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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Tue Jun 14, 2016 11:45 am 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Jun 14, 2006 4:19 pm
Posts: 2934
Location: Lethbridge, AB
bean wrote:
Hi Craig,
Has anyone suggested chalk on the sidewalls to during your runs to set tire pressures? Essentially you use chaulk on sidewalls to check if the side wall is rolling too much. Increase tire pressures until the chalk only wears off on contact patch and isn't coming off higher up sidewall.

Rabin



Yup - been using that old method for a while...not useless...just really close to useless information. These BFG's have sidewalls like girders and they don't flex a lot. So, I've started to measure things like crazy...using real data. Here's what I found.

This past weekend we ran our annual SoloPro School. I would highly recommend the experience. I was unsure if I was going to be home from a business trip in time to make the first day (Saturday) so I didn't register for the novice school. The organizers decided to open up a test and tune at the far end of the runway and it was only $30 for the day. 6 drivers...4 cars and I got in around 60 runs - for the record, you're lucky if you get 16 runs in a WEEKEND, let alone run after run in a day. This was the single best testing session I have ever had. I've got an Intercomp Pyronometer (probe type - surface IR is not really measuring tire temps very accurately) and with my fancy new Longacre digital tire gauge, I went to town developing a grip profile for my tires.

I started at 45/43 split front/rear and worked from there. Put in 3 consecutive runs (no waiting between) and then measure. The rear was still loose even with the new torque rods. I added a few pounds to the front and tried again. Repeated this over and over with checking end pressures against starting pressures and then letting things cool and raising the pressure again. I knew it would make a difference, but how much...I didn't know.

At the end, I settled on 48 - 49 in the front (max is 50 for the tire and hot, they were 53 psi) seemed best and the rears started to hook up HARD at pressures above 46 psi cold. So I set them at 47 psi. The grip profile of the tire is such that a 2 pound difference goes from loose to hooked up at the rear. I have yet to balance the tires in the opposite direction (lower front than rear) as I had hit a level where it wasn't loose and was neutral (if I drove it properly). A couple of engineers (former FSAE team members from UofC) went for a ride and were astounded by how planted and hooked up the car was.

So on to the SoloPro school - at almost $400 for the day it's not cheap, but we were running just two cars at a time and you got an instructor for each run. One of the instructors has driven my car lots and was surprised that I now had the car hooked up. He laid down his best run and I got it to within 3 seconds (two silly mistakes as I wasn't patient) and got a handshake for my efforts. In the afternoon, as I learned more and trusted more and got more aggressive with it, I was within 1.5 seconds of the other guy (who is very fast). That was a huge accomplishment and it has never felt better.

Take home,chalk doesn't mean much on this make of tire (there was no difference in the markings for the outside edge), measure using a probe (you stab it into the tire) and don't dick around with hot pressures on tires that are not racing slicks...it doesn't matter. Max grip is fun if you can keep the contact patch on the ground. I'm also now keeping a detailed racing log to record these things.

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Thu Jun 16, 2016 6:45 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Jun 14, 2006 4:19 pm
Posts: 2934
Location: Lethbridge, AB
Looks like I've got a bit of a brake drag on the right rear calliper. Lots of time to do a complete brake service before our next race. I've also ordered up some "E" compound pads to get me more cold bite. Happy with everything else for a change! Will also swap the tires front/rear to even out the ware.

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Mon Jul 11, 2016 8:13 am 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Jun 14, 2006 4:19 pm
Posts: 2934
Location: Lethbridge, AB
I just missed the event final at Street Wheelers this year! Literally by a hair (timing with cell phones...and I missed by 0.03 seconds). I know I left time on the track in a couple of areas, but my first run (we only get 2) was a DNF as I missed a turn (I'm not used to the big open parking lot tracks). You can see how bumpy this surface is and at the start of the video you can hear the hard hit my drivers side tire took in a little dip! No damage - that's what you get with camber plates.


