come on guys, be nice.

that torque-steer you get is from having a straight rear axle and a 3-link + panhard suspension set-up. when you gas it going forward, the axle shaft turns against the tire, against the traction, forcing the pinion up, pulling against the top link, pushing against the lower links and compressing the suspension, effectively lengthening the panhard. torque-steer is feedback from the inability of the drivetrain to blast forward immediately and smoothly, twisting the body in the opposite direction of the driveshaft, effectively compressing one side of the suspension while extending the other side. this effectively lengthens one side (compressed) while shortening the other side. this put the rear axle at an angle to the frame and therefore, as it moves forward, it "steers" the vehicle.

now, in reverse, you have the exact opposite actions and an opposite reaction. the pinion is forced down, pulling on the lower links, pushing on the upper, but guess what? the upper is centered, so, it does not create any steering effects.

reason why ring and pinion directional cut needs to be taken into account when making a claim that driving on a front axle is a good idea because MOST front axles use standard rotation R&P's, which are weaker when driven on the coast side, which is where they are driven in a front set-up. driveshafts turn the same direction, if the front R&P is backwards, the gear teeth get the power placed on their backside.

the fact that you only get one reverse gear was just a point i was making as to the irrelevancy of this whole argument.

Wow, Thats the most I've learned in one sitting.......Hope I dont think too much about it the next time I drop the shifter into 4wd......could cause a headache! <img src="/forums/images/graemlins/shiner.gif" alt="" />

Dave,

After I posted last time I started thinking about this in a lot more detail.

The Sportage has lower links connecting each side of the rear axel to the frame and only one center link connecting the top of the axel to the frame.

The steering movement experienced when rapidly accelerating is torque steer and comes from the directional rotational forces being applied to the rear end from the drive line components. This makes the rear end try and move to the left. With the rear end being lighter than the front due to the motor being placed in the front the rear end is allowed to slide to the left.

In reverse the vehicle tries to do the same thing, but with the added weight in the front from the engine there is more mass to move thus counter balancing the affect and what you experience is less torque steer.

This is why in a front wheel drive car you don't experience torque steer. In a rear or mid engine car torque steer is also almost non existent.

Having 4.11/4.10 axel ratios front to back works to eliminate torque steer, but only if you are going forward. When you go in reverse any advantage is lost and you would actually experience more torque steer.

Logansportage <img src="/forums/images/graemlins/patriot.gif" alt="" />

Dave is right. Torque steering (more correctly rear steering in our case) is due to the momentary change in wheelbase caused by the compression of one side of the rear suspension and the drooping of the other under acceleration/decelleration. The rear links on the compressed side tend to lengthen the wheelbase a bit compared with the drooping suspension, effectively "steering" the the rear axle away from perpendicular to the chassis. This momentarily changes the direction the rear of the vehicle takes wrt the front of the vehicle, and requires the driver to steer towards the drooping side to maintain the correct track.

This affects all londitudinal link based suspension systems (3, 4, and 5 link, and all variations of them) to greater or lesser degree, generally the longer the links, the less the steering issues will be. It also applies equally to suspensions on front beam axle vehicles (independant of normal steering inputs).

DAMNIT RYAN, i thought you did reverse engineering or something like that for a living!

you're still wrong.

the effect you're describing has nothing to do with gearing except that it is more obvious in vehicles with lower gearing, but only due to torque multiplication. go back, read my last post, then read gary's. i thought you were on the right track noticing the suspension, but you went the wrong way.

the reason a front wheel drive vehicle does not experience much in the way of torque steer or even torque lean, is because it has an INDEPENDENT SUSPENSION AND BECAUSE THE ENGINE IS MOUNTED SIDE-F-ING-WAYS!!! torque lean is almost non-existent, but if it were existing, it would create a rotation opposite the traction of the front tires, rotating the engine forward or backward, doing absolutely NOTHING to cause ANY side-to-side movement or lean, never creating a situation where traditional torque-steer can be exhibited.

when speaking of our Sportages, in forward and reverse, the reason you get no torque lean or torque steer in reverse is exactly like i said in my last post, there is no other reason for it, especially one having to do with gearing, except for the fact you would get microscopically less in reverse anyway because reverse gear is a numerically lower gear, meaning it is a higher gear than 1st forward.

now, back to your original statement that (for some reason) running a 4.11 gear up front would be better with a 4.10 gear out back, well, you're actually right about that, a little bit. i didn't catch it at first, don't know why, but i didn't, but that actually makes the front gear lower than the rear, which means the rear would be pushing against the front when it came time for binding, still not good, but i still think it is doubtful it would ever be noticed. if you were going to have different gear ratios, and there was no way around it due to an axle swap of some combo, this really would be the way to go, if only it were low enough for our vehicles, but 4.1 is not. (thanks to those who pointed that out some ways up the page).

"the reason a front wheel drive vehicle does not experience much in the way of torque steer or even torque lean, is because it has an INDEPENDENT SUSPENSION AND BECAUSE THE ENGINE IS MOUNTED SIDE-F-ING-WAYS!!! torque lean is almost non-existent, but if it were existing, it would create a rotation opposite the traction of the front tires, rotating the engine forward or backward, doing absolutely NOTHING to cause ANY side-to-side movement or lean, never creating a situation where traditional torque-steer can be exhibited."


ok stupid ass question. what is it in my front wheel drive cavalier z24, that when i hammer on the throttle it definately pulls very hard. as a matter of fact any front wheel drive with any sort of power i have ever driven. i have heard it refered to this as torque steer as well. is this wrong?

well, not exactly. in an open differential, power is almost always routed to one side over the other, depending on actual length of axleshaft and or whether the ring gear is centered and all that sorta thing, not 100% clear on all that yet, but the reason you may feel some steering going on is that the front tires in a front wheel drive vehicle are the steering tires, when one gets power over the other, it will grip the road and pull forward. the other side isn't pulling yet and so the side with power tries to move forward, being held back by the other side and pulled over toward it, effectively steering the tire with the traction to the road, therefore, steering the vehicle. i get that in my econobox Suzuki Esteem. the driver's side pulls. in this case it isn't likely to cause a lot of steering.

It pulls to one side or the other in a fwd because most have open diffs as Dave pointed out, so the power goes to the tire with least resistance.

With one tire pulling harder than the other that's what will cause the tug on the wheel and w/o the wheel being perfectly straight it will try to drift that direction.

If you're ever on a low traction or say gravel surface and you floor it usually the wheel will dance left and right as it fights for traction, cars with LSD's up front will tend to have little or no torque steer and pull straight away.