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Old 03-08-2016, 02:54 PM   #21
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Old 03-08-2016, 03:51 PM   #22
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Awesome! Thanks for digging that up.
It was kind of like that, except I was going slower and the pavement was smooth.
That video supports a lot of the info in this thread; it looks like he hits the bump stops hard and gets jostled on a harmonic.

I've taken all of the great advice in here and ordered new springs/front sway/endlinks and tubing to extend my tophats while I'm at it.

I'll try and get some video at the next event and tinker with this corner for some analytics.

Edit: didn't notice the other responses.
It is possible that the track surface was compromised, but this has happened once before. Generally the car feels ok (to me, not much to compare to).
While n/a I was running the same lap times of comparably experienced drivers in sti's/c5's on 200tw tires so its not terrible until something like this happens. Note that our track is on the unforgiving side in general and favors a smaller wheelbase.

Edit2: This is the track being discussed for the curious, 1.7 mile, post turn 5 is where things went wrong:


And this is a representative 3rd gear log showing my supercharger like boost curve (wastegate only)
Attached Thumbnails
Catastrophic uncontrollable oversteer-track.png   Catastrophic uncontrollable oversteer-turbo_log_2_21.png  

Last edited by leboeuf; 03-08-2016 at 04:19 PM.
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Old 03-08-2016, 04:59 PM   #23
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from what I know of kaaz diffs, transition from power to lift is abrupt and unforgiving, even at low speeds. if you lifted enough to unload the diff, it could upset the chassis a lot.

find a big, empty, unpatrolled parking lot and test it by driving in a circle under light power and just lift gently.
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Old 03-08-2016, 09:10 PM   #24
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as an aside, you say you are no good at saves...

I recommend spending some time with Rfactor or Assetto Corsa and a decent wheel and pedals (logitech etc). I have encouraged a number of friends down this path and ALL have seen significant improvements in laptime, control and understanding of car dynamics and tuning etc...the seat time versus cost and muscle memory gain is well worth it in my opinion.

Of course its not like the real thing but it does provide a lot of the real thing at little to no cost.....

edit: and treat it like a REAL car, not a video game...
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Old 03-08-2016, 10:06 PM   #25
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Last edited by GraemeD; 03-09-2016 at 06:16 PM. Reason: I was thread crapping
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Old 03-08-2016, 10:10 PM   #26
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Default Catastrophic uncontrollable oversteer

Quote:
Originally Posted by Double O 86 View Post
The tires, although still showing tread, are old and have hardened. Buy some new tires and watch this problem go away.
No. Stickier tires would mask the problem until he was at higher speed and then the results would be more dramatic.

If the suspension is wrong the car won't work at their limits of adhesion with any tires.
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Old 03-09-2016, 12:33 AM   #27
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I have been to that track multiple times. I think you probably lifted and it got you loose. The slowest corner on the track is right before where you say you had the problem, so you should have been accelerating hard and diving across that apex. You say you were straightening out when it happened, so a lift off seems most likely.
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Old 03-09-2016, 11:55 AM   #28
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Quote:
Originally Posted by Chilicharger665 View Post
I have been to that track multiple times. I think you probably lifted and it got you loose. The slowest corner on the track is right before where you say you had the problem, so you should have been accelerating hard and diving across that apex. You say you were straightening out when it happened, so a lift off seems most likely.
I was hoping someone who has driven there would drop in. This really is one of the simplest parts of the track...
One of the few things that I'm certain of is that I lost control under acceleration. I probably lifted as the oversteer got away from me though, and I'm not sure if that made it worse.
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Old 03-09-2016, 05:01 PM   #29
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Too bad no video. I would tend to support Andrew's analysis. Regardless of how much power it has or your skill level, that is a severely mismatched suspension setup which is going to have the characteristic of abrupt oversteer.

Contributing factors are a differential that is known not to be very smooth. That means it's locking on decel is rather abrupt so it is not conducive to abrupt throttle lift mid turn on a car that is already loose. Then you have the additional power which means your rear tires were probably hotter than they normally are. Then you have possibly slow hands/shuffle steer where you did not make a quick/big enough correction soon as it started to yaw. But ultimately your suspension is not correct. Fix that first and then post some video.
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Old 03-09-2016, 06:25 PM   #30
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Quote:
Originally Posted by sixshooter View Post
No. Stickier tires would mask the problem until he was at higher speed and then the results would be more dramatic.

If the suspension is wrong the car won't work at their limits of adhesion with any tires.


I found that my car is SUPER loose (tail happy) on bad tires and perfectly neutral on sticky tires. No change other than wheels/tires.


