This is a discussion on My STX Project / Build thread (56k warning!) within the Motorsports Talk forums, part of the Community - Meet other Enthusiasts category; Really nice thread here, I didn't know it existed until you linked it in the nasioc thread So overall my ...
Really nice thread here, I didn't know it existed until you linked it in the nasioc thread
So overall my setup is about 8x wimpier than yours... but I've been mucking around with what adjustments I have this season and am learning that this chassis is really quite sensitive to changes. I can go from a terminal-understeer setup to a chronic-oversteer setup with very few tweaks.
Anyway, do you guys running the big front bars suffer from inner front wheelspin on exit? Even in my most rear-biased stiff setting, I've never noticed rear wheelspin... but I can break that front inner loose quite easily exiting turns. My thinking was that if I'm going to slip a wheel on exit, I'd prefer it to be the rear since 1) we have a rear LSD and 2) you're transferring weight back there during accel so it would gather grip more quickly than the front which 1) has an open diff and 2) is getting lighter under accel...
2006 WRX Wagon
I have a WL 24-6mm set to 26mm in summer and I always get excessive inside wheel spin. Right handers are much worse than left handers so I definately prefer the course to run in a general counter-clockwise direction. This was with a Helix rear sway(21mm) at full stiff, STi takeofs with Espiler GT springs(280f/230 rear.Originally Posted by Mind
I have noticed the same thing. Simply changing the ride height from 13.75/14.25 to 14/13.5 made the car go from awesome to suckReally nice thread here, I didn't know it existed until you linked it in the nasioc thread
So overall my setup is about 8x wimpier than yours... but I've been mucking around with what adjustments I have this season and am learning that this chassis is really quite sensitive to changes. I can go from a terminal-understeer setup to a chronic-oversteer setup with very few tweaks.
Well, with only one event on the latest revision it's hard to say, but it looks like my rear wheelspin problems are gone (maybe it was the change in ride heights that did it, or the stiffer springs are doing a better job preventing roll, so both tires are spending more time on the ground, or some combination of both?)
As for the front I have never had it to where you could peg the gas at exit before the wheels were straight again, and not get a little bit of spin. With all the camber and the lack of the front diff I don't know that it can ever be eliminated.
When it comes down to it - I don't claim to be smart or right or know much about suspensions - I just know what has worked for me. I can hypothesize but I make no claims as to its accuracy
I hear ya... I've read up a lot on suspension tuning and vehicle dynamics, but Strano's quote nailed it... it takes a lot of trial and error due to the infinite variations between setup and driving style. There has been a lot of great tech info/analysis on various forums, and while I think it's really cool and have a lot of appreciation for it, it gets back to just trying different things to see what gains the best result.When it comes down to it - I don't claim to be smart or right or know much about suspensions - I just know what has worked for me. I can hypothesize but I make no claims as to its accuracy
One thing I think I've noticed is that when I crank up the front rebound, the front end grips like crazy on exit and the inner wheel doesn't spin. But it also resulted in stock-susp-RE92-like understeer on sweeper entries.
2006 WRX Wagon
Event 11: TSCC @ ACU-4, Norfolk
This is an awesome venue for autocross. It's big and concrete and mostly flat, overlooking the ocean, but surrounded by hangars and hovercraft. The course was a fairly quick and fairly long. I finished 1st out of 8 in STX with a 49.9 but couldn't improve on that time even though I got it on my 2nd run.
Just to give you some idea of the site, here's a video from Tom Bleh's DSP car. As he goes out you can see the water in the background and then when he comes back you can see the hangars and hovercraft. Tom Bleh is freaking fast - this run was good enough for #1 PAX and almost FTD.
Tom Bleh DSP BMW 325i at TSCC ACU-4 June 2008
(does he ever brake?)
Since I was traveling 3 hrs there (and 4.5 hrs back - 95-N sucks!) I didn't change tires and ran on the RE01R's instead of the Yokos. I ran them at about 39/36 and thought they felt pretty damned good, but I was definitely not pushing as hard as I needed to be. I PAX'd 23rd out of 130something. A 49.0 instead would have bumped me to about 10th.
The short version is that the car does feel damned good again and I am leaving it the heck alone until the DC Region points events are over, or until I am statistically eliminated from winning STX for the season (which could be the next event, sadly).
