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View Full Version : Stability?....toe in or toe out?


yasuji
2009.12.09, 01:00 AM
OK....i have had this discution with quite a few people.... and what i feel is opposite to some others.....heres the senerio...:rolleyes:
i run a "0" toe bar on mt mr02 with pnracing front end....and for any front end i have had thru the years....as you all know the pn front end will toe out ( \ _ / )
with a zero bar i like that as i feel it gives me better stability and control going down the stratght away an less twithchy initial turning!if i use a +0.5 ( | _ | ) or a+1.0 ( / _ \ ) bar i cant get down the stratghtaway with out "ping ponging" down the straight and it gives me overly twitchy steering and on throttle push.....now many have said that toe in = stability....but in my case this is not!
may be it is my radio setting...and or my drive style?????
I NEED TO KNOW

hrdrvr
2009.12.09, 08:21 AM
^ I think it may have to do with driving style, but it also heavily depends on the rest of the set up IMO. Ive been through this debate before, as I think it could go either way.

In theory (and popular belief) the front wheels of a toed in car will pull in towards each other helping the car to track straight while on power. The toed out car would have the wheels pulling against each other, making it twitchy, but giving better response on initial turn in.

On the other side of it, I believe the outside wheel gets loaded a lot more on these cars on high speed cornering. If you got toe out, this would make mid corner less aggressive, as the outside wheel wouldnt be turned in as mush as the inside. Toe in on the other hand would have the outside wheels placed in a more aggressive manner at mid corner, giving it more steering through and out of the corner.

FWIW, I like running 0 toe everywhere. My A-Arm car is the only one with toe out, and with all the bump steer, Ive still go toe in on cornering, lol.

briankstan
2009.12.09, 08:28 AM
I've under stood that toe out is for stability, and toe in would be a more twitchy setup, especially when running a larger track, but good on a tight short track.

Sinister_Y
2009.12.09, 09:12 AM
If you look at any race setup books: toe-in equals stability, toe-out better turn-in.

Toe-in should also give you more on power steering and toe-out more off-power steering.

yasuji
2009.12.09, 09:45 AM
funny thing is....i can remember way back to when i first started driving rc cars.....(mini-z 3 years ago) i had this same discussion with my buddy james....
and i would prefer the -1 toe bar (aluminum)over the zero(aluminum)....for the stability!

Sinister_Y
2009.12.09, 10:30 AM
I agree, I'm all about the toe-out. I love agressive turn-in and off-power steering. Guess that is from my 1/10 days as well. It's also how I learnt to drive (1/10 was my first scale).

It's all about driving style and setting up your car to do what it needs to. Your setup rocks for you and you're the star winning the race, but when someone else drives the same winning car, it sucks for them and their laptimes suffer. It's just the way it is.

On a related note, I find it funny in that everyone (including me) always wants the top driver's setups, i.e. Christian, etc... to try out. Fact is the best person to setup your car is you. You can learn from someone else' setup either in that you take what you need or know what you don't like or doesn't work for you.

ianc
2009.12.09, 10:33 AM
Where the confusion arises is with the use of the words 'negative' and 'positive' toe rather than toe-in and toe-out.

When using toe-in and toe-out, it is easy to visualize the wheels' attitude, and the effect it will have on the car's suspension. Assuming the car is moving toward the top of my post:

Toe-in -----> /---\

Toe-out----> \---/

Toe-in is like a skier snowplowing...

ianc

boroEF
2009.12.09, 04:21 PM
Also note that toe out effectively changes ackerman as well.
More ackerman (difference in the amount the left and right wheel is steered) equates to more off power steering. This also increases low speed steering and steering in a lower traction surface. It is partially for this reason that toe out gives better initial turn in response. If you are noticing that the car is more stable with toe out....i'm confused :) or you are steering on throttle a lot....or there is a lack of weight transfer to the front end when throttle is lifted...or a lot of things :)

Tjay
2009.12.09, 05:21 PM
Hi Grant,

I like running zero toe bar on my MR02 just because it has a little bit of toe out (\ _ /) on-power. This gives me the stability on the straight away running in 94mm config.

