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-   -   Front wheels stutter to turn, when cold? (https://www.6speedonline.com/forums/997/197995-front-wheels-stutter-turn-when-cold.html)

Cattman 01-11-2010 01:35 PM

Front wheels stutter to turn, when cold?
 
With the recent cold-spell here in ATL, I've noticed that after my car's been sitting for awhile, and I back out of a spot with the wheel turned all the way to one side or the other, there's a stuttering feeling in the front wheels through the slow speed turn. It goes away, and is only noticed on full wheel lock at low speeds after starting the car.

I assume the UV joint just needs to warm up a bit- is that about right?
CATTMAN

keninirvine 01-11-2010 02:24 PM

Same thing happened to me on both my C2S cab and my T4S. I concluded that it was worse when my tires were more worn, and it was colder. Given it was on the front wheels, and occurred on both RWD and AWD, I don't think it was related to U-joints. I think it is just the wide front tires having to squirm in a sharp slow turn (and always happened as I backed out of my driveway onto the street).

Dadio 01-11-2010 02:36 PM

Caused by the big tires. My C4S does adn has since new. No big deal.

Gpjli 01-11-2010 02:38 PM

The front steering has no conventional stop to prevent this. When cold you can turn past the steering angle the tires can manage (less grip) and the result is as you described. if you exceed the avalable turning radius the tires slide/skip on the road. Less of a problem w warm tires and road surface, but if you try real hard you can turn too sharply from a stop as in a parking lot for example even when warm. Reducing the steering wheel rotation slightly when you feel this is the solution (ie: countersteer). The plus side is that great turning radius under normal conditions.

JohnM 01-12-2010 08:11 AM

it is a product of the extreme caster needed to overcome the strut suspension geometry. When you turn the wheel all the way, the caster makes the tires ride on their edges, with a crazy scrub radius. In warm weather, and new tires, the tires flex and stretch to overcome this. Cold or worn tires cause the nasty skipping you are describing. I don't think you can change this unless they come out with a nice multi-link for the front suspension.

keninirvine 01-12-2010 08:15 AM


Originally Posted by JohnM (Post 2685094)
it is a product of the extreme caster needed to overcome the strut suspension geometry. When you turn the wheel all the way, the caster makes the tires ride on their edges, with a crazy scrub radius. In warm weather, and new tires, the tires flex and stretch to overcome this. Cold or worn tires cause the nasty skipping you are describing. I don't think you can change this unless they come out with a nice multi-link for the front suspension.

That is one excellent explanation! Thanks.

utkinpol 01-12-2010 08:18 AM


Originally Posted by Cattman (Post 2684179)
With the recent cold-spell here in ATL, I've noticed that after my car's been sitting for awhile, and I back out of a spot with the wheel turned all the way to one side or the other, there's a stuttering feeling in the front wheels through the slow speed turn. It goes away, and is only noticed on full wheel lock at low speeds after starting the car.

I assume the UV joint just needs to warm up a bit- is that about right?
CATTMAN

I do not see it in your signature - as I just got GT3 996 LCAs installed - I cannot believe how much better car handles now. I do not understand why Porsche does not install those LCAs by default on all cars. Would be cheaper for them to manufacture one part only than 3 different ones and everybody would be happier.

I probably should have not got ass tight and got upper GT3 mounts installed as well as they have steel monoball there instead of stock rubber joint. Anyway, steering is way better now and turns are improved big deal.

Cattman 01-12-2010 09:16 AM


Originally Posted by JohnM (Post 2685094)
it is a product of the extreme caster needed to overcome the strut suspension geometry. When you turn the wheel all the way, the caster makes the tires ride on their edges, with a crazy scrub radius. In warm weather, and new tires, the tires flex and stretch to overcome this. Cold or worn tires cause the nasty skipping you are describing. I don't think you can change this unless they come out with a nice multi-link for the front suspension.


Excellent, thank you! Rep points coming your way!
CATTMAN

doug2255 01-12-2010 11:49 AM

Thanks for the question and great reply -I have the same issue turning out of my driveway. Iwas not sure if it was "normal" or not.


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