There are a few things I would like to tinker with:
-Raising the front a little. It's at about 13.6" now - below the standard "14.0" recommendation but the control arms are still not parallel, presumably because of the Ground Control plates. Having spent two years on JIC's I know the "understeer from not enough travel" feel and I don't have that. However, going from 13.8" in the front to 13.6" made the ride quality on the highway noticeably worse - not bad, just worse. I'll probably have to raise the rear a little to keep the balance the same.
-Lubing the front camber plates. I may have to do this before then, but I do get some noises at low speeds.
-Figuring out the unholy clunk from the rear swaybar.
-Maybe a little less rear camber (i.e., closer to 0)
Event 12 (day 0): SCCA ProSolo @ Fedex Field
So for those of you who have never done a ProSolo, it goes something like this:
Friday: New-to-Prosolo program, tech, practice starts (you'll want to do a few of these to get a feel for it), and registration. There's food and some socializing too.
Saturday: 4 runs morning, 4 runs afternoon.
Sunday: 4 runs morning, bonus challenge, ladies challenge, street challenge?, super challenge
Practice starts went okay - first one sucked but the rest of them were good: 1.91 w/ .530, 1.87 w/ .540 and 1.93 w/ .640. 1.87 is the best I've ever gotten, which is nice considering my clutch feels like it could die at any minute :lol: Hey, free weight reduction.
The car weighed in at 3001 lbs with 1/8 of a tank and without me, disappointing since I thought I dropped more weight than that from last year. The scales at DC are never on a flat surface though so I'm not sure how seriously to take it.
Tomorrow, coursewalks and competition runs
good luck Sat/Sun! Pro Solo looks like so much fun, great for spectators as well (sadly not so for "regular" autox).
hope your clutch holds out
"Simplify and add lightness." - Colin Chapman
You're not corner balancing the car so the angle doesn't matter.
Also congratulations again on your trophy spot John.
This message printed on 100% recycled electrons.
looks like double congrats are in order- good job both you guys!
"Simplify and add lightness." - Colin Chapman
Ah. Yes, the FR corner (downhill) was definitely wayyy more than the FL.
Thanks! Bigger congrats to JR tho - 1.4 seconds behind Greg, but coned away .4 of that and can still pick up some time at the lights - that would put him right in the mix.looks like double congrats are in order- good job both you guys!
Full writeup later, it was a crazy weekend
john
Event 12 (day 1): SCCA ProSolo @ Fedex Field
OK, the parts I left out. There are two courses - left and right. In each heat (Saturday AM, Saturday PM, Sunday AM) you take two runs on each course. During those heats, you take your runs back to back to back to back - alternating sides. Since you are in a "hot" area you can't use water on your tires. If you're lucky enough to have a co-driver they can bleed air out of the tires as you roll up to the line, but that's about it.
Your best run from each side counts, and your time is the sum of those two runs. So if your best run on the left side on Saturday morning is a 35, and your best run on the right side is on Sunday morning and it's a 37, your total time is 72, no matter how many bad runs you had in between
The courses all start with a fairly long straightaway, so the AWD cars usually fare pretty well.
The forecast was calling for rain on Sunday, and possibly even rain late on Saturday. And you never know what's going to happen, so it behooves you to always have a decent set of runs to fall back on. You don't want to get caught not having a clean run on one of the courses.
STX was a class of 12 so there were 4 trophy spots. After coning away 5th last year in a class of 14 (5th being the last trophy spot) I had some level of confidence that I could trophy this year.
My car all stickered up
Saturday AM
My goal was to start off well and get in some good solid runs so I could spend the rest of the weekend driving "maximum attack" trying to eke out tenths.
For the first heat, the cars are lined up in their numerical order. Josh was #3 and I was #7, so we were at the front of the grid:
Our five minute warning turned into a one minute warning... in less than a minute. Crap! I did my first run on the right with only one glove on, Michael Jackson style, because I didn't have time to put the other one on.
I started on the right and ran a 30.660. This ended up being a reasonably good time for the right course. I then red-lit my next left side run, throwing away a 31.3 (which, taking into account the red light, may not have helped). My next run on the right course was slower (30.8?). With one run remaining on the left and the very-off-chance of rain in the afternoon I ended up with a clean 31.5.
After the first set of runs I was in 3rd, about .9 off of Greg and about three tenths off of JR. This is pretty much where I had hoped to be. Eric S in the black BMW was only a tenth off of me in 4th however, and there were some other very fast drivers that had not had good starts, so I knew that my Sat AM times were definitely going to be threatened.