So to aswer your question according to my experience in mini-z (same time as you did :)). I feel that toe out in the front, should give more straight-away stability which makes it less "ping-pong" effect or twichy steering as you mentioned.

VAzRACER
2009.12.09, 05:44 PM
Toe-out normally gives more turn in steering and less steering mid corner to corner exit. Toe-in gives less turn in steering and more steering mid corner and corner exit. In theory toe-in should be more stable on straights because it gives less inital response.

With stock cars I tend to leave them at 0 but for mod alot of times I end up with toe out, it helps tame the on power steering coming out of turns that you get from faster motors. It does make the car have alot of inital steering response.

VAzRACER
2009.12.09, 05:50 PM
Here is a link that may help explain it better.

http://users.telenet.be/elvo/

yasuji
2009.12.09, 05:59 PM
Hi Grant,

I like running zero toe bar on my MR02 just because it has a little bit of toe out (\ _ /) on-power. This gives me the stability on the straight away running in 94mm config.

So to aswer your question according to my experience in mini-z (same time as you did :)). I feel that toe out in the front, should give more straight-away stability which makes it less "ping-pong" effect or twichy steering as you mentioned.

ok so im not on crack....:confused:...so its not driving style.....lol...cause tjay is as smooth as butter.....and i am a lil bit burtal.....lol....may be it in the radio setting.....lol

CristianTabush
2009.12.09, 07:30 PM
ok so im not on crack....:confused:...so its not driving style.....lol...cause tjay is as smooth as butter.....and i am a lil bit burtal.....lol....may be it in the radio setting.....lol

No, you are both on crack... :P

Someone is playing Jedi mind tricks on both of you because there is no possible way, in any scenario that toe out adds stability in a straight line. It is simply impossible, and it goes against the laws of physics.

Having toe out, means that the front inside tire, when turning is already starting to steer in whatever direction you are going. This increases the reaction time of the car, hence creating the feeling of "twitchiness" which we can define pretty much the same as stability.

Toe In, makes the car track straight because the leading tire that is steering takes longer to start facing the direction it is going. Once the car is going through the middle and exit of the corner, toe in gives more mid corner steering and returns the car to center quicker because the tires have to travel less of a distance to center.

What you guys are experiencing is unexplainable, and although it could be the case, you are going against the laws of physics and geometry of the car. Just do a quick google search and do the research for yourselves. Anywhere from real life F1, to RC cars is consistent with the difference and effects of the 2.

Let's not confuse people on very basic concepts... :)

CristianTabush
2009.12.09, 07:35 PM
This is a great article on Toe-In vs. Out:

http://www.ozebiz.com.au/racetech/theory/align.html

bermbuster
2009.12.09, 07:56 PM
your camber setting will also have an effect on toe.....
a positive camber uses toe in
a negative camber uses toe out

what camber are you running on your cars???

yasuji
2009.12.09, 08:16 PM
your camber setting will also have an effect on toe.....
a positive camber uses toe in
a negative camber uses toe out

what camber are you running on your cars???

on the pn front end i run 1deg camber +1.08 camber gain and .9 caster....unweighted it is toe out,at rest "0"toe, compressed full toe in.....i run the "0" toe bar.... it is a very balanced set up and every time i try the +.5 or+1 my car is hard to drive down the straight....when i ran the std front end i ran 1.5 castor and 2degree camber and a "0"toe bar :D

Tjay
2009.12.09, 08:30 PM
ok so im not on crack.......so its not driving style.....lol...cause tjay is as smooth as butter.....and i am a lil bit burtal.....lol....may be it in the radio setting.....lol

No, you are both on crack... :P

hahahha! I've been on a 4 hours meeting that felt like it will never end... This is made my day. lol

