Why doesn’t the Civic Type R have torque steer? (Engineering Explained)

[360glitch]

A great video from my favorite YouTube series:

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[Vortexhunter]

I've asked him in the comments about the effects of changing to +45 offset on the wheels, let's see if he replies, it seems he will have that car for a while, so hopefully he'll give some insight!

 

[Bumflik]

A great video from my favorite YouTube series:

Fenske is awesome

 

[yargk]

I've asked him in the comments about the effects of changing to +45 offset on the wheels, let's see if he replies, it seems he will have that car for a while, so hopefully he'll give some insight!

When changing from +60 to +45, you are changing from zero scrub radius to 15 mm scrub radius (more than half an inch). Torque steer is directly related to scrub radius.

 

[CTR1633FK2]

Electric Power Steering blocks most of the forces, so this increase in torque steer is not noticeable.

 

[baldheadracing]

Electric Power Steering blocks most of the forces, so this increase in torque steer is not noticeable.

Really?

The difference going from ET60 to ET45 was pretty freakin' noticeable to me in low traction conditions, but I did also change wheel diameter, rim width, and tire.

What ET45 wheels are you running on your FK8, and what tires are you running on those wheels?

 

[CTR1633FK2]

I am comparing my ITR with my FK2. Much more feedback in the steering wheel of the ITR. FK2 steering feels numb and 'electric'.

 

[yargk]

I am comparing my ITR with my FK2. Much more feedback in the steering wheel of the ITR. FK2 steering feels numb and 'electric'.

I think numb steering and torque steer are different things.

 

[CTR1633FK2]

I think numb steering and torque steer are different things.

Not IMO. The feedback you get from the wheels to the steering wheel is the same. In case of torque steer it is caused by the drive axle. Normal feedback is caused by the amount of grip of the wheels/tires.
So, if an electrical PS blocks most of the forces coming from the wheels, it will also block most of the forces caused by torque steer.
If you look at the design of a regular EPS, you will understand why it blocks most of the forces getting to the steering wheel.
In the ITR I could feel every change in offset and tire diameter. Both have effect on the scrub radius. In the FK2 the difference in steering feel is much smaller.

 

[CTR1633FK2]

An EPS also has an electronic torque sensor on the steering column. When a force is induced by the wheels in the direction of the steering wheel, the electric motor will counteract to this force. This torque sensor will also sense the force in the other direction. From steering wheel to the rack.
Ideally, you would want some diode effect on this electric force. Only induce force when the driver is steering, but do not counteract on forces coming from the tires/wheels.

 

[jonnys_honda]

I feel zero difference with torque steer on my 18x9.5 +35 wheels installed on my FK8. And I have one track day down.

Maybe my sticky tires help? Bridgestone RE-71R's

 

[jonnys_honda]

To all who believe zero scrub radius trumps all... Please watch their video on the subject

"A positive scrub radius tends to be beneficial while braking into a turn. A negative scrub radius tends to better for braking stability in the event of brake failure or split-mu braking. Typically the scrub radius is configured to be as small as possible to minimize the effects under braking, but squirm (from zero scrub radius) is also undesirable."

Goal is to get close to zero. but not necessarily zero.

 

[baldheadracing]

I feel zero difference with torque steer on my 18x9.5 +35 wheels installed on my FK8. And I have one track day down.

Maybe my sticky tires help? Bridgestone RE-71R's

As would the lack of rain.

 

[yargk]

An EPS also has an electronic torque sensor on the steering column. When a force is induced by the wheels in the direction of the steering wheel, the electric motor will counteract to this force. This torque sensor will also sense the force in the other direction. From steering wheel to the rack.
Ideally, you would want some diode effect on this electric force. Only induce force when the driver is steering, but do not counteract on forces coming from the tires/wheels.

There's a difference between an EPS system filtering some intermittent forces (bumps) and counteracting something continuous like torque steer. Let's think about another continuous force, which is the "centering force" that brings the car back to straight driving. Turn into a turn at constant speed (constant speed is so that you don't induce torque steer because that's not what we are focusing on now), then let go of the steering wheel, you'll notice that you'll slowly stop turning and the steering wheel will slowly unwind by itself. This is due to the caster angle of the front wheels. It induces a continuous force that brings you back to straight ahead driving. If an EPS system counteracted continuous forces then you'd just keep turning right (or left) unless you physically pulled the steering wheel straight.

 

[yargk]

To all who believe zero scrub radius trumps all... Please watch their video on the subject

"A positive scrub radius tends to be beneficial while braking into a turn. A negative scrub radius tends to better for braking stability in the event of brake failure or split-mu braking. Typically the scrub radius is configured to be as small as possible to minimize the effects under braking, but squirm (from zero scrub radius) is also undesirable."

Goal is to get close to zero. but not necessarily zero.

I don't think he actually says word for word what you quote. Quotations are different from paraphrasing so if you are doing the latter, don't use quotation marks.
(edit: This was quoted from the description of the video, oops, but I think this description simplifies the matter a bit too much. I think the quote pulled below from the video is more useful)

A direct quote from the video is: "The goal is to get it basically at zero or close to zero, a small amount can be helpful in emergency situations like this" And by small about he means negative scrub, not positive scrub (negative scrub on a CTR would be ET greater than 60!)

I'd agree that in most cars zero-scrub isn't the most important thing and a few mm positive or negative could be fine. I have non-zero scrub on my WRX and my GT4. However, for a very powerful FWD car, zero-scrub becomes much more important because torque steer is stronger for more powerful FWD cars. Personally, I'm not interested in wheels that have an ET less than 55 mm for the type R. (which would keep the scrub radius less than 5 mm)

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