STR Prep - Suspension and Alignment
03-22-2012, 05:35 PM
#262
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Yea... I was thinking about the effects of high caster numbers during a high steering angle turn adding more grip to the front. In return causing the rear to be loose.
03-22-2012, 06:16 PM
#263
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So this weekend Random1 and I measured the AP2 rear toe curve on my car to compare to his AP1.
Both of us expected there to be some toe-in under compression and toe-out under rebound, just less then what is found on the AP1.
What we found was pretty surprising. There is no toe change on the AP2, and the track gets wider under compression.
At maximum ride height of 16 inches from axel center to fender there was 0 toe.
From 15.5 - 10.5 there was 1/16 of toe in.
We did get a measurement of 1/8 toe in at 12.5 inches but we figure there is a 1/16 margin of error in the measurements.
Both of us expected there to be some toe-in under compression and toe-out under rebound, just less then what is found on the AP1.
What we found was pretty surprising. There is no toe change on the AP2, and the track gets wider under compression.
At maximum ride height of 16 inches from axel center to fender there was 0 toe.
From 15.5 - 10.5 there was 1/16 of toe in.
We did get a measurement of 1/8 toe in at 12.5 inches but we figure there is a 1/16 margin of error in the measurements.
03-23-2012, 04:57 AM
#264
Wow, that's really interesting. Thanks for posting the results of the testing.
I wouldn't say that zero bump steer necessarily makes a car "stable". It just makes it less dynamic.
I wouldn't say that zero bump steer necessarily makes a car "stable". It just makes it less dynamic.
03-23-2012, 05:53 AM
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I think of it as more of a abrubt turn moment which changes the weight transfer and contact patch of the rear tire(S) more drastically than it does the fronts.
03-27-2012, 07:58 AM
#268
Edit: Or at least check it, get some toe plates and a digital level. The alignment will change but it's possible it'll still be OK for you if you only change ride height a little.
03-27-2012, 08:15 AM
#269
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Jon, what has your experience been in how far it changes from small adjustments?
I see people mentioning making ride height adjustments at events as a tuning tool, ie lower/raise rear to tune oversteer. For folks who make those adjusments, have you checked how far it throws the alignment off, and do you get an alignment each time or check it?
I see people mentioning making ride height adjustments at events as a tuning tool, ie lower/raise rear to tune oversteer. For folks who make those adjusments, have you checked how far it throws the alignment off, and do you get an alignment each time or check it?
03-27-2012, 09:10 AM
#270
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You need some tools that will give you repeatable readings. The actual measurements are irrelevant, but the delta is very important so that when you go to a TNT, if you want to make a change, you can get an idea of how the magnitude of an adjustment affects the handling characteristics of your car.
Bolded for emphasis. While other people's experience with adjustments is useful, and there is lots of discussion across the STR threads about people's observations and experiences with setting up these cars, the only way to go fast is to respond to the feedback your car gives you and to know how to adapt both the car, and your body to what you're experiencing on course.
The point is that the alignment is irrelevant. You could go out there with a car that is relatively square, and that is really all you need for a base line for setting up the car's alignment.
You also need two different skid pads. A Skid pad for optimizing mid-phase grip, and a skid oval to tune entry and exit.
Done.
Bolded for emphasis. While other people's experience with adjustments is useful, and there is lots of discussion across the STR threads about people's observations and experiences with setting up these cars, the only way to go fast is to respond to the feedback your car gives you and to know how to adapt both the car, and your body to what you're experiencing on course.
The point is that the alignment is irrelevant. You could go out there with a car that is relatively square, and that is really all you need for a base line for setting up the car's alignment.
You also need two different skid pads. A Skid pad for optimizing mid-phase grip, and a skid oval to tune entry and exit.
Done.