Steering steers & rattles when breaking...

If your car "breaks" at high speed, you're going to get hurt!! On the other hand you do want the car to "brake" from any speed.

 

When you say the "steering steers" do you mean:

1. it pulls to one side, or

2. the steering system oscillates back and forth?

(give year/model too please)

 

During braking, does the car vibrate or just steers to one side?

I would check the tyre wear and pressure first, if they are ok then you could check the balance of tyres but this is unlikely the reason as the car would vibrate at high speed regardless.

Although the car could be out of alignment, I don't think this alone is the problem. Unless the car is wildly out of alignment (unlikely unless you have other handling problems as well), it should not rattle.

I have a feeling it is to do with the suspension wear.

 

if it pulls to one side then check the front wheels and rotors if they are wet with fluid or some thing. A sticking caliper or brake pad issue will cause a pull to one side, leak in the caliper.
if the wheel is kind of juttering or a quick oscillation, check the rotors for warpage or wheel bearings if they are loose. If you just feel it when the brakes are applied, (rotors are uneven on the friction surface, not out of round)
my bet is on warpped rotors. Sometimes the you can accually warp them by tightening the lug nuts too tight on some cars/trucks....
you can easily check the rotors with a caliper.
I doubt there is any pressure differences between the left and right calipers but I guess that could happen if the rubber hose between the brake line and the caliper collapses. Seen that before.

Check the rotors for warpage.

 

More info required......

But if it dives off to one side when the front suspension dips, it could be a non centralised steering rack, or one front BRAKE working more than the other, or bad camber/caster angle.

If it still pulls to one side when BRAKing gently, without suspension travel, it's most likely a BRAKE problem.

IT is NOT wheel balance if it only happens when BRAKing, any steering shudder under BRAKing is from distorted discs or loose calipers usually.

If the steering shimmys left and right at quite slow road speeds (under 30mph/50kmh), it's most likely a tyre out of shape, over that and it's most likely a wheel balance.

Front toe setting will NOT cause pulling to one side on a FLAT road, but uneven roads/surfaces may encourage it. Pulling to one side on flat surfaces is usually a caster or camber problem, or a binding BRAKE, or tyre/pressure problem.

 

What if it goes back and forth between pulling but it doesn't move the steering wheel. When you press the brake even gently the car moves from left to right but you can hold the steering wheel still.

 

I agree with the warped rotors idea as the problem. If the steering wheel vibrates in your hand during braking, its almost certain to be warped rotors.

Warped rotors, unless they are really bad, can be easily remedied by having them turned. Local autoparts stores, like Kragen, will turn them for about $10 each.

 

The discs are marked with a minimum thickness. It usually allows 2mm of wear from new, but if you are going to track days you should keep within 1 mm of new thickness.

 

could be warped rotors and you better hope it is. or it could be suspension like lower control arms and/or bushings. same thing happened to me on my bmw, but it had 300K miles when it started. i thought warped rotors, but it was bushings and worn our lower suspension/steering parts. good luck

 

Are both things happening concurrently?

Is this only from high speed or is it at any speen under hard braking.

Do you perceive the rattling from front or rear, right or left, (or passenger seat)?

Has any work been done on the car recently, if so what?

Without more info, i would check, (assuming it is a 3x8):

Lower A arm mounting bolts front and rear.
Steering rack bushing, especially the right side.
Ball joints and tie rod ends.
Wheel bearings.
Anti roll bar bushings are a chronic noise maker, but wouldn't reallly cause the car to pull.

hth,\chris