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Old 04-12-2017, 03:19 PM   #1
Biggins
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Alignment Help/Tweaks

How do I get moving in the right direction? I know not everyone here is worried about alignments for autocross purposes, but...

I attached my last alignment data for the autocross car (FR-S). Until I can afford the MCS shocks or re-valved full-body Konis which might get me another -0.01-0.03 camber in the front on each side, that's all I can do legally with the camber in my class. Rear camber is not adjustable. I have off-the-shelf Koni inserts in OEM struts up front. I may finally add the legal, larger TRD sway bars front and rear by the end of the season which will also change the car a little. The toe-out front/toe-in rear was just what another FRS/BRZ driver and the forums seem to think is the consensus answer.

My driving is obviously never maxxed out, but the car has some habits that I wanted some experts to chime in with advice on how to potentially fix through alignment settings, tire pressures, or something else?

I like a car with oversteer. I warn everyone who has autoxed my car before they've driven my car and each one has agreed. I know some have hated the way mine drives compared to other FRS/BRZs and others have said it's the best. I've always been comfortable driving it but have noticed in the past year that I should be able to put the power down from mid-corner to especially corner exit, but my car oversteers a bit too much to the point where I know I'm losing valuable time, mainly on corner exit. I've read plenty on the topic on other forums with lots of good and bad information.

The other caveat is that the oversteer has been present for each of the five different tire brands/compounds I've run over the past several years, but I rarely play with tire pressures. Once I add the TRD bars I know the car will be slightly different, but the incremental increase both front/rear should not change much from my current set-up... I think.

Any other comments/critique/suggestions of the current alignment would be appreciated?
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Old 04-12-2017, 03:50 PM   #2
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I can never make sense of the degrees and +/- on those alignment sheets.


There's always the "call Sam" option.

Oh, and I wouldn't put a bigger rear bar on it. Is it loose on and off throttle?

edit:
Have you firmed up the front shocks a whole lot? Do you get wheel-spin (does that car have a diff?)

Last edited by bren; 04-12-2017 at 04:35 PM.
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Old 04-12-2017, 06:23 PM   #3
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My thought is to move the rear toe to zero or closer to zero because I have pretty good amount of toe-in in the rear. I only feel that it is loose on exit which slows me to the next element. It does have a diff but not a ton of wheelspin there (except launching from 0). I do have the shocks stiff up front and soft out back.

I've tried two cars with Sam's bar and they were good, but I was always faster in my car (back-to-back tests twiice). I'd go with his if I were in the STX version of my car though. I did drive a car with the TRD bars and good shocks and think it is the answer, but I guess my problem at the moment was hoping to fix this with an alignment tweak?
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Old 04-12-2017, 06:55 PM   #4
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Less rear toe isn't going to help put power down - you want more if anything.

I'm wondering if you're not getting enough weight transfer because of too​ much front rebound.
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Old 04-13-2017, 10:53 AM   #5
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Quote:
Originally Posted by bren View Post
Less rear toe isn't going to help put power down - you want more if anything.

I'm wondering if you're not getting enough weight transfer because of too​ much front rebound.
Hmm, I suppose you are right about the toe... I'll play around with the shocks this Saturday. I have a test-n-tune that will hopefully allow me to play around with settings. I have not adjusted the shocks much over the past few years once I found settings that were comfortable, but I guess comfortable is not always fastest.
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Old 04-13-2017, 11:11 AM   #6
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The driver usually likes more rebound damping than the car does.
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Old 04-14-2017, 06:57 AM   #7
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You have corner exit oversteer but how does the car behave elsewhere? Is it well behaved transitionally (slaloms)?

The shock settings are not what I would expect you'd want to run on that car but I know very little about the BRZ/FRS. How did you end up running a lot of front rebound damping and not a lot of rear?

The alignment looks fine. I'd actually want to set the car up to run less rear toe-in if possible, maybe by changing the balance with a bigger front bar. A car will drive with a shorter effective wheelbase with lower rear toe settings (going so far as making it negative like the RX-8 guys do). Based on what you're saying, your car seems like a prime candidate for a bigger front bar.

Also, one person's understeering pig is another person's uncontrollably loose car. It depends on how they're driven.
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Old 04-14-2017, 08:36 AM   #8
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Thanks for the suggestions. I'll play around with settings more tomorrow at the test day.

The car is mostly good everywhere except mid-corner to corner exit when I get the oversteer. It is very good on corner entry. In transitions, the car is good and easily manageable but not particularly stable, but I thought it was slightly better the season I had a little wider tires (235 vs. 225).

I hate to say this and it could be ignorance, but I really cannot tell a ton of difference in the OTS Konis when I do 1/2 turn increments. Most people run a little less up front (1.5 turns from soft vs. my 1.75) and a little more in the back (1 turn from soft vs. my 0.5). I've tried that and did not notice a difference, but I'm not convinced the OTS Konis make a huge difference vs. stock shocks on this car which is why I still am hoping to save enough for MCS.

I am running the smallest aftermarket front bar (19mm) on the soft setting, so I'll try the hard setting this weekend for a few runs. The TRD bar I want is 20.6mm and Sam's is 22mm hollow, but most people opt for the Whiteline 20mm on hard setting. The TRD rear bar is 17.5mm vs. OEM 14mm, but I'm not looking to change that until I can afford the MCS and really do some testing/tinkering.

For the less rear toe-in, just so I'm not screwing up the positives/negatives, do you mean go closer to 0 toe from the 0.17 on each side?

Another note is that the only time I ran data with Craig, I was always way faster on corner entry, he was faster on corner exit, but we still would run the exact same times (within 0.1). It could just be my driving style?
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Old 04-14-2017, 08:47 AM   #9
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Quote:
Originally Posted by John V View Post
The shock settings are not what I would expect.
I assumed he was running more rebound when he said he had the smaller fsb.

Quote:
Originally Posted by Biggins View Post
It could just be my driving style?
It could very well be. Sounds like you may be stuffing the car in with lots of trail braking. Think about weight transfer and what happens when you do that and then jump on the throttle.

Oh, and don't get a z06, your driving style won't work very well - ask me how I know.
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Old 04-14-2017, 10:27 AM   #10
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One of the things we always ask in the morning at the Evo schools is "How many of you think your car understeers?" We ask the same question at the end of the day and get a lot fewer people raising their hand. I agree with Bren's assessment, you might be standing the car on its nose and snapping the throttle open which can cause oversteer. Or it could be as simple as you're not unwinding the wheel. Do you have any video?

Positive toe on the alignment sheet is toe-in. Negative is toe-out. So you have about 1/8" of total rear toe-in, which doesn't sound excessive to me, but I like to run as close to zero toe in the rear as I can get away with. Now, more rear toe-out will make the car looser on corner exit and in transitions but theoretically the car will slalom faster like that. I like to be able to hammer on the car through slaloms and not have it come around on me. If I can't do that, I'll make shock changes until I can.

Look up some shock dyno curves for your shocks and see what the rebound curves look like at full stiff versus full soft. I don't remember how single-adjustable Koni curves look.
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