SpoolnG2

93 Civic hatch. Lowered on ground controls and koni yellows with camber kits in the front and the rear. While i'm driving and push hard on the gas pedal the car pulls to the left (if not corrected)....then when i let off the gas it goes back to a center position. All tires are inflated equal, all suspension components, ball joints and bushings are in good shape acording to myself and the place I had the alignment done at. I just had an alignment done today so I know everything is in proper specs as far as the camber, caster, toe, etc. Its just a stock b-series so I know its not from to much power. The car has brand new motor mounts and solid torque mounts.

Is this simply just torque steer? Anybody else have similar problems? What else could it be if it is anything else? I'm very confused, so any help would be great.

SpoolnG2

bump

johnlear

If the alignment is spot on (front and rear?) then it could be a tyre issue. Do a search for 'tyre conicity' on the web.

Is it possible that you have some damaged suspension component? I mean if you had something like a bent upright (knuckle) that affected camber, and then adjusted the camber to a correct spec with camber adjusters, then there could still be alignment issues related to king pin inclination (aka steering axis inclination) which could also be affecting scrub radius.

Your problem does sound like it could possibly be caused by unequal scrub radius. Does the steering pull to the right when you brake hard?

agrn93ls

Caster causes pull, if the caster is FOR SURE in spec's then one of two things is happening, 1. the bushings are flexing under acceleration causing the caster to change ( which may be why we get torque steer in the first place not really sure ) and causing a pull or 2. it is just plain ol torque steer and no need to worry.

If everything is tight and in good shape just deal with the fact that you have a front wheel drive car that pulls under acceleration, **** you should have drove my GSR on boost then you would have something to complain about

SpoolnG2

No, the car doesnt pull hard to the right under hard braking. So whats a good way to test the front A-arm bushings? I'd like to test them somehow before i go and spend 2 - 300 on new bushings for the front. So if I did change those out, then my only other thing is to deal with it.


Anybody elses car do this?

agrn93ls

unfortunately there really isnt a "good" way to test the bushings, you will have to get it on a rack and pry back and forth in the bushing area and look for excess movement, if you for some reason think it is tire realted as stated above ( which if it was it should be apparent when just driving ) then you can just swap the front tires and retest.

one cure is traction bars, they hold the lower a-arms and dont allow forward and rearward movement that changes the caster angle.

but my opinion, deal with it, they all do it to some degree.

elwuudz2

Might be unevenly worn tires if you spent too much time uncorrected. Staying unbalanced to a rough spec for too long and this will be the result.

Currently the inside of my drivers tire is worn due to excessive neg camber and causes the car to pull right... every thing else on the car is in great shape.. tire pressures camber, castor etc.. damn I have to go get some tyres what a b1tch!

johnlear

Well yes it does, and no it doesn't.

Commonly accepted theory says that the car will pull toward the side with the greatest caster (all else being equal), but 'accepted theory' tends to assume that some significant amount of ‘scrub radius’ also exists (as is more typical with RWD cars). However, many FWD cars have zero or only very slight SR.

A self centring steering force is created by torque forces fed into the steering around the axis of the 'steering axis' on each side of the car (at the front), and when these forces are in balance no pull will exist (all else being equal). When these torque forces are unequal at each side, or when the 'virtual lever arms' through which the torque forces are fed into the steering axis are different on each side then there will be a ‘pull’ felt at the steering wheel and the car will ‘want’ to veer away from the straight ahead direction.

There are two of these 'virtual lever arms'. One being the 'trail' (the degree to which the nominal centre of the contact patch 'trails' behind the steering axis, i.e. the length of the distance between the point at which the steering axis intersects the ground and the centre of the contact patch behind the steering axis). The second is the 'scrub radius' (the degree to which the centre of the contact patch is to the inside or outside of the point at which the steering axis intersects the ground).

Because both contact patches generate rolling resistance (i.e. a force), and this force is ‘fed’ into the steering by way of these lever arms (trail and SR), the lever arms create a torque at each front wheel that is fed to the steering wheel via the steering axis on both sides. If the torque is stronger on one side then the driver will feel a pull and the car will 'want' to steer away from the straight ahead. However, for the torque as felt at the steering wheel to be different on each side then both scrub radius and trail must both exist (disregarding other factors such as the forces being different due to things such as different tyre pressure etc).

If only trail exists (i.e. SR is zero) then the contact patch will 'want' to 'trail' directly behind the point at which the steering axis intersects the ground, with the road wheel pointing directly straight ahead, but if both SR and trail exist simultaneously then the contact patch tyre will 'want' to trail directly behind the steering axis but with the wheel at an angle to the straight ahead, and it will take an outside force (supplied by the driver or by an equal but opposite force from the other contact patch on the other side of the car) to keep the wheel pointing straight ahead. If this is equal on both sides then all forces will be in balance and no pull will exist.

Changing caster changes trail. If only trail exists (i.e. SR is zero) then increasing caster will increase trail and thus increase the strength with which the contact patch 'wants' to trail directly behind the steering axis, but since the contact patch is already trailing directly behind the contact patch this doesn't change the angle at which the contact patch 'wants' to trail behind the steering axis, just how hard it will be to deflect the contact patch away from this position. In this case (with zero SR) increasing or decreasing caster on one side won’t affect the direction in which the contact patch ‘wants’ to point, and thus won’t create a pull or tendency to veer from the straight ahead, though the steering will become heavier in one direction and lighter in the other.

If however SR is also present then both front wheels will ‘want’ to trail behind the steering axis at an angle to direction of travel, and increasing or decreasing caster / trail on one side will affect the strength of this self centring action more so on one side than the other and a pull will be felt and the car will want to veer.

