Auto-X tire pressures, and 4 cats on my car
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From: Mississippi
Car Info: 2004 STi Silver/Gold
Auto-X tire pressures, and 4 cats on my car
I need to know what people are running there STi at during an auto cross. Street is 36 front, 30 back. What do i chance for auto cross?
Also my mech and i were under the car today changing out and tires and there are 4 cats in my exhaust and a muffler. I thought 2 was what everyone says. ANYONE?????????
Also my mech and i were under the car today changing out and tires and there are 4 cats in my exhaust and a muffler. I thought 2 was what everyone says. ANYONE?????????
After 3 auto-x's, I've settled on 45/43 for the tires. With 2 other drivers tinkering with the car also, we learned that running the diff full rear (35/65) makes the car a lot more tossable and predicable. This is what I have picked up so far but it is still open for change.
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45/43?
doesnt that give you enormous understeer?...
on the stock potenzas, if you look at the arrows on the tire and adjust pressures accordingly for the sidewall wear you get something like 48/30 which is what i start out with at the beginning of an autoX and i go from there...
member, we have 4wd, so you want low pressure in the back to get more oversteer and for it to be gradual and predictable...
doesnt that give you enormous understeer?...
on the stock potenzas, if you look at the arrows on the tire and adjust pressures accordingly for the sidewall wear you get something like 48/30 which is what i start out with at the beginning of an autoX and i go from there...
member, we have 4wd, so you want low pressure in the back to get more oversteer and for it to be gradual and predictable...
Thread Starter
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Posts: 100
From: Mississippi
Car Info: 2004 STi Silver/Gold
Confused
I just dont understand the DCCD. Whats what? If your saying 35/45 where is that on the indicator thing? Do me a favor and exlain it in light numbers, like "one light down from lock", or something like that. Sorry for being a bonehead. Thanks. Auto-X in 5 hours. YIPPY!!!!!!!!!!!!!!!!
Re: Confused
1. Turn on the car.
2. Push the DCCD button on the center console and the DCCD 'AUTO' light will go out on the dash.
3. Roll the roller switch back until the green square is the the lowest position on the instrument cluster.
Each roll on the switch moves the bias 5%. The lowest position is 35% to the front and 65% to the rear (35/65). Do not set the bias at 50/50 or lock on pavement. It will cause the drivetrain to chatter when you turn.
As for the tire pressure, you've got two people recommending different things. I have been told that Subaru's take from a 50%/50% to 55%/45% front/rear to tire pressure bias. I could be wrong but it was coming from a guy who was first in his class (STS). Also with the tire pressures I recommended, my codrivers and I were able to get first in ST1-AS and respectively close to the FTD. It could be that they we are either really good drivers and/or the tire pressure is ideal. Honestly, I hope that TR11 is right (that my recommendation is wrong) because that means I will be faster in the car than I have been so far. Let me know what tire pressure you settle on.
2. Push the DCCD button on the center console and the DCCD 'AUTO' light will go out on the dash.
3. Roll the roller switch back until the green square is the the lowest position on the instrument cluster.
Each roll on the switch moves the bias 5%. The lowest position is 35% to the front and 65% to the rear (35/65). Do not set the bias at 50/50 or lock on pavement. It will cause the drivetrain to chatter when you turn.
As for the tire pressure, you've got two people recommending different things. I have been told that Subaru's take from a 50%/50% to 55%/45% front/rear to tire pressure bias. I could be wrong but it was coming from a guy who was first in his class (STS). Also with the tire pressures I recommended, my codrivers and I were able to get first in ST1-AS and respectively close to the FTD. It could be that they we are either really good drivers and/or the tire pressure is ideal. Honestly, I hope that TR11 is right (that my recommendation is wrong) because that means I will be faster in the car than I have been so far. Let me know what tire pressure you settle on.
Originally posted by Money Verone
I just dont understand the DCCD. Whats what? If your saying 35/45 where is that on the indicator thing? Do me a favor and exlain it in light numbers, like "one light down from lock", or something like that. Sorry for being a bonehead. Thanks. Auto-X in 5 hours. YIPPY!!!!!!!!!!!!!!!!
I just dont understand the DCCD. Whats what? If your saying 35/45 where is that on the indicator thing? Do me a favor and exlain it in light numbers, like "one light down from lock", or something like that. Sorry for being a bonehead. Thanks. Auto-X in 5 hours. YIPPY!!!!!!!!!!!!!!!!
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Re: Re: Confused
Originally posted by markpaco
1. Turn on the car.
2. Push the DCCD button on the center console and the DCCD 'AUTO' light will go out on the dash.
3. Roll the roller switch back until the green square is the the lowest position on the instrument cluster.
Each roll on the switch moves the bias 5%. The lowest position is 35% to the front and 65% to the rear (35/65). Do not set the bias at 50/50 or lock on pavement. It will cause the drivetrain to chatter when you turn.
1. Turn on the car.
2. Push the DCCD button on the center console and the DCCD 'AUTO' light will go out on the dash.
3. Roll the roller switch back until the green square is the the lowest position on the instrument cluster.
Each roll on the switch moves the bias 5%. The lowest position is 35% to the front and 65% to the rear (35/65). Do not set the bias at 50/50 or lock on pavement. It will cause the drivetrain to chatter when you turn.
Rolling the bias switch all the way down to the lowest setting will set the DCCD center diff to full open providing zero axle bias. This is indicated as being the green oval 'O' at the bottom most position.
