Suspension Experts - autocross/Track/swaybars etc (pics up)

[strx7]

This pic is my 4wd corolla, approaching the rev limiter in 1st, exiting a LH corner at an autocross. as you can see the LR wheel is clearly off the ground.





I'm running BAZDA ISC coil overs allround with factory front and rear swaybars.
Do i need a harder front bar? or a harder rear bar? or do i need harder front spring rates???

[Bazda]

Thats pretty normal in a FWD. You want it to pick up the rear wheel .
And thats mainly because there is not a huge amount of droop when you convert to coilovers.

Do you find the car pushes once the front is leaned right over?? if so then the easiest way to fix it is a harder sway bar or spring rates.
But the proper way to fix it is with custom made RCA adapters.

[strx7]

the car although it feels to be pushing a little, spectators have said that it looks to be turning way better than the WRX's etc which are having some major push.

i've got 3.5 degrees camber and my top plates are angled giving a couple of more degrees of caster too.

I suppose at the end of the day its a FWD platform, with 4WD, so its going to handle and have fwd type characteristics.

A harder front bar should lessen this effect but at what trade off? more push?
The torsen LSD in the back seems fairly un LSD, perhaps its poked? perhaps a plate type LSD would be better in the rear?

[Mr Revhead]

Can't see pic?

[strx7]

copy and paste it into a browser, i cant seem to host it anywhere

[Mr Revhead]

This content is currently unavailable

Is what happens when I do

[touge_ae101]

wouldn't hurt going to a harder front swaybar and changing the rear diff to a tighter unit to counter the understeer characteristics of putting a harder front bar in.

might be a bit of a trail and error job, would pay to get an adjustable bar with a certain degree of flexibility.

[Truenotch]

I can't see the pic but it sounds interesting.

Roll centre would definitely be the thing to play with, but it'll probably be a lot easier to go to a harder rear bar and possibly spring rates.


What spring rates are you running at the moment and what work does the car do?

[iOnic]

Can't see the pic but by the sound of things you should be looking at a thicker rear swaybar to resist the roll tendency in the back better and keep your rear wheels on the tarmac. Thicker rear bar also has the added advantage of giving you more front end traction. If you've been losing that much camber during hard cornering that you need to run excessive static camber in the front to compensate for it then a thicker front sway bar would benefit you too.

Roll Center Adjusters won't help you much unless your car is that much lower than stock that you've pretty much depleted the arcs that your lower arms travel through causing the car to be unstable on anything but smooth surfaces.

[touge_ae101]

thicker rear bar will result in more lift off of the rear wheels on hard cornering.

i try to imagine the cars handling as a pivot in the middle of the car, so if you harden the rear swaybar, it will want to 3-wheel more often and if you harden the front swaybar it too much it will want to sledge everywhere.

stiffening up the front swaybar will stop the front corner dipping as much(lifting rear wheel with a stiff chassis/cage), but may result in more sledging, so add a diff in the back which will bring the rear around during hard cornering and counter the sledging.
am interested in the front spring rates you are running, maybe they are too soft for the ?3sgte? sitting under the bonnet?

this is just the way i think about it and i don't have a lot of experience but i can see logic in it.

[iOnic]

http://www.whiteline.com.au/jim_wordpre ... oll-center

As most factory vehicles are biased towards understeer, fitting of the larger rear swaybar will help in providing a more neutral characteristic in the handling at the limit. This is due to the increase in roll stiffness at the rear, which loads the rear wheels more unevenly and provides slightly less grip at the rear than previous.

At first this may sound sacrificial, however, as the rear end is resisting more of the roll, the front end resists less in proportion, leaving the front wheels more evenly loaded, therefore more available front end grip. In the end an increase in overall grip can be achieved by balancing the vehicle. A WRX or other front torque biased all wheel drive vehicle will benefit even more due to combined front end steering/traction demand.

[touge_ae101]

yeah i've seen that many times but its barely a factory shock/spring combo? or factory spec corolla by any means.

[Truenotch]

Depending on how it's dipping in the front, a harder rear bar might pull the inside rear wheel down and balance the handling - or it might do the opposite. A harder rear bar will always reduce front sledge, but it sounds like this might need more than just a bar.

[iOnic]

but it sounds like this might need more than just a bar.

+1 It would be a start but I'd still consider looking at spring rates too.

[touge_ae101]

true pics would help!

[edwagon]

Torsen diffs need both wheels on the ground to work properly.

If that inside wheel lifts, or gets very light, the Torsen will not act as an LSD.

[strx7]

Torsen diffs need both wheels on the ground to work properly.

If that inside wheel lifts, or gets very light, the Torsen will not act as an LSD.

I suspected exactly that.

the first autocross i did in it, it had no rear swaybar in it, and it got more rear wheel lift.
springs are 8kg(450lb) front and 6kg(335) rear

perhaps the added weight of the 3SGTE and the transfer box upfront, i should look at harder springs? I do autocross, tarmac hillclimbs, tarmac rally sprints, taupo track 2 and hampton downs

[Truenotch]

You'll need a harder spring in the rear to make the 4WD/FWD chassis work propperly... And in my opinion it needs harder front springs and a bigger rear swaybar too.


What does the car weigh and what are you using it for? Tarmac rallies/autocross/track work? WRX guys tend to have their springs pretty balanced F/R for track work. A friend down here uses 850lb (15kg) front and 650lb (11kg) rear and big swaybars all round in his imprezza race car. It would weigh somewhere around 1200kg.

[matt dunn]

If you look at the first 2 pics,

when the car is turning Left,
the right rear wheel is being pushed up into the guard.

A sway bar tries to make both wheel travel the same,
so a stiffer rear bar will draw the left rear wheel further off the ground.

Nomally you always look at the opposite corner to fix the problem.
Stiffer front springs or swaybar would be my choice.

[strx7]

front bottom arms are just below horizontal at ride height.