wheels and sit low. It's just not the case. Sadly all the information seems to fall on deaf ears, and not only on this site. But, as long as the information gets out, and just one person reads and understands, it's a job well done. Even if you are in a super performance car trying to be boy racer in a local fast and the furious drift scene. (thats even a bit of a stretch)