Just to give everyone some background; I own a 92 EJ1, which is lowered on Skunk2 Pro-S coilovers. I bought the car with this coilover, and the handling is terrible...this is mostly due to bumpsteer, which to me, seems a bit excessive for how much the car is lowered (i.e. lowered very little).

Do I need a camber kit to fix this issue? I kinda doubt it...

Any suggestions/advice from the pros on this forum?

Thanks

 

What are your alignment settings?
In short, bump steer is the change in toe as the wheel travels upwards....
What tire/wheel combo?

What exactly are you experiencing? Driving on a bumpy road and your steering is erratic?

 

Could you describe in more detail and without using technical terms the problem you are having?
Bump steer is very specific suspension geometry terminology that you may be inadvertently using incorrectly.

 

Symptoms of bump steer could easily be confused with symptoms of 'kick-back', so Scott is corerect to ask for a more detailed description of your problem. Of interest here too is tyre tread width and current rim offset relative to stock rim offset (if different).

 

what's kickback?

 

When the tyre hits a bump at a point on the tyre that is laterally offset from the point at which the steering axis intersects the ground (or the average centre of the impact force is offset from this point), then this creates an effective 'lever arm' that causes the longitudinal force of the impact to push back against the tyre and cause the wheel to try to pivot around the steering axis.

If this force is great enough then it will cause the wheel to significantly change angle, i.e. momentarily steer (in fact both front wheels will steer because they are connected by the linkage), and the steering wheel will also change angle. However, if the driver can fully resist this force and hold the steering wheel still, then the steered angles of the front wheels will remain constant and the direction in which the car is travelling will not change. This is 'kick back', not bump steer, and will tend to be greater with wider tyres and greater wheel offsets.

Bump steer is associated with vertical motion of the suspension rather than longitudinal impacts on the tyre. As a wheel rises or falls over a bump or road irregularity, even if the driver can hold the steering wheel perfectly still (i.e. not allow any rotation), the road wheel will still 'steer' to some degree as it rises or falls, and the car will momentarily veer in the direction in which the wheel 'steered'.

Theoretically in this case, only the wheel impacting the bump will steer (or simply rising over or into a road irregularity), and the other wheel and the steering wheel will be unaffected. In reality it's probable that some force (impact force, and / or inertia force related to the mass of the first wheel) will be passed through the linkage causing some lesser steered angle at the other wheel and some movement at the steering wheel (this is a secondary affect).

This is also an issue with suspension motion that occurs in roll, i.e. body roll can cause 'bump steer' that manifests as 'roll steer'. Suspension designers will often deliberately design in some degree of bump steer in order that they have a degree of roll understeer, and this can be at either the front or rear, or both front and rear.

Racing car designers will typically want zero bump steer and zero roll steer (non-linearities are generally a no-no for racing cars because they can confuse the drivers), but (I've heard) might sometimes 'cheat' by using it as a means to counteract some other steering problem.

 

Tire size: 205/50/15
Wheel size: 15x6.5
Wheel ET: 42

When I'm usually cornering at high speed and there are bumps in the road, the steering steers in another direction by itself.

I can't remember if the steering jerks and steers in the direction of the turn or the other direction. But I can assure you that bumps cause it to jerk and steer by itself.

I do try to hold it hard, in order to complete the turn, but it still tries to break free through the turn, therefore completely destroying the "driving experience"!

Any other specific info required, please let me know...I'll explain as best as I can :-)

 

Is it possible that you're simply feeling the tires skipping over the road due to the springs being too stiff?

 

IMO, a 205 section width is quite a wide tyre for a small FWD car. It should be fine on smooth roads, but bumps and undulations in the road are likely to cause kickback that can be sudden when hitting a bump harder, or might feel like 'torque steers' as you traverse undulations (they will feel like momentary torque steers because in fact they are a kind of torque steer).

On a flat road the centre of average loading on the contact patch will be more or less in the middle of the contact patch (but somewhat to the inside with neg camber and outside with pos camber), but more importantly, on a smooth road this centre of average loading will be relatively stable in location within the contact patch.

However, on a rough or undulating surface the average centre of contact patch loading will move laterally across the contact patch as the tyre traverses bumps and undulations.

The wheel steers around the steering axis, which will intersect the ground at some point within the contact patch. If (when) this point is laterally offset from the centre of average contact patch loading then this creates an effective 'lever arm', and forces generated in the contact patch will then try to steer the wheel around the steering axis depending on the momentary nature of the forces at the contact patch.

Because of these 'lever arms', longitudinal force generated at the contact patch creates a torque centred at and acting on each steering axis, and this will be felt at the steering wheel if the torques being fed into the steering axes are not equal side to side.

This is fine on smooth roads where the 'lever arms' at both front contact patches / steering axes are more or less stable and equal (and therefore the forces being fed into the steering on both sides is equal or near equal), but when one wheel hits a bump / traverses an undulation then the effective lever arm on one side changes length and so the force being fed into the steering becomes unequal and the driver feels a pull at the steering wheel (weak or strong, abrupt or 'slow').

The wider the contact patch the more scope there is for the centre of loading to move laterally across the contact patch face and for the lever arm to become longer, which creates greater leverage for the contact patch forces to be felt at the steering wheel more strongly.

Stiffer tyre casing would contribute to these effects (i.e. lower sidewall profile, stiffer sidewall, stiffer tread, higher psi). Wide tyres, FWD and bumpy roads is not a good combination. With my car (CB7 Accord), I have used both 205/60/15 and 195/65/15 tyres, and on the 205 rubber the car is noticably more twitchy, tramliny and bump-steery (i.e. feels like bump steer but I don't think it is) than on the 195 rubber. My car would probably be more sensitive to this than a stock CB7 because of various suspension and geometry changes I've made.

As an experiment try borrowing some narrower wheels and see if this improves the problem...

 

I'm thinking the struts are going bad. My car has similar symptoms. It's very bouncy even driving down a smooth surface in a straight line, and violently bouncy going through the curves- yes the steering wheel feels like it kicks when turning onto the on-ramps.

I have a 93 Civic DX hatch with Tein Coilovers with god knows how old struts on 205/50r15 tires as well.

 

If your bump steer is that bad then I take it that you did not know anything about pre-loading your suspension.

This little loosen and tighten of your suspension bolts works wonders.

 

a lot of people run that wide of a tire with no problems. the above mentioned theory may in fact be the case but just to be on the safe side you should check your car for bump steer since it is pretty easy to do. if you need me to elaborate, i can, but basically, you remove the spring/ damper assembly from you car and put that corner on blocks so that it is sitting at ride height level, whip up a simple gauge using some plywood and a piano hinge and raise and lower the suspenion through it's range of motion all the while checking for a change in toe by using your home made gauge and a dial gauge.

takes all of the guess work out of it.

 

what in heaven's name are you talking about?

what does pre loading have to do with anything?

 

have you checked for play in your suspension/steering?

what about the condition of those shocks?

youre really not describing bumpsteer properly. i really dont think this is your issue. just sounds like your suspension/steering is jacked up in some respect.