Z is more difficult to drive after corner balance

obender66

Hi all!

Last year I corner balanced the car for the first time (before that I just eyeballed ride height and would jack offending corner up or down a bit
Currently I am failing to beat my pre-corner balance times by significant margin. Car feels heavier and having more understeer(more usteer turning right, although corner balance should have made car turn same left and right?) requires more effort in the corners and less planted in high speed sweepers. Same behavior on both RS4 and V730 . Straight line speed is the same, don't believe there's power loss.
Alignment and other suspension components did not change and there're no bad bushings or broken end links(adjustable, so sway bar preload is not an issue)
Pics of corner balance app before and after are attached. Any comments or suggestions? Does it look off? Am I missing anything?



Thank you!

Attached Images

	Screenshot 2024-07-08 184757.jpg (270.9 KB, 11 views)
	Screenshot 2024-07-08 184730.jpg (259.7 KB, 9 views)

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2016 370Z Base/Setrab/AEM/Uprev/M7 Japan/Magnaflow/Quaife/Wilwood/300 whp
2003 G35 sedan 6MT(good bye-after 15 years together )

Spooler

Did you add your weight to the drivers seat when you had it done?

obender66

Yes, it was added, I have other screens from tech indicating it.

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2016 370Z Base/Setrab/AEM/Uprev/M7 Japan/Magnaflow/Quaife/Wilwood/300 whp
2003 G35 sedan 6MT(good bye-after 15 years together )

Averying

What kind of “significant margin” are we talking about? Are your tires getting toward end of life? Depending on how much of an adjustment was needed to corner balance the car, maybe a realignment is needed?


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ZoomZ

You said Swaybar preload not an issue because they are adjustable. ok.

Did they disconnect the sway bar before alignment and then attach with no preload?

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BGTV8

^ .. what he said. Sway-bars need to be connected with the car on its wheels on level ground with zero pre-load.

Also, by how much did the camber change as a result of ride-height changing. Camber gain becomes larger the lower the ride-height goes.

Understeer usually comes from the rear if the car was previously well balanced so think about whether have you introduced more rear bar at the rear to impact understeer turning right. Re-measure everything (including toe, camber and caster as well as the corner weights and you should find your problem).

Also check the u-clamps on the front bar to ensure they are holding the poly-bush securely. I have had u/steer in the past as the poly bush "escaped" from the u-clamp (they were also FUBAR and were replaced - this item is now a service part - replaced every 8 events).

Spooler

My first corner balance I helped at the end. It was a pain to ensure the sway bars did not preload the suspension. If you didn't have them just right you could see the corner balance change. I never knew it was that sensitive.

obender66

Thank you all for comments. I did not supervise the tech when corner balance was done-I hope that all the proper steps about disconnecting sway bars were followed. Alignment was done in the same shop immediately after corner balance. Shop owner is a time attack champion and well respected in Toronto.

By "large margin" I mean 1.5-2 seconds off the pace per 85 second lap on fresh tires. V730 is slower than A520, but not by that much. I managed 1.2417 lap after I put front sway bar to "soft" (previous track day's best was 1.24.9-same weather, 2 weeks apart, front bar at "hard"). Still, car felt "difficult". My best lap on A052 and "butt corner balance" was 1.227 (front and rear sway bars at "soft")
Tires are fresh, installed about 2 months ago.

BGTV8-could you please elaborate on bolded out section? Can more bar at the rear result in more understeer-I thought it was the opposite?


Looked over my alignment sheets. Yes, I lost front camber after corner balance
Before CB L-1.8, R -2.0
After CB L -1.2 R-1.6 (makes no sense as L side is lower)
on A052 "butt balance"
L-1.6, R -1.9.

Thank you again!

__________________
2016 370Z Base/Setrab/AEM/Uprev/M7 Japan/Magnaflow/Quaife/Wilwood/300 whp
2003 G35 sedan 6MT(good bye-after 15 years together )

Averying

It’s my understanding that the A052, RE71RS, rt660 are in the ‘super 200TW’ category and are unmatched on pace. Grassroots Motorsports article shows v730 about 1.3 seconds slower on a 85 sec lap. Maybe the drop in camber accounts for the remaining loss of lap time.

https://grassrootsmotorsports.com/ar...hang-yokohama/


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2009 Sport Touring | Platinum Graphite | GTM Stage 1 Supercharger | BC BR Coilovers | Hotchkis Swaybar | Z1 FUCAs | AME TM-02 Wheels | Z1 2-piece Front Rotors | Z1 Clutch & Flywheel | Invidia Gemini Catback | GTM Resonated Test Pipes

BGTV8

Introducing understeer implies you have, prima facie, induced additional grip at the rear that has the front out of balance OR the change resulted in less grip at the front somehow.

You have 2 options, you can stiffen the rear bar to kill some of that extra grip OR you can soften the front bar to add some grip at front.

You could also drop the pressures at the front OR add pressure at the rear.

You can also play with the bump at the front (make the front shock softer) or stiffen the rear shock in bump to shift the balance to the front.

You could also lower the ride height at the front to increase front grip and change the balance

Since the handling change came about after the corner-weighting, it is reasonable to assume that might be the root cause BUT you also had new tyres - have you run the new tyres before the corner weighting session as now you have 2 potential root causes (are there any others) .....

Happy to continue the chat via PM if you'd like, but I don't get back here all that often.

OptionZero

Are those rear camber figures?

seems like significantly less camber than most track Z's are running.

-3 front and -2 rear seems most common

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