Suspension Tuning - how do you like yours ?

[~ ~ Cal ~~]

I prefer a bit of tail happiness myself and removal of any "wash out" style understeer.

Don't like a crashy ride but will lower my car on prodrive springs next year. Would love EDFC's for switching between road and track mode but i dont track my car often enough to warrant the purchase plus they cost a purdy penny.

I thought the below might be useful for you fellas ? GT4 for the PS2 is a great way to learn about these sorta things

Looking at the Litchfield T25 - that would be my ideal set up. Great turn in but able to swing oot the rear on demand !

********************************************************************************************

Understeer on entry to a bend - Increase the 'rebound rate' of rear shocks. Decrease the 'bump rate' of front shocks. Increase the rear brake bias or just brake earlier!

Oversteer on entry to a bend - Decrease the 'rebound rate' of rear shocks. Increase the 'bump rate' of front shocks. Decrease the rear brake bias, or brake later!

Mid-bend Understeer (constant 'wash-out') - Stiffen rear spring and/or anti-roll bar. Soften the front springs and/or anti-roll bar.

Mid-bend Oversteer (constant 'tightening' without driver input) - Stiffen front spring and/or anti-roll bar. Soften the rear springs and/or anti-roll bar.

Exit Understeer - Increase rebound of front shocks. Decrease bump of rear shocks. Stiffen rear springs/anti-roll bar. Soften front springs/anti-roll bar.

Exit Oversteer - Decrease rebound of front shocks. Increase bump of rear shocks. Soften rear springs/anti-roll bar. Stiffen front springs/anti-roll bar.

Car is slow to respond to driver's input - Stiffen the car by (in this order) springs then anti-rollbars then shocks. Increase tyre pressure check heat spread.

Car hops over the bump - reverse of the above.

Pinched from the MLR site

Cheers

Cal

[wilky]

Outstanding, I am now sharing a forum with sir Colin Chapman.[]

[st3ph3n]

As ashamed as I am to admit it I prefer just a wee touch of the understeer as I think my talent runs out around the point where the oversteer says hello in any meaningful way.

I know with more practice I'd be better, but coming from a background of front runners it is where I am more comfortable.

I do feel a bit more comfortable with a bit of oversteer after a bit of slideways action last Saturday in the rain []

[ANDYJDMSTI]

I like mine abit twitchy!!

is it, isn't it..........makes me not get too over confident with it. All to easy to set these cars up perfect then have it bite you in the ar$e when you outpush your capabilities!

 

[wilky]

Your car is twitchy because you have dccd and to cut a long story short you will more readily get oversteer because you have more torque going to the back wheels.

Understeer feels a hell of a lot more controlable than oversteer, but controlled oversteer can be made to make you corner a bit more productively 9 times out of ten.

I dont think your post from the dark side is true for a quick subaru however as alot of the understeer is down to the central diff set up on a car, say your wrx will understeer more readily than one with more torque to the rear wheels like a jap dccd set up like andys.

I stiffened the rear of my car and was still having to induce rear wheel torque slide to compensate for understeer, as The Squirrel will testify to.

 

[col666]

Oversteer []

Diff control has never moved from the furthest back setting since i bought it....can i just remove the front driveshafts and make it completely rear wheel drive?![]

[~ ~ Cal ~~]

"I dont think your post from the dark side is true for a quick subaru however as alot of the understeer is down to the central diff set up on a car, say your wrx will understeer more readily than one with more torque to the rear wheels like a jap dccd set up like andys."

True but a Whiteline adjustable ARB / solid drop links has meant that more power can be fed to the rear wheels on my car so it does not plough into the bends the way it used to. A stiffer rear end = more oversteer and less roll which means the power can be more evenly distributed. The FastOne followed me round some large roundabouts and witnessed the craziness in the wet.

DCCD will only really help to a certain extent. The Stig had the WR1 understeering like a pig. Manufacturers dial in understeer as it makes for a safer drive.

