What's with the toe-out??

[Coelacanth]

Over and over again, on this forum and others, on eBay and other auction ads, I keep seeing cars with an obvious degree of toe-out. From my earliest memory building these hobby-grade RC cars, I'll always remember the important note to adjust the front wheels so they toe-IN, not OUT--the purpose for this being to cause the car to track in a more straight line.

So, I'm wondering why I'm seeing so many guys' cars adjusted with significant toe-out? Is there some performance secret I'm missing, or are that many people unable to adjust tie-rods so that the front wheels are slightly toed-in, or at the very least straight?

It seems that the majority of RC buggy models look like pigeons walking backwards.

Sorry, I just had to mention it. I see it all the time and I had to wonder if there was a reason for it...

[THEYTOOKMYTHUMB]

I don't know all the physics or geometry behind it, but toe-out gives you more aggressive steering while toe-in gives you more stable straights. And I agree toe-out is annoying to look at, but I guess under some circumstances it's a necessary evil. I'm sure someone will have a much better and more informative answer though.

[scr8p]

i'm sure some of it has to do with camera angle.

some of it could just be the geometry setup. something as simple as bump steer (that wasn't addressed) could do it.

[Coelacanth]

i'm sure some of it has to do with camera angle.

some of it could just be the geometry setup. something as simple as bump steer (that wasn't addressed) could do it.

I don't know about the camera angle...in the same picture, you see the rear wheels as parallel or slightly toed-in, but the fronts are splayed out...I tried taking that into consideration, but this is something I've been noticing for several weeks now, not just here and there.

[Charlie don't surf]

In racing toe out can give you a more aggressive turn in on power, and better corner exit control- also like Scr8p said, depending on the vehicle you may have vast amounts of static toe, but at ride height it may be at 0deg or how your bump steer is or is set-up.

[Coelacanth]

Here's the thing, though...looking at turning setup from a physics point-of-view, the most neutral steering would result from a perfectly parallel front wheel setup. With toe-in, you get a slight benefit to straight-line tracking, with a slight impediment when full-steering. With toe-out, you get a slight benefit in more aggressive turning, but also get an impediment when straight-driving (being overly touchy, I'd presume) and even with the more aggressive steering, although the inward wheel is turning more aggressively, the toed-out outbound wheel would actually be 'dragging' through the turn, as it's pointing outward from the turn, not into the turn.

[scr8p]

i've never been good at explaining technical suspension stuff. but i'll try it again here.

just because the wheels are toed out down the straight, doesn't mean that during suspension compression, while turning into the corner, the toe doesn't return to neutral.

[Mikeyboy]

Yes!

[justinspeed79]

I don't really know how to explain it in technical terms, but I can say from my experience that it seems like everything drives better with toe-out. To me it feels like cars/trucks with toe out are more stable. I don't think it is necessarily because of bump-steer either, my racing GT's have virtually zero bump-steer.

[Charlie don't surf]

i've never been good at explaining technical suspension stuff. but i'll try it again here.

just because the wheels are toed out down the straight, doesn't mean that during suspension compression, while turning into the corner, the toe doesn't return to neutral.

I guess I will have to be less "technical" with words like "static" and the like

As far as the dragging wheel you are partially ( 1/2 ) correct, but the inside wheel is the one dragging which causes the rear end to rotate ( more steering ) giving you more initial steering ( better steering ). Now ( now ) this is really only during high speed sections, low speed turns and 180 deg turns are effected negatively with toe out.

[RichieRich]

i'm sure some of it has to do with camera angle.

I think it's camera angle too. Since the camera is a single lens, it distorts, especially at close angles.

[Jay Dub]

"Here's the thing, though...looking at turning setup from a physics point-of-view, the most neutral steering would result from a perfectly parallel front wheel setup." -wrong. This might seen like the case, but you are either forgetting, or don't know about ackerman, slip angles, and tire deflection, and types of steering (rack type vs. bellcrank) as it relates to the specific surfaces we race/run on.

As your car "turns" through a corner, it rotates around an imaginary "pivot" or center of its turning radius. The inside tire on your car turns a tighter radius than the outside tire. This is necessary, for the tires NEED to turn at different radiuses (to avoid scrubbing) and will effectivelly have toe out when turned. The wider the car, the more difference in radius (ackerman) they need. Now this is in a perfect scenario (no tire slip, no tire deformation, etc.). On surfaces that are loose, or with tires that have allot of squirm or deflection, this is less important because the tires are not binding against each other in the turns to the same extent. On the other hand, on high bite surfaces your steering adjustments need alot more attention for the car to carry proper corner speed and not scrub in the turn. This is a very tough adjustment to get right, as every adjustment one makes to the front end ultimately effects your ackerman. ( static toe, camber gain, bump steer, spring rate, etc. etc. etc.)