Saturday PM
This time, since I was in 3rd place, I started out on the left course. This should have helped
I was still in 3rd at the end of the day, but now Jason Wong (co-driving Greg's car) was eight thousandths behind me. He threw down a 31.001 on the left course, which ended up being the 2nd-fastest time on the left in STX. Josh was closely behind him. If I remember right, slots 2-10 in STX were separated by less than a second.
I was in a good spot, but again knew that if it wasn't raining on Sunday I would have to find some time on one of the courses
Sunday AM
Once again I started out on the left first. Once again I couldn't improve. There were basically two killer spots on the left course - both were heavy braking zones into "gotta stay tight so you don't plow through the next element" left turns. I was consistently plowing out of the 2nd one, after not slowing the car down enough for it. (I wish I had video but I was having technical difficulties). My right-side run was no help either. My final left-side run started with a dismal .704 reaction time with a 2.083 60-foot. After launching well for most of the weekend, I was struggling. Again no help on the left - 6 tenths off my best run.
As I came in from that run, I heard over the radio that Eric Chiang had pushed himself into 3rd with a 31.239 on the left course. He was now about a tenth in front of me. I only had one run left - my 2nd run on the right course. I got it together with a good start - .597 RT with a 1.825 60-foot - and then found another .136 to put myself back into 3rd. Woohoo! Not as fast as I was hoping for, but it was a clutch run when I needed one at least. It ended up being enough to keep me in 3rd, even after the co-drivers ran. Since Subaru pays contingency for 3rd in class, this meant $50 from Subaru, my first contingency money ever.
When the dust had settled I was in 3rd, .333 off of JR and 1.7 seconds off of Greg (ouch). Of all the 3rd-place cars at the event, I was the second-furthest back from 1st place - only in FSP was the margin bigger. I was happy to be 3rd, but at the same time I didn't feel like I had driven very well. Three weeks prior, I had been .1 off of Josh at a regular Fedex Field event, without the drag start, and here, with a .5 advantage per side, I was only .1 faster overall.
I felt like I was having real problems getting the car to turn, especially out of the heavy braking zones. Even with all the stuff I have done to increase front grip I am still not 100% sure I am happy with the setup. Turn-in is good but the car does seem to push a little still. I'm going to re-assess after the July 13th Fedex event which will be a better picture of how things are (since it's a normal event without the drag start). If I feel that the car is plowing still, I will raise the rear pressures, add some rake or decrease camber in the rear to get the car to turn better (the rear bar is already on full stiff). The front may also be too low.
Wait, stop reflecting. The weekend isn't over yet!
("The text that you have entered is too long. Please shorten it to 10000 characters long." Doh!)
Last edited by ButtDyno; 07-06-2008 at 09:04 PM.
Bonus Challenge
At a ProSolo there are several Challenge events after the normal class competition is over. In a Challenge round, you are faced against someone who may be in an altogether different class. I'm not sure I'm explaining this right, but here goes: They give you a dial-in time, based on either your fastest time or the fastest time of your class winner. You stage against your opponent. The person whose dial-in time is slower goes first, and the clock starts for both cars. So if my dial-in was a 31.0 and I am running against an SS car whose dial-in was a 29.0, I would get the green light two seconds before they would. You run once per side, and whoever has the fastest time wins. It's complicated and I'm still not sure I understand it. The moral of the story is, it's head to head with some sort of handicapping involved. It works based on seeding, like the NCAA Basketball tournament. 1 vs 32, 2 vs 31, etc etc in a bracket.
If you red-light or DNF, you lose instantly - game over. If you cone, you're in trouble, but not out
The challenge events are as follows:
* Ladies Challenge: Top 8 Ladies class competitors.
* Super Challenge: All the class winners who competed in a class of at least 5 competitors. If that is not 32 people, they add the people who were the closest to 1st in their class. So if you are not within .1 of your class winner you will probably not make it. They bracket the 32 people and go until someone wins.
* Honda Tuner Challenge: This is either the top ST* cars in the Super Challenge, or the top Hondas in the Super Challenge. Can't remember.
* Bonus Challenge: Everyone who doesn't make the Super Challenge has the opportunity to put their name in a hat. Eight names are chosen and those people compete in the Bonus Challenge. It's like the Super Challenge but your dial-in is set off of your time, not your class winner's time.
The last two years at the DC Pro I had volunteered to work the course for the Challenge rounds so I really wanted to try competing in one this time. As luck would have it, my name was chosen!