Note that if trail is equal side to side, but SR is unequal, then this will also create a pull, and the pull will be toward the side with the greater positive SR (i.e. positive SR being when the steering axis intersects the ground to the inside of the contact patch centre). A bent upright (knuckle) will often affect KPI (king pin inclination, being the inward lean of the steering axis as opposed to the rearward lean, which is caster), and this will affect SR. In such a case you can fix the camber problem caused by the bent upright (with camber adjuster), but since the KPI and SR is affected you can still have a pull.

I hope my explanation of this isn’t too hard to understand, it’s not all that easy to explain clearly. My car (CB7 Accord) has zero or very little SR, and when trying to track down a mystery steering pull I made substantial asymmetric changes to caster angle in an attempt to isolate the cause of the pull. I found that even quite substantial differences in side to side caster angle made little if any difference to the pulling problem. Even with 2° side to side caster difference the pull remained largely the same, and did so even when I ‘swapped’ the caster difference side to side. The only significant noticeable affect was on steering weight in left vs right hand corners.

agrn93ls

well he did have the car checked already and aligned, if the scrub radius was off then his camber "should" have been off too, or he is running way different offsets on the front wheels which i think is safe to assume he is not, if he is then he deserves to have issues.


Tires are the most common denominator we see here cause a pull, but that is during all driving not just acceleration.

what ended up fixing your elusive pull on your accord?

johnlear

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by agrn93ls &raquo;</TD></TR><TR><TD CLASS="quote">
well he did have the car checked already and aligned, if the scrub radius was off then his camber "should" have been off too, or he is running way different offsets on the front wheels which i think is safe to assume he is not, if he is then he deserves to have issues.</TD></TR></TABLE>

I meant that if it was assumed that an incorrect camber on one side had been 'rectified' using a camber adjuster (or whatever means, I've done a similar thing by 'slotting' the inner mounting holes one of the the upper wishbones). I don't know whether this is the case or not, just exploring possibilities. The OP stated that camber and caster measured OK, but didn't mention KPI or SR (not that an alignment sheet is going to list a SR value).

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by agrn93ls &raquo;</TD></TR><TR><TD CLASS="quote">Tires are the most common denominator we see here cause a pull, but that is during all driving not just acceleration.</TD></TR></TABLE>

That's what I would assume most likely too, but odd things happen...

It's that the pull seems stronger when accelerating than not that made me think of unequal SR as a possible cause. I would expect this to cause an opposite pull under braking though.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by agrn93ls &raquo;</TD></TR><TR><TD CLASS="quote">what ended up fixing your elusive pull on your accord? </TD></TR></TABLE>

I assume it was unequal tyre conicity.

After checking every angle on the suspension, every bush, free spring lengths, and even checking all the upper spring seat mount height (all seats in the same plane to a 1mm tolerance, as best I could measure with fluid filled plastic tube), the left pull persisted. I tried all sorts of things to get rid of it, or even to make it pull to the right (which I thought might narrow things down), it still pulled to the left. Even with camber adjusted equally and unequally, even with caster adjusted equally and unequally, even with rear toe set equally or deliberately introducing thrust angle (both ways), the pull still remained.

It had been the same with the old tyres and the new tyres so I didn't think it likely to be the tyres, but one day on an impulse I swapped front wheels side to side, and the pull disappeared (!). Now I knew it must be associated with the tyres, but if so I couldn't figure out why swapping the front tyres side to side didn't then result in a pull to the right (?).

A couple of weeks ago I found a split front ARB link rubber (one of the little donut type bushes) that I'd missed in my earlier inspections, and so replaced all the old rubber ARB bushes with poly bushes. At this point the car picked up a right pull (very slight but very real).

Now it made more sense, the earlier more substantial pull to the left must have been caused by both the tyres (i.e. unequal tyre conicity, since the tread wear appeared identical and the left pull had existed with the old tyres and when the new tyres were new I couldn't think of anything else), as well as by a pre-load in the front ARB caused by the split bush. Swapping the tyres side to side must have caused a right pull that was being effectively countered by the pre-loaded ARB as a result of the split bush. Now that the bush is fixed the ARB must have zero (or at least less) pre-load, so it's now pulling slightly to the right, but less strongly than it used to pull left.

SpoolnG2

So your saying your problem was your A-arm bushing?

SpoolnG2

So I took the wheels off while its jacked up and tried moving the shock from side to side to see how the bushing was, and i could move it with my hands back and forth just a little bit which seemed to be equal on both sides. I didnt see any cracking or any abnormalities. What do you guys think? What else could this be? What other bushings or suspension components could be wrong?


Modified by SpoolnG2 at 1:56 AM 3/14/2008

johnlear

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SpoolnG2 &raquo;</TD></TR><TR><TD CLASS="quote">So I took the wheels off while its jacked up and tried moving the shock from side to side to see how the bushing was, and i could move it with my hands back and forth just a little bit which seemed to be equal on both sides. I didnt see any cracking or any abnormalities. What do you guys think? What else could this be? What other bushings or suspension components could be wrong?
</TD></TR></TABLE>
Do you mean that you can twist the damper body ("back and forth")? If so then I think this is normal, you're just applying a torque to the lower bush which being rubber elastically deforms a little then springs back into place.

The only way to test bushes without taking them out and visually inspecting them is to pry against them with a lever in the direction of loading (as near as you can) looking for excessive movement in the bush. This isn't really possible with the front radius rod bushes (if you car has that type of lower 'wishbone'), you need to take this out to have a look.

SpoolnG2

So what i'm going to do is just replace both bushings in the lower control arms on both sides. I'm just going to OEM bushings since i can have them pressed in for free. After I do this....lets say the problem is still there... what other problems could there be? What else could be the problem?

SpoolnG2

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