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higgsti

what can i do to stop understeer

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UNDERSTEER

Corner entry understeer: car initially points in and then washes out

Excessive toe-in or toe-out (car is usually "darty")

Insufficient front droop travel (non droop limited cars only)

Insufficient front damper bump resistance (similar to roll stiffness example)

Insufficient front roll stiffness - car may feel like it is pointing in but may actually be falling over onto the outside front tyre due to insufficient front roll stiffness or diagonal load transfer under heavy trail braking. Initial understeer can often be cured by increasing front roll resistance, even though doing so may increase the amount of lateral load transfer.

Non linear lateral load transfer due to spring and/or bar geometry. Or to non-optimal roll axis inclination

Corner entry understeer: car won't point in and gets progressively worse

Driver braking too hard, too late

Relatively narrow front track width

Excessive front tyre pressure

Excessive front roll stiffness (spring or bar)

Relative lack of front download (excessive rear download)

Insufficient front toe-in

Insufficient Ackermann effect in steering geometry

Front roll centre too high or too low

Insufficient front damper bump force

Insufficient front toe-out

Excessive Ackermann steering geometry

Can also be caused by unloading the front tyres due to rearward load transfer under acceleration - cures include:

- Increasing front damper rebound force

- Increasing rear damper low speed damper rebound force

- Increasing rear anti-squat

- Droop limiting front suspension (will also make turn in more positive and will reduce overall understeer)

Mid-corner (mid-phase) understeer

Excessive front tyre pressure

Excessive relative front roll stiffness

Excessive front toe (in or out)

Excessive Ackermann steering geometry

Relatively narrow front track width

Corner exit understeer: slow corners

Often a function of excessive corner entry and mid-phase understeer (whether driver induced or car induced) followed by throttle application whilst maintaining the understeer steering lock. The first step must be to cure the corner entry and mid-phase understeer. If this is impractical, then corner entry speed should be reduced slightly in order to allow earlier throttle application. Sometimes we have to be patient.

Corner exit understeer: fast corners

Relative lack of front download - often caused by negative pitch angle (squat) due to rearward load transfer on acceleration. Can be helped by increasing rear anti-squat and/or by increasing rear low speed bump force, increasing front droop force and by limiting the front suspension droop travel.

Relatively narrow front track width

.

Understeer stronger in one direction than in the other

Uneven caster

Uneven camber (especially front)

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You could just enter the corner a bit slower................... :(  if that's not an option (and it rarely is in a Westie) then a very gentle bit of left foot braking helps in faster corners, just remember its not the clutch! :cry:  In a slow corner a more aggressive initial turn in or a Scandinan 'flick' before you turn in to change the weight balance. Or softer tyres, or play with front tyre pressures, softer rear suspension or................ buy a bec like me! 

 

Enjoy! :t-up:

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buy a bec like me! 

 

 

The car was a bec, a blade to be exact, and I doubt Higgsti will read the reply, the original post is over 6 years old :laugh:

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This may not suit every one or every situation but this is how my car is set up and how I drive it. Car is very neutral and goes where you point it.

Set up

1. Wide track fitted . Race poly bushes to wishbones.

2. Toe 0 deg

3. Camber 1.5 deg.

4. Shock settings on front 3 to 4 clicks up from dead soft dependant on circuit.

5. No ARB.

6 22psi cold tyre pressure

Driving style.

1. Late braking all done in a straight line and go fairly deep into corner with late turn in

2. Turn in immediately on release of brakes and aim for late apex if possible.

3. Gently back on throttle early before apex if possible. WOT by apex or very soon after. (This works on the principle of the quickest way between two points is a straight line.) There are probably a few professional drivers out there that have a better technique or line but this is how I was taught to drive a 7, rightly or wrongly.

I am now getting into the old farts category so there are plenty of young blokes who are quicker than me but I am able to hold up my end of the stick amongst those mates in my age group, so I must be doing a few things right. I have had the most success with soft suspension settings. In your own Locost race series they run very soft springs in those and given that, I still think that I am still a bit stiffly sprung and there is more room for improvement.

This setup appears to have dialled out the understeer in the car.

The other thing that can induce understeer is an LSD that is locking on over run as well as power, in other words a 2 way LSD. Common in rally Escorts. I fitted one to my car and it was a disaster. Since then I have fitted a TranX which has 45/90 ramps and light preload and only engages on power out of the corner. Fantastic little unit. Has really made the car.

Don't know if any of the above will assist you, as often setup has a bit to do with your driving style and technique, but hopefully you may glean something out of it all.

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