Car slightly pulls to the left

[Limbo]

any noise? a wheel bearing going perhaps?

[SHOGUNOVDDRK]

any noise? a wheel bearing going perhaps?

That my friend is something I didn't think of.

This also should be in the check list.

[Ally Angel]

I actually have a simular problem myself with my car, i know its not alignment.., rear bushes have just been replaced a few weeks ago. but mine does it also when i brake and when driving. Sometimes its there real bad and sometimes its not. But im getting new 17'' wheels put on in a about a month so see what happening if its still doing it then.

But sounds like a real simular problem, ive had for a about a year and only gotten worse

[FastFwd]

I actually have a simular problem myself with my car, i know its not alignment.., rear bushes have just been replaced a few weeks ago. but mine does it also when i brake and when driving. Sometimes its there real bad and sometimes its not. But im getting new 17'' wheels put on in a about a month so see what happening if its still doing it then.

But sounds like a real simular problem, ive had for a about a year and only gotten worse

Yes exactly...its when braking and accelerating. some times its worse and sometimes its not to bad. Occasionally gives a really loose steering wheel feeling.

And when under boost, im holding my steering wheel steady and strong straight it feels like i keep having to re-correct the car when im just going straight. It will pull to the left then i have to turn the wheel left a little. Mixing this with torque steer, LSD and 230hp occasionally doesnt feel so good.

Car feels like it wants to take off without me in different directions.

[string]

When your tyres generate a forward or backwards force from acceleration or braking it attempts to rotate the upright around the steering axis. The further the centre of the contact patch from the intersection of the steering axis and the road (the scrub radius) the greater the magnitude of this force.

RWD vehicles experience the exact same force, except obviously only when braking.

This is all well and good when the tyre forces are equal (and the scrub radii are equal left and right) because one side pushes on the rack and the other pushes back and the forces balance and you get zero net force. At any time when the tyre forces are NOT equal, you get unbalanced forces, and as a result you get steering pulls (and they are real forces: you have to counter them entirely or else the steering will change directions).

A helical LSD does not always put the same torque through both wheels therefore under heavy acceleration you might be getting more steering kickback from one wheel than the other. The same applies for braking on an uneven surface.

When one wheel is providing more torque than the other, it is likely deforming the bushings more than the other causing a greater change in geometry and a further imbalance.

Further more, you likely have near stock ratio spring rates front:rear meaning the front track is doing the majority of the yawing work. This means that toe changes to the front axle will greatly affect the yaw of the vehicle. The first thing I noticed when changing from a front stiff to a rear stiff setup was that the front end has a much harder time yawing the vehicle on it's own - i.e. torque steer is near gone.

[FastFwd]

When your tyres generate a forward or backwards force from acceleration or braking it attempts to rotate the upright around the steering axis. The further the centre of the contact patch from the intersection of the steering axis and the road (the scrub radius) the greater the magnitude of this force.

RWD vehicles experience the exact same force, except obviously only when braking.

This is all well and good when the tyre forces are equal (and the scrub radii are equal left and right) because one side pushes on the rack and the other pushes back and the forces balance and you get zero net force. At any time when the tyre forces are NOT equal, you get unbalanced forces, and as a result you get steering pulls (and they are real forces: you have to counter them entirely or else the steering will change directions).

A helical LSD does not always put the same torque through both wheels therefore under heavy acceleration you might be getting more steering kickback from one wheel than the other. The same applies for braking on an uneven surface.

When one wheel is providing more torque than the other, it is likely deforming the bushings more than the other causing a greater change in geometry and a further imbalance.

Further more, you likely have near stock ratio spring rates front:rear meaning the front track is doing the majority of the yawing work. This means that toe changes to the front axle will greatly affect the yaw of the vehicle. The first thing I noticed when changing from a front stiff to a rear stiff setup was that the front end has a much harder time yawing the vehicle on it's own - i.e. torque steer is near gone.

Cheers for that string good info...

Ive got installed:

scunk2 camber kit Front
scunk2 camber kit Rear
G4 36 point adjustable coilovers
Whiteline Xtra Heavy Duty Sway Rear 28mm
Whiteline Heavy Duty Sway Front 22mm
Generic front and rear Strut braces.
MPR Rear LCA's

New Front LCD Bushings

I was thinkin about purchasing a poly urethane bushing kit soon also.

One thing i did notice yesterday was i was running 21psi on my rear tyres and 40 on my fronts...i changed the rear to 40 also and that cleaned up the ride a little but im thinking its what you said. I setup the camber myself and it was fairly half assed when i did it, i had no measuring tools or nothing. Just all by eye sight and the front or the rear could be in a difference of 2 degree's or so and that would be effecting the scrub as you would say.

Might take it to a suspension joint and get them to calibrate it all.

[Ally Angel]

I had my rear trailing arm bushes replaced with the poly urethane ones, did make a big difference to me.. but thats what im doing next going to a pedders and getting them to check it out when i get new tyres put on in about month..

Thanks guys i been trying to work this shit out for ages, its annoying and rather dangerous

[hotdc2]

my friend has G4 coilovers on her silvia and they're the worst thing she has ever done to it.. With all the money you've spent on the rest of your car i'm suprised you shorted yourself in the sussy department hey...

[FastFwd]

my friend has G4 coilovers on her silvia and they're the worst thing she has ever done to it.. With all the money you've spent on the rest of your car i'm suprised you shorted yourself in the sussy department hey...

I love em tbh.

I've had two sets of d2's in two s15's also and i loved them.

I like a really stiff ride, and thats what they give. I've not had one issue with them and ive been running them for 2 years. I was going to get other brands but you need to spend at least 3-4g to get the compression and stiffness i wanted. G4's give that.

