Violent Steering Wheel Shake Under Heavy Braking

[Rafic]

Hi there,

I've been experiencing a very violent steering wheel shake under high speed heavy braking.

Here's the history so far, around the 1000 miles mark, a knocking sound developed while steering left/right standing still. It turned out to be a faulty steering box. The dealer replaced it under warranty.

Around the 3000 miles mark, I started experiencing a sever steering wheel shake under heavy braking. The shake becomes more pronounced with the steering wheel slightly turned to either side or if theres the smallest pot hole or crevice in the road, all the while under heavy braking.

The dealer checked the car and said the rotors need resurfacing and they performed the hydro bushing TSB as well. And they did a complete wheel alignment.

I just picked her up, lo and behold, the shake is still there. I didnt have the time to turn back and drop it off again because of work.

I'm starting to feel the stealership are not figuring out what's the source of the problem!

Can you guys please throw in you opinions as what might be causing this shake. Here's a video to better illustrate the shake:

[youtube_browser]79a3P9AnZc4[/youtube_browser]

 

[RSH427R]

Looks like you need new rotors, to me.

 

[Rafic]

Looks like you need new rotors, to me.

I'm leaning towards that also. But could it be that the EPAS - Electric Power-Assisted Steering - is acting up in some weird way?? I read on some posts that there was a TSB for 2011 GT500s where the EPAS PCM needed to be reflashed. could this be a somewhat similar issue.

I dont want the dealership trying out different theories and keep taking the front end apart if you know what i mean.

 

[USV8PWR]

I'm leaning towards that also. But could it be that the EPAS - Electric Power-Assisted Steering - is acting up in some weird way?? I read on some posts that there was a TSB for 2011 GT500s where the EPAS PCM needed to be reflashed. could this be a somewhat similar issue.

I dont want the dealership trying out different theories and keep taking the front end apart if you know what i mean.

IMO, as said above it is definitely the rotors. Were you really hard on them before they had a chance to break in/set? If the rotors get hot (and I bet it is hot over there!) they they will warp. And turning rotors on a car as heavy and built for speed as this isn't a good idea as they will just quickly warp again. Turning the rotors means shaving off some of their metal and making them smooth again, which makes them thinner, and thus even easier to heat up. While turning rotors on a basic sedan may work, a car like this is which is expected to make very abrupt and repeatable high speed stops will get to hot for turning the rotors to be an option.

See if you can get some new rotors (and have them replace the pads if they will too).

Btw...your post above regarding the black 2013 totaled Shelby helps prove my other thread (the future collectibility of these cars) and the extreme likelihood that the ones sent overseas will never be seen again in the American market. Do you have the VIN per chance on the totaled one?? Anyway, take car of you car man and you will never lose any of that $115K you paid for it over there! :beer:

 

[railroad]

I going to bet it is not the rotors. That is the same conclusion the dealer came to. Unless he did not have them mounted true on the lathe when he turned them, they have already been turned. I think they need to go back to the steering box and related components. Without hands on, my opinion is just that. Have them raise the front and turn the wheels by hand. If the rotors are bad, you will feel the drag change. I would check both sides.

 

[raustin0017]

Warped rotors. That is my guess. Even if they were resurfaced...that will not fix the warp.

 

[SlowVert]

I've had the same issue with my Infiniti G35S.... the big rotors seem to warp real easy/fast and once they warp, they are done - even cutting them is a short temporary fix. When the car was still under warranty the dealer kept cutting them each time I brought it in until they finally had to replaced them (2x). Seems like that car warps rotors every 4-5K.

I'm on my third set with 35K on the car and it's our "family" car so no real beating on it. I've noticed it starting again... At speeds lower than 60-65 it's just fine. If you're doing 80-85 and step lightly on the brake you get the dreaded wheel shake.


J.

 

[Myfast70]

Something in the EPAS isn't happy

 

[Kapy]

Sounds like multiple things might be in play here.

I think from what I am reading it is probably more likely to be the rotors.

But I also would not discount the fact since the steering box was replaced did they re torque necessary fasteners at the specified torque values?

I have seen many vehicles especially that needed collision repairs, transmission replacements, major suspension replacement, subframe replacement etc., and at times techs just throw the air gun on the components to torque instead of taking the time to do the job right and torque to spec with a precise torque wrench. I have witnessed many times major repairs like this and most techs do not take the time to do properly as they are always trying to beat the clock. Sad, but true.

So this leads to over torquing or under torquing of critical fastener values all the time. Which in turn causes dramatic issues in containing vibration, noise and chassis control.