For on-road 10th scale sedan and awd miniz, we have to run toe-in rear and toe-out (or zero) front. This set-up makes the car stable. Toe-in will definitely gain more stability vs toe-out or zero toe. In 2wd mini-z, I only have two types of toe bar, 0 and .5. Both felt the same. lol... it must be the +1 wheels that I have. ;)

CristianTabush
2009.12.10, 04:00 PM
on the pn front end i run 1deg camber +1.08 camber gain and .9 caster....unweighted it is toe out,at rest "0"toe, compressed full toe in.....i run the "0" toe bar.... it is a very balanced set up and every time i try the +.5 or+1 my car is hard to drive down the straight....when i ran the std front end i ran 1.5 castor and 2degree camber and a "0"toe bar :D

This my friend, is called bump steer :) This behavior is actually right in line with what I have discussed before, as the suspension compresses, the car's tires steer inward and create the wandering feeling that I have been telling all of you guys for ever. If you increase the toe-in angle, the bump steer problem is exacerbated even further. The PN Front toes in less at a certain setting, I believe Davey G had posted somewhere on the forums the adjustment that gave the least amount.

VAzRACER
2009.12.10, 06:02 PM
Put the camber adjustment to 12 o'clock to minimize the bump steer.

yasuji
2009.12.10, 09:28 PM
This my friend, is called bump steer :) This behavior is actually right in line with what I have discussed before, as the suspension compresses, the car's tires steer inward and create the wandering feeling that I have been telling all of you guys for ever. If you increase the toe-in angle, the bump steer problem is exacerbated even further. The PN Front toes in less at a certain setting, I believe Davey G had posted somewhere on the forums the adjustment that gave the least amount.

so... what u r saying is that in my case ....toe in = instability!lol....
may be that is why i have no clue why bump steer even exists.....i have ZERO INSTABILITY with the zero bar
tried it once again tonight...."0"toe wins out again!
as for dave g's setting.... i tried that as well....good with the 0 bar..... un driveable with any toe in at all!....i read all the lit u guys have posted and i think i have come up with my answer...maybe the car is more stable....and slower to react.....and things just dont happen as quick as i need them to with toe in....
kinda like driving a SLINKY....LOL

CristianTabush
2009.12.11, 04:29 AM
so... what u r saying is that in my case ....toe in = instability!lol....
may be that is why i have no clue why bump steer even exists.....i have ZERO INSTABILITY with the zero bar
tried it once again tonight...."0"toe wins out again!
as for dave g's setting.... i tried that as well....good with the 0 bar..... un driveable with any toe in at all!....i read all the lit u guys have posted and i think i have come up with my answer...maybe the car is more stable....and slower to react.....and things just dont happen as quick as i need them to with toe in....
kinda like driving a SLINKY....LOL

Essentially yes, the case is different with the PN double A-Arm due to the "bump steer flaw". By having more toe, the bump steer becomes more drastic. If RCP was perfectly smooth then this problem would not exist, but unfortunately the surface we race on is not very even. By having 0 toe, you are able to mitigate the bump steer to a certain level. I hope PN takes a page out of the Kyosho book and releases knuckles and tie rods that eliminate this issue. If this is done, (and maybe widened by 1mm on each side) the front end would be unbeatable...

yasuji
2009.12.11, 09:51 AM
Essentially yes, the case is different with the PN double A-Arm due to the "bump steer flaw". By having more toe, the bump steer becomes more drastic. If RCP was perfectly smooth then this problem would not exist, but unfortunately the surface we race on is not very even. By having 0 toe, you are able to mitigate the bump steer to a certain level. I hope PN takes a page out of the Kyosho book and releases knuckles and tie rods that eliminate this issue. If this is done, (and maybe widened by 1mm on each side) the front end would be unbeatable...
i would not necessarily call it a "flaw"......imo....bump steer ,as u call it, gives me the best of both worlds.....it does everything i need it to ,when i need it to

think about this....
"unweighted it is toe out,at rest "0"toe, compressed full toe in.....i run the "0" toe bar"
this is something that cannot be achived with fixed toe....there is always a compromise......there is much less with active toe/bump steer

i do not think that this would make any difference on a smooth surface...understand that it doesn't "ping-pong" in all the same spots....;)

pedrocamp
2009.12.11, 03:45 PM
Take your Ferrari, or rent one, and raise the steering rack in the car 1". Try and drive it, fast.

