vibration when wheels turned all the way at slow speed??

Not this one again - look up Ackerman on Wikipedia - or here.....

 

Bent fender lips.


Very common on 360

 

i beleive he has a F430...
I feel the same thing on my F430 spider... i just asked another F430 owner, he said it's normal...
don't mind seeing Fchat comments...

 

Yup.

 

I was wondering the same thing on my F430. I get the same feeling when my wheels are close to max lock. Seems no harm done but it feels uncomfortable when it does it......Steve

 

Happens on my 360 too. I was a little worried also.

 

I was told it is the LSD doing that....as if it is in AWD on a hard surface and the wheels can't slip.

 

E-diff

 

This is caused because the inside tire has to turn in a tighter circle than the outer tire. (in a turn)

The steering geometry is set to account for this but it is turned for regular driving, not max ratio turns. If you park the car with the wheel turned hard left you'll notice the left wheel points out at a greater angle than the right points in. (did that make sense?)

The vibration you're experiencing is the tires slipping on the pavement as they turn at different steering ratios. (ie: they do not track properly at max deflection)

While this might be a sign of a problem if it is excessive, it's probably normal.

Try it in the rain and you'll probably notice it is decreased.

 

In cold weather, my 430's tires skip sideways when turning sharply, too. It seems less severe after the tires warm up a bit. My other car does this, as well. It likely has something to do with a sports car's steering geometry and cold, hard summer tires.

 

I might have phrased that poorly... It's not that they are skipping BECAUSE turning at different speeds.

(As I understand it but not be explaining it right...) The steering ratio is non-linear. In other words, as you turn tighter, the inner wheel needs more deflection. -- But mechanical linkage can't do that perfectly. So at full deflection the wheels are not 'in sync' as well as they are at drive speeds. (I don't know the proper nouns for all this, sorry) So your tires are not tracking perfectly. Or that's how it was explained to me by a guy who does this for a living... although he'd probably chuckle at my tortured verbiage.

A similar problem can be felt if you have old brittle tires. If you have this problem more in the cold and your tires are old, ya might replace them.

I edited the post above. I said the wheels turned at different 'rates.' And I meant different 'steering rates' (ie ratios) not 'different speeds.' - Poor choice of word.

 

I had this very strongly with Pirelli tires. Now, I went for Michelin PS2 tires and in the same conditions, I almost didn't have this issue anymore, just very slightly. After changing the 4 springs, lowering the car and a serious realignment, this problem 100% disappeared :

Left Max steering Left Wheel: +21°36' -> +29°00'
Left Max steering Right: +20°57' -> +26°19'
Right Max steering Left Wheel: +29°29' -> +26°41'
Right Max steering Right Wheel: +32°48' -> +29°29'

Stef