The Official Autocross Thread
#22
07-30-2009 | 07:37 PM
New Member
Joined: Jul 2009
Posts: 8
From: Springfield, MO
New to scca
I've done one event so far in my stock base 09 fit, and I loved it. I dont have a lot of money to put into my car so I want to stay in H stock class. Can I put 16" or 17" wheels on my car and still be in H stock. I know the sport comes with 16" so that should be fine.
Also how wide can I make the wheels and stay in H stock.
I had a ton of roll with my 15" wheels and stock tires, so getting bigger rims, with a small sidewall will help right?
and While I"m on my 15"s, anyone know a good tire pressure for the stock wheels and tires?
Also how wide can I make the wheels and stay in H stock.
I had a ton of roll with my 15" wheels and stock tires, so getting bigger rims, with a small sidewall will help right?
and While I"m on my 15"s, anyone know a good tire pressure for the stock wheels and tires?
#23
07-30-2009 | 07:52 PM
I've done one event so far in my stock base 09 fit, and I loved it. I dont have a lot of money to put into my car so I want to stay in H stock class. Can I put 16" or 17" wheels on my car and still be in H stock. I know the sport comes with 16" so that should be fine.
Also how wide can I make the wheels and stay in H stock.
I had a ton of roll with my 15" wheels and stock tires, so getting bigger rims, with a small sidewall will help right?
and While I"m on my 15"s, anyone know a good tire pressure for the stock wheels and tires?
Also how wide can I make the wheels and stay in H stock.
I had a ton of roll with my 15" wheels and stock tires, so getting bigger rims, with a small sidewall will help right?
and While I"m on my 15"s, anyone know a good tire pressure for the stock wheels and tires?
Using 15" wheels you can use street tires or R compound tires and remain in H stock class. 205/50-15 is common.
Tire pressure does vary but you can chalk the side walls to check for wear and roll over and use 36 to 38 psi in the front and 34 to 35 psi in the rear. Some drivers like higher pressures using street tires. Usually higher pressures in the front since lower pressures would allow for more rollover.
#24
07-31-2009 | 09:44 AM
New Member
Joined: Jul 2009
Posts: 8
From: Springfield, MO
Understeer
Thanks for the help, good thing I didn't buy bigger wheels already.
I have another question, when I'm racing I had a ton of understeer, some of this is probably because I'm just starting to race but is there anything I can do to my car to help reduce this? I think in H stock I can have a front anti roll bar, will this help reduce roll and understeer?
Thanks again
I have another question, when I'm racing I had a ton of understeer, some of this is probably because I'm just starting to race but is there anything I can do to my car to help reduce this? I think in H stock I can have a front anti roll bar, will this help reduce roll and understeer?
Thanks again
#25
08-04-2009 | 12:27 PM
Member
Joined: Jan 2008
Posts: 4,371
From: NC USA
15x6 rim is required, no changing that.
H stock requires stock suspension (or nearly so) and limits front and rear camber.
I have tried stock and modified front wheel drive cars on the track using identical new 15" wheels and track tires and found the lack of front negative camber to have- poorer handling and faster treadwear on the outside edges.
That is a big handicap in stock classes that don't allow for enough front negative camber in a front wheel drive car.
Using overly wide tires may not give you as good results as you expect.
Wider tires may not even fit without rubbing. Have you tried it in a Fit with stock suspension.
I know that 15x8 rim +36mm offset and Kumho V710 225/50-15 will fit in a Fit Sport with stock suspension. One driver only.
275/35-15 Hoosier tires will normally fit rims 9 to 11" wide. 6" wide rims would be? at the limit?? Not sure if I could get my trusty mechanic to agree to that install. Usually when you install wide tires on a narrow rim, the narrow rim will force the wide tread to have less surface to interact with the road so it is not the full tread you use.
To me, if you want to use a $244 tire for competition, you'd want to match it to a rim that will do it justice. Hoosiers are fast wearing and usually are optimal for about 6 events then performance degrades. If you are sponsored and get tires free that's different.