Either way- OP's suspension sounds like it could use some adjusting.
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Old 03-09-2016, 07:21 PM   #31
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Quote:
Originally Posted by leboeuf View Post
I was hoping someone who has driven there would drop in. This really is one of the simplest parts of the track...
One of the few things that I'm certain of is that I lost control under acceleration. I probably lifted as the oversteer got away from me though, and I'm not sure if that made it worse.
Ok, if you say so, but the turn you lost it after is not a hard turn at all and is cambered in the direction you are going, so absolutely catastrophic oversteer is the only other rational explanation, brought on by your suspension set-up.
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Old 03-10-2016, 02:04 AM   #32
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I really should pick up an action cam... I ski a lot and a chunk of that is in resorts; I need to get over my general distaste derived from the gopro clowns.
It would be funny to see my "awww geee Cletus I think I'm losin this here thing here" reaction time.
Thanks again for the help.


Chilicharger, any chance you're going to the event at ASR later this month?
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Old 03-10-2016, 10:58 AM   #33
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Without video/data what you think you did is probably wrong. Humans don't remember things properly, you're remembering what you think you would have done. Not what you actually did.
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Old 03-11-2016, 01:24 AM   #34
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Quote:
Originally Posted by leboeuf View Post
I really should pick up an action cam... I ski a lot and a chunk of that is in resorts; I need to get over my general distaste derived from the gopro clowns.
It would be funny to see my "awww geee Cletus I think I'm losin this here thing here" reaction time.
Thanks again for the help.


Chilicharger, any chance you're going to the event at ASR later this month?
Unfortunately not, work calls.

I did just buy a factory hardtop 06 specifically to make into a track car, though, so hopefully my schedule will line up at some point to take it to ASR or Motiva sometime this year. I will let you know.
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Old 04-07-2016, 02:08 AM   #35
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I had my first track day with the new sway bar and rear springs.
Things seem to be much improved! I'm still taking it pretty easy but I managed to cut 1 second off my best lap time (pre-turbo and definitely not taking it easy).
I also got some time on the skid pad. I've never really done a donut so I'm not sure how exactly it was supposed to go, but it did seem to break loose in a fully predictable manner.

It seems the track maintenance guy decided to leave my exploded tire wall as I left it. You can also still see my skid marks. It looks like my mspaint diagram is fairly accurate.











Attached Thumbnails
Catastrophic uncontrollable oversteer-20160403_123357.jpg   Catastrophic uncontrollable oversteer-20160403_123415.jpg   Catastrophic uncontrollable oversteer-20160403_123238.jpg   Catastrophic uncontrollable oversteer-20160403_123253.jpg   Catastrophic uncontrollable oversteer-20160403_123309.jpg  

Catastrophic uncontrollable oversteer-20160403_123325.jpg  
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Old 04-07-2016, 10:18 AM   #36
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Cat's given for tire wall destructive performance art. If I could give a second cat for listening, learning and being persistent, I would.

Back on the horse!
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Old 04-08-2016, 08:05 PM   #37
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Tires are more effective as an attenuating device when strapped together in bundles. It is interesting that they are loose. Loose tires have the potential to launch cars airborne.

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Last edited by sixshooter; 04-08-2016 at 08:20 PM.
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Old 04-08-2016, 11:37 PM   #38
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My thoughts exactly. Between that, and no-one tidying up after they were scattered, I wonder about track standards, and what other shortcuts the owners/operators are taking. Do tracks over there have to be licenced, or is a case of throw down a bit of tar, and throw open the gates?

I think I would be looking for a new track, if any were available ...
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Old 04-09-2016, 01:16 AM   #39
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Quote:
Originally Posted by sixshooter View Post
Tires are more effective as an attenuating device when strapped together in bundles. It is interesting that they are loose. Loose tires have the potential to launch cars airborne.

I watched a mustang go under that same wall, tires bolted together, a couple years ago. That's The Bitch at Hallett
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Old 04-09-2016, 11:09 AM   #40
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Quote:
Originally Posted by Gee Emm View Post
My thoughts exactly. Between that, and no-one tidying up after they were scattered, I wonder about track standards, and what other shortcuts the owners/operators are taking. Do tracks over there have to be licenced, or is a case of throw down a bit of tar, and throw open the gates?

I think I would be looking for a new track, if any were available ...
The track is in New Mexico. The poorest state. Don't expect anything fancy in New Mexico. The next closest track is Arroyo Seco outside of Las Cruces, NM. It is just an open field with some tar, basically.
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