This is also useful info that I stumbled across :-

To Reduce Understeer or Increase Oversteer

Front tires:

Increase tire pressure in 2.5psi increments

Increase Section Width

Lower the Aspect Ratio

Reduce front tread depth

Rear Tires:

Reduce tire pressure in 2.5psi increments

Reduce section width

Install higher aspect ratio tires

Increase rear tread depth

Front Wheels:

Install wider wheels

Install lighter wheels

Rear Wheels:

Install narrower wheels

Install heavier wheels

Front Alignment settings:

Dial in more negative camber

Dial in More toe-out

Dial in more positive caster

Rear Alignment settings:

Dial in more positive camber

Dial in more toe-out (Same as front)

Anti-Sway bars:

Soften the Front

Stiffen the Rear

Spring rates:

Soften the Front

Stiffen the Rear

Shock absorbers:

Soften the Front

Stiffen the Rear

Suspension Bushings:

Soften the Front

Stiffen the Rear

Brake Proportioning

Reduce Front brake pressure

Increase rear pressure

Weight Distribution

Reduce front weight

Increase rear weight

Aerodynamics:

Increase Front Downforce

Reduce rear downforce

[wilky]

How do intend feeding more power to the rear wheels?

 

[~ ~ Cal ~~]

What I should have said is that it allows way more grip to be transferred to the rears ( not power).........this copy n' paste from the Whiteline site explains things nicely.........

 

On-Road Results

The adjustable 22mm rear swaybar absolutely

transformed the WRX's handling - this really is the biggest bang-forbuck

handling mod you can make!

Mid-corner is where the new 'bar makes its biggest difference. The WRX is now much more obedient during its

approach to the apex of a corner - you no longer have to combat understeer and more understeer. The front-end

points much closer to the steered angle and the chassis remains more neutral - especially through tight corners that

would otherwise have the Rex plough understeering. From the driver's seat you can really feel the outside rear tyre

being loaded and, relatively speaking, the outside front tyre is under less stress. For the first time you can hear the

rear tyres yowling through a corner, not just the fronts; this is a good indication that the cornering loads are now being

evenly distributed through the front and rear outside tyres. Tyre wear, as a result, will be less focussed to the

shoulder of outside front tyre.

The new swaybar improves turn-in, though the difference is not as tremendous as the middle stages of the corner. If

you come into a corner too fast or your steering input is too rough, there is certainly less tendency for the nose to

plough ahead. It

will understeer in these situations, but not terminally. Given a smoother steering approach, the rear

swaybar won't make a huge difference to turn-in.

Corner exit is slightly improved thanks to a more accurate approach to the apex that effectively 'opens out' the exit

line. Previously, it was easy to understeer wide of the apex and be forced to tighten you exit line; with the Whiteline

swaybar, you can more accurately follow the optimal line. If you apply power while there is significant steering lock

wound on you'll get power understeer - though it doesn't feel as pronounced as previously.

And how reactive is the car to mid-corner throttle offs?

Well - first - we must emphasise there's now much less requirement to lift off the throttle in order to get the front-end

to tuck in. With the chassis more balanced, there are only few occasions (such as when negotiating a tight roundabout)

when a slight mid-corner lift-off will be of benefit. Depending on entry speed and your steering input, a sharp

throttle-off

can cause a considerable oversteer action. Other than looking spectacular we're not sure if this is a great

characteristic, but it shows the car now has much more balance - you're not limited to just understeer.

The three different swaybar adjustments make a considerable difference to the handling attitude of the car. The

softest roll setting still gives all of the abovementioned but is quite benign in its transition to lift-off oversteer. In the

other extreme, the firmest setting is perhaps a bit much with otherwise stock suspension and road-spec tyres. Be

aware that the tail can step out quite a long way - and very rapidly - when the car is unsettled by factors such as road

camber changes or loose gravel atop of the bitumen. The firmest setting is, however, probably ideal for track use.

And now we arrive at the middle setting - the setting we are currently most content with for everyday street duties.

The centre swaybar hole provides much improved mid-corner attitude and its lift-of oversteer characteristic is

manageable in everyday conditions - in dry weather conditions, anyhow.

[~ ~ Cal ~~]

Some good information in here w.r.t Jap Spec DCCD ( John Felstead)

http://bbs.scoobynet.com/drivetrain-11/143...ranslation.html

[wilky]

Very interesting Cal, thank you.

[gogsie]

DELIVERED!!!!!!!

Still waiting on my AST kit! Well actually the ARB's for the kit. Whiteline UK out of stock so waiting for them coming from AUstralia. 8 weeks now IIRC