Bump steer is when the steering geometry changes over the range of suspension travel (Ackerman angles). So yes, you could have a bump steer issue caused by worn bushes / ball joints / alignment or even bent links somewhere. Also, if you're running large offset wheels this can cause a "falling into ruts" feel to the steering. Just check things out, one at a time. Replacing even good looking bushes on a 15 + yr old car can have a huge impact on its drive feel.

 

Phil, in reference to your "falling into ruts" feel to steering with offset rims, is there a remedy other than switching rims back to either a smaller offset or a stock rim?

 

BUMPSTEER is "TOE" change during normal suspension travel on the front .. It does not affect live axle patrols only IFS independent suspension ..

Example .. Toyota Prado .. at normal ride height with the toe adjusted to 4.0mm positibe toe (toe in) when you compress the front end by pulling down on the front the toe can change upto 4mm to the negative ...

It changes because when looking at the tie rods/rack ends at normal height they are usually on a angle, so when you compress the suspension the tie rods change angle and can either shorten or lengthen ..

 

also the best way to check your front end is with the motor running on level hard ground , get a mate to quickly move the steering wheel left to right a few inches. Visually inspect the tie rods for any sideways or up down movement in the ball link. also check for excessive movement in the steering box

 

hi also check play in steering box as mine had a little play when i bought it but only noticed when i put new tyres on it
cheers cam

 

change all the front end bushes it will behave alot better (mine did)

 

Let me guess, it feels like its bumping and hopping to the right over rough bumps?

Check all your bushes and your shocks might be too soft as well.

 

You can get a kind of bump steer with a beam axle in the front. I've seen someone stuff up the geometry where their steering linkage was not parallel with the panhard rod. As the diff moves up/down left/right because of travel and the panhard rod the steering linkage was swinging in a different arc and effectively turning the wheels left and right. You could see that particular vehicle dart right when landing after jumps. He used to compensate by launching to the left. Scary.

<trying to remember where the front panhard rod goes in a patrol>

Lifted suspension with the incorrect castor corretion might cause this. Worn panhard bushes or steering joints are most likely.

 

That angle difference always happens with a lift because the panhard is shrter than the draglink. Also the as the suspension is cycling with the extra travel of the lift the axle will move to the right of the body and chassis as the suspension droops and vice versa when it compresses.
Because the panhard is fixed to the drivers side of the chassis .

 

Check all steering links for movement, check suspension bushes, and the steering box.
There is an adjuster on top or the steering box very easy to do just dont overtighten it as it cause excessive wear in the box.
I realised I had to adjust mine when the steering wheel had lots of movement from one side to the other without moving the wheels.
I had the most problems with mine not on bumps but when the road camber changed from one sid to the other
Hope this helps

 

Check all steering links for movement, check suspension bushes, and the steering box.
There is an adjuster on top or the steering box very easy to do just dont overtighten it as it cause excessive wear in the box.
I realised I had to adjust mine when the steering wheel had lots of movement from one side to the other without moving the wheels.
I had the most problems with mine not on bumps but when the road camber changed from one sid to the other
Hope this helps

Thanks guys. Thats exactly the kind of movement I get too. My steering wheel is not quite centered either. It seems to be the steering box.

 

Have you got lifted suspension?
Once you get over 2" lift and above the fixed length draglink shortens the distance between the steering box and left hand steering knuckle because of the angle.
Its enough to lose a bit of your turning circle to the left and puts your steering wheel off centre.
Best fix is an adjustable panhard and drag link but in the meantime, take the pitman arm off the steering box, get the sector shaft positioned exactly in the centre position, move the front wheels to the straight ahead position, then put the pitman arm back on the sector shaft spline as close as possible to centre.
You'll probably have to adjust your tie rod ends as well to get correct toe in.
This will even out the turning circle both ways and after its all done, take off the steering wheel and reposition it on the column spline with the wheels straight ahead.

I know someone who makes draglinks but not adjustable ones, but he can make the lengths to suit different height lifts and also offset at each end near the rods ends so that the rod ends are square to the pitman arm and left hand steering knuckle at nominal ride height.

Hope that helps and makes sense.
cheers, sudso