Author Topic: Why can't I carry speed?  (Read 177 times)

Offline lprmesia

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Why can't I carry speed?
« on: June 13, 2017, 12:24:44 PM »
Please help! Sorry about the long read. Need suggestions/feedback!!!  :'(

I spent a while after the Match Tour watching side by side videos of some other folks in similar cars. I found that while my gratuitous amounts of front toe out helped me in a lot of the transitions, I was getting killed in harder turns. A given obviously, but I didn't realize how bad it was killing me. This became even more apparent at a Wyotech course a few weeks back. So I zeroed out my front toe and added a bit of toe out to the rear since the WRX likes to push and can't rotate under throttle.

Sure enough, both Peru and Toledo were transition dominant courses (with PAX confirming that). But I noticed when Ben let me use his SoloStorm in my car that my lateral Gs are much lower than my competition. I don't just mean the twins, but even compared to heavier cars on less camber and the same tire (Focus RS). Also, feels like I could add even more rear toe out after the last 2 events, but they were on concrete, so I don't want to jump to that conclusion too quickly since with upcoming local events I don't want my car to be stuck in spin cycle for the entire event.

It's frustrating because I don't know what to fix. I'm at -2.7 degrees of camber while I know the faster STX twins are running around -4.0 degrees in front. Do I just need more camber? But then I know the heavier Focus RS isn't running that much camber. I'm maxed out currently, so I'd need aftermarket control arms to make it happen.

Is it the tires? I'm on RE71Rs (245/40/17 - can't go higher in STX). I know the new BFGs are good, but even the heavier RS is beating me on them in terms of lateral Gs. I'm running 30/30 for pressures and WAS getting even wear and perfect rollover until I ran on concrete (upped to 32 in front and it was fine).

Are my shocks over damped? They feel absolutely wonderful and outside pics of the car shows the car's not too stiff and it's still able to transfer weight well.

Is it my driving? I'm usually pretty good about rolling into weight transfer and not abusing the car (unless intentionally to upset my diff and transfer more power to the rear in certain situations). I'm usually able to hop in just about anything and lay down fairly competitive times. I'm not saying I'm the best or most consistent driver, but usually I can pick out what I did wrong, where, and how much time it's costing me to a fairly accurate degree when I eventually do clean it up. Looking at side by side videos of some of the people beating me in PAX at these events with similar cars (factoring in other things like drivetrain configuration, power, weight, etc.), the only truly noticeable difference tends to be cornering speeds. I'm listening (both audibly from the tires and from steering wheel feedback) to the grip limits and not trying to ask the car to do too much. Yet it feels (and looks like) the limit is much lower in my car.

I'm not too eager to dump a bunch of money into the car this season since STX seems like a lost cause this year and STH should be the way to go for next year, especially since my wallet is still recovering from a $4K transmission rebuild last month. But before I start hypothetically throwing money at a problem I can't figure out - I first need to define what the problem statement actually is.

Any ideas?  :-\ :-\ :-\
2014 Subaru WRX - 27 STX

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Offline GTI_Speed

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Re: Why can't I carry speed?
« Reply #1 on: June 13, 2017, 12:40:31 PM »
I'd say more front bar and camber? -4.0 sounds a little crazy but strut front suspension design... So who knows? Sounds like front end may be getting overloaded where other cars can send more power to other wheels to help distribute the grip elsewhere.
Alex A.

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Current: 2016 Subaru WRX STI - 77 BS
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Offline spud_majic

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Re: Why can't I carry speed?
« Reply #2 on: June 13, 2017, 01:20:33 PM »
Alex p talk to me about the camber issue 2.75 is too low. I have soltions for that without control arms. I'll need to see your top hats though. You also could use caster. Same deal. Rear tow is a band aid on these cars as the suspension has little change through it's travel unlike some other cars.

Offline gmaloy

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Re: Why can't I carry speed?
« Reply #3 on: June 13, 2017, 01:45:21 PM »
I found that while my gratuitous amounts of front toe out helped me in a lot of the transitions, I was getting killed in harder turns. A given obviously
Common suspension tuning myth (that I used to believe).  More toe out does not cause an increase in understeer in sweepers (to a point).  It only causes an increase in the required steering wheel angle to maintain the same arc radius.  That increase in steering wheel input only gives the illusion of understeer.

It's frustrating because I don't know what to fix. I'm at -2.7 degrees of camber while I know the faster STX twins are running around -4.0 degrees in front. Do I just need more camber? But then I know the heavier Focus RS isn't running that much camber. I'm maxed out currently, so I'd need aftermarket control arms to make it happen.

Yes to more camber.  Under 3 probably isn't enough especially on something as heavy as a WRX.  Also be wary when comparing to other chassis.  Camber curves, bumpsteer etc. are likely not the same.

Is it the tires? I'm on RE71Rs (245/40/17 - can't go higher in STX). 

Probably not.

Are my shocks over damped? They feel absolutely wonderful and outside pics of the car shows the car's not too stiff and it's still able to transfer weight well.

An overdamped shock will usually make the car bounce and skitter because the tire (which is a pneumatic spring) has now become the softest thing in the suspension.  And the tire is not damped.  Remember shocks have no effect on how far the car rolls, they only effect the speed in which it gets to max roll.  Looking at the roll angle from pictures outside the car probably isn't super revealing to shock effectiveness.  In your car I would bias rebound to the rear and compression to the front.

Is it my driving?