So when it comes right down to it, whether the car has a "neutral" feel or not, or reacts "neutrally" is related to how the steering is tuned for a particular track surface.

You will see alot of front toe out on many offroad buggies, in particular 1/8th scale 4wd buggies. These cars seem to lack the proper adjustment to make them aggressive on and off the throttle. So what tends to happen is you will have a car with thick front diff fluid (for on power steering), and then a few degrees of toe out in the front to make the car aggressive going into and through the turns (more static toe will give you more ackerman). Another factor is that all 1/8th scale buggies use rack type steering systems, and they generaly have very poor ackerman curves -providing ackerman only (and very progressively) near their steering extents. A few degrees toe out will make these cars feel more neutral through a corner as it will flatten out their ackerman "curve". This said, rack type steering system will generally feel more agressive off center, and is best suited for loose or low bite situations. A bellcrank type system (think rc10) is best suited for higher bite situations. where your corner speed is greately effected by poor ackerman and tire scrub. -Jeff

[Jirka]

"Here's the thing, though...looking at turning setup from a physics point-of-view, the most neutral steering would result from a perfectly parallel front wheel setup." -wrong. This might seen like the case, but you are either forgetting, or don't know about ackerman, slip angles, and tire deflection, and types of steering (rack type vs. bellcrank) as it relates to the specific surfaces we race/run on.

As your car "turns" through a corner, it rotates around an imaginary "pivot" or center of its turning radius. The inside tire on your car turns a tighter radius than the outside tire. This is necessary, for the tires NEED to turn at different radiuses (to avoid scrubbing) and will effectivelly have toe out when turned. The wider the car, the more difference in radius (ackerman) they need. Now this is in a perfect scenario (no tire slip, no tire deformation, etc.). On surfaces that are loose, or with tires that have allot of squirm or deflection, this is less important because the tires are not binding against each other in the turns to the same extent. On the other hand, on high bite surfaces your steering adjustments need alot more attention for the car to carry proper corner speed and not scrub in the turn. This is a very tough adjustment to get right, as every adjustment one makes to the front end ultimately effects your ackerman. ( static toe, camber gain, bump steer, spring rate, etc. etc. etc.)

So when it comes right down to it, whether the car has a "neutral" feel or not, or reacts "neutrally" is related to how the steering is tuned for a particular track surface.

You will see alot of front toe out on many offroad buggies, in particular 1/8th scale 4wd buggies. These cars seem to lack the proper adjustment to make them aggressive on and off the throttle. So what tends to happen is you will have a car with thick front diff fluid (for on power steering), and then a few degrees of toe out in the front to make the car aggressive going into and through the turns (more static toe will give you more ackerman). Another factor is that all 1/8th scale buggies use rack type steering systems, and they generaly have very poor ackerman curves -providing ackerman only (and very progressively) near their steering extents. A few degrees toe out will make these cars feel more neutral through a corner as it will flatten out their ackerman "curve". This said, rack type steering system will generally feel more agressive off center, and is best suited for loose or low bite situations. A bellcrank type system (think rc10) is best suited for higher bite situations. where your corner speed is greately effected by poor ackerman and tire scrub. -Jeff

Again Jay Dub explained setup things well.

What I have found out, toe-out will make the car steer more on (very)low speed and less on (very)high speed, toe-in makes the opposite. In Off-road when driving straight on bumby surface, the car wants to change it's direction during and after every roughness on the track. If you have toe-in in front, the car will steer itself automatically to centerline of the chassis and correct it's unwanted movement, so the car is more forgiving. Toe-out will do again the opposite thing and it try to increase the unwanted movement and is very twitchy and unforgiven.

Jirka

[Eau Rouge]

4wd = toe-out
2wd = toe-in

Toe out on a 2wd car makes it violent to drive in almost all situations. Pre-touring cars, the only car I ever drove that needed toe-out was the 4wd Dominator. That's it. And we're only talking a degree or two—nothing noticeable on camera. The cars you are probably seeing are adjusted by people who don't know that those settings are important to handling and performance.

[Coelacanth]

i'm sure some of it has to do with camera angle.

I think it's camera angle too. Since the camera is a single lens, it distorts, especially at close angles.

If that's the case, how come pictures I take of my own car from various angles show toe-in and not toe-out? And how come pictures taken from the front of some guys' cars show the rears toed-in and the fronts toed-out? Camera angle still?

Jay Dub & Jirka--thanks for your explanations; I would agree with both of you.