CristianTabush
2009.12.11, 04:01 PM
i would not necessarily call it a "flaw"......imo....bump steer ,as u call it, gives me the best of both worlds.....it does everything i need it to ,when i need it to

think about this....
"unweighted it is toe out,at rest "0"toe, compressed full toe in.....i run the "0" toe bar"
this is something that cannot be achived with fixed toe....there is always a compromise......there is much less with active toe/bump steer

i do not think that this would make any difference on a smooth surface...understand that it doesn't "ping-pong" in all the same spots....;)

Bump steer is a flaw in this case, there was no way to get around it initially until we saw the simple, but genius solution Kyosho came out with. Sorry, but any engineer with decent automotive design knowledge knows this. In off-road, sometimes it is used since there is not as much traction, so instability is not an issue but in on-road racing scenarios, traction is higher and this creates instability. Remove the bump steer (like on the 03) and see how much more stable the car becomes and how much straighter it tracks.

Active toe making the car better??? The car's tires are constantly pulling in different directions, if you can't see this being a problem, well, I honestly don't know what to say...

As I have said before, this front end is great, and it gives you massive steering traction and corner speed. But it COULD BE better if the bump steer is eliminated.

On a smooth surface, bump steer does not affect the car as much. I hope you can one day make it to MMS in Hong Kong, you will understand what high traction on a super smooth surface is and see how bumpy and inconsistent RCP really is.

CristianTabush
2009.12.11, 04:02 PM
Take your Ferrari, or rent one, and raise the steering rack in the car 1". Try and drive it, fast.

I guess you need to let people know that by doing this you would create massive Bump steer issues... :P

Tjay
2009.12.11, 06:41 PM
As I have said before, this front end is great, and it gives you massive steering traction and corner speed. But it COULD BE better if the bump steer is eliminated

On a smooth surface, bump steer does not affect the car as much. I hope you can one day make it to MMS in Hong Kong, you will understand what high traction on a super smooth surface is and see how bumpy and inconsistent RCP really is.

Thank you!

This is what I have been trying to tell everyone, both locally and on the web. PN's double A-Arm is a great product and the lap time you'll get with a standard front-end vs A-ARM is not even close to competitive, that is if you can drive the A-Arm around the track consistently for the entire race. With the bumpsteer, it is almost impossible to stay consistent. This is where the kingpin type MR02 frontend favors. Its consistency to go around the track without having to fight it... very forgiving.

RCP is a great versatile track. If you dont have a shop to go to, you can just buy blanks and make your own turns by using ropes or plastic pipes. However, for racing, the track is very inconsistent. Even if they came from the same shipments, few of the tile are about half to a mill taller than the other tile on the track. Half a mill in this scale is like running over a curb on a real car and thats every block at full speed! I have tried carpet (to try only not race) and man let me tell you, it felt like you're in control of the car it's precision is just amazing! As if I was driving a 10th scale sedan onroad.. Very predictable and every little adjustment is very noticeable.

Grant, you should also consider running the MR03. It's an awesome car. :)

pedrocamp
2009.12.11, 11:38 PM
I guess you need to let people know that by doing this you would create massive Bump steer issues... :P

Poster assumes no liability for wrecked Ferraris! Don't try it on your Civic either.

I run the PN A-Arm on my LM car and like it. I ran it for a while on my 96mm Stk Class car but could not get used to the dartiness on bumps exiting some of the corners at our track. The LM car with it's longer wheelbase doesn't become upset as easily. The PN A-Arm is a beautiful piece of work, it is just hampered by a fixed length tie rod, a design constraint of the chassis. The steering system worked very well with the stock kingpin suspension. The trick, as many have found, is to use the right length tie rod to place the bump steer arc so it goes from slightly toed out to slightly toed in. I run the 0 bar on my LM for this reason.

