My HS build

[Jason@SportsCar]

Originally Posted by CoryM

Late reply as I was moving house and having surgery.

Thanks for the input guys.

Looking at the 2016 rules, it looks like this truly was a useless post . I use the Yaris in a winter series, so up until now I was still on 2015 rules. Looks like this winter I'll just be racing for fun as I'm not doing a STF build. I run on NT01s because I get them cheap to the point I'd be stupid to run anything else. The raw grip, and resistance to heat cycling makes them a pretty good street/autoX tire IMO. Enough to forgive the low responsiveness.

Regarding the front bar at autoX, have you guys tried this exact setup? The front bar was the last change I did (after 5yrs), and definitely seems faster. I am familiar with suspension design (I have designed/built a car from scratch), and I understand that the front bar is "wrong" for a FWD. However I saw pictures of my car with only 1-2" of rubber on the drive wheel contacting when on power in corners: I figured I would try a front bar to reduce the savage body-roll. From photos it appears to have nearly doubled the amount of rubber on the road, without causing the understeer to be unmanageable. It is absolutely faster in many elements with the front bar. Slaloms, offset gates, keyhole turns. Also allows me to brake later/harder without losing the rear. Basically anything except corners on launch, and bumpy sweepers. The only place (which never happens at autoX) that the front bar shows massive understeer is trying to turn hard without transferring the weight to the front (turning without braking or lift-off). That being said, it's certainly possible that I have gone too far, and that the 2015 bar may be a better option. For my driving, I'd say the current setup is pretty solid.

On the track, or with stiffer springs, I doubt you'd want the front bar. You really need that aggressive weight transfer like you get at autoX. I'm not a track guy, so I can't say for sure, but I bet it would be worse.

Cheers.
Cory

If you are happy with it dont change it.

Body roll is not a bad thing if you have enough camber, and with the crash bolts you should be way better off camber wise than most HS cars. The softer front bar really helps mid corner rotation, and will certainly help power down with that open diff. I will take corner exit over transitional speed every time - you can pick the transitional speed back up with better shocks.

[CoryM]

Originally Posted by Jason@SportsCar

If you are happy with it dont change it.

Body roll is not a bad thing if you have enough camber, and with the crash bolts you should be way better off camber wise than most HS cars. The softer front bar really helps mid corner rotation, and will certainly help power down with that open diff. I will take corner exit over transitional speed every time - you can pick the transitional speed back up with better shocks.

Yeah, it always comes down to keeping the driver happy. You're right, mid corner shows a hint of understeer, but immediately transitions into rear rotation so I am OK with it. It's very brief, to the point you don't have time to correct it before it sorts out. As far as camber, I was after more contact patch on the inside tire, which the front bar gains and more neg camber reduces.

I would say it is in your head. Its like when someone tells me they changed from 87 octane to 91 octane and the car feels more stronger....

After 5 years, maybe the driver mod has improved? Like Jason said, if you feel like its faster, then stick with it.

If you are going to be running NT01, that will throw you in F Street Prepared.

I have ran that setup, and its just dead weight. You can control much more with just tire pressure in autocross

I can't see it being in my head. After 4.5 years of racing the car, put the F bar on and after 3 events to get used to it and tune pressures: I'm certain on this car at these autoX events it is faster. I realized last night I'll just run my wet tires for the winter series and hope for enough wet days to compete. You've run this setup? This exact setup? On a 5dr with 205/50/r15 on 15x5.5" rims? .... why?

As far as the front bar goes I want to be clear: I did not install the front bar to control balance. When chassis tuning, I always try to maximize grip first, then adjust until balance is right. This is the same as tire pressure tuning; maximize grip with temp probe or chalk, then adjust pressures to reduce grip where needed for balance. The sway bar does the same, except I am using it to help compensate for the high CG. I wanted more grip from my inside front tire, and the front swaybar accomplished this. I was able to reduce neg camber up front to -2.5° (which I forgot to include in my first post), this not only improves the inside tire contact patch further, it also makes a large difference to the braking grip(VS -2.8° which was my previous). After adjusting the balance with rear tire pressures, I am comfortable that it is well set-up, and the co-drivers (once they get used to timing the soft springs) agree so far. I also have pictures to show I have much more contact patch than before.

