Huge Steering Dead Spot under Acceleration—Causes?

[Roadway 5.0]

My steering is great most of the time, but under mid to full throttle I get a huge (1” or more to each side) dead spot in the steering wheel. I get this issue in both straight line acceleration and in the curves under throttle.

What would be the cause(s)? EPAS safety feature? Alignment change under throttle (I’m at .06 toe-in static on each front tire)?

Thanks,

-Mike

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[NightmareMoon]

Hmm. What are your f/r shocks set to? Toe in would be an easy thing to try changing, a quick front wheel toe alignment should be cheap.

You have a 10/11 wheel stagger which might be contributing a little to understeer. Under throttle, steering is going to be less sensitive on any car. How old are your front tires?

I’ve never noticed any problem with my car and run 0 front toe. The expected result of front toe-in is a dead spot.

 

[Roadway 5.0]

Hmm. What are your f/r shocks set to? Toe in would be an easy thing to try changing, a quick front wheel toe alignment should be cheap.

You have a 10/11 wheel stagger which might be contributing a little to understeer. Under throttle, steering is going to be less sensitive on any car. How old are your front tires?

I’ve never noticed any problem with my car and run 0 front toe. The expected result of front toe-in is a dead spot.

All dampers are fixed; ProAction fronts and Bilstein rear. Tires are on the newer side of mid life, and right now I’m running my winter setup which are the same diameter and width wheels/tires as OEM PP.

You sparked a thought: I aligned the car with my 20” stagger setup, but now I’m on my 19” winters. Could be the problem, or at least why I’m noticing this all of a sudden. I’ll give a go at a 0.00 toe alignment with the winters on and see what happens. Thanks.

 

[Bluemustang]

All dampers are fixed; ProAction fronts and Bilstein rear. Tires are on the newer side of mid life, and right now I’m running my winter setup which are the same diameter and width wheels/tires as OEM PP.

You sparked a thought: I aligned the car with my 20” stagger setup, but now I’m on my 19” winters. Could be the problem, or at least why I’m noticing this all of a sudden. I’ll give a go at a 0.00 toe alignment with the winters on and see what happens. Thanks.

Yeah, the winter tires and the toe-in is likely the cause of what you're describing. I've tried toe-in before and that's why I don't care for it. It's easier to cruise yes but also makes it seem like the steering has a dead spot.

 

[Roadway 5.0]

Have you guys ever tried a small amount of front wheel toe-out on the street? Maybe .02 or so?

I’m willing to sacrifice a bit of high speed stability/tram-lining effects/tire wear if response increases. If the juice isn’t worth the squeeze, though, I’ll stick with 0.00.

 

[Bluemustang]

Have you guys ever tried a small amount of front wheel toe-out on the street? Maybe .02 or so?

I’m willing to sacrifice a bit of high speed stability/tram-lining effects/tire wear if response increases. If the juice isn’t worth the squeeze, though, I’ll stick with 0.00.

I have that now. -0.02 -0.03
That wasn't what I was targeting just turned out that way. No reason to though for a street car. Just set it at zero IMO. I've done the toe in thing and the more relaxing manners are easily forgotten once I realize the response is less than desired. Going back to zero toe again it feels right to me.

 

[NightmareMoon]

Have you guys ever tried a small amount of front wheel toe-out on the street? Maybe .02 or so?

I’m willing to sacrifice a bit of high speed stability/tram-lining effects/tire wear if response increases. If the juice isn’t worth the squeeze, though, I’ll stick with 0.00.

i didn’t notice a whole lot of difference between slight toe out and zero toe. Its not much worse with some toe out, but I ended up going back to zero toe out of paranoia for my already bad tire tread life and the highway manners are pretty good (for me anyway) with zero toe.

now, same zero tow but slap on 2+” wider front track 305 tires which are nearly bald from racing and its darty as hell and tramlines all over. :shrug:

 

[Grintch]

I wouldn't expect a toe issue to change with throttle setting unless you have a lot of bump steer . So I would suspect a shock issue.

 

[CCIWDO]

Just a theory... But could it be caused by a drop in weight over the front tires due to the shift in weight during acceleration? It would decrease the coefficient of friction on the front end.

 

[NightmareMoon]

Just a theory... But could it be caused by a drop in weight over the front tires due to the shift in weight during acceleration? It would decrease the coefficient of friction on the front end.

Not just theory, thats exactly what happens, and It will take more steering to effect the same about of yaw change when the front end is light. Soft sidewalled tires (like winter tires) are also soft and squirmy, so they may not respond to steering very quickly either. Then combine with alignment toe physics (not well understood by me), electronic steering (no feel) and a heavy GT that doesnt *really* want to change directions in the first place and you may have a perfect storm of dead feeling steering.

 

[bnightstar]

Speaking of Toe I watched Kenny Brown yesterday and he recommend -0.3 toe for street/track use as this really make the car turns into corners. What you guys think about that ?

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