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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Wed Jul 13, 2016 9:01 am 
First volvo in outer space
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Joined: Fri Dec 14, 2007 1:46 pm
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Location: East L.A.
Was awesome to see the car in action for the first time, really looked flat in the corners!! Too bad about the first run, and the timing system breakdown was... #-o

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Jim

66 122S (Garage Queen)
89 244 (Hers)
90 745Ti (Mine)
89 744 (SOLD/Bought back for other daughter)
78 242GT (Project... LOL)
91 244 (Don't Ask!!)


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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Sun Jul 24, 2016 6:09 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Jun 14, 2006 4:19 pm
Posts: 2934
Location: Lethbridge, AB
Racing Tournament Challenge Weekend. Format - race against a time that you set and go head to head with other drivers in a elimination knock-out one run, closest to your time wins style event. Run 1...Volvo vs. Porsche 911 - WIN Volvo. Run 2...Volvo vs. C6 Corvette Z06 - Win Volvo. Run 3...Volvo vs. Caterham Super 7 - Win Volvo. Final - Volvo vs. Pontiac Solstice Turbo...loss (video to come). The solstice ran faster than his previous time and I nailed mine to 0.01 second. If it was a pure bracket racing format, I'd have won. My last three runs were within 2 tenths of a second. Second in class is pretty good. I'll get them next time. Video to come.

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Sun Jul 24, 2016 6:25 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Jun 14, 2006 4:19 pm
Posts: 2934
Location: Lethbridge, AB

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Wed Jul 27, 2016 9:06 pm 
Somehow completely sideways in 4th

Joined: Sat Dec 24, 2005 11:21 am
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Location: a theatre somewhere
I say, well done old chap!

Great fun to watch!

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Sun Apr 30, 2017 9:54 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Jun 14, 2006 4:19 pm
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Location: Lethbridge, AB
Group: SMOD (Street Modified classes)
Rank Car# Class Driver Car Raw Time PAX # PAX Time Score
T 1 242 SM Craig C 1981 Volvo 242 GLT 124.823 .861 107.473 100.000
2 27 SM Ashton R 2011 BMW 335xi 131.945 .861 113.605 94.602
3 28 SM Ed C 2008 BMW M3 136.213 .861 117.279 91.638

Now at 89% of the fastest. 5% improvement over last year.

My first class win.

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Sun Apr 30, 2017 10:22 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Thu Dec 29, 2005 12:29 am
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Location: Eating tofu and legumes in my hippie shack
Nice! Well done!! =D>

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Tue May 02, 2017 10:33 am 
Somehow completely sideways in 4th

Joined: Thu Nov 10, 2011 11:43 am
Posts: 235
Location: Regina, SK
Congrats Craig! What was your feedback on the car after this year's event? (I like reading about your analysis of the car's behaviour on course.)

Rabin


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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Wed May 03, 2017 1:10 pm 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Jun 14, 2006 4:19 pm
Posts: 2934
Location: Lethbridge, AB
bean wrote:
Congrats Craig! What was your feedback on the car after this year's event? (I like reading about your analysis of the car's behaviour on course.)

Rabin


There's a reason I have to buy Matt presents...Every time I race, I want to change something and I end up chewing his ear off over email debating the merits of various changes. If I posted all that here, I'd have to ban myself :lol: . I've had a number of physical challenges over the past month and was just glad that I was able to make the grid for practice on Saturday. I've had a neck issue, my back has acted up and I'm currently dealing with dueling Achilles tendon issues that are leaving me quite literally on the limp. So doing little things like changing my tires and vital fluids (oil and trans) was about all I could do on FRIDAY evening...out on the wet gravel.

I swapped my tires front to back from last season - the BFG's are almost done but the CDN dollar is also worthless so I have to run these for a few more events. They are a 340 TW, so really the wrong compound. Last year when I first put them on they were night and day better than what I was running and I had more tire than driver, we've now switched that up and it's really easy for me to overdrive the tire.

No other changes to the car were made over last year. The rear end is waiting on Kaplhenke to get off his backside and actually machine the parts (which I paid for in Feb) - so no rush there I guess. Engine has been flawless and a fluid change is what's needed every time the trans starts to feel like I'm shifting a box of wrenches. It just keeps getting better as the parts wear in.

