ATTS in Autox - Honda Prelude Forum

JaseJ · 01-21-2002, 02:17 AM

you guys ever feel ATTS work in autox? Only time I ever feel it.. is if I'm in the mountains or onramps

ImagePree · 01-21-2002, 03:21 AM

yea, just about EVERY turn.

Jacques · 01-21-2002, 04:11 AM

Quote:

Originally posted by ImagePree
yea, just about EVERY turn.

Ditto. Better yet, try accelerating BEFORE the apex of a turn.

ImagePree · 01-21-2002, 04:17 AM

Quote:

Originally posted by Jacques

Ditto. Better yet, try accelerating BEFORE the apex of a turn.

yes!
it needs some getting used to, trust me.

Darth Luder · 01-21-2002, 06:26 AM

Yeah, cheaters...

Oh well, I will have the quaife in soon enough and then I will get to accelerate before the apex...

vwong · 01-21-2002, 10:26 AM

The 3rd run in yesterday's San Diego event was the first auto-x that I ran without ATTS (for some reason, probably the ATTS computer decided to malfunction on me when I got to the slalom, so I was running without ATTS for the later half of the course). Let me tell you, what a difference!!! The car pushed at couple of turns where I was slightly oversteering during my 1st and 2nd runs. Basically without ATTS, the SH is just like a base or any other front drive car with open diff.

SilverSH · 01-21-2002, 10:49 AM

Quote:

Originally posted by Darth Luder
Yeah, cheaters... Oh well, I will have the quaife in soon enough and then I will get to accelerate before the apex...

I must be missing something.. if you are braking/cornering at the limit and you get on the power before the apex with an LSD, shouldn't you expect to understeer wide in a FWD car?

ssh

Darth Luder · 01-21-2002, 11:13 AM

Quote:

Originally posted by SilverSH

I must be missing something.. if you are braking/cornering at the limit and you get on the power before the apex with an LSD, shouldn't you expect to understeer wide in a FWD car?

ssh

Not with an lsd... If you have that in you can accelerate sooner just as you can with your SH...

Pork Chop · 01-21-2002, 01:08 PM

Quote:

Originally posted by SilverSH

I must be missing something.. if you are braking/cornering at the limit and you get on the power before the apex with an LSD, shouldn't you expect to understeer wide in a FWD car?

ssh

That's the main benefit of an LSD (and ATTS): you can get on the gas early and not understeer like an open-diff car would.

SilverSH · 01-21-2002, 04:51 PM

It seems to me that what the two of you are saying violates the circle of friction. But I could be wrong, so could you please explain again how an LSD allows a fwd car to get on the throttle before the apex without understeering wide on the turn?

Thanks!

ssh

Pork Chop · 01-21-2002, 05:43 PM

Ok, I'll take a try at this one. Disclaimer: just my guess at what's going on, so hopefully it makes sense. Feel free to pick it apart and straighten things out for me.

You're right, you can't violate the friction circle. But shouldn't each tire have its own friction circle? The inside tire has substantially less grip in midcorner than the outside tire (weight transfer, contact patch is smaller, etc). I think it makes sense to assume that the outside tire is not at the limit of its friction circle but the inside tire is.

In your open-diff car, if you floor it at this point, you're sending a lot of power to both wheels, however, the inside wheel is already at the limit of the friction circle and off you go. You've gone from a situation where you had grip on both tires and now you're spinning that inside front and have no grip there at all.

Take the same situation on your LSD/ATTS car. You're at the limit and you floor it midcorner. The fancy (or not so fancy) diff sends more power to the outside tire, which isn't at the limit of the friction circle, and thus can take the added power and put it to the ground.

Jamie · 01-21-2002, 07:02 PM

Quote:

Originally posted by Pork Chop
Take the same situation on your LSD/ATTS car. You're at the limit and you floor it midcorner. The fancy (or not so fancy) diff sends more power to the outside tire, which isn't at the limit of the friction circle, and thus can take the added power and put it to the ground.

