raamaudio

Ok, though the car feels incredibly balanced and predictable with the mods thus far completed I know there is always room for improvement.

My son and I took a couple of hours today measuring and calculating a few critical areas and to our unhappy supprise found we are faced with very serios mods to make things the way we want the car to perform.

Droppin our car 2", Tein SS-P, resulted in the same approx drop of the center of gravity, cool.

But, the angle changes on the lower control arm have resulted in a roll center nearly 4 inches lower than stock, not good at all, it is at less than 1" !!!

What does that mean? It means since the roll center is a bit low compared to the center of gravity there is a great increase in the leverage the weight of the car has on lifting the inside tires during a turn, something sways cannot help to fully cure and can hurt if to stiff. To stiff up front causes the inside tire to break traction coming out of turn and causes additional understeer, not what you want if you want to corner fast.

Adding more rear bar helps alot but then you start lifting a rear tire, not really that critical but now you are cornering basically on two tires instead of four.

Of course you can add stiffer springs, they can help a great deal but to combat the severly low roll center the springs would be so stiff that you end up losing traction over bumps, etc.

Then there is the issue with bump steer as arc of the suspension is now in conflict with the tie rods that control steering. Hit a bump, steering changes, not good mid turn.

What is the cure, raise the car, how much, we measured, 1" higher would make it tolerable but to tall for our tastes and too tall for optimum handling.

Must be another cure, we checked for all of them, camber change does a bit of help but do not want to run full negative camber in the rain, snow, long drives, etc....And it only helps a little bit anyway.

So, we are faced with rebuilding the outboard ends of the control arms to incorporate extra long ball joint shafts to lower the end of the arm to stock or near height. There will be a bit of clearance issues with the Wilwood BBK we are installing soon so can only go so far but it should make things much better and aleviate any bump steer issues. We have to remove the springs and run the suspension through the full range of travel and plot out the arcs to make sure we get it dealt with as well.

This was just the front of the car, we need to check the rear next and then work out a balanced plan of action to get to where we intend, very neutral handling with a bit of oversteer on tighter, slower corners and slight understeer on high speed sweepers.

We will be examining the castor angle during this as well, may need some adjustments there but have to be conservative on a FWD.

And we intend to get a full corner balance first, then jack the car up when on the scales to get the actual center of gravity numbers. Ours will be quite different than most other tC's, we started installing our CF/Kevlar roof yesterday. Super light race seats, relocating the batter to the rear above the axle and centered side to side in the chassis(to help offset having a turbo and intercooler on the front of the car) Many other mods to bring weight down are happening as well but will still be a very comfortable and fully functioning street car on those days we feel like having some fun

Rick

Kinesi5

I am real interested in improving handling first and foremost when i get my car in a few weeks. that will be my first priority, above and beyond power. I think its awesome that you measured and found out info and shared with us all. I am thinking of Super streets and Bars all around..which bars are most effective? Good luck with ur project sounds promising

BigSteve

I'm not saying your wrong at all but wouldn't you want to place the battery slighty behind the center line of the rear axle in order to counteract the weight of the intercooler and turbo set up since they would sit in front of the center line of the front axle? Once again, not bashing just trying to understand.

raamaudio

Not a problem, actually it is best to put all the weight between the axles, mounted as low and as centered side to side in the vehicle as possible Since we will keep the back seat, most of the time will be out of the car, the area we are going to use is the best place possible.

Rick

BigSteve

I realize its best to keep it centered and low but since the turbo and intercooler will be in front of the axle center line wouldn't you need to place the battery behind the rear axle center line to counteract the turbo and intercooler weight?

lo_bux_racer

Thanks for the bad news Rick. I expected something like this, even though the car is pretty good with the Tein setup, I suspected they doubled the spring rates from stock for a reason.

So the roll couple is twice stock or worse? I've been meaning to do this myself for a little while but have been sidetracked with Supra wheel bearing issues.

