Help! Front wheels/ direction feeling light/floating

[MTROIS]

Guys,

I need your help right now as I am attending a HPDE @ VIR!

Long story short:

- the steering wheel feels like "floating" when going up the back straight and does not feel "planted" anymore. Zero vibrations.

- tire pressure is ok and the AD-08s are mounted in the proper direction

- wheels are balanced... And if not, I would feel a shimmy in the wheel anyway, right?

- also checked the tie rods and connecting links to wheels, all seems ok and tight... Same for wheel bearing which are both new

I have made an emergency appointment with Crown BMW tomorrow morning.... But do you guys have any thoughts ????

I am thinking that the alignment was not done properly or something like that. I recently asked my dealer to put max negative camber but the car pulls a tiny bit to the left and does not feel the same as before, probably due to the toe they have out in.

Can someone send me " ideal" alignment specifications when running max negative camber?

Any other thoughts??

Thanks in advance guys!!

[CanAutM3]

Originally Posted by MTROIS

probably due to the toe they have out in.

You lost me with this one bro...

I have a stock suspension with GC camber plates. I run -2.8 and -1.8 front and rear camber with stock toe settings. Perfect for the track, but a bit aggressive for the street though. With this setup the front is very well planted with excellent steering feel.

[Porschefile]

What changes were made between the last time the car felt good and now?

You would feel vibration if it was a balancing issue.

Toe changes dramatically affect the stability (or lack thereof). My guess would be your front toe is off without further info.

A good baseline toe for max neg. front is either zero or 1/32 total out.

Rear should be somewhere around -2.0 and either 0 toe or 1/16 total in.

[OmegaE92]

Rotate front to back if you can to see if it changes anything and check to see if you lost any weights would be my best guess. I ran into a wicked shimmy at Fontana that I havent been able to figure out yet, might be a wheel bore issue, hope your's is easier to figure out!

[MTROIS]

Ok, the results are in!

No, I am NOT talking about the Powerball lottery, but about my issues.

I actually had Chris Mitchum and his team Jared and Trevor from Mitchum Motorsports, take care of this issue. These are indeed GREAT guys and it will be great to see them again on TV racing at Mid Ohio in a month or so.

Anyhow, here is how they proceeded:

- First and foremost, they checked the torques on the sway bars, control arms, sway bar end links, wheel bearing mount, etc, etc.
--> all was ok up to here!

- Based on the lack of vibrations, we had ruled out an issue with the wheels... But just to be sure, we indeed rotated the wheels left-->front to validate this assumption. since the previous step was performed, the car was deemed safe to be driven at speed...
--> I could confirm that the problem had not changed based on the wheel swap (good idea OmegaE92 )

- lastly, they put the car on weight cells, etc. to check the alignment... And VOILA the culprit!!! I need to dig out the numbers before and after in my car later, but as Porschefile noted , TOE was completely off since I had asked my dealer to add negative camber a few weeks ago. The toe values for the rear were -1 and -3 (!!) and toe in in the front
--> they put slight toe out in the front, equalled the toe in the rear... And the car felt DRAMATICALLY different during the next session!

I am still a "beginner" when it comes to car setup etc, but I was really so surprised that these settings did affect so dramatically the behavior of the car!

Anyhow, problem solved and here comes another day. I am still learning VIR and I find this track quite challenging in many different places (turn 10 for example!). I am not sure if I will be able to keep dropping my times below my current 2'22"s as they are calling for rain today.

Will see but I am psyched that the car feels planted again.

[Malek@MRF]

Originally Posted by MTROIS

Ok, the results are in!

No, I am NOT talking about the Powerball lottery, but about my issues.

I actually had Chris Mitchum and his team Jared and Trevor from Mitchum Motorsports, take care of this issue. These are indeed GREAT guys and it will be great to see them again on TV racing at Mid Ohio in a month or so.

Anyhow, here is how they proceeded:

- First and foremost, they checked the torques on the sway bars, control arms, sway bar end links, wheel bearing mount, etc, etc.
--> all was ok up to here!

- Based on the lack of vibrations, we had ruled out an issue with the wheels... But just to be sure, we indeed rotated the wheels left-->front to validate this assumption. since the previous step was performed, the car was deemed safe to be driven at speed...
--> I could confirm that the problem had not changed based on the wheel swap (good idea OmegaE92 )

- lastly, they put the car on weight cells, etc. to check the alignment... And VOILA the culprit!!! I need to dig out the numbers before and after in my car later, but as Porschefile noted , TOE was completely off since I had asked my dealer to add negative camber a few weeks ago. The toe values for the rear were -1 and -3 (!!) and toe in in the front
--> they put slight toe out in the front, equalled the toe in the rear... And the car felt DRAMATICALLY different during the next session!

I am still a "beginner" when it comes to car setup etc, but I was really so surprised that these settings did affect so dramatically the behavior of the car!

Anyhow, problem solved and here comes another day. I am still learning VIR and I find this track quite challenging in many different places (turn 10 for example!). I am not sure if I will be able to keep dropping my times below my current 2'22"s as they are calling for rain today.

Will see but I am psyched that the car feels planted again.

You have Toe-OUT in the front and the rear?? The rear should always have Toe-IN.