I have an 03 and love it. The Kyosho designers did a good job giving us an active camber front suspension with minimal bumpsteer by placing the tie rod on the bottom. The lower arm doesn't swing which minimizes the potential problem.

All cars have bumpsteer, even open wheel F1/Indy front suspensions with very long arms, though it is adjusted to minimize it in the expected range of suspension travel.

yasuji
2009.12.12, 03:22 PM
Bump steer is a flaw in this case, there was no way to get around it initially until we saw the simple, but genius solution Kyosho came out with. Sorry, but any engineer with decent automotive design knowledge knows this. In off-road, sometimes it is used since there is not as much traction, so instability is not an issue but in on-road racing scenarios, traction is higher and this creates instability. Remove the bump steer (like on the 03) and see how much more stable the car becomes and how much straighter it tracks.
i have driven the o3 and pushed on the front end.....it toes in just slight ly....minimal compared to the pn front but if these engineers @ kyosho were so great then u would think that they would have been able to not overcorrect the initial toe out effect...;):D
Active toe making the car better??? The car's tires are constantly pulling in different directions, if you can't see this being a problem, well, I honestly don't know what to say...
i do not see it as a problem.....and understand it is due to the fact that my car is faster and more consistent than it has ever been.....i even us less brake:p i can be on throttle earlier an and hold it on longer than i could with a kingpin front.....(if it was a bad thing...wouldnt my car be worse!):D


As I have said before, this front end is great, and it gives you massive steering traction and corner speed. But it COULD BE better if the bump steer is eliminated.
i feel if the active toe is reduced it will also reduce the steering traction and corner speed.....it is simple....for me, king pin front end everything fixed position....slower and less consistent lap times!....AAarm....active everything
faster and more consistant lap times!:cool:

On a smooth surface, bump steer does not affect the car as much. I hope you can one day make it to MMS in Hong Kong, you will understand what high traction on a super smooth surface is and see how bumpy and inconsistent RCP really is.

i think we have the bumpiest tracks here in so cal.....and the grippiest....without a doubt!....all of the guys here in socal use the AAarm front end and are faster and more consistent that they have ever been
i have done numerous tests going from a std front end to the AAarm front end...when ever i go to another track where the people complain that the rcp is bumpy and inconsistent ....i feel that its alot smoother than my track....lol:D

CristianTabush
2009.12.12, 04:07 PM
Grant, you don't get the point... I am not saying that it is not faster or better than a king-pin set-up, but what I am saying is that the front end would be better without bump steer... If you still believe that it isn't, you probably never will, after all you are a PN guy, all the way...

I try to be objective as I can with my evaluations, be it a Reflex, PN, Atomic or 3 Racing part. I look for the best parts, regardless of brand. This is delicate topic for me because we do make a front end, and I try not to bring comparisons for this reason, because I respect Philip very much and his product line. The truth is, when I find a product that can be improved, I try to manufacture it, if it can't be improved, I simply run it, regardless of brand. If the 03 had not been released, you would have definitely seen a geometry correction kit for the PN front. I was already working on a different steering rack with adjustable tie rods to adjust toe and ackerman.

Fact is, my findings are consistent with everyone's on the PN front end. Be it Reflex drivers (who I tried to get to run the front for touring cars), forum members, or drivers from all over the US and Europe, the consensus is they feel the PN front makes their car wander more than the king-pin type front, not that it makes them slower lap per lap.

I am not debating the capability of an advanced driver to control this car quicker around the track with a PN double A-Arm system than with a king-pin type. Especially when you run as much scrub as you do with +3 front wheels. While you have an unorthodox driving style, car dynamics, are car dynamicss and what I am trying to get to is that for all practical applications, bump steer is not a desirable characteristic when engineering a front end. You eliminate it and you have a TRULY superior product that is both more consistent and faster around the track.

Basically, in a perfect world, a PN front with bumpsteer vs a PN front without bumpsteer the one without bumpsteer would be king.

