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Discussion Starter #1
Anyone actually tried an emergency lane change after going from a 16 mm to 19 mm rear bar on a fourth generation?
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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Anyone actually tried an emergency lane change after going from a 16 mm to 19 mm rear bar on a fourth generation?
How would the result actually get measure and quantified for analysis and representation?

45 MPH Moose Test on a closed course filmed with a GoPro from the same angles?

Who has a VBOX they can donate?
 

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Discussion Starter #3
Instrumentation would be great, but a basic step would be seeing how much oversteer is generated and whether the ESC can still catch it, right?
 

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The bar upgrade still leaves the OB a looong way from being an oversteer beast.
My car still understeers even with judicious trail braking. I predict I could probably mess with the tire pressures enough to get it to oversteer, but it would not be a setup that would be used on the streets for conventional driving.
I've yet to hang the back end out on dry pavement and that is not for lack of trying. If the driver does their part in an emergency maneuver, the car behaves predictably.
 

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2016 3.6 Limited with ES
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Brucey is our Mikey from the Life cereal commercials.
 

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How would the result actually get measure and quantified for analysis and representation?



Measure lateral G, Steering angle, and , if you can afford it, rotational velocity via a gyroscope. Plot the rate of steering angle change against the rate of lateral g change.


You can also measure the suspension motion ( gets a little tricky setting that up on struts) and plot the rate of roll against the steering rate and lat g's rate as well.
 

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2016 3.6 Limited with ES
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Measure lateral G, Steering angle, and , if you can afford it, rotational velocity via a gyroscope. Plot the rate of steering angle change against the rate of lateral g change.


You can also measure the suspension motion ( gets a little tricky setting that up on struts) and plot the rate of roll against the steering rate and lat g's rate as well.

I hate you but also admire you at the same time.
 

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Master Caster
2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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A lot more that can be measured, but I kept it simple! :)
Yes, of course.

My question was ... How do WE actually do it.

So far, butt dyno is the best quantifier we have, and that sux.
 

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Probably the best you can do without instrumentation would be to use a stopwatch to time the period from steering input to when the car first settles down from that input. You could do it with maybe a fast 90 degree turn of the steering wheel as the starting point input, to maybe the first return to the car being level. Lots of possibilities for errors there, but with recording something like 6 cycles, you should get a decent enough average. To help minimize the errors, you would want to sweep the test area thoroughly, and at least try to run the same track on each test to minimize errors from differences in track surface textures.

After that, having a large enough parking lot to use as a skid pad ( 100+ ft radius) can tell you how much you have decreased push by measuring the steering angle needed to keep the car circling at a specific speed and turn radius. The change in steering angle will be small, so some sort of tell-tale indicator on a degree wheel could be rigged up to do the measurement.

Unfortunately, neither of those test will tell you what the cars yaw angle is - which would tell you when the car has transitioned from steady-state understeer to oversteer as you increase rear roll bar stiffness. However, you can sometimes be close in determining that via the use of a video camera to see where the rear tires are tracking compared to the front.



And yes, with an experienced driver, the butt dyno is a marvelous instrument - and a heck of a lot less expensive than the $50-100k+ systems we use in our race cars! :) One of our long-time drivers - a now- retired Firestone chemical engineer who was responsible for the Firestone/Bridgestone Indy tire testing program, with 8 national championships under his belt and still kicking the young guys butts at the age of 76 - when blind testing Goodyear race tires for them on one of our Formula Fords a couple decades ago at Mid Ohio, could tell them what the differences were in cord construction on a set he just ran laps with! All the Goodyear guys could do was consult their notes and shake their heads in disbelief.



Guys like him make us engineers feel like total wankers! :)
 

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OK.



Simplest thing to do, assuming that you can find a place big enough to be a skid pad of at least 75-100 foot radius, will be to chalk a circle that you can try to make your front wheels follow. Set up a camera on the car somehow - maybe a long stick - that can record both front and rear tires at the same time ( or 2 cameras that you can time-link together) and drive around the circle at ever increasing speeds until you get to what you feel is the limit - it is only when you find the limit that your tires will be acting on the load/slip angle curve about the same as if you were doing an emergency maneuver.