I realize lowering the ball joint is one solution, but are you talking about two full inches? Having a two inch extension is going to add a lot of stress to the lower joint, and those things are already taking the bulk of the weight of the car under hard use. Ouch.

raamaudio

Lance, I should of mentioned I was rather burned out when posting this and some of the numbers I am estimating, we needed my buddies stock height car here to measure a couple of more things on so be more accurate on the differences. I overlooked a couple of things when checking his then he left and came back quite late. Either way, we will double check it all one more time, I reploted the data on a full size drawing to eliminate as much error as possible and our roll center came up as 1/2" !!!!! Even worse!

We will work out a compromise plan of sorts, probably raise the car 1/2" in the front and check all the measurements over again. Our shop floor is not as flate as I wish it was so will find a place I can do this more precisely as well, probably when we put it on an alignment rack, when I can find somebody competent and interested enough in doing a real performance alignment;)

Then we can look at maximizing camber, possibly a slight move of the inner control arm location, less droping of the outer one, etc, etc.

We are going to look into spring rate changes as well but not until we get things dialed in the best we can, I do not want to mix to many variables at once.

We could end up having to much sway bar once done, especially considering loosing at least 40 lbs on the roof alone, may as much as 45.

I see this part of the project taking quite a bit of time to get it perfected but you know it is worth it

Rick

panasoanic

Any more information concerning the battery relocation? I am interested in how did you mount it, how you ran the wires, and where did you ground the battery to the body? Did you set up an external kill switch?

Also, what type / brand of battery did you use? Braille Auto Development's battery looks promising:

http://www.brailleauto.com/ProductCa...=2&idproduct=1

lo_bux_racer

So if the roll center is 1/2" at static height, it's likely going negative under compression. Damn. I wish it were easier to raise the pick up points 2". I can see maybe 1/2" with the existing subframe, but anything more is going to be a major fabrication effort. Figures.

raamaudio

We have not done the battery relocation yet and it will be a very tight fit when we do. Since this car is also a demo car for our business it is massively sound deadened but that only added ten lbs of weight because we removed all factory deadening and did it our way. That is another story in itself, to be told more indepth later

We have a 15" flush mounted with the rear floor sub system and three amps in the back of the car, another only added 10lb story to be told again later. 10lbs is a very close estimate on both of these stories. The weight is more centered, overall lower in the chassis and more forward than the stock weight with the now deleted spare tire, etc.

The only place left for the battery that I am considering is right behind the rear cross member, cut through and a sunken enclosure, the patter ends up being just 1" flush with the height of the rear area under the cargo covers floor but above the share tire well depth. The amps would fit over thay, two smaller four channels side by side, one larger (1,000 watt A/B) amp over them, centered, just under the rear floor covering. A very tight fit for everything, so close it will be hard to make it work but I have measure it a couple of times so sure it will go. We may put two amps under the front seats, we have plenty of room up there now with our race seats installed.

The battery is the Odyssey PC1200MJT, chosen for it;s output, deep cycle and size plus reliability. I would like to use a smaller battery but we are running a pretty big audio system.

We will be able to easily remove the audio system and install a smaller Odyssey battery for races if we chose, that and removing the rear seat would take approx 120 lbs off the car.

The plan was originally to leave the interior and system in when we race SCCA autocross, just to do it, that was before we found out STI and EVO cars are in SM class now, bad enough we have to deal with M3's(the very fastest usually)

We will see how things go once we start really developing some power and have the chassis all dialed in. We do not expect to win with the serious competition we have to face but do plan to beat most of them, who knows, maybe we can win a few in time, will shoot for the best and see where we end up

We removed alot of weight with our seat change out,

http://racetechseatsna.com/race_seats/RT1000.html

We had to extensively modify the seat brackets, while doing so lowered the seat height a bit and more so on the passenger side, we removed a couple of lbs of excess weight from the brakets as well and the 4 point harneses weight about half the stock front belts, have not weighed it all yet but the drivers side saved 30 lbs at least, passenger side will be a bit less.

WHY are we doing this to race a tC against such fearce competition? Because of the challenge and reward from doing what most would not attempt to do. Anybody can buy an M3, EVO, STI and with a few mods very very very fast, just not challenging enough, we prefer to be the gross underdog clawing and fighting our way up the finishing order, doing something a bit different, taking a FWD to very high levels of performance, with a world class audio competition system, to places most would never believe it can go and one hell of a good looking car to do it with

Rick

raamaudio

I agree Lance, not going to be easy to correct but we will find the best compromise of ride height, adjust what we can, chop the ends of the control arms off and rebuild them but to the least amount possible.

