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Unread 03-22-2012, 06:00 PM
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Fair! Fair! is offline
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Default Re: Vorshlag 2011 Mustang GT 5.0 - auto-x/track build

Project Update for March 22, 2012: Sorry it took me nearly a week after the last double-header event weekend to get this update up, but we've been slammed at Vorshlag and with a 3 day work week last week I'm still way behind. I was also hoping that the TX2K12 folks would have some sort of results posted for the track day, but alas - the only results up a week after their event weekend are for drag racing. I checked the usual forums that have TX2K threads (which usually have more info than the Tx2K website), but they are just full of street racing stories, videos showing who had the biggest burnout at the "street meet", their "dyno day" numbers, and other things I don't care about.

My pictures and videos from TX2K12: http://vorshlag.smugmug.com/Racing-Events/TX2K12-MSR-H/



So let's back up a tick. Where we last left off here the Mustang was being hurriedly prepped, washed, and loaded into the trailer. There was some wheel bearing noise I noticed at the Harris Hill Road track event (RTTA) and it was louder at the last autocross earlier this month. Ryan and AJ pulled the rear axle apart, yanked out the right side axle shaft, and we inspected the bearings, shaft, and differential for wear. It all looked perfect. Was I hearing the noise correctly?? I know it was from the right rear... or was it? Weird.



We had found some 275/35/18 Hoosier A6 (autocross compound) DOT tires to mount to the D-Force 18x10" wheels, which were to be used at the MSR-Houston track event held by TX2K12 last Thursday. Our newly repaired tire machine was finally ready to use for the first time... but one more little issue cropped up (fixed this week!) so we took them to Discount Tire once again. I hadn't run the Mustang on track with anything but street tires up until now so some R compounds were long overdue. I could have thrown the 315/35/18 Kumho V710s on there but... I just had a bad feeling about the event and didn't want to burn up brand new tires at this one. That was a smart move.



The 275/35/18 is super short and looks ridiculous (to me) on the Mustang, but hey, its the spec tire for the GRAND AM Mustangs so I went ahead and tried it. Meh, it works I guess, but has a ton of wheel gap at the fender. A little skinny for an 18x10" but it had some grip. We got the car loaded up, strapped in, and AJ and Ryan loaded out the trailer with the toolbox and all the track gear for the first time. First long tow with the trailer, and no spare wheel/tire to be found. Oh well, wish me luck! We left Dallas around 5:30 pm (rush hour traffic = FML) but got to Pearland around 10 pm and crashed out.



The next morning we got to MSR-H early and set-up our trailer next to Costas & Anna's set-up, right next to Track Entrance where NASA normally grids... but with only 40 cars split amongst 4 sessions, there were very few cars to grid, so it worked. Great trailer/paddock location, whatever - thanks Paul! We went to the driver's meeting, turned in our self-tech forms, and made sure they had our AMB transponder numbers registered. It was clear that Peter and the TX2K crew had stepped up their game for 2012; this event was better organized, safer, and more enjoyable than in 2011. Costas and I were put both in group Advanced 1 (A1) which had 8 cars, there was an A2, and we had to work with beginner (B1, B2) drivers all day.



I took a GT500 Mustang driver around the track in my first A1 track session with the 275s at all 4 corners and he had a BLAST (you can see his GT500 in the bottom right pic). He'd never done a track day, autocross, nothing - so his eyes were huge as we bombed around MSR-H on Hoosier A6s, drifting the rear out of most corners - these tires had been sitting for over a year before I bought them, so I was "cleaning off old rubber". Managed nothing better than a 1:49.48 lap in this session, going the ClockWise direction, meh. I was shifting around 6K to keep from hurting anything, as it makes peak power around 6200 anyway. The laps felt slow, and it was loose as hell out back. Was the splitter actually helping front grip and the lack of rear wing hurting the overall balance? All I knew was that it was loose in high an low speed corners. And the track was BUMPY... coming out of turn 10 there's a huge dip, so if I do any more track events in this car the 175# rear springs (which work great for autocross) we might need to bump up a tick in rate, to keep the rear from bottoming out on tracks like this.



The wheel bearing noise was getting loud in session #1 and sounded like it might be the right front tire, and not the right rear as I had thought? We came in after our 20 minute session and I took a look - tire pressures went up to where they should be but the RF wheel bearing felt tight when I rocked the RF wheel, while it was in the air. I took Amy out with me in A1 session #2 and we didn't make it 100 yards before we knew something was WAY wrong; came right back in after one lap for a better look. Click the video below and you can hear the loud WAH! WAH! WAH! noises above the wind noise, but it was VERY apparent in the car that something was BAD wrong with the TIRE now. Steering wheel was shuddering like mad - and it wasn't the electronic gremlins this time, it was the tire. Sure enough, the RF tire had grown about 3" in diameter on one part of the inside shoulder; it was grossly out of round. This happened during the half hour of down time after I had re-checked hot tire pressures and wiggled the RF wheel bearing immediately after session #1. WTF? Costas :" Oh yea, that tire has popped some cords".