Yes, probably.  Sounds harsh I know but just keep reading.  First year doing national events right?  First time on concrete?  You're probably under driving the fast parts and over driving the slow parts.  Believe me, one of the best things you can do to get better in autox is to not get caught believing in your own myth.  The best drivers I've raced against all had one thing in common:  they always blamed themselves before the car.  Even if there is a problem with the car your first question should always be, "Why wasn't I able to adapt?" or "What could I have done with my driving to make the car suck less?"  This is important for several reasons but the biggest being that the car will almost NEVER be perfect and you will ALWAYS have to adapt at some level.  The more you do these reflection exercises the stronger your arsenal will be at making quick adjustment decisions.  Example....Problem: The car understeers on entry.  Answer: Drag the brake into the turn.

Don't confuse this with being results focused, however.  Even the best drivers in the world can only do what the car will give them (See F1).  You're goal is just to maximize what is available.
Greg Maloy
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Offline Josh R.

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Re: Why can't I carry speed?
« Reply #4 on: June 13, 2017, 02:02:48 PM »
I found that while my gratuitous amounts of front toe out helped me in a lot of the transitions, I was getting killed in harder turns. A given obviously

Common suspension tuning myth (that I used to believe).  More toe out does not cause an increase in understeer in sweepers (to a point).  It only causes an increase in the required steering wheel angle to maintain the same arc radius.  That increase in steering wheel input only gives the illusion of understeer.

It's frustrating because I don't know what to fix. I'm at -2.7 degrees of camber while I know the faster STX twins are running around -4.0 degrees in front. Do I just need more camber? But then I know the heavier Focus RS isn't running that much camber. I'm maxed out currently, so I'd need aftermarket control arms to make it happen.


Yes to more camber.  Under 3 probably isn't enough especially on something as heavy as a WRX.  Also be wary when comparing to other chassis.  Camber curves, bumpsteer etc. are likely not the same.

Is it the tires? I'm on RE71Rs (245/40/17 - can't go higher in STX). 


Probably not.

Are my shocks over damped? They feel absolutely wonderful and outside pics of the car shows the car's not too stiff and it's still able to transfer weight well.


An overdamped shock will usually make the car bounce and skitter because the tire (which is a pneumatic spring) has now become the softest thing in the suspension.  And the tire is not damped.  Remember shocks have no effect on how far the car rolls, they only effect the speed in which it gets to max roll.  Looking at the roll angle from pictures outside the car probably isn't super revealing to shock effectiveness.  In your car I would bias rebound to the rear and compression to the front.

Is it my driving?


Yes, probably.  Sounds harsh I know but just keep reading.  First year doing national events right?  First time on concrete?  You're probably under driving the fast parts and over driving the slow parts.  Believe me, one of the best things you can do to get better in autox is to not get caught believing in your own myth.  The best drivers I've raced against all had one thing in common:  they always blamed themselves before the car.  Even if there is a problem with the car your first question should always be, "Why wasn't I able to adapt?" or "What could I have done with my driving to make the car suck less?"  This is important for several reasons but the biggest being that the car will almost NEVER be perfect and you will ALWAYS have to adapt at some level.  The more you do these reflection exercises the stronger your arsenal will be at making quick adjustment decisions.  Example....Problem: The car understeers on entry.  Answer: Drag the brake into the turn.

Don't confuse this with being results focused, however.  Even the best drivers in the world can only do what the car will give them (See F1).  You're goal is just to maximize what is available.


'97 Integra GS-R - ITS/DSP

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Offline FigglyWiggly

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Re: Why can't I carry speed?
« Reply #5 on: June 13, 2017, 02:21:11 PM »
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Offline neonmike22

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Re: Why can't I carry speed?
« Reply #6 on: June 13, 2017, 02:29:54 PM »
As I mentioned on Faceballs, you've basically got equal suspension frequencies front and rear, which is going to balance the car towards understeer.  Switching from the 560/560 f/r setup you're running now to 500/650 springs will allow the car to settle from a bump more quickly, and give you a bit more neutral balance without the wheel lift from a swaybar.
Michael Carpenter
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Offline lprmesia

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Re: Why can't I carry speed?
« Reply #7 on: June 13, 2017, 04:50:46 PM »
Is it my driving?

Yes, probably.  Sounds harsh I know but just keep reading.  First year doing national events right?  First time on concrete?  You're probably under driving the fast parts and over driving the slow parts.  Believe me, one of the best things you can do to get better in autox is to not get caught believing in your own myth.  The best drivers I've raced against all had one thing in common:  they always blamed themselves before the car.  Even if there is a problem with the car your first question should always be, "Why wasn't I able to adapt?" or "What could I have done with my driving to make the car suck less?"  This is important for several reasons but the biggest being that the car will almost NEVER be perfect and you will ALWAYS have to adapt at some level.  The more you do these reflection exercises the stronger your arsenal will be at making quick adjustment decisions.  Example....Problem: The car understeers on entry.  Answer: Drag the brake into the turn.

Don't confuse this with being results focused, however.  Even the best drivers in the world can only do what the car will give them (See F1).  You're goal is just to maximize what is available.

Not harsh at all, no worries. I've always blamed driver mod as a first step, haha - but it's why I'm asking questions too because I'm stuck. Dragging the brake is a great idea. :) But I'm seeing evidence too that the car should be achieving more factoring out fixing the nut behind the wheel - as I'm stuck there too, haha.
2014 Subaru WRX - 27 STX

Previous
2014 Subaru WRX - 27 STU
1994 "Ford" Probe GT - 27 STS