dunville trackday 5/23/09

[somedude_001]

I logged 97 miles on the track in my 1990 MTX yesterday. What a beast this car is going to be once I get some of the kinks ironed out. Arrived to the track at noon and went through the driver meeting and then through tech, and then about 10 people were poking fun at me about it catching fire again or dumping oil on the track... so on and so forth. A first timer asked to go for a ride to learn the track and I agreed to show him the track. I have never driven the track without my R comp tires on and needless to say I over estimated the amount of traction I thought I had going through the long sweeping corner. the 4th lap I went 2 wheels off and the side of my car got all conned up. Pulled into the pits to inspect the car. No damage of course. I felt like a complete noob but the kid definitely appreciated what my car had in it after he went out in his car and felt that. "WOW I can't believe how much more grip your taurus has than my audi A4 in those corners"

I went out for another session to learn the line of the track better and I got behind a S2K that was going at a good clip. He certainly was not pushing his car super hard but he had a good line and I learned. About 10 laps in he signals me to pass. I step up my game and he was chasing about 5 laps later I was watching him instead of the braking markers and I failed to slow enough coming from the back straight into gilles. I sent the left 2 off again at the end of barack's because of this excess speed. So I pit agian to give the car quick look. No damage once again. I noticed that the outer edge is getting hammered on the front tires. So I jacked the front end up and loosened the strut towers and slid them all the way in for max camber. OMG what a huge difference. The car now has a very nice amount of oversteer off the throttle and when trail braking it seems to step out nicely.

So I managed to catch up to the very same S2K again and follow him for a few laps, and he signals me to pass. about 5 laps later I decide I want to whip the car into gilles at a insane speed and see if I can induce a pretty hard tail slide in hopes that I can ride it through barack's then power out. Well that was a good idea in theory but my car does not have nearly enough rear wheel drive to pull that off... or so I thought. My 11.6" brakes were no really up to the task of stopping this car so I decided to not use them as much and let the rear end swinging out slow me down. This was definitely the most fun I have had in a long time... scratch that. EVER in my SHO. I had been entering gilles at 50-55mph and now i'm entering in the 65mph range with the ass end completely out. I would brake a little then give a quick spike and give the wheel a quick yank to the right and WEEEEEEE.

As the day went on and the gas tank emptied the rear tires started to chatter a lot when the car was sideways. I asked nick (hotrodkid) to watch the car to see if he could figure out what is going on with this. It was starting to get really annoying because it was beginning to get kind of violent as I neared a empty tank of gas. He said that my rear tire looks like it is folding under the car like something is flexing giving my rear tire positive camber. After hearing that I jack up the car just to give it a good once over and to check bolt tightness for all critical rear end components. Everything looked perfect. So this leaves me with a couple of thoughts.

1. I have BMR rear lateral arms and a H-brace so I know those are solid.
2. maybe the strut towers are flexing a lot due to my lack of STB.
3. maybe it is the fact that I have 225/50/16 falcon azenis on 6" slicers and the tire is way to big for the rim. The possibility of massive sidewall flex is reasonable.
4. I remember reading something about a knuckle brace on shotimes. Maybe my rear knuckle is flexing under the massive load of sliding sideways on almost every turn all day. (I don't want to break it!)
5. too much ass hatting in a sedan not built for it. :wave:

at the end of the day I ran a 1.2X when we did the timed event. Which is not bad for street tires but I could have ran a **** of a lot better had I bolted my R comps on. nearly everyone else that ran the timed event was on race tires. fastest car of the day ran a 1.13 but it is not street legal.

quick walk thought the track.

Starting at turn 1 the padock. This is a low speed turn at about 40mph but about half way through club I am WOT in second and just before sunset swerve I shift into third and never let off the throttle through that turn. Full power down the back straight. quick whack of the brakes and stuff it into second gear coming into gilles, quick yank of the wheel sends me into gilles sideways at about 65mph. Quick blip of the throttle to settle the rear end then tap the brakes to **** some speed for barack's then back to full power in second gear. Into 3rd and take the kink at a unsettling speed and get on the brakes hard while still turning to get the rear end out for the carousel, and once the rear end is out I drop in into second and get back on the power and half way through the center straight shift back into 3rd. quick whack of the brakes and snap the wheel left and you take len's with the rear end slightly out (had problems with this turn all day) stuff it into second and hit the brakes for the upcoming right hander (also never got this corner down). This is a relatively low speed turn so the rear end was firmly planted with no sliding at all (but boy did I try) The curve grande is taken full power in second a bit wide but about half way I have to shift into 3rd and the rear end gets pretty loose in that brief period between 2nd and 3rd. fortunately I didn't miss shift here because I would have spun off for sure. Once in 3rd you stay WOT through the chicane (which is almost non existent now) through the front straight bump the revlimiter in third a couple times and ******* the brakes for the paddock.

most of the day I would not run the front straight hard because of my brake issues. I would hit about 6K in third about half way through the straight and maintain speed then lightly get on the brakes for the paddock. good time for sure! best 100 bucks i've spend in a long time! My upper body is really sore today! :laugh_ti:

 

[somedude_001]

just for a idea of what the track look like. here is my Saturn running it a couple of years ago.

http://videos.streetfire.net/video/NYSpeed-track-day-2-SL2_136025.htm

just enter in more traction, power, oversteer tendance, and grip. and you have my SHO.