Click either pic above for in-car video and hear the RF tire doing its death howl


The tread looked fine but the carcass of that Hoosier was toast; luckily I had a back-up plan and brought along a pair "vintage" 305/30/18 Hoosier A3S5 autocross tires with a DOT stamping date of 2005... so that's like 7 year old tires. I had used these early on with the E36 LS1 Alpha car, so they were good back then... but "then" was around 2007. Amy and I pulled the Right Front and one Rear wheel off, took them to the MSR "Office Shop", and they swapped on the 305s for us (sure wish I had my Taylor Dunn track vehicle up and running at this point! That was a lot of walking around with wheels and tires). We put these 305s on the back and moved two of the better 275s up front for a non-square set-up. Not ideal, but it was what I had for spare R compound tires in the trailer. Went out in session 2 with Amy riding along again (mistake!). Here's that highlight video...


Click for video from my A1 Session #3...mistakes and all


So I had one warm up lap where I took it pretty easy, trying to scrub the rear tires in - they really did have some OLD rubber that needed to go away. Come around for my first hot lap and got sideways under braking and had a quick off and on. I managed to steer around the curbing and saved the splitter from curbing crash testing, but Amy was still pissed. This was her daily driver, she bemoaned, and "you are never tracking my car again!". Well, crap... so I took it easy for the rest of session #3 but still managed to go 2.2 seconds quicker with the old 305mm rears, running a best lap of 1:47.26 lap. The rear was still a bit loose in high speed corners but it was clear that the car responded quickly after having a wider rear tire... All of you that think I'm crazy for wanting more than a 275mm tire, well, I beg to differ. I do wish we had found a trunk in time to make a wing mount (I have a 68" wide CF APR GTC-300 wing sitting here waiting to be mounted to something), as I think it could have gone much quicker with some rear down force.


Left: The RF tire #2 gave its life to the MSR-H gods. Right: The 305 looked right at home

So we came in after she said she had "had enough", checked the tires and found another RF tire that had been destroyed. WTF?! There was only one corner on the track where you really load the RF going clockwise, but it was the fastest turn there. Was it a combination of a bad wheel bearing and this corner? Too much negative camber? Something else? We checked the RF wheel bearing again (it now had some serious resistance when spun - took a lot of force to turn the hub by hand; not good), and the camber (-3, right where it should be). I think we're done for the day... not going to kill a 3rd tire to maybe squeak out another second or two, if I'm lucky. The higher powered cars at TX2K12 were far quicker than I was going to get to today - Costas GT-1 car had the top spot but some race prepped big power GTRs, a couple of Vipers and Z06s, and a Supra were all several seconds faster than the Mustang. I wasn't going to make the Top 5 Time Trial shootout, so Amy and I mounted the 18x9s and RS-3 Hankooks for the upcoming National Tour on Saturday and loaded up the car.



Costas had a pretty good day - his GT-1 car ran great in 3 sessions, putting in more trouble-free laps all day than I've seen that car do in the last few events combined, where I saw it run. He was pushing the car harder each session but taking it pretty easy; he had a small deficit going into the Time Trial but was confident the car had more time in it. Sure, he had an off in session #1 on some older/harder tires, but we gave him sufficient quantities of grief. GT1 Lawn Service, "We cut your grass fast!". It was on FB before he had even un-belted; by the time he had his helmet off there were 3 more "captions" for that pic.



So his GT-1 car, 3 GTRs and a Viper went out for the Time Trial Shootout at the end of the day. 3 hot laps later a GTR was on top - wish we would have had used his helmet/pit radios so he would have known to push it on lap#3. There was some potential blocking by the first place car but he didn't mind and still had a great day - anytime you get to bust off a lot of trouble-free laps in a GT-1 car on 14" wide slicks, its a good day.


Click the above left picture for the Time Trial Shoot-out Compilation Video

After we left the MSR-H site we went and ate some kickass Mexican food at Los Cucos, then made it back to our hotel and crashed. We had another busy 3 days ahead of us....

...Texas National Tour continued in part 2, tomorrow...
__________________
Terry Fair - www.vorshlag.com

Vorshlag project cars: $2010 GRM Challenge E30 V8 + E46 DSP Autox Build + 2011 Mustang GT autox/track car

Last edited by Fair!; 03-22-2012 at 06:21 PM.
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