About the 03; yes the 03's still bump in slightly, but it is a MASSIVE improvement over the PN front and the cars run much better and tracks straighter than a PN front ever has. I think I speak for the majority of drivers out there that this yields a more consistent car that is easier to drive lap in- lap out, all while still gaining the advantages of increasing camber.

I am not even going to touch on the active toe. You truly believe this is beneficial, and I will have to respectfully disagree with this as this is at odds with all theory and implementation of car design as well as with my 20+ years of experience racing RC cars.

mleemor60
2009.12.12, 04:36 PM
Grant is a motorcycle guy. It is hard to work with bump steer with only one front wheel. That is why he likes so much caster. Right Grant?

rocketman
2009.12.12, 09:49 PM
Most of my competitive racing experience is in 10th scale off-road and my team of racers did everything we could to eliminate bump steer. I ran some incredibly crazy steering geometries on my 2wd and 4wd cars because I was generally the worst guy on my team and so I was testing things for others and whether the track was slick or had tons of grip we hated bump steer. Never knew bump to be my friend.

CT is right on regarding toe theory and general practice.

Theory is great but it doesn't take into account your own abilities and skills and so sometimes you just got to go with what got you to the dance even if it isn't the best/fastest way to go.

yasuji
2009.12.13, 04:47 AM
Grant, you don't get the point... I am not saying that it is not faster or better than a king-pin set-up, but what I am saying is that the front end would be better without bump steer... If you still believe that it isn't, you probably never will, after all you are a PN guy, all the way...

I try to be objective as I can with my evaluations, be it a Reflex, PN, Atomic or 3 Racing part. I look for the best parts, regardless of brand. This is delicate topic for me because we do make a front end, and I try not to bring comparisons for this reason, because I respect Philip very much and his product line. The truth is, when I find a product that can be improved, I try to manufacture it, if it can't be improved, I simply run it, regardless of brand. If the 03 had not been released, you would have definitely seen a geometry correction kit for the PN front. I was already working on a different steering rack with adjustable tie rods to adjust toe and ackerman.

Fact is, my findings are consistent with everyone's on the PN front end. Be it Reflex drivers (who I tried to get to run the front for touring cars), forum members, or drivers from all over the US and Europe, the consensus is they feel the PN front makes their car wander more than the king-pin type front, not that it makes them slower lap per lap.

I am not debating the capability of an advanced driver to control this car quicker around the track with a PN double A-Arm system than with a king-pin type. Especially when you run as much scrub as you do with +3 front wheels. While you have an unorthodox driving style, car dynamics, are car dynamicss and what I am trying to get to is that for all practical applications, bump steer is not a desirable characteristic when engineering a front end. You eliminate it and you have a TRULY superior product that is both more consistent and faster around the track.

Basically, in a perfect world, a PN front with bumpsteer vs a PN front without bumpsteer the one without bumpsteer would be king.

About the 03; yes the 03's still bump in slightly, but it is a MASSIVE improvement over the PN front and the cars run much better and tracks straighter than a PN front ever has. I think I speak for the majority of drivers out there that this yields a more consistent car that is easier to drive lap in- lap out, all while still gaining the advantages of increasing camber.

I am not even going to touch on the active toe. You truly believe this is beneficial, and I will have to respectfully disagree with this as this is at odds with all theory and implementation of car design as well as with my 20+ years of experience racing RC cars.

i guess it just boils down to my driving style.....:D

yasuji
2009.12.13, 04:49 AM
Grant is a motorcycle guy. It is hard to work with bump steer with only one front wheel. That is why he likes so much caster. Right Grant?lol...motorcycles have bump steer....it is called tucking the front......:D
and the other is called trail

bermbuster
2009.12.13, 06:45 AM
i guess it just boils down to my driving style.....:D

Show em your driving style at the Tekin 1/28th Nats.....:D

ianc
2009.12.13, 01:07 PM
i guess it just boils down to my driving style...

lol....nope....bump steer is never a good thing...lol

ianc