If I had 15x6 rims and wanted to use wider than recommended tires then I'd try-
225/45-15 - fits rims 7-8.5" wide and has a stiffer sidewall.
or
225/50-15 - fits rims 6-8" wide and has a taller tire diameter by 0.9" which is not as good for lowered gearing advantage.
vs.
205/50-15 - fits rims 5.5-7.5" wide
H stock requires stock suspension (or nearly so) and limits front and rear camber.
I have tried stock and modified front wheel drive cars on the track using identical new 15" wheels and track tires and found the lack of front negative camber to have- poorer handling and faster treadwear on the outside edges.
That is a big handicap in stock classes that don't allow for enough front negative camber in a front wheel drive car.
Using overly wide tires may not give you as good results as you expect.
Wider tires may not even fit without rubbing. Have you tried it in a Fit with stock suspension.
I know that 15x8 rim +36mm offset and Kumho V710 225/50-15 will fit in a Fit Sport with stock suspension. One driver only.
275/35-15 Hoosier tires will normally fit rims 9 to 11" wide. 6" wide rims would be? at the limit?? Not sure if I could get my trusty mechanic to agree to that install. Usually when you install wide tires on a narrow rim, the narrow rim will force the wide tread to have less surface to interact with the road so it is not the full tread you use.
To me, if you want to use a $244 tire for competition, you'd want to match it to a rim that will do it justice. Hoosiers are fast wearing and usually are optimal for about 6 events then performance degrades. If you are sponsored and get tires free that's different.
If I had 15x6 rims and wanted to use wider than recommended tires then I'd try-
225/45-15 - fits rims 7-8.5" wide and has a stiffer sidewall.
or
225/50-15 - fits rims 6-8" wide and has a taller tire diameter by 0.9" which is not as good for lowered gearing advantage.
vs.
205/50-15 - fits rims 5.5-7.5" wide
We had a little free time and decided to check out two Fits, one stock suspension and automatic and the other manual with lowered suspension. Both had been improved with suspension balancing to as close to neutral handling as reasonably possible. The two owners, both experienced A/Xers, traded cars on several runs..First we quickly found that 205/50x15 on 7" rims is faster than using 225/50 or 225/45 tires on both cars.Neither came close to Mini times. we had Kuhmos and BFG tires on hand to test.
Hoosiers are the fastest but make the Fit a little tipsy on fast sharp corners. The Hoosiers had that much 'grab' when initiating turns.
The lowered Fit was faster than the stock suspension primarily because its balancing with roll bars is better. The automatic is as much to blame as the lowered suspension with stiifer springs is to benefit.
Second, we finaklly decided that the manual is a trifle faster than the automatic.
Both cars were fun to hurl thru the cones but just lack enough power to really push. we did drive a stock 09 Fit during cool-down time and its massive understreer defeats any attempt at quickness. If there is just one thing to improve Fit handling it is to balance understeer/oversteer with antisway bars. Remember though that it is preferred to remove front understeer than tio add rear oversteer to balance handling. It is always better to add stiffer springs than overdo antisway bars.
cheers.
#26
08-11-2009 | 12:02 AM
Push My Button
Joined: May 2007
Posts: 4,997
From: Calgary, Alberta
Tire pressure does vary but you can chalk the side walls to check for wear and roll over and use 36 to 38 psi in the front and 34 to 35 psi in the rear. Some drivers like higher pressures using street tires. Usually higher pressures in the front since lower pressures would allow for more rollover.
When I lowered it down to 36psi front and 37psi rear for the next 3 events my runs felt a lot tighter and faster, but I slipped back like 8 positions consistently
Very bizarre, I am thinking that I am getting better runs with the higher pressures even though it makes the car a lot more squirrely and difficult to control. (I am running RE-11's, not R-comps though)
Last edited by Sugarphreak; 08-11-2009 at 12:14 AM.
#27
08-14-2009 | 06:26 PM
New Member
Joined: Jul 2009
Posts: 10
From: Fremont, CA
Loose is fast... 
