STR Prep - Suspension and Alignment
02-05-2012, 08:56 PM
#211
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Once I get my car back together I'm going to some how mount a gopro to videotape my shocks compressing/rebounding at the 12.5" height. I'm interested in how close they get to the bump stops during a normal autox run since my rears are going to be shorter. I should have tons of room. I'll also put zipties on them to see the max they compress.
02-10-2012, 07:18 AM
#212
Thread Starter
Copied out from the differential thread, appropriate here too. Some of the information in the flows is for the BMW M Coupe, but the fundamental principles apply. Thanks Jon
Get fresh tires, accurate alignment, and enter a test n tune. Ive used this chart to help setup the car numerous times, the only thing you need to do is be willing to make the changes instead of sticking to what you "think" works. The chart will point you in the right direction.
Originally Posted by josh7owens' timestamp='1328760809' post='21397872
After watching Matt’s video I'm very intested in a diff. I just don't know if I'm interested in spending $500 on a spare diff, $1600 on the LSD, and then another $200ish (however much puddydog charges? anyone know?) for install. Plus the whole to by a 1.5 or 2 way.
Over $4000 worth maintenance, sway bars, shock repair/rebuild in the last two months has eaten up my "offseason autocross mod funds." I'm not that interested in trying to spend another couple grand before the season starts. Anyone want to buy me a diff?
If I can just settle down the rear of my car without making it too pushy on corner entry I'll be happy. It's typically pretty "fast" as it is now besides I feel like I'm catching the rear end a lot during corner exit when I try to get on the gas. I only ran 1/8" total rear toe last year due to a rear seized bolt that I didn't want to fix midseason because of downtime and cost. Since my set-up resembled a lot of the top national winners besides they ran twice the rear toe I did. I'm hoping going to 1/4 inch or so rear toe will fix the loose rear-end. I'm also thinking my rebound was possibly way too high last season. I haven't got my shock dynos back yet but I was at the top of my adjustment range with rebound (12/14F, 10/14R) and in the 0-3 second range it might have been really aggressive compared to the mid-range shock dyno I got. I'll know sooner if James ever finishes my freaking shocks. PM me if anyone has anytips on how to settle the car down on corner exit but not upset the turn in.
Over $4000 worth maintenance, sway bars, shock repair/rebuild in the last two months has eaten up my "offseason autocross mod funds." I'm not that interested in trying to spend another couple grand before the season starts. Anyone want to buy me a diff?
If I can just settle down the rear of my car without making it too pushy on corner entry I'll be happy. It's typically pretty "fast" as it is now besides I feel like I'm catching the rear end a lot during corner exit when I try to get on the gas. I only ran 1/8" total rear toe last year due to a rear seized bolt that I didn't want to fix midseason because of downtime and cost. Since my set-up resembled a lot of the top national winners besides they ran twice the rear toe I did. I'm hoping going to 1/4 inch or so rear toe will fix the loose rear-end. I'm also thinking my rebound was possibly way too high last season. I haven't got my shock dynos back yet but I was at the top of my adjustment range with rebound (12/14F, 10/14R) and in the 0-3 second range it might have been really aggressive compared to the mid-range shock dyno I got. I'll know sooner if James ever finishes my freaking shocks. PM me if anyone has anytips on how to settle the car down on corner exit but not upset the turn in.
Get fresh tires, accurate alignment, and enter a test n tune. Ive used this chart to help setup the car numerous times, the only thing you need to do is be willing to make the changes instead of sticking to what you "think" works. The chart will point you in the right direction.
02-13-2012, 12:50 AM
#214
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Just to throw a wrench in this toe change discussion.. Has anyone take a good look at the oem bushings to see if bushing flex could be contributing to toe changes?
I know certain oem cars are designed to utilize this effect from the factory, e.g. the FR-S - see picture #4 here, (and the text at the top of the next page, too): http://www.motoiq.com/magazine_artic...cion-fr-s.aspx
I know certain oem cars are designed to utilize this effect from the factory, e.g. the FR-S - see picture #4 here, (and the text at the top of the next page, too): http://www.motoiq.com/magazine_artic...cion-fr-s.aspx
02-13-2012, 05:28 AM
#215
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Has anyone take a good look at the oem bushings to see if bushing flex could be contributing to toe changes?
02-14-2012, 04:44 AM
#216
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Has anyone take a good look at the oem bushings to see if bushing flex could be contributing to toe changes?
Ah, so an older car on original bushings may be more unstable under trailbraking? And thus require more static toe in to compensate?
02-14-2012, 06:08 AM
#217
Former Moderator
Ah, so an older car on original bushings may be more unstable under trailbraking? And thus require more static toe in to compensate?
There are a lot of variables that affect what's the best alignment settings for a particular driver and car: What tires are you running? Are you smooth or abrupt, especially at turn in? Do you trail brake heavily? Are you more comfortable with a loose or tight car? Is the track fast with long sweeping corners or tight & twisty? Do you favor the geometric line or like to late apex to get the power down? Is the car running forced induction? Is the car running a clutch differential? . . .
02-14-2012, 06:20 AM
#218
I'm not sure that's a safe assumption. The rear knuckle is held in place by 3 arms. The amount of deflection in each arm will sum and the result of this sum will be seen at the wheel. Your hypothesis would certainly be accurate if there was just one control arm that deflected rearwards but this is not the case.
The sum of the deflection could result in a zero toe change or even a toe in... It's most likely a toe in since the toe arm is in the front of the knuckle and when the knuckle moves rearward, it becomes farther away from the toe arm which will draw the front of the knuckle inwards.
The sum of the deflection could result in a zero toe change or even a toe in... It's most likely a toe in since the toe arm is in the front of the knuckle and when the knuckle moves rearward, it becomes farther away from the toe arm which will draw the front of the knuckle inwards.
02-14-2012, 07:05 AM
#219
Former Moderator
It's most likely a toe in since the toe arm is in the front of the knuckle and when the knuckle moves rearward, it becomes farther away from the toe arm which will draw the front of the knuckle inwards.