They typical cheap drift/race setup suspension. Dont really recommend them for the daily driver. But it doesnt bother me.

[Ally Angel]

Yeh ive defently noticed it stiffen up but that was the whole point of it... its your own personal choice really what u like.. ive only got that on that rear tho at the moment just cos they needed replacing but when the fronts need doing then ill do the same

[JohnL]

When your tyres generate a forward or backwards force from acceleration or braking it attempts to rotate the upright around the steering axis. The further the centre of the contact patch from the intersection of the steering axis and the road (the scrub radius) the greater the magnitude of this force.

String is talking about 'scrub radius' here, i.e. the nominal lateral distance from the nominal centre of the contact patch, to the point at which the steering axis intersects the ground.

(note: positive SR = when the steering axis intersects the ground to the inside of the nominal contact patch centre, negative SR = when the SA intersects the ground to the outside of the nominal contact patch centre)

Notice that I deliberately used the word "nominal", which is because on the drawing board we assume that the centre of the contact patch is on the centreline of the tyre, but in reality it in effect usually isn't since the wheel is usually always cambered to some degree.

Camber affects ‘real’ (or ‘effective’) SR because when we have substantial negative camber it's reasonably obvious that the outside of the tread is often not even on the ground, so can't be part of the actual contact patch. Thus, if the nominal (positive) SR were X, then the 'effective' SR must be X- (or the effective SR might even be negative, i.e. instead of some degree of positive SR there could be some degree of negative SR).

Even if the full width of tread is actually touching on the ground, but more heavily loaded on the inner edge than then outer edge, this will still affect the effective SR in the same way as if tread were so unevenly loaded that it was only resting on it's inner edge, the only difference is in degree. Whenever part of the contact patch is more heavily loaded than another part, the ‘effective centre’ of the contact patch moves toward the more heavily laden part of the contact patch.

Now, 'effective SR' is influenced by camber angle and tyre pressure because both camber and pressure affect the location of the ‘effective centre’ of the contact patch.

For example, if you had X negative camber at Y tyre pressure, then the effective centre of the contact patch will be offset to the inside of the tyre centreline (increasing effective pos SR over the nominal pos SR). If we now increase the camber, then the outside of the tread will become more lightly loaded and the inside become more heavily loaded and the effective SR will increase further. If we significantly increase tyre pressure then the loading across the width of the contact patch will change, and the affect of any camber will increase, i.e. with existing X neg camber the inside of the tread will become more heavily loaded and the outside less heavily loaded (with pressure increase), resulting in a change in location of the effective centre of the contact patch toward the inner edge of the tread and thus an increase in effective SR.

So what?

If the static camber is unequal side to side (especially with high tyre pressure), then the effective SR will be unequal side to side, and this will tend to cause a steering pull when accelerating, and an opposite pull when braking.

This is because the SR is in effect a 'lever arm' through which forces generated within the contact patches are 'leveraged' into the steering axis on each side, and forces leveraged into the steering axis through a lever arm generate a torque force around the SA that is felt by the driver as a steering pull, but only when these are unequal side to side.


When you accelerate you create a force that tries to ‘pull’ the contact patch forward, and there are two ways in which it can go forward: by turning around the steering axis, or by moving forward in a straight line if it is not allowed to turn. When you brake you create an identical dynamic but in reverse.

Any difference side to side will result in the driver feeling a pull. Note that the effective SR changes every time the dynamic camber changes, i.e. any time a wheel rises or falls relative to the chassis (causing dynamic camber change), whenever the contact patch encounters a change in road camber or the effective centre of loading traverses across the face of the contact patch.

This is the case even when the nominal SR is zero, i.e. the effective SR rarely - if ever - actually is zero unless the car is travelling on a dead flat perfectly smooth road with zero wheel camber angle (obviously a situation that almost never actually occurs in the real world).

Just to make things very confusing, camber also causes a tendency to pull that is related to the manner in which a rolling ‘cone’ tends to roll in a curved line (a leaning / rolling coin being an easily visualised example). This has nothing to do with any pull caused by effective SR, and may even be a counteracting or an additional factor re any other pull, and one cause of pull may overwhelm another cause of an opposite pull some of the time, yet add to it at other times.

RWD vehicles experience the exact same force, except obviously only when braking.

This is all well and good when the tyre forces are equal (and the scrub radii are equal left and right) because one side pushes on the rack and the other pushes back and the forces balance and you get zero net force. At any time when the tyre forces are NOT equal, you get unbalanced forces, and as a result you get steering pulls (and they are real forces: you have to counter them entirely or else the steering will change directions). .

Agreed (of course), and this is all part of what the driver interprets as steering ‘feel’. The other part of the ‘feel’ equation is the forces generated by the ‘trail’, which in principle is similar to SR except that the distance of the SA ground intersection point from the nominal centre of the contact patch is longitudinal not lateral (note that trail too can have nominal and effective values, as does SR).

Further more, you likely have near stock ratio spring rates front:rear meaning the front track is doing the majority of the yawing work. This means that toe changes to the front axle will greatly affect the yaw of the vehicle. The first thing I noticed when changing from a front stiff to a rear stiff setup was that the front end has a much harder time yawing the vehicle on it's own - i.e. torque steer is near gone.

You’ve lost me here, I don’t follow what you’re trying to say (but, I suspect I might disagree if I understood you clearly…).

[Ally Angel]

Awesome, so mine could be simply my tyres then i think... mines front wheel drive but had new tyres put on the front when i got it but not the back cos they were alright and the pulling wasnt that bad and wasnt wheel alignment... but since then its gotten worse and my back tyres are now pretty ****ed.. would that effect it even tho my car is front wheel drive and its the back tyres that are ****ed?

Either way im getting a full new set going up to 17'' so hopefully that sounds like it will fix it?