But, seriously you do want it to oversteer some. Autox is usually such a tight course that you want the rear to come around to some degree. That way you can get the turn done sooner and get back on the gas sooner.
BTW, on an ST '89 civic RE-11's like to be around 40-44psi. Heavier car (fit) probably works with 44psi up front (depending on surface). Maybe try 34 psi out back. If it is too much of a handful, let the rears build up some pressure and maintain 40-44 up front.
Good luck.
But, seriously you do want it to oversteer some. Autox is usually such a tight course that you want the rear to come around to some degree. That way you can get the turn done sooner and get back on the gas sooner.
BTW, on an ST '89 civic RE-11's like to be around 40-44psi. Heavier car (fit) probably works with 44psi up front (depending on surface). Maybe try 34 psi out back. If it is too much of a handful, let the rears build up some pressure and maintain 40-44 up front.
Good luck.
Intake manifold put me into FSP, but I do well in this class
I have been wrestling with this myself a lot lately, I ran a few events with about 38psi front and 40psi in the rear and it felt pretty loose and twitchy... but I placed 11th overall. I had run those kinds of pressures when I was doing the race school as well and I even posted FTD on the first day.
When I lowered it down to 36psi front and 37psi rear for the next 3 events my runs felt a lot tighter and faster, but I slipped back like 8 positions consistently Very bizarre, I am thinking that I am getting better runs with the higher pressures even though it makes the car a lot more squirrely and difficult to control.
(I am running RE-11's, not R-comps though)
I have been wrestling with this myself a lot lately, I ran a few events with about 38psi front and 40psi in the rear and it felt pretty loose and twitchy... but I placed 11th overall. I had run those kinds of pressures when I was doing the race school as well and I even posted FTD on the first day.
When I lowered it down to 36psi front and 37psi rear for the next 3 events my runs felt a lot tighter and faster, but I slipped back like 8 positions consistently
Very bizarre, I am thinking that I am getting better runs with the higher pressures even though it makes the car a lot more squirrely and difficult to control. (I am running RE-11's, not R-comps though)
#28
08-16-2009 | 02:27 AM
Push My Button
Joined: May 2007
Posts: 4,997
From: Calgary, Alberta
Sounds like a plan, I will give it a try and see how it feels and performs. Looks like I might be able to get a camber kit in before my next event as well which should help too.
Just saw some pics somebody took from that weekend, was a good one of my car in there. hehe, I see my co-pilot ASIMO flying around in the corners pretty good.
Just saw some pics somebody took from that weekend, was a good one of my car in there. hehe, I see my co-pilot ASIMO flying around in the corners pretty good.
Last edited by Sugarphreak; 08-16-2009 at 02:30 AM.
#30
08-21-2009 | 12:38 PM
On fast courses, I have pressures setup to provide an extremely loose rear end. What I like to do is throw the rear end around the corner fast enough to almost break it loose at turn-in, then brake mid-apex to send weight to the front outer wheel. It breaks the rear inside free, and then the entire rear end.
It's rather complicated to explain, but easy to do in practice.
If you take a look at the really fast FWD cars, they all run stiff rear setups, and it's not uncommon for them to lift rear wheels.
It's rather complicated to explain, but easy to do in practice.
If you take a look at the really fast FWD cars, they all run stiff rear setups, and it's not uncommon for them to lift rear wheels.
#31
08-24-2009 | 04:29 PM
Push My Button
Joined: May 2007
Posts: 4,997
From: Calgary, Alberta
Bla, I got killed this weekend on the morning runs... got lost on all the official ones
Afternoon event wasn't much better, but I pulled out a half decent one on course which was good enough for 2nd place in the rookie championship.
Car ran great, felt really planted and I could have probably powered it through a lot harder than I did... but the mental side is what was killing me... damn multi-lap figure 8's w/ reverse course changes kept throwing me off.
Afternoon event wasn't much better, but I pulled out a half decent one on course which was good enough for 2nd place in the rookie championship.
Car ran great, felt really planted and I could have probably powered it through a lot harder than I did... but the mental side is what was killing me... damn multi-lap figure 8's w/ reverse course changes kept throwing me off.