In the quarterfinals I was paired against Chris Franson, driving Mike Shields' DSP BMW. I started out on the right side. I ran a 30.771 - about two tenths off of my best right course time - with a dismal .840 reaction time, but a 1.797 60 foot. If I had a reaction time in the 5's, it could have been my fastest time on the right. They announced that the BMW was winning after the first set of runs. Crap! We then switched sides - I went to the left course and he ran the right. I ran a 31.321 with a .575 reaction time and a 1.838 60-foot. This was almost a two-tenths improvement on my best left course time! As a bonus, the BMW coned his right-side run so I advanced. (According to my super rough calculations, I would have won anyway, but I'm not positive about that).
In addition to advancing, I had driven pretty well - beating my left course time by almost .2 and (ignoring the RT) beating my right side course time by a little bit, probably less than a tenth. Given a choice, I would much rather have had these be my Sunday AM runsAh well.
Here's a great series of shots from Team WTF?! of me launching against Chris:
Before the next round, Junior Johnson came up to me to give me some words of encouragement, reminding me to stick with it until the end. (His wife Diane had won the Ladies Challenge despite picking up a cone on her first run.)
In the semifinals, I drew Scott Hoffman in his HS RSX. Scott had won the Super Challenge in 2006 at the DC Pro so I knew it would not be easy. This time I started on the left. I ran a depressing 32.226 - almost a second slower than the left course run I had just run against Chris - with a .758 RT and a 1.894 60-foot, both subpar. They announced that I was down nine-tenths to Scott. So we switched and I ran on the right. I almost made it up, running a 30.946 - they announced that I lost by two tenths. Adding insult to injury, I lost this round at the lights - my right side run was even worse at the tree, with a .805 RT and a 1.918 60-foot. My clutch went out on me shortly after the event, so that's my excuse
Scott went on to win the Bonus Challenge. I was happy to have done as well as I did though, especially the strong runs in the quarters. As a bonus to the Bonus Challenge, Subaru pays contingency for it, too, so I should have another $200 from Subaru in addition to the $50 for finishing 3rd in class.
A big thanks for Evanthe, Josh, Junior, and everyone else who wished me luck - it means a lot
I then went out to my work assignment, shagging cones for the Super Challenge, which was won by Andy Hollis.
Closing
I still may make some minor setup changes. Overall I feel like the car is in good shape and should only need tweaks. As usual I just need to drive better. 3rd place is cool, but 1.7 seconds is a heck of a distance from 1st at a ProSolo. I definitely need to get my video setup fixed soon so that I can get better feedback about where I am making mistakes. In the heat of a Pro it's really difficult to remember every little detail, since you don't have much time between runs to contemplate!
Congrats to Greg and JR for driving so well, to Eric C and Josh for breaking up the AWD monopoly and really to everyone in STX for making it such a tight class. I know that several of the 2WD folks would kick my ass at a normal event
Next national event is the Finger Lakes ProSolo at the end of July, with three local events between now and then.
Congrats! A trophy is a trophy.
Love the water mark on the photos. WTF?
Cones don't count at Hillclimbs.
nice writeup!
are the lights just like at a drag strip? what's your technique for the launch?
definitely sounds like fun
"Simplify and add lightness." - Colin Chapman
I've never been to a drag strip, but I think so. Two staging lights and then yellow-yellow-yellow-green with a red light if you leave too early.nice writeup!
are the lights just like at a drag strip? what's your technique for the launch?
definitely sounds like fun
As for technique...
For the first few years I owned the car I could just slip the clutch a little at 3500 RPM and the car would just go without bogging. For the last couple years if I do that, the car would bog - the clutch was clearly not where it used to be. So for the ProSolo it's something like this (since it was on a hill)
-Pull up until both staging lights light.
-Back out until 2nd staging light un-lights.
-Pull up until 2nd staging light barely relights.
-Pull handbrake.
-Wait til the "shot clock" is down to about 5 seconds.
-Start revving the engine between 4000 and 4500 RPM
-Wait until horn sounds.
-Wait until 2nd light goes out
-Drop handbrake, peg gas, release clutch pretty fast (almost a clutch drop)
-Continue pegging gas, enjoy sounds of squealing tires
With a properly functioning clutch I'm not sure how I would do it. I was really displaying a total lack of mechanical sympathy all weekend
For a hillclimb in Wyoming I did a 6000 rpm clutch dump. Not pretty, but I was at ~8000' and the power was down.
I checked the mirrors, as it was a long flat foot corner next, and the Sheriff was sanding next to the line in a blue smoke cloud.
Cones don't count at Hillclimbs.
Posting Permissions
LinkBack URL
About LinkBacks
Reply With Quote
Bookmarks