b_griggs1

I autocrossed my 5spd tc once before installing the TRD springs,shocks and rear bar. The light rear end (oversteer) is much more revealing after the susp upgrade. Getting a FWD to be neutral, let alone oversteer is no easy challenge. Honestly, I would take this oversteer any day over the ugly, understeering, 3-wheel-cornering civics. My second car is a 71 Datsun 240z with tokico illuminas and progreesive springs. It gets a bit confusing sometimes driving them, one you lift to drift, the other, mash it hard lol

I wasnt able to autocross the tC last season after the suspension upgrade but am looking forward to this year. Another that I have noticed with the tC is that the air pressure can make or break the handling. I can inflate/deflate my 240z 5psi in any wheel and hardly feel a difference. In the tC, i can notice just a 2psi loss in the rear.

On a side note, anyone looking for a killer tire cheap, the new BFG g-force sport has unreal grip, its quiet and the treadlife seems to be pretty good. I have 8k on them, 1 autox, plenty of HARD offramps and i am at 5/32.

b_griggs1

Thought you guys might want to have a look at the amount of body roll in an autocross. Car is 100% stock at time of pic.

Notice how much rear end squat there is under hard cornering/accel, dive into the corner with the brakes on and all the weight goes to the front.....

yesti

thanks for chiming in b_griggs. it seems the tc is easier to make neutral than most FWD cars possibly due to suspension design? 4 psi in the rears did make a huge difference for me, but that may have to do with the sucky stock tires i'm guessing. i was looking at samsclub.com and the BFG KDW tires look pretty good also. Thanks for the tip. can't wait to read your review after the auto-x.

b_griggs1

yesti,

i hated those tires soooo much. a friend of mine bought a mazda 3 s a few months before i bought my tc and it came with goodyear eagle rs-a. i thought they were the worst oem tire made until i came accross the RE92. i got a nail in one at 10k and that was all i needed to ditch them.

costco.com has a good price for the bfg kdw right now. they are showing a pic of the KDW2 and listing it only as a KDW though. i have been meaning to find out exactly which one it is.

first autox of the new season should be around april.

Joe_Dezod

With stock suspension the lift-off over steer is horrible... But after I installed H&R springs it was a lot more controllable, even at the new, higher limit. Car rides as soft as stock over bumps, but with the back end more planted.

Also, I've slid the back end out at about 50 before, and it's definately with little warning. With H&Rs, I have to go at least 60-65 and reall get on and let off to start sliding the back end out. I bought 18x8 wheels with new tires, that should help evwn more.

On another positve not... I bought the Apexi RSM for my tC. I equpped it with the g-sensor that tells me front to back, and left to right G's. I can measure G's with the stock tires and H&R springs. Then I'll measure G's with 18x8s, then with better bars and so forth. This way, we can see what the mods actually do to the car.

yesti

thanks joe looking forward to seeing the results.

kileil

I've had this before but I expected it after reading the Tc's specs, it pretty much comes down to:

- Weight transfer: the softer stock suspension allows quite a bit of it. Swap to stiffer springs will help.

- 60/40 front bias: (If i remember the # right) When you lift throttle that heavier front will dig in nicely and the booty can slip out a bit. Not necessarily a bad thing for some, adding a rear sway bar thats too large can exaggerate it though.


All depends on what you like

yesti

thanks, kileil. i agree springs may help. usually the spring rates are higher in the back than front so even though the 'problem' may still be there it should be lessened enough.

about the weight bias, maybe i'm just used to my ancient 85 civic with similar weight distribution but nothing short of a FAT rear sway bar and organ exploding stiff rear shocks could get that car to rotate. but that car also weighed 1000+ less pounds so less weight sloshing around.

sdparks

I took my tC to the track last weekend, check out my post: http://www.clubsciontc.com/modules.p...ewtopic&t=2597

yesti

sdparks, am i correct in assuming you had the sway bar set to 'race'? do you think it would handle better on 'street'?

maybe you could try swapping tire pressures so the rears are higher than the fronts to help with the oversteer also.

what brake pads are you going to try? porterfield r4s are great street pads, but people faded them on the track in crx's so maybe the r4's are needed since the tC is so heavy.

thanks for sharing your experience!

oldman

I took my car to the autoX today:

1st thing the car is too quite with helmet on I can't here the engine to shift, there is not time during an autoX to look at tac it is all by sound and I can't hear it with helmet even with windows open. I gotta yank the axle back on race day.

Second thing: the car seem to work pretty well on Yokohama AVS ES 100 36 PSI front 42 PSI rear. rear never step out a single time, front plow was evident as expected from FWD with bone stock suspension. I drove the car with stock RE92 long enough to know that 90% of the suspension problem is the POOR tire. I'm sole that 36 / 42 was a very balance setup.

It was raining on and off so I did not run the full autoX tires. I got spanked bad by a Toyota XRunner that truck is way underclass in H stock! What a truck, it was ahead of many Vetts, Miata, MRS even! IT IS A TRUCK!

sdparks

I was happy with the rear sway setting (race) in the turns; the car was quite neutral. I don't think that the rear sway should have much effect on the back end getting loose when braking in a straight line anyway. That's really not oversteer because there's no steering being done in the first place.