Last edited by Sugarphreak; 08-24-2009 at 04:31 PM.
#32
08-24-2009 | 04:33 PM
No kidding. Stupid courses where you go through the same gate 3 times in different directions......
#33
08-24-2009 | 07:25 PM
Member
Joined: Nov 2006
Posts: 450
From: Detroit
Thanks for the help, good thing I didn't buy bigger wheels already.
I have another question, when I'm racing I had a ton of understeer, some of this is probably because I'm just starting to race but is there anything I can do to my car to help reduce this? I think in H stock I can have a front anti roll bar, will this help reduce roll and understeer?
Thanks again
I have another question, when I'm racing I had a ton of understeer, some of this is probably because I'm just starting to race but is there anything I can do to my car to help reduce this? I think in H stock I can have a front anti roll bar, will this help reduce roll and understeer?
Thanks again
But just for information, on a FWD car with a Front placed engine.
A larger front anti roll bar will increase understeer.
A smaller front anti roll bar will decrease understeer.
As a matter of fact I heard some people actually remove the Front sway bar all together for Auto X... Or they just remove one link basically disconnecting the sway. It make the front end move around a lot and makes the rear really stiff in comparasion, basically makes the rear slide all over the place, but it makes it easier to slide around cones.
I race ST class, So i just used the progress RSB and Dunlop Z1 Star Specs. Tire Help A LOT with understeer, but don't expect to much life out of them.
#34
08-24-2009 | 10:39 PM
I dunno, you can make the rear of the fit slide pretty easily to begin with, I wouldn't remove a front sway.
Yes, in Stock you are allowed to substitute or remove any front anti-sway. You can't do anything to the rear though.
Yes, in Stock you are allowed to substitute or remove any front anti-sway. You can't do anything to the rear though.
#35
08-26-2009 | 09:04 AM
Any type wheel may be used provided it complies with the following:
it is the same width and diameter as standard, and as installed
(including wheel spacers if applicable) it does not have an offset
more than +/- 0.25 inch from a standard wheel for the car. The
resultant change in track dimensions is allowed.
it is the same width and diameter as standard, and as installed
(including wheel spacers if applicable) it does not have an offset
more than +/- 0.25 inch from a standard wheel for the car. The
resultant change in track dimensions is allowed.
Please stop spreading misinformation and read the rules. Kthx.
#36
08-26-2009 | 04:52 PM
Wrong. You can use a 16x6 wheel on a base.
Which means you can take your pick between 15x5.5 or 16x6, because you can mix and match between different trim levels of the same car, given that classification list does not make a distinction between those models.
Please stop spreading misinformation and read the rules. Kthx.
Which means you can take your pick between 15x5.5 or 16x6, because you can mix and match between different trim levels of the same car, given that classification list does not make a distinction between those models.
Please stop spreading misinformation and read the rules. Kthx.
#37
08-26-2009 | 05:27 PM
You can swap honda civic EX parts onto a honda civic DX, so why would that not hold true in this case?
Base and Sport are different trim levels, different factory configurations. You could build to order a base fit with the Sport wheels on it, and it'd roll off the truck with those sport wheels. Is that not the intent of the law?
Base and Sport are different trim levels, different factory configurations. You could build to order a base fit with the Sport wheels on it, and it'd roll off the truck with those sport wheels. Is that not the intent of the law?
#38
08-26-2009 | 05:34 PM
I went on to the SCCA forums to ask about several things about the STS now ST class and they told me if I don't see it specifically in the rule book it's not allowed. If you see dx ex civics running different set ups just be glad they got away with it. But, it's really up to your local SCCA to set the law. If in doubt start there.
#40
08-26-2009 | 06:44 PM
Don't get mad just make sure you check with your local SCCA first but, I'm pretty sure Mini's going to be right in most areas.
Anyway there's no handicap running any of the two sizes running r compounds in HS class. 15s lighter more forgiving, 16s stiffer sidewalls better in slaloms. Good luck, and the main thing have fun!!!!!!