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Old 18th August 2009, 18:34   #31
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Here's a link from Wikipedia on Torque Steer:

Quote:
Root causes for torque steer are:

1. Incorrect sidewall ply design allowing deformation of the tire sidewall.
2. Nonsymmetric driveshaft angles, e.g. due to
  • Nonsymmetric design of the vehicle, e.g. different driveshaft length
  • Transient movement of the engine
  • Tolerances in engine mounts
3. Different driveshaft torques left to right
4. Suspension geometry tolerances
5. Unequal traction forces due to road surface (-Split) in combination with kingpin offset
6. Open differentials may not equally distribute the torque between the two driveshafts, due to friction in the side gears etc. The same will be seen if a limited slip differential is used. Either way there is a tendency for the slower wheel to receive more torque.
Quote:
Note that rear-wheel-drive vehicles do not suffer from the torque steer effects on the rear wheels, since the engine is not connected to the steering gear unless it has all wheel steering.
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Old 18th August 2009, 20:10   #32
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Just a question but do RWD cars with engine at the back (like certain Porsche 911s) have this problem too? Or is it exclusively FWD front engine cars only that suffer?
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Old 18th August 2009, 20:48   #33
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Sorry Pulsar, didn't read your last quote.
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Old 18th August 2009, 23:20   #34
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Other thing i have observed is Elantra with similar acceleration as Verna does not have prominent torque steer,Is it due to some mechanical difference or is it Traction control working?
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Old 18th August 2009, 23:32   #35
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Traction control cannot eliminate torque steer.
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Old 19th August 2009, 02:15   #36
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Quote:
Just a question but do RWD cars with engine at the back (like certain Porsche 911s) have this problem too? Or is it exclusively FWD front engine cars only that suffer?
Its not about where the engine is placed. Torque steer can only happen on cars where the torque is being delivered to the wheels that help steer the car.

A regular RWD does not power the wheels that steer the car.

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Old 19th August 2009, 02:28   #37
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Quote:
Traction control cannot eliminate torque steer.
Depends on the cause of torque steer. If its due to uneven wheel speed under hard acc, then TCS can def help control it.

Like in this case -


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Last edited by Shan2nu : 19th August 2009 at 02:31.
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Old 19th August 2009, 09:09   #38
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This may become a big problem in electric Cars as motors develop maximum torque at stall, i.e. 0 rpm. Let us seeand wait for the Tesla and its siblings. If there are separate motors for each wheel then the problem may go by another name, but will still be there.
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Old 24th August 2009, 20:11   #39
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@Shan2nu : Where in the video does TCS help keep that old hunk of junk on the straight and narrow?
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Old 27th August 2009, 12:15   #40
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The point we are trying to talk about here is torque steer, which by definition is the change in direction of the "steering" due to the torque characteristics of the engine. Essentially, the steering wheel is connected exclusively to the front wheels of most cars, which is why the torque steer effect is observed only in FWD cars. Try it out on a Swift D if possible, take it on an empty road (with a slightly loose surface for more dramatic results), shift into 2nd gears and floor the accelerator while leaving the car to steer itself - just when the turbo kicks in, you will note the vicious pull to the left on the steering - good entertainment

However please be advised that this is not the safest way to learn about torque steer, you are advised to use caution if attempting this.

The rear wheel drive case is a little different. Imagine two "fixed" rear wheels - we all know about how a differential works, allowing one wheel to turn more than the other - now imagine a scenario where the final drive shafts for the rear wheels are not identical (quite a normal scenario, no two drive shafts are "exactly the same") and add a huge amount of power coming in from the engine (typical Detroit muscle cars) and voila!! You have two rear wheels which are not turning in exact sync with each other.. final result, the rear wheels will cause the car to change direction. The change in direction will be minuscule, however it will be enough to unsettle a car especially when the driver over/under compensates for the same. In my opinion, no torque "steer" is possible in RWD cars for the simple reason that the rear wheels are mostly not connected to the steering. However, the rear wheel drive will definitely influence the driving dynamics of a car, including pulling (atually pushing) the car in a certain direction.
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Old 27th August 2009, 13:40   #41
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Quote:
@Shan2nu : Where in the video does TCS help keep that old hunk of junk on the straight and narrow?
It doesn't coz this car doesn't have TCS. But if it did, the car wouldn't be spinning its wheels, not causing it to veer to the right.

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Last edited by Shan2nu : 27th August 2009 at 13:46.
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Old 31st August 2009, 16:59   #42
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Torque steer is primarily caused by the length difference between the left and right half shafts. Wheelspin exacerbates the problem, but it is not the cause. And because of this, TCS cannot fix torque steer. Even the Focus RS with ESP and TCS on top of the trick differential and special suspension torque steers. It is not an easy problem to overcome.
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Old 1st September 2009, 16:45   #43
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Quote:
Torque steer is primarily caused by the length difference between the left and right half shafts. Wheelspin exacerbates the problem, but it is not the cause. And because of this, TCS cannot fix torque steer. Even the Focus RS with ESP and TCS on top of the trick differential and special suspension torque steers. It is not an easy problem to overcome.
Exactly, its the lenght diff that causes unequal torque to be transferred to both wheels. This causes one wheel to spin faster than the other and make the car veer to one side.

On such cars, TCS can make a diff since it controls unwanted wheel rotation.

Not all FWD cars will veer under hard acc. Some will do so only if there is loss of traction.

When my OHC had the s322 tyres, i used to get a lot of torque steer but when i upgraded to the G3s, it has stopped happening. The reason is not the tyre but the amount of traction provided by them that prevents the wheels from spinning.

But sometimes, on a dusty surface, i still get it, bcoz the dust prevents the wheels from gripping to the road causing unequal wheel speed.

The kind of torque steer you are talking about prob has something to do with the flexing of the longer shaft when there is excess torque acting on it. Which causes the car to change direction even when there is no loss of traction.

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Last edited by Shan2nu : 1st September 2009 at 16:47.
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Old 1st September 2009, 16:52   #44
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I have sometimes experienced feeble torque steer in my Santro Xing AT. But generally it is pretty neutral.
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Old 1st September 2009, 16:53   #45
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Traction steer, or more broadly, torque steer, is a phenomenon that describes a steering moment generated about a vehicle's kingpin axes that is of sufficient size to overcome the typical forces that return a steering wheel toward the straight-ahead position. Such a steering moment may be caused by a tire having more traction during acceleration than the opposing tire. The resulting net force in the steering rack generates a decrease in steering wheel centering torque, and possibly results in a positive steering wheel torque in a direction that is not desired by the driver.


Source - TRACTION STEER DETECTION AND COMPENSATION - Patent

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