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> First Autocross and tire question
mister2
post Oct 2 2013, 08:57 AM
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Group: Autocrosser
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From: Tucson
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Long story short, I am going to autocross a 2004 Sentra on October 20. This will be a completely stock 1.8s with automatic. Like I said, long story short.

If you have AX'd a B15, I just have a few questions:

1. Weak/failure points when under racing stress
2. Tire pressure recommendation. I've got 3 year old Potenzas (RE960AS)
3. Tires being the biggest single factor, IME, are RE-11a and Toyo R888s legit for H Stock? Direzza IIs? BFG Rivals? Still on this topic, my stock wheels are 15 x 6. Anyone have an opinion as to whether they will efficiently mount a 195/50 tire?

The last thing I want to do is to be spreading Oil-Dri on the track and picking up engine and tranny parts, so any help is appreciated.

Thanks in advance. Slam if you want, but at least say something constructive, too!

MR2


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Victor Lim
BS 1999 Corvette FRC
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Wheelbuilder
post Oct 2 2013, 09:38 AM
Post #2





Group: Autocrosser
Posts: 65
Joined: 17-July 11
From: Tucson
Member No.: 26271



1. Weak/failure points when under racing stress- This an autocross and not a track event. Your car will only see hard driving for around 45 seconds. If you car is in good mechanical condition for the road it can do an autocross. Check wheel bearings for any play and make sure your battery is bolted down, otherwise if your car can be accelerated from 0 to 40 and back to 0 without problems than it can be autocrossed.
2. Tire pressure recommendation. I've got 3 year old Potenzas (RE960AS)- Start with the stock pressures listed in the door jam and raise and lower from there. There is no way to know what the ideal pressure is for your car, driving style and tires without just trying things when you run.
3. Tires being the biggest single factor, IME, are RE-11a and Toyo R888s legit for H Stock? Direzza IIs? BFG Rivals? Still on this topic, my stock wheels are 15 x 6. Anyone have an opinion as to whether they will efficiently mount a 195/50 tire?- Yes, Yes, Yes and Yes 195's will work just fine on 15x6's.




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Troy Watson
2005 350Z Ultra Yellow
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Clint Child
post Oct 2 2013, 09:41 AM
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Group: AZ Region Member
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Howdy, welcome to the forum and autox.

Here is a video that outlines a typical day of autox, the scenery will be different in Marana, but the basic concepts will be the same. http://www.youtube.com/watch?v=olepdvcCEzs

As far as tire pressure goes, a good starting point is 5 psi over what your car requires normally (pressures listed in the drivers door area). That should keep your tires from rolling over drastically and you can adjust if needed later.

If you run the HS OPEN class all of those tires would be legal. If you decide to run HS in the "Street" category that Border region offers, then the Toyo R888's would not be legal, but the other tires you mentioned are. The Street category used to require a tire with at least a 140 treadwear rating and I believe it is now 200, but not positive. That being said all the tires you mentioned are 200 TW besides the R888 which is 100 TW.

As far as getting your car ready, top off all your fluids if needed, make sure the battery is secured well, and take any loose objects out of the car.

(one more side note - forum rules state you need to list your real name somewhere, either in your forum name or signature line)


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Clint's YouTube channel Lots and lots of autox videos.

VTEC'n again
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brado
post Oct 2 2013, 11:43 AM
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Group: AZ Region Member
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Previous comments are all 100% correct. I'll just add that I started out in a B15 many years ago. Many others have been in them over the years. The Spec-V was especially popular when it came out. Mine saw about 2-3 years of autocrossing before being retired to strictly daily driver duties. For a data point it is still going strong at 246k miles and gets me to work everyday. Everything but the AC compressor and wheels are still original. Besides the usual maintenance items belts/hoses, motor mounts, brake pads, etc. The original clutch, wheel bearings, and everything else are still on there.

No idea how the 1.8 or the auto will do at an autocross, but follow the above advice and I would not worry about it.


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If you're having understeer problems I feel bad for you son. I got 99 problems, but push ain't one.
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renfield90
post Oct 2 2013, 01:21 PM
Post #5





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Heat can be a problem for the automatic. Keep your gear selector in L or 2 to minimize downshifting (which is where most of the heat comes from), keep the car running in grid with the hood up, and you'll be fine.

I autocrossed an automatic for about 7 years. Motor gave out before the transmission did (and it did so on a full track, not an autocross).