 

[Shoaz]

Everything looked perfect. So this leaves me with a couple of thoughts.

1. I have BMR rear lateral arms and a H-brace so I know those are solid.
2. maybe the strut towers are flexing a lot due to my lack of STB.

It's unlikely they're moving enough to cause a lot of trouble, but a rear STB doesn't hurt. With street tires it's unlikely you're putting enough side load to move things a lot.

What was your static rear camber setting?

3. maybe it is the fact that I have 225/50/16 falcon azenis on 6" slicers and the tire is way to big for the rim. The possibility of massive sidewall flex is reasonable.

What sort of rear tire pressures were you running? What type of tire?

4. I remember reading something about a knuckle brace on shotimes. Maybe my rear knuckle is flexing under the massive load of sliding sideways on almost every turn all day. (I don't want to break it!)

The knuckle braces are mostly for strength, to make the rear arm attachments look like a big double-shear joint rather than two single-shear joints. Flex shouldn't be an issue, especially on street tires.

5. too much ass hatting in a sedan not built for it. :wave:

It always takes a while to sort out how best to drive a particular car or setup. It's always tempting to blame the setup, but nearly always the primary adjustment needed is to the nut behind the wheel.

 

[somedude_001]

It's unlikely they're moving enough to cause a lot of trouble, but a rear STB doesn't hurt. With street tires it's unlikely you're putting enough side load to move things a lot.

What was your static rear camber setting?

I think it was set up for 1.5 deg front and 1 deg or 1.2 deg rear

What sort of rear tire pressures were you running? What type of tire?

I settled on 45 front and 45 rear. The rears were not using the entire shoulder of the tire which indicates too much pressure but I wanted to decrease rear grip for better rotation so I left the pressure high. The front tires were rolling onto the sidewall at 40psi once I started throwing the car into corners so I bumped it upto 45psi and the tire wear was very even once I added pressure and increased camber in the front.

the tires area a falcon azeni 615. I think it is in the max performance class of tire. 200 tread wear. My R comps are kumo victoracer V770 but I did not install those because I wanted to learn the cars limits better and my street tires are way more predictable to learn on that my R comps.

The knuckle braces are mostly for strength, to make the rear arm attachments look like a big double-shear joint rather than two single-shear joints. Flex shouldn't be an issue, especially on street tires.

I am concerned about issues when I am running my R comp tires. They have a indescribable amount of grip compared to the azenis.

It always takes a while to sort out how best to drive a particular car or setup. It's always tempting to blame the setup, but nearly always the primary adjustment needed is to the nut behind the wheel.

this is the first time I have ever tried throwing the car into corners sideways . I love this style. I just don't like the chatter from the rear end, and i'm a bit concerned that it may break something once I bolt my better tires on the car if it continues to chatter like that. I am certainly not claiming to be a great driver I have a lot to learn. input is welcome.

 

[Shoaz]

I think it was set up for 1.5 deg front and 1 deg or 1.2 deg rear

I'm guessing that's negative.

That's pretty much street alignment camber, which is fine for the street. For track use you may want to consider more negative camber. However, it won't hurt to leave it there for now.

I settled on 45 front and 45 rear. The rears were not using the entire shoulder of the tire which indicates too much pressure but I wanted to decrease rear grip for better rotation so I left the pressure high. The front tires were rolling onto the sidewall at 40psi once I started throwing the car into corners so I bumped it upto 45psi and the tire wear was very even once I added pressure and increased camber in the front.

Perhaps you've identified the problem?

Was that cold pressure or hot pressure?

I am concerned about issues when I am running my R comp tires. They have a indescribable amount of grip compared to the azenis.

Many, many people have run SHOs with R-comps without trouble. You shouldn't need to get too crazy with mods just to run R-comps.

this is the first time I have ever tried throwing the car into corners sideways . I love this style. I just don't like the chatter from the rear end, and i'm a bit concerned that it may break something once I bolt my better tires on the car if it continues to chatter like that. I am certainly not claiming to be a great driver I have a lot to learn. input is welcome.

I'd suggest picking a very moderate setup, leave it alone, and concentrate on learning to drive smoothly, assuming you want to learn how to be fast. If you want to be a drifter you have the wrong car. Chasing improving your driving skills and car setup at the same time is a recipe for screwing up both processes, IMHO. Chasing setup before honing the driving skills is a recipe for winding up with a setup that's not very useful when you do hone your driving skills (and therefore wasting a lot of time), again, IMHO.

Aside from off-track excursions I'm not aware of anyone breaking any suspension components just from running R-comps. My car even has stock bushings everywhere (other than Al SFBs and the BMR arms) and I've not had any trouble.