With one difference between the two systems: an LSD seeks to equalize the rotational speed of both axles, so either through a variable-viscousity fluid or a mechanical connection, it'll try and lock the more rapidly spinning inside axle to slower outer one and equalize the torque going to both. In practice, the diff never locks completely, so the outer side only "gets back" as much torque as the differential is set to slow the inner side.

With the ATTS, the system actually seeks to speed up the outside axle, generating more torque to the outside wheel that has the grip. More thrust through the outside tire than inside makes the car turn in without cranking in more steering angle, so you're steering by means of both side force and thrust -- more efficient use of the tire with the most grip. Unload the inside tire enough, and it'll spin merrily.

Exceed the friction circle in either case, and off you go -- neither the LSD or ATTS increases the total grip available, they just make it possible to use more of it to generate thrust. At this point, an LSD is better for tight corners, where you'll lean the car over hard enough to unload the inside tire no matter what; ATTS is better for the wide sweepers and medium corners that allow you to carry more speed, or potentially for a car with a *really* stiff suspension.

Darth Luder · 01-22-2002, 06:23 AM

It in a sense changes the friction circle for the car, from one where the inside tire of the car will push the car off line to one where the outside tire helps to "push" the car inside the line but never going inside the line because that vector is not stronger than the one created by the momentum of the car and works to an equalibrium to turn on line.

You can visulise it on a peice of paper by drawing a cricle. The driving force vector is now pointing inside the line, the car wants to go straight down tangent to the driving line. With the lsd/atts, the two vectors create a resultant vector along the driving line. Conversly, with the open diff and the inside wheel spinning with more power that pushes you out, that vector is now pointing ouside the line. Combine that with the momentum of the car which is tangent and you have a resultant vector going more tangent or even outside that.

SilverSH · 01-22-2002, 11:04 AM

Hm. I think the question I was meaning to ask was not quite what you guys were answering, but thanks all the same!

Cheers,

ssh

ImagePree · 01-22-2002, 12:13 PM

Quote:

Originally posted by SilverSH
Hm. I think the question I was meaning to ask was not quite what you guys were answering, but thanks all the same!

Cheers,

ssh

yea.. they get just a BIT too excited and technical, don't they?

Darth Luder · 01-22-2002, 05:12 PM

Quote:

Originally posted by ImagePree

yea.. they get just a BIT too excited and technical, don't they?

Says who?!?!?!

PilotSH · 01-23-2002, 06:10 PM

"It in a sense changes the friction circle for the car, from one where the inside tire of the car will push the car off line to one where the outside tire helps to "push" the car inside the line but never going inside the line because that vector is not stronger than the one created by the momentum of the car and works to an equalibrium to turn on line. "

??? I have no idea what ur trying to say here. I think it's best to start with basics, cuz I think some ppl have a misunderstanding about LSDs. In an open diff, power from the engine will follow the path of least resistance, and if the inside tire is unloaded and spinning slower then the outside tire (inside tire = smaller turn radius), then the tranny will will send equal amounts of power to both wheels until the inside tires starts spinning, tehn the inside tire will be getting the most "power" from the engine becuase like i siad b4, it follows the path or least resistance (an unloaded spinning tire has very little resistance compared to the outer tire). An LSD doesnt "send power to the outside tire," but really limits how much of a difference each tire can receive. Theoretically, with an open diff, You can send almost all the power to one side. Lemme show you an example. One one axle, you have a normal tire on a normal pavement. On the other axle, you have a wheel made of ice riding on a sheet of ice ( I know this looks stupid, but bear with me!). If tried to accelerate, the the coefficient of friction is SO low on the ice side compared to the normal side that the car would barely start to accelerate and i mean just barely. In that situation, you have almost 100% of the power going to the ice side. Now try the same thing in an LSD eqiupped car. Initially, the same thing will happen, the ice side will spin and start recieving more power then the normal side. But when the ice side starts getting a certain % more power then the normal side, lets say 70% goign to ice side and 30% going to normal side, the LSD at that point will prevent the ice side from getting any more power and keep it at that % differential, ie 70%/30%. So although the ice side is sitll spinning like crazy, teh car will accelerate much more quickly. People have this common misconception that when they get an LSD that their inside tire will stop spinning, which it will not. All it does is limit how much of the engine's power goes to the spinning wheel.
Now on to Silver SH's question and Darth Luder's reply. I too am a lil confused by Darth Luder's remark about getting on the power before the apex. Is this assuming that the driving technique is similar with or without LSD? Becuase if we're talking about using the same technique, getting on the gas before the apex shoulnd't matter with or without LSD. Take a classic autox turn, hairpin exiting into a nice long sweeper. If I'm late apexing the turn ( which I assume most of us would), then whether or not I have an LSD I'd get on the gas at the same point. The LSD equipped car would just come out of it really slow becuause it's spinning the heck out of teh inside tire. I know this because i've extensively autox a Maxima SE (viscous LSD) and a Honda Accord V6. The first time I went into a turn like that in the Accord, I thought something was wrong with the tranny because coming out of the hairpin, the RPMs were really high (compared to the teh vehicle speed) and the damn thing wouldn't accelerate. Then I saw my friend drive the car thru the same turn and noticed massive amounts of wheelspin. A similar turn in the Max, the inside wheel would still spin, but the car pulled much harder out of the turn. But no matter the car, if I'm late apexing, then I got on the gas at the same point. So I don't see why you'd be able to get on the gas earier cuz you should be on the gas at that point anyway with an open diff car UNLESS

