vue torquesteer under hard accerleration

[eddierod04]

my 02 vue pulls hard under acceleration. why!!! and is there a fix?

[Ritz]

my 02 vue pulls hard under acceleration. why!!! and is there a fix?

Welcome to VUE ownership. They're all like that...even the ones with "AWD". On anything besides a clean, bone-dry road, if I nail the gas from a stop, I can spin the front wheels and walk the front end over towards the curb until after a very pregnant second or so the "AWD" kicks in and it lurches back towards whatever direction the front wheels are pointed.

Getting better tires will help, but more traction just masks the problem. When I punted the Duelers for my winter rims/tires, the problem largely went away.

Cheers,

[burlyvue2]

The Vue has a strong engine/tranny. The combo with FWD off the line can cause the torquesteer you have experienced. Ritz wrote the AWD kicks in after a noted delay. The solution you ask for is simple. Try not to pound the pedal in a turning acceleration from stopped. Get'er pointed in a straight line then nail the gas. It'll save you gas and tire life. Also .... it's a hoot to feel the power of the Vue !!

:flag:

[NOLA-Vue]

From what I've heard and read, the "why" of your question about torquesteer is supposed to be caused by unequal lengths of a vehicle's drive shafts on FWD. On a few occasions my 2.2L vehicles exhibit torquesteer. No doubt a V-6 with much higher torque would be worse. Saturns are not the only cars/trucks that do that since just about any car with unequal length drive shafts are subject to it.

[1saxman]

You get used to it and eventually will compensate with steering input without even thinking about it. It surprised me at first too, and I had powerful FWD cars before.

[louis1971]

They all do it...esp the V6's

The fix? Don't stomp on the gas, (just what you want to hear, right?) Or, get used to over-steering to the left to compensate for the pull. It is a pain, but you do get somewhat used to it after a while.

my 02 vue pulls hard under acceleration. why!!! and is there a fix?

[D C]

From what I've heard and read, the "why" of your question about torquesteer is supposed to be caused by unequal lengths of a vehicle's drive shafts on FWD.

Unequal length driveshafts CAN cause torque steer, but the VUE does not have unequal length shafts (nor do most FWD vehicles these days).

This is possibly the best explanation I've found online of "Torque Steer"
http://www.saabnet.com/tsn/bb/NG900/index.html?bID=124169

Without arguing too much about terminology, let us call any change in steering wheel position as a result of an accelerating wheel torque "Torque steer".

A wheel is steered about the "kingpin axis" The kingpin axis is defined on a strut by the line that intersects both the lower ball joint, and the upper strut mount. The "spindle length" is defined as the horizontal distance from the center of the tire to the kingpin axis. (On most struts the spindle length is about 60 mm, SLA type suspensions can be much lower ~20mm) There is one more definition and that is the scrub radius. the scrub radius is defined as the horizontal distance from the kingpin axisa to the center of the tire at ground level.

Let us assume that the bushings are infinitely stiff (revoulte joints). This will aid in understanding and we will go to the case of compliant bushings next. Also lets assume that the fore/aft tire force distribution can be replaced by a single force acting at the center of the tire. (For smooth roads this is a decent assumption) Since there is a horizontal span between the place where the tire force is acting, and the axis that the wheel is steered about there will be a steering moment induced on the wheel equla to the force at the tire times the spindle length.

If the forces acting on the left and right tires are equal than there will be a balance and there will be no net steering torque and the user will not feel any torque steer. If the force on one wheel is greater than that on the other, their will be a net steering moment. The wheels will steer and the driver will feel the steering wheel tug in the direction that the wheels are steering.

So how do we eliminate torque steer? The best thing to do is ensure that the force acting on each tire is as close to equal as possible, and to minimize the spindle length (the lever arm that generates the steering torque).

Unfortunately there are practical packaging limits as to what the spindle length of a strut type suspension can be. The top mount is usually already moved as far out as the package will allow. The lower ball joint is also about as far into the wheel as the package will allow.

There is the posability of using a multilink lower control arm. This type of arm forms a "virtual" ball joint at the intersction of the two links. This could allow a very short spindle length by moving the virtual ball joint way out. The dproble is that as the ball joint is moved out the kingpin inclination as well as the scrub are increased beyond their acceptable values. In order to get everything, the upper mount must move outboard. with a SLA type suspension, the upper ball join can be above the wheel and far enough outboard to maintain an acceptable spindle length, scrub, and kingpin inclination.

Back to the force times distance concept. Uneven forces come from things such as road irregularities and unequal torque input. As someone previously mentioned use of unequal length halfshafts can lead to a torque imbalace due to the fact that the front view angles of the shafts are not the same. Use of equal length shafts reduces this possability, but it is still very possible when the body rolls relative to the ground. So the use of equal length halfshafts and short spindle lengths help to minimize the torque steer.

Steer induced by toe changes with vertical wheel movement is known as "bump steer". Modern cars have very linear toe curves with very little change in toe -vs- wheel position. Bump steer is usually a mimal affect.

As we take into account bushings we will find yet another source of torque steer. If the movement of the suspension relative to the rack due to bushing compliance is great, it could cause unwanted steer affects as well.

All that said I have driven a 9-3 SE 5spd and it most definately suffers from torque steer. My guess is the cause is a combination of the long spindle length, and the chassis/bushing compliance.

-Joe

[Venomized]

All FWD vehicles will torque steer.

My old Mustang would walk the back end to the right from the torque while roasting the tires.

Just a fact of physics. The only cure is not to have fun.:x

[Ritz]

There is a good explanation of causes and possible design cures for torque steer here:

http://en.wikipedia.org/wiki/Torque_steer

I'm not sure which of these issues is plaguing the VUE, but with the 3.5L the VUE's torque steer is one of the worst I've experienced under WOT in a long while. If you're not aware of it being there, you could get yourself into hot water pretty quickly if you're not careful.

Cheers,

[D C]

I'll advise against using that wikipedia link as a reference for torque steer. :dizzy: Not only is it incomplete, some of it is flat out incorrect.

The primary reason that unequal length halfshafts result in torque steer isn't because of the halfshaft torsional stiffness (flexing) which can be the source of some initial torque steer as the torque is delivered at different rates. But that's just a startup transient problem. Once the torque has been applied, the windup doesn't matter any longer.

The primary reason is that the unequal halfshafts are also at different angles. The short one is generally at a steeper angle (when viewed from the front or rear) from the trans down to the hub. What that means is that the steeper shaft results in a greater vertical moment about the kingpin axis than the longer shaft. So there's a net moment in the steering system toward one side. That's why cars with unequal length halfshafts generally torque steer to one direction (right). The fix is generally to raise one side of the engine to make the halfshafts closer to equal in angle. But there's a difference in angle between normal driving and hard acceleration. So it's a balance between fixing torque steer under hard acceleration and having some torque steer in the other direction under light acceleration.

The part about the scrub radius being a factor is completely incorrect. Drive torque isn't reacted at all in relation to the scrub radius. It's reacted about the kingpin by the spindle length.

There are two main things that generate torque steer. One is the geometric effect from halfshafts. The other is how you're reacting torque. basically that amounts to which side of the canoe you're paddling harder on. If the right tire is able to react more torque to the ground and generate more tractive forces, the car will want to steer left.