 

[somedude_001]

pics of my tires as they sit right now. I have driven about 200 miles since trackday and they are still pretty tore up.

left rear

left front

right front

right rear

These tires have spend most of their life on my turbo car which has never had a proper alignment. You can tell how they where wearing on the track though.

I'm guessing that's negative.

That's pretty much street alignment camber, which is fine for the street. For track use you may want to consider more negative camber. However, it won't hurt to leave it there for now.

I didn't mention the full story here. the 1.5 deg in the fron is what I had the car aligned to for the street. after a couple sessions I loostened the front strut plates and slid them all the way in to increase camber (which probably screwed with the tow too but oh well). The right plate was already in all the way but the left one was out all the way so I slid it in all the way. The RF tire looked to have the 1.5 deg like I am used to seeing on my SHO's but the LF had a substantial amount of camber maybe close to 3deg if I had to guess. After I made that camber change the rear end was a lot more loose and I like it. The understeer is frustrating. I can get the car to rotate decently by trail braking but I often end up locking the inside front tire. That camber change was really what the car needed. My corner entrance speed picked up by at least 5mph on every turn which in turn let me brake later because my brakes were running cooler. My rotors are stress cracked though... again.

Perhaps you've identified the problem?

Was that cold pressure or hot pressure?

my pressures were 45psi cold on all 4 corners. So they were probably over 50psi hot

 

[somedude_001]

they just posted the leader board

 

[Shoaz]

I didn't mention the full story here. the 1.5 deg in the fron is what I had the car aligned to for the street. after a couple sessions I loostened the front strut plates and slid them all the way in to increase camber (which probably screwed with the tow too but oh well). The right plate was already in all the way but the left one was out all the way so I slid it in all the way. The RF tire looked to have the 1.5 deg like I am used to seeing on my SHO's but the LF had a substantial amount of camber maybe close to 3deg if I had to guess. After I made that camber change the rear end was a lot more loose and I like it. The understeer is frustrating. I can get the car to rotate decently by trail braking but I often end up locking the inside front tire. That camber change was really what the car needed. My corner entrance speed picked up by at least 5mph on every turn which in turn let me brake later because my brakes were running cooler.

Sounds like your subframe isn't centered.

My rotors are stress cracked though... again.

Just surface checked or cracked all the way through? The surface checking is normal, but you have to keep an eye out for cracks that penetrate through.

my pressures were 45psi cold on all 4 corners. So they were probably over 50psi hot

45 cold probably translated to 55-60 hot if you were pushing it very hard at all, and that's way too high for the rear IMHO. No wonder you were having trouble.

 

[HotRodKid]

 

[gmail]

that track looks sweet id love to hit that up some time this year.
already had planned to go to englishtown NJ some time.

looks like a blast.

 

[somedude_001]

Sounds like your subframe isn't centered.

That is what i'm thinking too. That would also explain the slight shift in the steering under heavy braking i think.

Just surface checked or cracked all the way through? The surface checking is normal, but you have to keep an eye out for cracks that penetrate through.

I check them regularly. They are just surface cracks right now. I have destroyed a lot of brakes on my turbo car.

45 cold probably translated to 55-60 hot if you were pushing it very hard at all, and that's way too high for the rear IMHO. No wonder you were having trouble.

I really enjoy the oversteer. I was just unsure of regarding the chatter when I had the rear end way out. I kept getting out of my car saying "this really needs more rear wheel drive!"

that track looks sweet id love to hit that up some time this year.
already had planned to go to englishtown NJ some time.

looks like a blast.

the track is a complete blast and for 100 bucks you can be on the track almost a full 8 hours because it is not that busy.

 

[somedude_001]

Sounds like your subframe isn't centered.

That is what i'm thinking too. That would also explain the slight shift in the steering under heavy braking i think.

Just surface checked or cracked all the way through? The surface checking is normal, but you have to keep an eye out for cracks that penetrate through.

I check them regularly. They are just surface cracks right now. I have destroyed a lot of brakes on my turbo car.

45 cold probably translated to 55-60 hot if you were pushing it very hard at all, and that's way too high for the rear IMHO. No wonder you were having trouble.

I really enjoy the oversteer. I was just unsure of regarding the chatter when I had the rear end way out. I kept getting out of my car saying "this really needs more rear wheel drive!"

that track looks sweet id love to hit that up some time this year.
already had planned to go to englishtown NJ some time.

looks like a blast.

the track is a complete blast and for 100 bucks you can be on the track almost a full 8 hours because it is not that busy.

 

[HotRodKid]

heres me riding shotgun in Bing's car. I love the car and i love how he drives it till it breaks. w/ a helmet on my head hits the roof of the car, which isnt good news for me on my 240 project .... no room for a cage

 

[SHO_DOODmorrris]

sweet man... i think i might make my car a track whore soon this looks like fun...

 

[somedude_001]

do a oil change and throw some good front brake pads on it and have a blast.