Actually you want to set the control to the last triangle of the four which will be bounded in green in order to gain a 35/65 rear bias.
- Janq
Re: Re: Re: Confused
Originally posted by Janq
Correction.
Rolling the bias switch all the way down to the lowest setting will set the DCCD center diff to full open providing zero axle bias. This is indicated as being the green oval 'O' at the bottom most position.
Actually you want to set the control to the last triangle of the four which will be bounded in green in order to gain a 35/65 rear bias.
- Janq
Correction.
Rolling the bias switch all the way down to the lowest setting will set the DCCD center diff to full open providing zero axle bias. This is indicated as being the green oval 'O' at the bottom most position.
Actually you want to set the control to the last triangle of the four which will be bounded in green in order to gain a 35/65 rear bias.
- Janq
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No worries.
Everyone seems to forget about the full open setting.
I haven't tried yet but I would think that a front bias would be most advantageous for auto-x use rather than rear.
But then with zero bias set the axles can both do their thing without input or affect on the chassis (?).
Folks will have to play around with the various settings to see what works best under what conditions and at what nominal speed.
- Janq
Everyone seems to forget about the full open setting.
I haven't tried yet but I would think that a front bias would be most advantageous for auto-x use rather than rear.
But then with zero bias set the axles can both do their thing without input or affect on the chassis (?).
Folks will have to play around with the various settings to see what works best under what conditions and at what nominal speed.
- Janq
Thread Starter
Registered User
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Joined: Jul 2003
Posts: 100
From: Mississippi
Car Info: 2004 STi Silver/Gold
Auto-X Info
Well i raced today and did good. Hears what ive learned so far.
I had a WRX and now have and STi. I was very good with the WRX, placed first in my area last race. Im learning the STi now.
Ran it at 40 front and 34 rear all 5 times with the DCCD on AUTO. This felt pritty good and quite fast. I cant emagine running the tire pressures at the higher numbers i see hear. But like i said im learning the STI. (Lots to learn)
I think i thought the car was sliding on over inflated tires, but what it it was actully doing was a "push" through the turns. I needed more overstear i believe. Im confusing myself if it means anything.
So i believe i need to do exactly what you mentioned above to solve this problem. Cool. Will race in 3 weeks try again.
Tip of the day:
USE THE HELL OUT OF THE ABS WHEN DOING AUTO-X, ITS INCREDIBLE.
I had a WRX and now have and STi. I was very good with the WRX, placed first in my area last race. Im learning the STi now.
Ran it at 40 front and 34 rear all 5 times with the DCCD on AUTO. This felt pritty good and quite fast. I cant emagine running the tire pressures at the higher numbers i see hear. But like i said im learning the STI. (Lots to learn)
I think i thought the car was sliding on over inflated tires, but what it it was actully doing was a "push" through the turns. I needed more overstear i believe. Im confusing myself if it means anything.
So i believe i need to do exactly what you mentioned above to solve this problem. Cool. Will race in 3 weeks try again.
Tip of the day:
USE THE HELL OUT OF THE ABS WHEN DOING AUTO-X, ITS INCREDIBLE.
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Re: Auto-X Info
Originally posted by Money Verone
Tip of the day:
USE THE HELL OUT OF THE ABS WHEN DOING AUTO-X, ITS INCREDIBLE.
Tip of the day:
USE THE HELL OUT OF THE ABS WHEN DOING AUTO-X, ITS INCREDIBLE.
Powerful stuff indeed.
- Janq
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AutoX Tire Pressures
Wouldn't running a lower rear tire pressure increase understear? Lowering the front pressures should increase the contact area of the front tires and increase grip and therefore reduce push. This seemed to work for me on a front drive car. Is it different with AWD?
I just picked up my STi yesterday and its my first AWD car.
I just picked up my STi yesterday and its my first AWD car.
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Currently I run 40F/34R on the street (maintaining a 6 psi bias as per the factory suggestion) and find understeer to be quite manageable. I'd go so far as to say almost neutral. Less than 40 up front increases understeer greatly.
I've not had my alignment checked & reset though as most everyone reports should be done.
Of course I'm not accouting for diff action as when the front Suretrak kicks in watch out, that motha sucka wants to oversteer in a big way.
Congrats on your new STi.
- Janq
I've not had my alignment checked & reset though as most everyone reports should be done.
Of course I'm not accouting for diff action as when the front Suretrak kicks in watch out, that motha sucka wants to oversteer in a big way.
Congrats on your new STi.
- Janq
Alignment out of the factory is to 'spec' which is for understeer and the tolerances are large. These are my before and after settings:
Front Before After
Camber (L/R) +0.11/-0.13 -1.03/-0.99
Toe (L/R) -0.21/+0.09 +0.05/+0.05
Caster (L/R) +4.65/+5.16 +4.69/+4.99
Rear Before After
Camber (L/R) -1.28/-1.31 -1.65/-1.70
Toe (L/R) +0.34/-0.08 +0.03/+0.07
The rear left toe was way out and the front left camber was positive!
Front Before After
Camber (L/R) +0.11/-0.13 -1.03/-0.99
Toe (L/R) -0.21/+0.09 +0.05/+0.05
Caster (L/R) +4.65/+5.16 +4.69/+4.99
Rear Before After
Camber (L/R) -1.28/-1.31 -1.65/-1.70
Toe (L/R) +0.34/-0.08 +0.03/+0.07
The rear left toe was way out and the front left camber was positive!