Who knows, maybe I'm crazy but I've always figured the whole point of suspension was to keep as much rubber in contact with the road as often as possible (or at least when it's required). The front bar seems to accomplish this without causing too many compromises so I am happy.

All that being said, the Yaris is now getting totally forgotten about while I sort out the E-mod car for it's first season.

Cheers.

[Jason@SportsCar]

Originally Posted by CoryM

Yeah, it always comes down to keeping the driver happy. You're right, mid corner shows a hint of understeer, but immediately transitions into rear rotation so I am OK with it. It's very brief, to the point you don't have time to correct it before it sorts out. As far as camber, I was after more contact patch on the inside tire, which the front bar gains and more neg camber reduces.



I can't see it being in my head. After 4.5 years of racing the car, put the F bar on and after 3 events to get used to it and tune pressures: I'm certain on this car at these autoX events it is faster. I realized last night I'll just run my wet tires for the winter series and hope for enough wet days to compete. You've run this setup? This exact setup? On a 5dr with 205/50/r15 on 15x5.5" rims? .... why?

As far as the front bar goes I want to be clear: I did not install the front bar to control balance. When chassis tuning, I always try to maximize grip first, then adjust until balance is right. This is the same as tire pressure tuning; maximize grip with temp probe or chalk, then adjust pressures to reduce grip where needed for balance. The sway bar does the same, except I am using it to help compensate for the high CG. I wanted more grip from my inside front tire, and the front swaybar accomplished this. I was able to reduce neg camber up front to -2.5° (which I forgot to include in my first post), this not only improves the inside tire contact patch further, it also makes a large difference to the braking grip(VS -2.8° which was my previous). After adjusting the balance with rear tire pressures, I am comfortable that it is well set-up, and the co-drivers (once they get used to timing the soft springs) agree so far. I also have pictures to show I have much more contact patch than before.

Who knows, maybe I'm crazy but I've always figured the whole point of suspension was to keep as much rubber in contact with the road as often as possible (or at least when it's required). The front bar seems to accomplish this without causing too many compromises so I am happy.

All that being said, the Yaris is now getting totally forgotten about while I sort out the E-mod car for it's first season.

Cheers.

Swaybars build grip on the opposite end of the car they are attached to. They do this by providing a lifting force to the inside tire - as the outside tire compresses the swaybar transfers the load and pushes the connected tire in the same direction. You are in fact reducing grip on the axle the bar is attached to.

Swaybars in general are a crutch for a poorly tuned suspension. That said, you are limited in HS with the mods you can do, and one of them wont be fixing the lack of spring rate, so you do what you can. In a fwd car the last thing I want to do is remove front grip, and that is what a bigger front bar is doing.

I would go the other way and find a way to transfer as much grip from the rear of the car to the front. Go with a bigger rear bar, or get a set of proper rear shocks that will help suck up that back tire quicker, forcing grip to the front.

In our car we dont even run a rear bar, just droop limiters in the rear shocks that pick the back tire up almost instantly.

[CoryM]

Originally Posted by Jason@SportsCar

Swaybars build grip on the opposite end of the car they are attached to. They do this by providing a lifting force to the inside tire - as the outside tire compresses the swaybar transfers the load and pushes the connected tire in the same direction. You are in fact reducing grip on the axle the bar is attached to.

Swaybars in general are a crutch for a poorly tuned suspension. That said, you are limited in HS with the mods you can do, and one of them wont be fixing the lack of spring rate, so you do what you can. In a fwd car the last thing I want to do is remove front grip, and that is what a bigger front bar is doing.

