Guys I have a bit of an issue here that noone can seem to fix. My car has a shimy at 75mph. The steering wheel will rock back and forth at about 75mph and higher. I have taken the car to both the dealership and a local tireshop and both of them were not able to find anything wrong except the tires being out of balance. The tire shop did mention that my rotors were slighty warped which the dealership said they took care of. Well the steering wheel still shakes at 75mph and when I step on the brake the shaking is even worse at that speed. I also have the steering shimy when step on the brake at any speed. Neither place is willing to road test my car at this speed either (which I can understand). They will only road test up to 55mph. I checked the rims and they don't seem to be bent and like I said this only happens at about 7mph. Anybody have any ideas as to what this can be. I'm almost positive the rotors need to be cut to fix the brake issue but as to the 75mph steering shimy I haven't a clue. Any help would be much appreciated.
Steering issue at 75mph
- Thread starter Jrodd
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UrbanRedneck
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- Mar 27, 2008
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Shimmy is usually caused by a tire out of balance or a defective tire, but since it gets worse when you hit the brakes I would say that is brake vibration, which needs new rotors to fix (or rotor cut, but they may need a lot of material to be removed for that).
As far as the fact that noone will road test it at that speed.. A lot of interstates in IL and IN have 75 MPH speed limits, I'm sure rural NY does to, so that's bull. I road test cars up to 75 all the time when looking for vibration, even if it exceeds the speed limit, we all know the car has no problem doing 75 (even the junk I work on, as I am a Honda/Acura tech), and if the customer has a problem at that speed it isn't your place to tell them to slow down, you FIND THE PROBLEM.
As far as the fact that noone will road test it at that speed.. A lot of interstates in IL and IN have 75 MPH speed limits, I'm sure rural NY does to, so that's bull. I road test cars up to 75 all the time when looking for vibration, even if it exceeds the speed limit, we all know the car has no problem doing 75 (even the junk I work on, as I am a Honda/Acura tech), and if the customer has a problem at that speed it isn't your place to tell them to slow down, you FIND THE PROBLEM.
Art161
Member
My suggestions:
1. Correct the warped rotors (cut, replace, whatever is needed).
2. Find a shop that has a Hunter GSP9700 wheel balancing machine.
If the above two steps don't work, then it might be suspension. This is a problem that can be corrected. It's a case of finding a competent tech with the proper equipment.
1. Correct the warped rotors (cut, replace, whatever is needed).
2. Find a shop that has a Hunter GSP9700 wheel balancing machine.
If the above two steps don't work, then it might be suspension. This is a problem that can be corrected. It's a case of finding a competent tech with the proper equipment.
What mods do you have, suspension wise? What size wheels/tires and brand of tires are you running?
If you don't have any suspension mods, I would get your rear wheels/tires checked with a Road Force balancing system. The standard balancing systems are marginal at best. This is the system the above post was referencing. You can find a local shop that has one here: http://www.gsp9700.com/pub/search/findgsp9700.cfm
If you don't have any suspension mods, I would get your rear wheels/tires checked with a Road Force balancing system. The standard balancing systems are marginal at best. This is the system the above post was referencing. You can find a local shop that has one here: http://www.gsp9700.com/pub/search/findgsp9700.cfm
NastyStang113
New Member
Get new rotors and pads, maybe stainless steel brake lines. It'll be a great improvement in braking performance and it'll fix your shimmy. Also find a place that has a Hunter "Road Force Balancer". It takes all of the guess work out balancing a wheel/tire, anyone can balance amazing using this machine, so you're much more likely to get a good balance.
I don't have any mods on the car at all
yeah I know. As far as tires I have the Pirelli P-Zero Neros. I can check on whether the shop I used has that balancing system.You know I really really want the stoptech stage 2 brake upgrade from Brenspeed and this might just be the reason to get it. Thanks for giving me the incentive to get it.
Guys thanks for all the responses. I knew you would all help me out. I knew I had a warped rotor but I didn't think it would cause the shimy when I wasn't using the brakes. I will look into getting new rotors and maybe the stage 2 brake upgrade and let you all know how it works out. Thanks again.
FastHorse
New Member
when you step on the brakes and it shakes its def the rotors needing to be resurfaced.... Especially if the brake pedal pulsates up and down with the vibration. As far as the steering wheel shaking at that speed... i think its the tire balance issue I have already balanced my car once since last December and am fixing to do it again right now as we speak.... cause the nitto nt555 seem to get out of balance alot. But then again I live in a city with crappy (bumpy) streets.
FastHorse
New Member
I balanced my tires and the steering shake has stopped. I did notice that some of the weights had fallen off. You might want to check yours, sometimes they do fall off.
Hope this helps
Hope this helps
UrbanRedneck
New Member
- Mar 27, 2008
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that Hunter balancer does help a lot too, because it measures tire radial and lateral runout and allows you to account for road force variation. A Ford dealer should have that machine.
After Ford balanced them the first time I thought they might have forgotten to put the weights on or they fell off on the highway but when tire place balanced them the second time I knew that couldnt be the case. I'm thinking now that it has to be a warped rotor. Time for some new ones I think.
Marine One
New Member
I had a similar situation with my 1995 GT and it did in fact turn out to be the front rotors. I pulled them and took them to a local machine shop, told them what was happening, and asked them to just cut them the minimum required to true them. It cured the problem. This was after I had a guy at a tire shop tell me the problem couldn't be the rotors. My experience with Mustangs (95 GT, 96 Cobra & 07 GT) is that it doesn't take much to warp the front rotors on these cars. As a result I always insist that lug nuts are hand torqued to factory specs. I'm also a big beliver in the Hunter 9700 Road Force balancing system. It will allow the tech to ensure that you don't have an out of round tire problem or something hard to diagnose like a high spot on a tire mounted over a high spot on a wheel.
NastyStang113
New Member
Well I was able to take my car to a local repair shop and told them about the problem and that the rotors are warped. The mechanic took a look at it and said that they were warped especially the left front one. He had to cut alot out of that one to get it true. He also changed the pads. Looks like the problem is solved. I didn't have the time or the money to go with the stoptech stage 2 kit but now that the problem is fixed I will look into the stage 1 kit or the steel brake line kit and some ceramic pads. Thanks again all of you for your help.
