also... its really personal preference, if you dropped it and like the way it feels, then good... i dunno how you will actually feel this effect on the track, its just a bunch of math...

 

this is also true....

i was thinking i would drop the ball joints 1/2" or so and see how that does...

the magic number according to a bunch of people is about a 1.7" drop...mine is farther than that...

 

You can download a demo from the web site. I haven't tried it my self, but I have heard that the demo reads from a text file that can be edited. Even if the demo will not allow you to save changes you can at least edit the file so you can see your car on the screen.


That will avoid all the torrents and cracks and allow anyone to use the (legal) demo for a car as long as they can handle the file edits needed.

 

Yeah I found that too, it was only a month old as well

 

the trd drop does not look bad at all. it grew on me. supposed to give better handling at that height right ?

 

I would have to do all of those calcs on paper to see why you came out that way.

Dan Gardner, Rado I believe, Rick (raamaudio), one of the car mags that did a project tC, etc have all settled on 1.48 inches of drop being the sweet spot for the car. The roll couple should get shorter for a bit, then start getting longer if you drop too far on a MacPherson strut setup. You want to stop lowering before it starts getting longer. You also have to consider the effect of changing the active part of the camber curve. At -1.4 the control arms should be near level and not already into the positive portion of the curve. Since you are lowering you should be running significantly stiffer springs and much less wheel travel of course, which will keep you from getting too far on the positive side of the camber curve.

That is why I harp on springs like the stechs. They are WAY too low to begin with, so geometry is not optimal. Then, they have extremely low rates for that amount of drop, making them even worse.

I have my SS-Ps set on about a 1.4 inch drop and they are 550F/390R springs. Less body roll than the TRDs (which are a great setup as we have mentioned) by a good amount. I have had them on for 2 autox events and a test n tune where I put about 30 runs in, so I have a pretty good idea for the feel. The only downside is that with the much higher rates you have to deal with skittering around a bit more on the rough pavement and more inside wheel spin on corner exit.

 

Designing new spindles (which, with the right measurements, a good rendering and a CNC setup can be done.. .and I may just have the person to do it soon :D ) with higher centers will allow you to lower the car further without affecting the geometry in a bad way.

In the rear of the car, you should be able to cut some of the chasis mount bushings down and get some "free" lowering back there without any negative effects. I think Rick is doing this on his track tC.

Of course, if you are running in sport where you care about the class you are put in, then all of these mods may have a negative effect. Custom spindles or mounting points, for example, would kick me right out of STS and into a class where I would be less competitive either way....

 

As I mentioned above, I have never heard anyone say 1.7". 1.4 is what everyone I mentioned in my post above have come up with.

 

I went ahead and contacted Scion and asked what factory options were available in 2005. This is the response I got:

It sounds like there really aren't any 'factory' options. But, given that, to me, the rules seem to say you can run port-installed options, there's still a chance. I asked in a follow-up email what options there were that were port-installed, so I'll see what they say.

 

I wonder what nearly means? I asked about some more parts in a follow-up email.

BTW, in the rules that standard part definition has the port-installed section italicized. Apparently that means that it is a recent change from last year. That's probably why people didn't think port-installed was allowed.

Update:

I wonder if that will make the tC a competitive HS car now?

http://trdsparks.com/displayparts.ph...1&parts_id=583

 

I dont know if anyone has asked about sways but im thinkin about pickin up the eibach swaybar kit. Anyone have ne opinions on the eibachs and is it necessary to have both front and rear.

 

First I like to say thanks for putting in the effort to check with Scion. But Scion gave you the response I expected. This is probably just a case of the customer service side not knowing how the manufacturing/sales side operates.

Here is the current list of accessories that are available for port/factory install:
2009 and 2010 tC

Code Description
HR TRD Rear Sway Bar
MU TRD Quickshifter
L5 TRD 18" 5-spoke black finish alloy
L7 TRD 18" 5-spoke sliver finish alloy
37 TRD Sport Muffler (open under class rules anyway)
5y TRD Front Strut Brace (won't make a difference in stock class)
8S TRD Brake Upgrade (track friendly not autocross friendly)

The exception is the 2009 Release Series tC, it comes with the the TRD springs installed as part of the the package.

If you have a 2006-2008 tC this is your list:
HR TRD Rear Sway Bar
37 TRD sport muffler (open under class rules anyway)
5Y TRD front Strut Brace (won't make a difference in stock class)
SC EMX super7spoke 18 alloy wheels

2005 tC:
37 TRD sport muffler (open under class rules anyway)
SC emx super7spoke 18 alloy wheels
HR TRD rear sway bar (this became port/factory installed toward the end of the model year)

Scion is wrong about the TRD springs and struts being port installed for 2005-2008 models.
Scion hasn't had the ability to port install TRD springs and strut until just recently.
This is because until a several months ago they didn't have alignment racks at the port facility and with out the alignment racks they couldn't install springs or struts and be sure that the car was aligned to proper specs before being sent to the dealers.

So for those of you who want to stay HS legal do not install TRD springs.

 

So the RS5 comes with the TRD springs and TRD rear sway... unless they make some sort of exclusion for that particular model, you should be able to run both TRD springs and TRD rear sway on another 2010 model in HS without issue. But if you're running a different MY, then no.

 

I got the camber bolts installed last night, so I will be (hopefully) going in for an alignment tomorrow. Right now I'm leaning towards:

-1.5 degrees camber front
1/16"? total toe out front (not sure on this, maybe neutral toe?)
-?? degrees camber rear
1/16"+ total toe out rear

On the rear camber, I noticed some of you are running quite a bit of negative rear camber. Would that make the car resist rotation more than a more neutral camber setting?

 

That looks like a good place to start . You are right about the rear camber, I'd say a good rule of thumb for rear camber is to run about half of what you have your front set at.

 

I feel that I would rather get the car to rotate better under traction than I would to give up traction by making the rear more loose, if that makes sense. I run about .5 degrees more in the front than in the rear with my current setup.

With the TRD springs I ran 1.75 degrees up front and 2 in the rear and it rotated very well (in some cases, more than it does on my new setup). The camber curve, springs, sways, etc also come into play so you cant necesarilly compare the front to rear camber numbers directly.

 

Ya I understand what you are saying.

I was able to get the car aligned today, these were the specs we ended up with:

DS Front: -2.1 degrees camber, 0 toe
PS Front: -1.9 degrees camber, 0 toe
DS Rear: -1.2 degrees camber, .15 degrees toe out
PS Rear: -1.3 degrees camber, .15 degrees toe out

I was going to aim for -1.5 degrees in the front but -2 sounded better, I'm surprised I got that much out of it. Since the front was so far negative I left the rear pretty much where it was.

 

That seems pretty good. Close to where I'm at actually and I've got camber bolts up front (probably some more adjustment left in the OEM setup). I'd probably still try to get rid of that rear toe, but it is still in spec. My rear toe is like .3...

I need to get that fixed at some point.

 

I actually wanted the rear toe out, I figured it might help the rear end want to rotate a touch more than 0 toe. I'll have to see how it does.

 

Toe out in the rear will make it rotate a bit more. Think of it this way. When you turn hard, the weight of the car is on the outside, the inside rear will actually be off the ground many times in autox situations. This means that the outside tire is the "steering" tire for the back of the car. If it is toed out, the rear will tend to steer outward.

The downside is that the more negative camber you have, the more feathering you will have of the inside edge if you run toe out. You are probably fine with your settings though. On some cars, people will crank a LOT of rear toe into it for autox events.