Torque steer vs understeer

[Jarflow]

whats the difference

[xivera]

Torque steer occurs off of a launch. Understeer occurs when a taking a turn.

[fritz_269]

Understeer - when cornering at maximum grip, the front tires begin to lose traction before the rear tires. This causes the front of the car to push wide of your intended line. It's called understeer because the car turns less than where the steering wheel is pointed. Most production cars exhibit understeer, as it is much easier and safer to control a skid.

Oversteer - when cornering at maximum grip, the rear tires begin to lose traction before the front tires. This causes the rear of the car to swing wide of your intended line. It's called oversteer because the car turns more than where the steering wheel is pointed. Oversteer is useful on rally courses and such where turning is difficult; but is very dangerous in general as it is easy to lose all control and spin the car.

Neutral steer - when cornering at maximum grip, both the front and rear tires begin to lose traction at about the same time. Neutral steer results in the maximum cornering speed possible since all four tires can use all their traction; it's what race drivers aim for.

Torque steer - in a FWD vehicle with an open differential (i.e. almost all FWD cars) if one drive wheel gets more power than the other, it will try to pull the car around in a circle. In a common case, one wheel loses traction briefly, either from power application or a slippery road surface, and the car is suddenly 'steered' away as the wheel with traction attempts to pull it in a circle.

If you want to know what torque steer is - just launch your Honda from a standstill - that tug to the side in the steering wheel is mild torque steer. Also often occurs when you're just driving normally in the rain or snow.

[xivera]

Pls. tell me that you copied & pasted that from a source... somewhere...

[Someguy]

Nah, this is Fritz you're talking to.

[fritz_269]

Originally posted by xivera

Pls. tell me that you copied & pasted that from a source... somewhere...

Just wrote it up on the fly. If I borrow from somewhere else, I always try to cite my sources.

A couple of other notes:
--Somtimes you hear race drivers or announcers refer to a car as 'loose' or 'tight'. A loose car is one that oversteers - it feels very squirrely around corners, like you are about to lose control. A tight car is one that understeers - it pushes the front outside through corners. Thus you'll often hear - "he's getting a little loose in turn number three, I think they'll tighten it up when he comes into the pits" - meaning: "he is oversteering a bit in turn three; when he pits, the crew will probably adjust the aerodynamics or the suspension to make the car understeer more"

--If you want to understand why understeering is generally safer than oversteering, try this little experiment: Go to your local uber-mart and find a shopping cart that has both rear wheels locked into the straight ahead position, and both front wheels on 360 swivels. Take it out to an empty spot in the uber-parking lot. Now push the cart forward with a moderate running start, let go and watch it's trajectory. Now, turn the cart around, push it backwards with a moderate start, let go and see what happens.

The swivels wheels simulate the wheels with no traction - they don't have a preferred direction of travel. The fixed wheels simulate the wheels with traction - they'll only go straight forward.

Enjoy!

PS> This is also a good demonstration of why it's a good thing that cars steer with their front wheels and not their rear ones.

[texan]

Originally posted by fritz_269
The swivels wheels simulate the wheels with no traction - they don't have a preferred direction of travel.

No preference my ass, haven't you ever gotten the gimp cart before? It's like 75% of the carts manufactured have polio, either that or the homeless really do steal all the good ones

[fritz_269]

Originally posted by texan
No preference my ass, haven't you ever gotten the gimp cart before? It's like 75% of the carts manufactured have polio, either that or the homeless really do steal all the good ones

This is a simulation of a tire with poor traction AND bad alignment.

[Moppie]

Interesting slip into German there Fritz.



As an extra note, Honda's generaly dont have very much Torque steer, infact my little civic has almost none. Even at 7,500rpm on a wet off camber road the car still tracks in a very straight line. Both axles are the same length and both are balanced to be very close to the same weight. (Fritz laws of physics behind why they do this please, I know but Ill be damned if I can explian it, (something to do with rotational intertia))

FWD cars with unequal length driveshafts will however suffer very sever torque steer. The worst iv ever experiance was a DOHC Turbo Mazda Famillia, (89ish Ford Escort to you americans). It had about 160+hp, and the moment it came on boost it required both hands to hold the wheel straight, and even counter steer. Its quite odd driving in a stright line with the car wanting to move left, while the wheel is turned to the right.

[sparq]

Originally posted by Moppie
FWD cars with unequal length driveshafts will however suffer very sever torque steer. The worst iv ever experiance was a DOHC Turbo Mazda Famillia, (89ish Ford Escort to you americans). It had about 160+hp, and the moment it came on boost it required both hands to hold the wheel straight, and even counter steer. Its quite odd driving in a stright line with the car wanting to move left, while the wheel is turned to the right.

Ehehehe, I know the feeling... try driving a pre '96 Taurus SHO w/ 350 WHP ~ three words come to mind...

UPPER... BODY... STRENGTH...

[Davidov Speed WRC]

Don't all FF cars have unequal driveshafts?? Since the transmission has to be mounted to the side of the engine block?

Correct me is I am mistaken...

[Moppie]

Originally posted by Davidov Speed WRC


Correct me is I am mistaken...

Yip, your mistaken.
Your almost right, most FWD cars (at least those with lower hp No.s) have enequal length driveshafts becasue the G/box is over towards one side of the car and the diffrential housing is on the far end.
However many newer designs, and in Honda's case a lot of the older designs have the differntial housing on the G/box located at the engine end, where it is possible to place it in the center of the car, and so have equal length driveshafts.

[rybred]

Thanks for the easy to understand explanation fritz! I never really got a good explanation of that, but i never really looked it up either! anyways, my lude has a quite uneven drive shaft and i was just wondering if they made any sorta racing shafts that would minimize torque steer or if there is any mod i could do to help that a bit?? It doesn't seem to be a problem right now but when the turbo goes i don't want to have that problem! thx

[Someguy]

A good limited slip differential would help.