I would go the other way and find a way to transfer as much grip from the rear of the car to the front. Go with a bigger rear bar, or get a set of proper rear shocks that will help suck up that back tire quicker, forcing grip to the front.

In our car we dont even run a rear bar, just droop limiters in the rear shocks that pick the back tire up almost instantly.

That way of thinking is definitely the right path for the vast majority of FWD cars. This is why I waited so long to try a front bar on my car. Where the traditional way of thinking goes wrong is Stock class when the CG is high and/or springs are too soft. High body roll, high neg camber and struts cause the inside front tire to lose a large amount of contact patch. In my car I was losing ~1/2 of my inside F tire contact patch. That's a lot of rubber, and it shows everytime I try to accell out of an element.

Yes the F bar loses grip by transferring weight to the rear, but it also gains grip by almost doubling the contact patch of the inside F tire (and gains a little outside F contact patch due to reduced pressures). Is this enough to net more F grip over all? No idea, but it sure feels like it. If I had the tire-curve, I could do a bunch of measurements and math to figure out which gains more grip (on paper). In practice, it would take a serious test and tune session to confirm one way or the other.

Again, this pretty much only applies to HS cars and maybe only over-tired HS cars. It's possible it needs R-comps to see gains, and maybe this winter running my street/wet tires will show the front bar to be detrimental.

[Jason@SportsCar]

Originally Posted by CoryM

That way of thinking is definitely the right path for the vast majority of FWD cars. This is why I waited so long to try a front bar on my car. Where the traditional way of thinking goes wrong is Stock class when the CG is high and/or springs are too soft. High body roll, high neg camber and struts cause the inside front tire to lose a large amount of contact patch. In my car I was losing ~1/2 of my inside F tire contact patch. That's a lot of rubber, and it shows everytime I try to accell out of an element.

Yes the F bar loses grip by transferring weight to the rear, but it also gains grip by almost doubling the contact patch of the inside F tire (and gains a little outside F contact patch due to reduced pressures). Is this enough to net more F grip over all? No idea, but it sure feels like it. If I had the tire-curve, I could do a bunch of measurements and math to figure out which gains more grip (on paper). In practice, it would take a serious test and tune session to confirm one way or the other.

Again, this pretty much only applies to HS cars and maybe only over-tired HS cars. It's possible it needs R-comps to see gains, and maybe this winter running my street/wet tires will show the front bar to be detrimental.

Not sure who sold you on that, but if you like it go with it.

[invader166]

Originally Posted by CoryM

That way of thinking is definitely the right path for the vast majority of FWD cars. This is why I waited so long to try a front bar on my car. Where the traditional way of thinking goes wrong is Stock class when the CG is high and/or springs are too soft. High body roll, high neg camber and struts cause the inside front tire to lose a large amount of contact patch. In my car I was losing ~1/2 of my inside F tire contact patch. That's a lot of rubber, and it shows everytime I try to accell out of an element.

Hmmm...your OP states that you have Tokico blues installed? I've heard they are a pretty stiff shock. Why not try some softer shocks with the front bar? That way, maybe you can load and unload your tires at a faster rate and be able to further increase your tire contact with the road.

Just another idea, but like you stated above. No way to really find out without some serious tests, and proper math.

[CoryM]

Originally Posted by invader166

Hmmm...your OP states that you have Tokico blues installed? I've heard they are a pretty stiff shock. Why not try some softer shocks with the front bar? That way, maybe you can load and unload your tires at a faster rate and be able to further increase your tire contact with the road.

Just another idea, but like you stated above. No way to really find out without some serious tests, and proper math.

I could definitely do better in the shock department. I'm not sure what the blues are intended for, but stock springs is not it. I only got them because I needed something to replace a damaged OE strut. The Yaris only gets new parts when it *needs* them. The whole point of me driving the economical car is to spend less on it so I can spend more on faster cars . This is also why I've stayed in HS as it reduces the temptation to buy stuff for the little car.

Cheers.