--------------------
Manfred Reysser
2001 Celica GT - gone to the clearing at the end of the path
2013 FR-S

"As long as my car goes I drive it. I like racing to the limit, first and last." - Gilles Villeneuve
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mister2
post Oct 2 2013, 04:37 PM
Post #6





Group: Autocrosser
Posts: 110
Joined: 23-August 13
From: Tucson
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Thanks for your inputs, gents. Especially on tire legality and automatic performance. Good info, especially on how to keep the tranny cool. The tires, given they really need their own set of wheels, are not cheap, so it will probably come at a later stage of this AX discovery season.

Hope to see you on the 20th!


--------------------
Victor Lim
BS 1999 Corvette FRC
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Fuzzy_Wuzzy
post Oct 20 2013, 06:14 PM
Post #7





Group: Autocrosser
Posts: 83
Joined: 1-November 10
From: Tucson, AZ
Member No.: 2727



QUOTE (mister2 @ Oct 2 2013, 05:37 PM) *
Thanks for your inputs, gents. Especially on tire legality and automatic performance. Good info, especially on how to keep the tranny cool. The tires, given they really need their own set of wheels, are not cheap, so it will probably come at a later stage of this AX discovery season.

Hope to see you on the 20th!


Well, what did you think?


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Dan Gurney
2007 CTS-V -- ESP CAM... Sure 245 tires are all a 3900 lb car needs
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mister2
post Oct 21 2013, 05:13 AM
Post #8





Group: Autocrosser
Posts: 110
Joined: 23-August 13
From: Tucson
Member No.: 140721



QUOTE (Fuzzy_Wuzzy @ Oct 20 2013, 06:14 PM) *
QUOTE (mister2 @ Oct 2 2013, 05:37 PM) *
Thanks for your inputs, gents. Especially on tire legality and automatic performance. Good info, especially on how to keep the tranny cool. The tires, given they really need their own set of wheels, are not cheap, so it will probably come at a later stage of this AX discovery season.

Hope to see you on the 20th!


Well, what did you think?



My very first participant impressions:

1. Great community!

2. I would like to have a famous name to emulate, too.

3. Hahaha. Our venerable, faithful Sentra looked out of place on the grid. It stood tall, real tall, on its worn, all-weather 60 series tires while everyone else looked lowered with 50 or lower series sidewalls. In reality, everything about it ran dull and bland, but a balanced dull and bland, so the times were somewhat decent for a car with original suspension, engine and brakes as it came from some dealer in VA, almost 10 years ago. Oh, did I mention it's an automatic? Watch out, Jim Hall and Chaparral! First thing it could use is tires, but I won't go into that because right behind the tires is driver improvement. I'm working on it.

4. PAX is a godsend. But I think my disabled license plate deserves a bonus.

5. I think I want to do it again!

Thanks for asking. How did you do?


Victor


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Victor Lim
BS 1999 Corvette FRC
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JasonP
post Oct 23 2013, 12:07 AM
Post #9





Group: Autocrosser
Posts: 133
Joined: 18-December 12
From: Tucson, AZ
Member No.: 73856



Congrats on the first event. And if you think your Sentra stood out, you should have seen me at the last event I did, which thus far was my first and only event. I was in an 88 Accord with Nitto's mounted on a set of Rotas. Quite hysterical if you ask me.

And do it again. It's addicting for sure!


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Jason Prock

1992 Honda Civic CX - HS class for the moment. ;)
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Brock
post Oct 23 2013, 07:47 AM
Post #10





Group: Autocrosser
Posts: 1227
Joined: 14-July 08
From: Chandler
Member No.: 1339



QUOTE (mister2 @ Oct 21 2013, 05:13 AM) *
because right behind the tires is driver improvement. I'm working on it.


Tires would be more immediately noticeable, but I would recommend staying on your current tires until they're dead. Running less grippy tires will amplify driver errors and help you develop faster as a driver.

Interesting people are saying to run factory recommended tire pressures.
When I started, people said to run high pressures (start from maximum printed on the tire and drop from there) to keep the tire off its sidewall.
Another interesting effect that could slightly benefit a stock car is that tire pressures can allow you to adjust the effective spring rates by ~5%. Of course, this compromises the footprint.
When my Impreza was stock I ran max pressure in the rear to help it rotate.


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Brock Palmer
WTF is a PAX?
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Littlezeke77
post Oct 23 2013, 09:53 AM
Post #11





Group: Steering Comm., voting member
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From: Tempe, AZ
Member No.: 61013



QUOTE (Brock @ Oct 23 2013, 06:47 AM) *
QUOTE (mister2 @ Oct 21 2013, 05:13 AM) *
because right behind the tires is driver improvement. I'm working on it.


Tires would be more immediately noticeable, but I would recommend staying on your current tires until they're dead. Running less grippy tires will amplify driver errors and help you develop faster as a driver.