Day 1 - Practice Event - test and tune. Set the pressures to 50 PSI and left for the track. Consulted my notes from last year (if you don't have a race diary, you're not serious) and dialed the pressures in - 49 front, 47 rear is enough again. ± 2 psi makes a big difference and I found that when it is cold there is no need to reset pressures between runs. So set and forget when below 20° C. Re-read my notes concerning driving. Ran pretty good, didn't even care to look at my relative ranking. It's practice. I need to work on wringing it out in first gear (the reason for the rear swap) as I launch at 3.5K RPM and just break the rear tires loose a little out of the start box...then you're on the cones and running out of RPM. Grab 2nd too soon and you kill speed (it will bog), get it right and it's worth about 2 tenths. Usually, the shift point is in a slalom. That sucks. I did manage to shift into 3rd at the finish and klicked over the line at about 140 KPH.

I'm trying to race with a nearly empty fuel tank as well this year until I get the fill neck issue sorted...I slosh significant amounts of fuel out of the car as the bottom lip of the fill neck is just worn out from years of use. I have the part - don't have the time to fix it. That was better (like almost on R) - less fuel lost and fewer complaints about how much my car stinks in the grid. Boys - race cars stink like gas!

Main event - The Nissan GTR has been replaced with an uber sweet 2012 911 Turbo (first white car I haven't hated), so he's out of Street Mod...leaving behind the BMW's noted above. They're both rookies and one of them is tragically on bags. Yup, a stanced BMW...racing. Well, props for trying kid. He's getting lost every run (think fast...not an attribute of a BMW driver that bags his car). So I take him on a ride so he'll get a look at the track. If I was a douche, I wouldn't have taken him as DNF is a DNF. He was surprised how fast the 242 is - "Better tighten down that seat belt..." my last comment before thrashing it around the track.

Anyway, they weren't really very close and were hitting cones like that was the objective. It's a rookie mistake - the cones are the LIMIT of the track...they aren't the track. I tell him to think about where he wants to put his car and why. Probably lost on the poor kid. If you drive a 240, you have to focus on being very precise and every detail counts because I can't unleash the fury of Odin and squirt between elements. That's all she's got Capt'n...

Track was very technical with tricks at each stage. I loved it - lots didn't as it wasn't as fast as practice. No 3rd gear heroics.

So what needs to happen - tires for sure. The rear should help build boost in 1st and speed in second. I still feel I need caster to gain front end grip in turns. We have three consistent elements - two turn arounds and one sweeper. The front end will just wash out or understeer (which are sort of the same thing, but I think of them as different as different as in the understeer condition while you may be pushing (and sometimes you generate it) i.e. generating too much front tire slip angle, so you've exceeded the grip of the tire, the tire is still with you and if you modulate the throttle or tap the brake (weight transfer) you can get it back under control. When it washes out - you're probably going to spin.

Just found my caster - I somehow got my ball joints on backwards. :oops: One year...many hours thinking and this afternoon, before I broke out the parts cannon and sawsall, I just checked and FRACK, I did do that - in my own defense (this is not a defensable mistake) I think I had that front suspension apart three times last year alone and it was always a rush to get to a race. I've got a month to correct it - so no problem.

So I spend a lot of time trying to dance with the limit of grip on the front. When I do my course walk, that's part of what I'm thinking about - how to load the tire progressively in these two elements to best effect for maximum grip. It does seem like many competitors are looking for the fast line, I'm looking for the efficient line.

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 Post subject: Re: Autocross - The latest bit of fun.
PostPosted: Fri May 05, 2017 12:21 pm 
First volvo in outer space
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Joined: Fri Dec 14, 2007 1:46 pm
Posts: 1572
Location: East L.A.
Great job on the improvements from last year!! As well thanks for the detailed explanations, don't understand it all but learning all the time.

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Jim

66 122S (Garage Queen)
89 244 (Hers)
90 745Ti (Mine)
89 744 (SOLD/Bought back for other daughter)
78 242GT (Project... LOL)
91 244 (Don't Ask!!)


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