if you hate all that inside wheel spin, you might early apex the turn so you get more braking room, got the car turned, and when the wheels are pretty much straightened out THEN got on the gas. If that is your current technicque, then I guess the LSD would let you get on the gas before the apex, PROVIDED you changed your turning technique to late apex.

I didn't write this in any sort of disrespect to anyone, with mebbe teh elementary tone this post may carry, but more for all the people that read this and don't know what an LSD really is. I read quite a lot, but hardly post ( I think this is my 4th post?!?!). Hope this very long winded post helps. hehe

I miss my Maxima's torque and LSD but the VTEC and ATTS are so much fun!

Darth Luder · 01-24-2002, 07:01 AM

Quote:

Originally posted by PilotSH
??? I have no idea what ur trying to say here. I think it's best to start with basics, cuz I think some ppl have a misunderstanding about LSDs. In an open diff, power from the engine will follow the path of least resistance, and if the inside tire is unloaded and spinning slower then the outside tire (inside tire = smaller turn radius), then the tranny will will send equal amounts of power to both wheels until the inside tires starts spinning, tehn the inside tire will be getting the most "power" from the engine becuase like i siad b4, it follows the path or least resistance (an unloaded spinning tire has very little resistance compared to the outer tire). An LSD doesnt "send power to the outside tire," but really limits how much of a difference each tire can receive. Theoretically, with an open diff, You can send almost all the power to one side. Lemme show you an example. One one axle, you have a normal tire on a normal pavement. On the other axle, you have a wheel made of ice riding on a sheet of ice ( I know this looks stupid, but bear with me!). If tried to accelerate, the the coefficient of friction is SO low on the ice side compared to the normal side that the car would barely start to accelerate and i mean just barely. In that situation, you have almost 100% of the power going to the ice side. Now try the same thing in an LSD eqiupped car. Initially, the same thing will happen, the ice side will spin and start recieving more power then the normal side. But when the ice side starts getting a certain % more power then the normal side, lets say 70% goign to ice side and 30% going to normal side, the LSD at that point will prevent the ice side from getting any more power and keep it at that % differential, ie 70%/30%. So although the ice side is sitll spinning like crazy, teh car will accelerate much more quickly. People have this common misconception that when they get an LSD that their inside tire will stop spinning, which it will not. All it does is limit how much of the engine's power goes to the spinning wheel.

All true. This is pretty much how a limited slip works. However in the case of the SH, more power is actually being sent to the outside versus the inside, just as if you put on the lsd like a quaife, there is more power being applied to the outside wheel vs the inside wheel, realatively speaking.

Quote:

Now on to Silver SH's question and Darth Luder's reply. I too am a lil confused by Darth Luder's remark about getting on the power before the apex. Is this assuming that the driving technique is similar with or without LSD?

Right, we are assuming that the driving line is the same for both the car with a regular open diff, and one with a lsd.