Interesting people are saying to run factory recommended tire pressures.
When I started, people said to run high pressures (start from maximum printed on the tire and drop from there) to keep the tire off its sidewall.
Another interesting effect that could slightly benefit a stock car is that tire pressures can allow you to adjust the effective spring rates by ~5%. Of course, this compromises the footprint.
When my Impreza was stock I ran max pressure in the rear to help it rotate.


+1 . I too ran stock tires for the first several events and was able to play with the pressures to find the sweet spot. I used the chalk method to see just how much they were rolling or NOT rolling onto the sidewalls. I know this method isn't perfect, but it's a good method for a newbie to use to see a visual of what the tire is doing during runs. With those stock tires my car understeered horribly, so I put those rear pressures up quite high to help it rotate. I still have to run 48F, 52R on my RS3's and Rivals, but on the stock Kumhos I had I think I ran about 45F, 55R or some crazy differential like that. Granted I think your Sentra is about 500lbs lighter than my car, so that's going to affect things as well. Either way, have fun with all the experimenting and we're glad to have you out there with us!


--------------------
Derek Bellamy
Assistant Director & Treasurer
1992 "Bass Boat Sparkly Red" Miata (STS)
2005 Scion tC (STF)
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Crarrs
post Oct 23 2013, 02:34 PM
Post #12





Group: Autocrosser
Posts: 248
Joined: 27-September 11
From: Surprise, AZ
Member No.: 36121



QUOTE (Brock @ Oct 23 2013, 07:47 AM) *
When I started, people said to run high pressures (start from maximum printed on the tire and drop from there) to keep the tire off its sidewall.



In my experience, this worked for me and is the same advice I'd give because newer drivers tend to have overexuberant corner entries that lead to understeer and sidewall scuffing...


--------------------
Chris Markmann
2004 Mazdaspeed MX-5 - The underprepped BSP project
2010 Mazdaspeed3 - STX Battle Wagon Re-stockified and SOLD
2015 BMW M235i - The one I promised not to mod
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mister2
post Oct 23 2013, 03:06 PM
Post #13





Group: Autocrosser
Posts: 110
Joined: 23-August 13
From: Tucson
Member No.: 140721



Thanks for chiming in, folks.

I started at 42#s in front (for lack of any benchmarks) and between sorting out driving errors and compensating for the warming track and spraying the radiator (and tranny cooler) with water between runs (never shut the engine off), I managed to get down to LF-42#s, RF-40#s and kept the rears at around 35#s. I guess that was the old fashioned way to stagger tire pressures to encourage rotation, which I sensed in some of my runs, though with 5 runs, everything's a blur. I DNS'd 4 of the 5 TO runs because I needed the car to get to work the next day. Turns out the car was OK, just an anxious owner. More TOs might have allowed further experimentation. BTW, I used shoe polish and it showed I never even got close to the sidewall at the pressures I was running. Is the idea to go as low as possible without getting on the SWs?

I know, they say take notes. I either need to talk into the videocam or have a secretary biggrin.gif

I may run the rest of the season on my tires (thanks for advice along the same lines) and save the money for something other than a 1.8 liter automatic full-race grocery getter. Maybe I'll try going higher than 42 in the rear and down to ~38 for the fronts next time. No doubt the car's faster than I am, as it stands.

While I've got you gents on the line, could anyone comment on a possible strategy to run in STF (which specifies the SpecV, but not the 1.8s) because it's got a more favorable PAX compared to HS (.795 vs .804)? Principally, ST may allow more tuning than HStock.

Thanks in advance.

Victor


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Victor Lim
BS 1999 Corvette FRC
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Brock
post Oct 24 2013, 07:44 AM
Post #14





Group: Autocrosser
Posts: 1227
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From: Chandler
Member No.: 1339



QUOTE (mister2 @ Oct 23 2013, 04:06 PM) *
...save the money for something other than a 1.8 liter automatic full-race grocery getter
[snip]
While I've got you gents on the line, could anyone comment on a possible strategy to run in STF (which specifies the SpecV, but not the 1.8s) because it's got a more favorable PAX compared to HS (.795 vs .804)? Principally, ST may allow more tuning than HStock.


If you plan on selling it in the near future, leave it stock. Mods tend to decrease the sale value of a car.
However, if you plan to keep it for a while (continue autocrossing it or use it as a second car), go ahead and make it you own, but don't do it for PAX. The reason HS PAX is harder is because it assumes race tires (and crazy shocks)... I believe the race tire allowance is going away soon though, so PAX will eventually be adjusted.
You can run a stock car in its ST class if you wanted. Locally, we have a competition category for "stock" cars on street tires though, so there's not much reason to go to ST other than wanting to mod your car.
If you wanted to start adding parts, you can still stay in the "stock" class (which is not at all stock). You can do a rear sway bar and a cat-back exhaust (and crazy, custom valved shocks, but those cost as much as a different car).


