Post-Track Alignment Mystery???

[Honcho]

I just picked up my NSX from Acura after checking the alignment and we discovered something very strange. Need a few gurus to chime in here- I'm stumped!

1-week before the track, we set the alignment to the following. Note all measurements are in DEGREES.

FRONT L R

Camber -0.43 -0.37
Caster 7.99 7.98
Toe -0.16 -0.12

REAR L R

Camber -1.53 -1.57
Toe 0.19 0.15

Then I spent a half day at HPR running 4 sessions. We never hit any bumps, nor did we ever go off track. The only change to the suspension was stiffening the shock rebound. On the same rack yesterday at Acura, here is what we saw. Significant changes are in BOLD:

FRONT L R

Camber 0.17 -0.16
Caster 8.11 7.63
Toe 0.01 0.03

REAR L R

Camber -1.53 -1.55
Toe 0.21 0.30

Also, the front lug nuts, which I had double torqued to 90 ft/lbs had come loose and the wheel was wobbling on the hub. Strangest of all, the Right caster WOULD NOT adjust any higher than 7.63. My question: What the hell happened to my NSX???? Should I be concerned? Acura is stumped. :frown::frown::frown:

 

[R13]

I assume the second set of measurements was taken after they tightened the lug nuts back up, right?

I've had a not-named alignment shop take a wheel off to fix something, put it back on, but not seat it all the way, and alight the car (and let me drive off) on a loose wheel....needless to say the specs weren't right.

I wouldn't think the camber would be prone to slippage if the eccentric bolt is secured correctly. I'd be tempted to take it to another alignment shop to check the dealer's numbers. Those racks do have to be re calibrated periodically.

 

[Honcho]

I assume the second set of measurements was taken after they tightened the lug nuts back up, right?

I've had a not-named alignment shop take a wheel off to fix something, put it back on, but not seat it all the way, and alight the car (and let me drive off) on a loose wheel....needless to say the specs weren't right.

I wouldn't think the camber would be prone to slippage if the eccentric bolt is secured correctly. I'd be tempted to take it to another alignment shop to check the dealer's numbers. Those racks do have to be re calibrated periodically.

Yes, I think it was after the wheels were tight. Most unsettling to me is the inability to adjust caster beyond 7.63. That suggests to me something is broken in the suspension, but they inspected it and found nothing wrong. What could possibly be causing this?

 

[docjohn]

how can wheels that were truely torqued to 90 ftlbs come loose

 

[Honcho]

how can wheels that were truely torqued to 90 ftlbs come loose

Good question! I torqued them myself, drove around and then re-torqued them again the day before the track.

 

[docjohn]

I know you are technicly savy,but I have logged many track miles always using 80ftlbs and never had a lug-nut issue.So why are you using 90? and after inspection the threads are intact? Do the affected lugs srcew on and off easily?

 

[CL65 Captain]

I know you are technicly savy,but I have logged many track miles always using 80ftlbs and never had a lug-nut issue.So why are you using 90? and after inspection the threads are intact? Do the affected lugs srcew on and off easily?

+1 on 80 lbs for all my street AND track driving. Never had one come loose.

 

[Honcho]

Maybe my wrench is off?? I was using 90 for a margin of error. Though, I have never had a loose lug issue in 4 years of driving the car, using the same wrench. Stud threads are clean and all nuts spin easily.

 

[R13]

Maybe something was interfering with the wheel/hub interface somehow. If something was stuck in there when you torqued it down and aligned it, then wiggled out?

That's a shot in the dark and I really couldn't imagine what might do that such that you wouldn't notice as you put the wheel on though.

 

[dquarasr2]

Maybe my wrench is off?? I was using 90 for a margin of error. Though, I have never had a loose lug issue in 4 years of driving the car, using the same wrench. Stud threads are clean and all nuts spin easily.

Sorry if this is too basic an observation, but you didn't happen to change the lug type recently, did you?

 

[Mac Attack]

Sorry if this is too basic an observation, but you didn't happen to change the lug type recently, did you?

+1. Also, I don't know what kind of wheels you have for the track, but did you paint your wheels? Most people have a ratty set of track wheels that they spray paint themselves, but don't bother to clean up the lug nut seating surfaces.

I doubt your torque wrench calibration would be THAT far out of whack. But it may be something else to check.

Finally, there's a high-volume Toyota dealership near my home. It took them three tries to align my Sienna correctly not too long ago. And that was with the latest "high $, high accuracy" Hunter machine. I have my friends DIY alignment tools when I want to align the NSX. Works fine, and saves a lot of money if you want to try various changes. Also pretty cheap if you share the costs with local friends.

Dave