Quote:

Becuase if we're talking about using the same technique, getting on the gas before the apex shoulnd't matter with or without LSD. Take a classic autox turn, hairpin exiting into a nice long sweeper. If I'm late apexing the turn ( which I assume most of us would), then whether or not I have an LSD I'd get on the gas at the same point.

Agreed, if you are talking the same technique and driving line for both cars then you are getting on the gas at the same point, and in this discussion we are talking getting on it before the apex. However, if that is so, and you are on the same line, then both cars act differently when you get on that gas in the turn.

Quote:

The LSD equipped car would just come out of it really slow becuause it's spinning the heck out of teh inside tire. I know this because i've extensively autox a Maxima SE (viscous LSD) and a Honda Accord V6. The first time I went into a turn like that in the Accord, I thought something was wrong with the tranny because coming out of the hairpin, the RPMs were really high (compared to the teh vehicle speed) and the damn thing wouldn't accelerate. Then I saw my friend drive the car thru the same turn and noticed massive amounts of wheelspin. A similar turn in the Max, the inside wheel would still spin, but the car pulled much harder out of the turn.

I think you meant in your first sentence that the car with the open diff will come out slower. You site two good examples of this. The Accord, with an open diff in your example came out of the turn slower because of the massive inside wheel spin. In fact, the open diff Accord was probably pushing you outside the line as well if you have the wheels cranked and the inside wheel is spinning so. The Max with the LSD in the Max spinned both wheels more equally, yet sending more of the power out to the inside wheel by reducing the inside wheels spin. This results in less pushing out of the inside wheel, you are on line better, and you have better grip and power coming out of the turn.

Quote:

But no matter the car, if I'm late apexing, then I got on the gas at the same point. So I don't see why you'd be able to get on the gas earier cuz you should be on the gas at that point anyway with an open diff car UNLESS if you hate all that inside wheel spin, you might early apex the turn so you get more braking room, got the car turned, and when the wheels are pretty much straightened out THEN got on the gas. If that is your current technicque, then I guess the LSD would let you get on the gas before the apex, PROVIDED you changed your turning technique to late apex.

Well, currently, if you wheel spin, it is slower as you have seen. The faster way to take the turn is to feather the throttle, cannot really get on it and wait for the apex to come to you, then you can hammer it coming out of the turn. You have pretty much answered your own question here. You do have to change techniques of driving, not necessarly early apex the turn as you can drive the same line and carry speed thru it, just where you hammer the throttle changes between the lsd car and open diff car.

Quote:

"It in a sense changes the friction circle for the car, from one where the inside tire of the car will push the car off line to one where the outside tire helps to "push" the car inside the line but never going inside the line because that vector is not stronger than the one created by the momentum of the car and works to an equalibrium to turn on line. "

This was more of a mathematical way of looking at it with the force vectors created by which tires have the power and which ones are just spinning.

Quote:

I didn't write this in any sort of disrespect to anyone, with mebbe teh elementary tone this post may carry, but more for all the people that read this and don't know what an LSD really is. I read quite a lot, but hardly post ( I think this is my 4th post?!?!). Hope this very long winded post helps. hehe

I understand. I agree, not a lot of people really know how they really work. Sometimes it is easier to talk realative though when certain things come up. Realatively speaking, the inside wheel does get less power and the outside has more power when the car goes thru the turn by the reduction of power to the inside wheel. The open diffs just act like peg legs though sending all the power to one side and that is the inside in the turn due to the weight transfer and it just blows the friction coefficient of that tire out of the water, that tire starts to just push the car out and you are screwed and slow. The lsd, atts, quaife(for those that say it works differently than all others) all are great ways to help get more power earlier to come out of the turn faster and on line.

Jacques · 01-24-2002, 10:21 AM

The March 2002 issue of "Fastrack" (SportsCar magazine supplement) mentions ATTS under the Solo section. Here's the magazine pdf link: http://www.scca.org/news/fastrack/02-03.pdf

Darth Luder · 01-24-2002, 11:18 AM

Ahh, so you cant even just pull the plug and go in STS... Man, it sounds like it is going to stay in STX... I personally think though if they do do that that all of the viscous coupler and awd cars should have to move as well...