I would go to the rotors first. If that doesn't work I would demand that the dealership put a highly trained tech on the car to retorque all front end components to correct specifications and go from there.

 

[PLATIADO]

(THIS) But could it be that the EPAS - Electric Power-Assisted Steering - is acting up in some weird way?? I read on some posts that there was a TSB for 2011 GT500s where the EPAS PCM needed to be reflashed.

 

[04SVTMystic]

Warped rotors. Very often turning rotors in modern cars does nothing. Given what you describe they sound warped and need to be replaced.

 

[Rafic]

Thanks for the replies. Dealer will change the rotors and the pads under warranty. Got an appointment for next week to bring the car in. Yet my gut tells me its gonna be the EPAS. I think they did something wrong when they replaced the rack. There's a slight intermittent vibration in the steering wheel when traveling at speed and you twitch the steering wheel to the left or the right, say to change a lane or over take traffic. Would warped rotors cause that? And if the rotors are warped, wouldn't the steering wheel shake even if the brake pedal is slightly depressed and not only under heavy braking? And shouldn't the brake pedal pulsate as well?

 

[Kapy]

Thanks for the replies. Dealer will change the rotors and the pads under warranty. Got an appointment for next week to bring the car in. Yet my gut tells me its gonna be the EPAS. I think they did something wrong when they replaced the rack. There's a slight intermittent vibration in the steering wheel when traveling at speed and you twitch the steering wheel to the left or the right, say to change a lane or over take traffic. Would warped rotors cause that? And if the rotors are warped, wouldn't the steering wheel shake even if the brake pedal is slightly depressed and not only under heavy braking? And shouldn't the brake pedal pulsate as well?

If the rotors are that warped you should feel it in the pedal as well.

You should not feel a vibration either when changing lanes.

Maybe it is the EPAS. I am definitely interested in knowing what they find as I am sure the rest of us are as well on this thread.

Good luck Rafic, let us know what happens after you take it in.

 

[SlowSVT]

If this was warped rotors the wheel would shake anytime he touched the brakes and the dealer would have easily spotted a warped rotor with a dial indicator.

Sounds like this might be an EPAS problem that thing is tied into the ECU. Can the EPAS steering rack be disconnected electrically and the car driven to see if that removes the steering wheel shake?

 

[GT Premi]

OP, I'll bet dollars to doughnuts it's your EPAS. I get that exact same vibration in my steering wheel, except I get it over bumps and through curves. Like Kapy said, if it were your rotors, you'd be getting feedback/pulsing in your brake pedal, too. And the steering wouldn't shake that badly from warped rotors. The steering bushings would damp most of that out. With the EPAS, it's oscillating the steering rack left to right in rapid succession for some unknown reason.

I had my EPAS unit replaced very shortly after buying the car because it kept malfunctioning. I wonder if it's malfunctioning again. The previous malfunction, though, was that the power steering would completely die and a message would pop up in the message center. Each time it would get ready to die, there would be a slight tug to the left. The weird thing about my current issue is that it only misbehaves over some bumps, mostly the joints at the ends of bridges, and in mild curves. In sharp or high speed curves/turns, it behaves normally. The slight vibration I get under braking, I wrote off as being caused by my slotted rotors. Looks like I might be wrong on that account.

 

[Rafic]

The dealer is insisting on addressing the issue by process of elimination. They wanna address the brakes first. They replaced the front rotors and pads under warranty. They called me up and insisted that the service manager and I test drive the car after the rotors replacement. They will not touch it unless I'm present. They said that if the vibes continue, they will address the EPAS. Will report back tonite. Cheers!

 

[Crowley]

The dealer is insisting on addressing the issue by process of elimination. They wanna address the brakes first. They replaced the front rotors and pads under warranty. They called me up and insisted that the service manager and I test drive the car after the rotors replacement. They will not touch it unless I'm present. They said that if the vibes continue, they will address the EPAS. Will report back tonite. Cheers!

Glad they are working with you!

Crowley

 

[BMR Tech]

If, what happens in that video....is the same exact "way" the wheel acts when you are not braking, but turning slightly....I am 100% certain it is your EPAS acting up.

 

[Rafic]

Bad news, the new rotors and pads didn't solve the problem. The shake seems to be more pronounced now. It used to require greater pedal effort before to induce the shake. Now it almost needs half the pressure on the brake pedal for the wheel to shake violently. I am pretty sure this is steering box/EPAS related. They're gonna take it back in. I'm gonna insist on a new box. Will report back.

 

[Rafic]

Here's a video from this morning

[youtube_browser]FKK2wsnCv88[/youtube_browser]