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Brock Palmer
WTF is a PAX?
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mister2
post Nov 9 2013, 12:42 PM
Post #15





Group: Autocrosser
Posts: 110
Joined: 23-August 13
From: Tucson
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Some follow up questions, please:

1. For Stock classes (which as stated is NOT stock, but that's another discussion), the rules say original wheels' (no up/back-dates) diameter and width. What's the local enforcement on this as I have found wheels that fit my sucky 4 x 114.3 BCD but are 6.5 (vs. 6.0 original). Good to go?.. or Not...

2. Also, my understanding is that modifications are allowed for front sway bars, but the rules appear silent on the rear sway bar, which my car came without, so fitting one looks like a reach, from where I sit.

Thanks for your time.

MR2


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Victor Lim
BS 1999 Corvette FRC
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SMeyers
post Nov 9 2013, 05:56 PM
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Group: Steering Committee
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QUOTE (mister2 @ Nov 9 2013, 01:42 PM) *
Some follow up questions, please:

1. For Stock classes (which as stated is NOT stock, but that's another discussion), the rules say original wheels' (no up/back-dates) diameter and width. What's the local enforcement on this as I have found wheels that fit my sucky 4 x 114.3 BCD but are 6.5 (vs. 6.0 original). Good to go?.. or Not...

2. Also, my understanding is that modifications are allowed for front sway bars, but the rules appear silent on the rear sway bar, which my car came without, so fitting one looks like a reach, from where I sit.

Here you go....

1. Not. Stock class wheels must be of the same diameter and width for the rest of this year. NEXT year Stock/Street wheels may change the
DIAMETER by + 1" or - 1", but not width.

2. For the past year, as well as next year, you may change front OR rear sway bars, but not both.

Anything else? smile.gif


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Scott Meyers
2006 Mazda3S .......(Really just a Miata with four doors and a trunk......and +500#)
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mister2
post Nov 9 2013, 11:02 PM
Post #17





Group: Autocrosser
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From: Tucson
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Scott, I appreciate your quick response.

1. Based on new info, running my 15 x 7 wheels now keeps my 2004 Nissan Sentra 1.8s in H Stock. I have found a 2004 option package includes sunroof (which I have) and alloy 15 x 7s.

2. I am assuming "you may change front OR rear sway bars, but not both" means I can install a rear sway bar where there was none, as long as I leave the front one stock. Nice thing about this reversible mod is that it's easy enough to reconfigure the car to original for possible resale.

Thanks,
Victor

Edited 11-14-13: Option package details in text.


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Victor Lim
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mister2
post Dec 1 2013, 03:22 PM
Post #18





Group: Autocrosser
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Second event!

Same driver, new RE11As. Seemed less understeering in the corners, could go into oversteer if provoked. However, over the edge, meaning, coming into the corner wayyy too hot, it's still terminal understeer. But BIG improvement over DD tires.

Here's another thing about the RE11As: they're sensitive to temperature. My all-weather 760AS Potenzas ran the same temps, or close to them the entire first autocross event. So here's the hilarious part of the day - when I was checking out which tires to buy, I read in various posts that RE11s are sensitive to temperature and it's important they not get greasy, and I had the As, check. Since I ran in the afternoon, I had tire temps in the back of my mind and when I saw people already starting to spray their tires, well, the monkey-see, monkey-do went into effect. I sprayed and only afterwards remembered how I took a row of cones out on cold tires. I could only hope my tires would dry, let alone stay warm enough. Nope. This time, it was the row of cones outside the sweeper. No sense flogging the car at that point. I called it a day. And myself, stupid.

Ain't this fun, though?


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Victor Lim
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SMeyers
post Dec 1 2013, 04:08 PM
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I ran a little toe-out in the front of my Sentra at autocrosses; about 1/8" to 1/4".

I'd set at the track, and then restore to stock before heading home. Helped the turn-in some.


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Scott Meyers
2006 Mazda3S .......(Really just a Miata with four doors and a trunk......and +500#)
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Dave Rock
post Dec 2 2013, 12:13 PM
Post #20





Group: Autocrosser
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QUOTE (mister2 @ Dec 1 2013, 03:22 PM) *
However, over the edge, meaning, coming into the corner wayyy too hot, it's still terminal understeer.


There is no tire that will fix that. The only way to fix terminal understeer is with the fixing the nut behind the wheel. Brake early then power out of a corner.


--------------------
Amsoil Dealer
So many choices, not enough events.
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2002 MR2 Spyder - STR - 2014 Mineral Wells ProSolo STR winner
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