Note the speed.


Switch to the larger bar and repeat.


The larger bar runs should show a greater speed - it may be only 2-3 mph faster, so you need to be as precise in your reading as you can - as well as the rear tires following the circle line closer to what the front tires are doing.


This steady state test is by far the easiest to perform to see how the balance of the car has changed. It WILL NOT tell you anything about a change in dynamic behavior.


If you want to see how the dynamic behavior changed, probably a simple traffic cone slalom will suffice. Start off with the cones maybe 50-75 feet apart, and increase, decrease until you are comfortable that you can drive it consistently. You need only 4 cones to give you good feedback.


Run first with the small bar. Record how the car responds with a camera set up to record the full run from directly behind. Record your speed.


Repeat with the larger bar.
 

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Brucey
'17 3.6
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OK.



Simplest thing to do, assuming that you can find a place big enough to be a skid pad of at least 75-100 foot radius, will be to chalk a circle that you can try to make your front wheels follow. Set up a camera on the car somehow - maybe a long stick - that can record both front and rear tires at the same time ( or 2 cameras that you can time-link together) and drive around the circle at ever increasing speeds until you get to what you feel is the limit - it is only when you find the limit that your tires will be acting on the load/slip angle curve about the same as if you were doing an emergency maneuver.



Note the speed.


Switch to the larger bar and repeat.


The larger bar runs should show a greater speed - it may be only 2-3 mph faster, so you need to be as precise in your reading as you can - as well as the rear tires following the circle line closer to what the front tires are doing.


This steady state test is by far the easiest to perform to see how the balance of the car has changed. It WILL NOT tell you anything about a change in dynamic behavior.


If you want to see how the dynamic behavior changed, probably a simple traffic cone slalom will suffice. Start off with the cones maybe 50-75 feet apart, and increase, decrease until you are comfortable that you can drive it consistently. You need only 4 cones to give you good feedback.


Run first with the small bar. Record how the car responds with a camera set up to record the full run from directly behind. Record your speed.


Repeat with the larger bar.
I promise I will do this to the best of my ability as soon as I figure out how to turn off my TPMS light.
 

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02 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
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I promise I will do this to the best of my ability as soon as I figure out how to turn off my TPMS light.
wire cutters. to the gauge cluster, and center stack screen, = no more offending notifications.

I am free to post obvious suggestions on this thread,...but not your thread,:wink2:
 

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Something else you can do - but it might scare you :) - is to paint 3-4 white lines from the tread on to halfway down the sidewalls ( or a bit past halfway) to see just how far the tire is rolling on to the side all. it can be rather surprising sometimes how much of the sidewall is being used!


Also, between runs, let the tires cool back down to the same temps - hotter rubber will grip a bit better, screwing up your comparisons.
 

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I promise I will do this to the best of my ability as soon as I figure out how to turn off my TPMS light.



Have you tried just simply removing the damned bulb? :)


Works every time! :)
 

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Brucey
'17 3.6
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Have you tried just simply removing the damned bulb? :)


Works every time! :)
As stated in the my quarantined thread I would happily do that except the center info screen still displays an error message as well.

So there is no real point. I would no longer have a blinking light but I would still have an error message.

If it was as simple as that I would have done it years ago.
 

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As stated in the my quarantined thread I would happily do that except the center info screen still displays an error message as well.

So, put a piece of tape over that display! Presto! :)
 

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2005 XT, Mildly Modified...2006 XT Limited, Highly Modifed
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Discussion Starter #20
I grew up driving a 1971 2002 (purchased new) which had a huge amount of trailing-throttle oversteer. Great fun once I learned how it worked and what to do about it.

I'm happy with the change to my 2011 Outback. I can lift just before the apex of many turns and there's a mild movement to the outside, easily stopped with a little gas.

The question is whether that oversteer becomes too much in an emergency lane change at 60 mph and I'm still wondering if anyone has tried it.
 
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