I'm just glad we are able to remove so much weight off the car up high, makes the job much easier;)

If not for class rules I would probably just rebuild the subframe and control arms and be done with it, that would be one cool DIY project!

Rick

sensay

what are your plans wheel and tire wise? my personal dream would is 255/40-35/18 but i dont think thats gonna happen on a tC but i wasnt sure. mabe with a wide body kit i could cut the factory fenders to fit something that wide but im just not knowledged enough in that area to know these answers. to me amazing response is one thing, and extreme grip to pull G's is another

lo_bux_racer

Rick:

I was at the junkyard today looking at the uprights on early 90's Camrys. They have 5 lug hubs, and they have a unique ball joint set up on them. I'm thinking about buying one to see if I can graft it onto a tC. Here's why - they have two bolts at the bottom of the upright instead of inserting the ball directly into the bottom. The ball joint still has the three mount bolts just like the tC, but because there are the two mount bolts instead of the ball joint pin on the bottom, you could put shims between the ball joint and the bottom of the upright and correct your lower arm geometry pretty easily, and retain a great deal of the strength of the original configuration. If you take a peek at a '96 Camry lower control arm you'll see what I'm talking about. It just might be the ticket.

raamaudio

Sweet, great find buddy I will call around tomorrow and check it out.

I have been searching around here like mad trying to find my FWD performance handling book, Corky Bell Turbo book and a few others but they just seem to have vaporized in our move I drove 30 miles to a couple of bookstores today just to try and find a copy of the suspension one but could not and I know both stores carry that book normally

Anyway, I cannot remember the title off the top of my head but it has a red Prelude on the cover.

Since I am going shopping for books it seems, any suggestions Lance?

I like to read all I can, ask the few I can find that actually know more than gossip and make believe and come to my own conclusions on how best to solve a problem, it has worked very well for me all my life;)

BUT, I sure like your Camry suggestion, that would be a low cost and easy to source fix.

I just seached http://www.car-part.com for hubs are as low as $35 each.

I know the Camry lug pattern is a 4.5", at least as I recall, have not owned once since sold the 92 in 96.

Then there is axle fitment, etc, etc, I am trying to figure this out from memory as to how it may all go together, not having much luck, lol!

Rick

raamaudio

I also took a look at the control arm and was envisioning the a tubular unit with rod ends and relocated pick up points
I was wondering if only the forward inboard end would need to be relocated, the rear one, hmm I suppose trailing arm? would not have to be even though it would be easy to do so, the front one not so easy.

Could end up being a bit clunky for a street vehicle but sure would tighten up any slop remaining since I have the pillow ball upper mounts already Then Rod ends for the sway bar mounts, dang would sure be sweet!

Rick

lo_bux_racer

I'm thinking I want to see if I can get the tC bearing to press in. then it's just a few clearances to see if the hub will work. I bet it's all pretty similar. That's why I was looking really hard at buying one from Pick n' Pull, but I already wasted $50 on swaybar end links hoping to find something to work with the Hotchkis.

I'll be really happy when Scion parts are listed online like the rest of the Toyco cars. Then I can see which models have the same pieces...

raamaudio

I have the latest gen camry and the tc micro fiche parts files and a reader, if you think that may be any use;)

Only $15-20 for other sets normally on Ebay Motors as well.

Just searched, a bit more but found all years from 82-02, six different sets, for $24.99 plus shipping.

Rick

lo_bux_racer

I've got EPC, but it's only up to '98. I wish I could get an update. It's great for Supra parts, that's why I got it.

raamaudio

I should of said those sets are $24.99 plus shipping, each! Not going to buy them all but if you have a certain model you think is the ticket, I just may order it if you think it will help us

I do not have any deep contacts in Toyota right now but I do have the business card that was handed to me at an autocross in 2003, President of NA Toyota, lol, not going to call him over this issue

Rick