Bumping up the rear pressures is worth a shot. I always kept the pressure higher in the rear with rear wheel drive, but figured that should be swapped with front wheel drive. In general, increasing pressure in the rear will increase oversteer.

I decided on EBC Redstuff Ceramic brake pads. It is claimed to be a good heavy use street pad that is up to occasional track day use. The road course at TWS isn't very demanding on brakes.

yesti

i was asking about the rear sway bar setting since in your post you said: "The back end gets loose under braking - very loose." I thought you meant while turning but I may have been mistaken.

Increasing tire pressure will INCREASE grip on that tire (up to a point).

Let us know how the redstuff works.

sdparks

yesti,

The back end gets loose even when braking in a straight line. Very discomforting. I would actually keep some steering input while braking so at least I would know which way the back was going to go.

Tire pressure is certainly the first thing that should be experimented with. I should also discuss it with my alignment guy.

BTW, I have a video up on clubsciontc. In the Videos forum.

yesti

dang, guess there is way too much weight transfer going on even with springs/shocks?!?! guess you gotta put some old batteries in the hatch j/k ;)

you were right about higher tire pressure on rwd cars, that will reduce oversteer. on fwd cars usually you do want higher in the front to reduce understeer but our cars are seemingly an exception to that rule especially if modded (even lightly).

cool video, looks like fun

oldman

I will say my last ride with a real performance suspension a VW with Shine Real Street. features very stiff front springs at stock height and stiff rear springs about 1.25 lower then stock. The is no magic to keep the weight off the front the rear has to go down, the front stay the same and the front spring to go up.

My Shine setup was 225 lb-in front at stock height, 180 lb-in rear 1.5 lower then stock. there is also a 1.75 lower 200 lb-in rear the should even perform better but the car looks bad with the butt dragging.

The VW and the tC have about the same weight and loading same front suspension design.

I know the performance "looks" people will just freak out that a FWD needs to be high in the front and low in the back for ultimate grip.. but dat's the truth of the matter.

yesti

since february, it has come to my attention that the reason for the freakish nature of our cars seems mostly due to the glass roof (namely, the WEIGHT of it). with so much weight so high up it exaggerates front/rear weight shifting so tremendously as to induce lift throttle oversteer in a stock FWD car.

therefore, if i do springs/shocks then my likely strategy (following oldman's advice) is (if such parts exist without a custom job):

linear front springs (0.5-1.0" drop) to keep the weight from shifting as much
progressive rear springs (1.0-1.5" drop) to keep the ride quality good for the street
koni adjustables (front slightly stiffer than rear, rear being slightly stiffer than stock if not stock setting) to keep up with the higher spring rates and because a stiffer front shock setting doesn't affect ride as much as rear (but if it is rebound only adjustment then that helps a lot too)

the front is ~0.25" lower than the rear stock so i won't be 'looking at the sky' too badly. but reading about the price/install of konis...might have to save a few more pennies.

make_shift

So since this thread came back from the depths...Which VW are you referring to? The MkIII suspension geometry is quite different then the tC, and the rules for GTI tuning doen't really apply to the tC. The weight may be similar, but proportions are different, the center of gravity is different, suspension travel is different.

BTW, Shine rocks the VW suspension tuning world. I had a similar setup on my GTI before switching to PSS9s.

Anyway.

Yesti:
Have you read up on the "progressive" springs? There is much debate as to whether or not a progressive springs really exist/work. Not all FWD cars need to be tuned the same way. Consider coilovers and corner balancing...I am a converted spring/shock user after I had my CO equipped GTI corner balanced....a much better autocrossing suspension set up than the Shine gear that I replaced was. Shine may have rocked on a road course (it did), but the COs handled the quick transitions of a tight AX course better.

My .02.

yesti

I had prokits (progressive) on the rear of my old civic (front was torsion bars, yeah THOSE civics) and liked them a lot. I also had illuminas and those really roughed up the ride (can you say CD player turning OFF, not just skipping! ;P) if you set them high enough (past 3). so it's nice koni is making rebound only adjustable shocks/struts.

adjustable rebound coilovers cost more than the adjustable rebound shock/spring setup and i don't need the height adjustability of coilovers other than it would be 'cool' i don't autox, 'spirited' street driving at best (when not stuck in traffic daily). people with the trd springs (progressive) have said the ride is actually 'better' than stock in some cases (most likely due to keeping the stock shocks) and have also reported that the rear end unloads quite a bit under heavy braking with that setup so i think what oldman said makes sense.

but if im wrong anywhere let me know, i want to learn!

zilasram

i'm not really sure why you would be lifting the throttle late in the turn. at the apex you should be adding more thottle, not letting up .. .

did you trail the brakes going into the turn?

if its a fast corner that only needs to ease off the throttle, it still would occur before the apex.

are you taking the corner to fast? . . .do you need to take a different line thru the turn?

i must say, i do experience the the rear end swing out during trail braking. . . or i should say after too agressively trail braking.. .i get too much grip in the front and back seems to want to hop out. . . .it could be from the back being so light as well.