Let's talk turn-in...

I love the Fiesta and am used to driving it, so I think I have just accepted some of its autocross shortcomings. Having a few co-drivers recently, they all commented the same thing: it doesn't grip at turn-in and is hard to rotate. So, if you had a FWD car and wanted to reduce underseer and improve initial bite to get the car rotating, what would you do? 

having no experience with that car specifically, in general I'd add toe out up front for turn in and I'd add toe out out back for rotation. 

Go slow, and do one end at a time. 

Can you add Ackerman in your rules?

What's your starting point?  Is the suspension stock and at stock ride hight?  Is this primarily a street car that sees some autocross action?

Toe out, stiffer rear bar. 

z31maniac said:

Toe out, stiffer rear bar. 

That's it. To start with, you can unbolt one end of the front sway bar.

I mean it's a heavy fwd car with relatively small tires...turn in is never going to be its strong suit. You've been autocrossing it for a while, I can't imagine you're still on the stock alignment, but if you somehow are, taking out the front toe in was the single most noticeable change I've made to mine. Assuming it's already got an alignment, more front toe, maybe toe out the rear a bit if you feel like dealing with shimming the axle or whatever is needed to achieve that. More front camber, more roll stiffness all around. More rear stiffness and/or tire pressure to make it rotate better.

Thanks all, it does have some work done to it but I wanted to get the general rules for rotation.

The car has larger front and rear bars to increase roll stiffness all round. It is lowered on coil-overs, with -3 camber front and -2 in the rear. I can play with toe up front, but not out back...yet. I do play with tire pressures, usually running higher in the back for more rotation. I can also adjust the shocks, again, I go loose up front to keep tires in contact with the ground (a big front bar) and stiffer in the rear. Am I doing antying backward?

The rear bar is not adjustable, so I am thinking that going to an adjustable rear bar would allow me to test different settings to see the effects.

pinchvalve (Forum Supporter) said:

Thanks all, it does have some work done to it but I wanted to get the general rules for rotation.

The car has larger front and rear bars to increase roll stiffness all round. It is lowered on coil-overs, with -3 camber front and -2 in the rear. I can play with toe up front, but not out back...yet. I do play with tire pressures, usually running higher in the back for more rotation. I can also adjust the shocks, again, I go loose up front to keep tires in contact with the ground (a big front bar) and stiffer in the rear. Am I doing antying backward?

The rear bar is not adjustable, so I am thinking that going to an adjustable rear bar would allow me to test different settings to see the effects.

Generally speaking to improve turn in you want to soften the front or stiffen the rear.  Toe out on the rear will improve rotation but at the expense of straight line stability and (in extreme cases) increased drag. Toe changes in the front are somewhat geometry dependent with static straight line toe compensating for any inherent Ackerman error.  I prefer to set toe where the math says it should be and adjust balance in other ways but it's worth experimenting with.  It's quick and easy to measure and adjust with minimal tools.

The stiffer bars make the car more responsive because you're not waiting for the body to catch up with the wheels on turn in.  They also keep the suspension in a range that has acceptable geometry.  If you can do it without sacrificing the above you can soften the front bar.

Adding rebound stiffness to the rear shocks and softening compression in the front will help with initial turn in under braking.

Adding rake will also tend to free up a car. 

You mention that car is lowered.  Is it hitting the bump stops?  That'll give you a push that's very difficult to adjust out.

We started autox in a 2001 Ford Focus ZX3.  

1. Konisport single adjustables . We'd go mostly full soft up front and full stiff in the back, then adjust from there.

2. big rear sway bar.

3. I didn't mess with rear toe but I would pump the back tires up to aid in rear rotation (along with the big rear sway bar)

4. I marked the front tie-rods with wife's fingernail polish.  I'd give it a round of toe-out for the event and put it back before driving home.  I forgot to put it back at one event 300 miles from home and it wasn't pretty...,  Had to buy new front tires before the next event.

5. This was back when Azeni's were the hot street tire.  Later on folks figured out a big front sway bar would prevent camber loss on compression by not letting the front suspension move!  (any suspension will work if you don't let it...,)

In reply to djsilver (Forum Supporter) :

#5 would also reduce understeer if you were on the bumpstop(s).  By making the roll stiffness greater, you would be preventing it from going "infinite", in effect the bigger bar would be reducing front roll stiffness...