Austin – I have a ’97 Mustang GT 4.6 with 64K miles on it. The problem I have isn’t new, its actually been with the car since I bought it four years ago. I just didn’t know who to ask.
It shakes at the oddest times, and I can’t duplicate anything to make it happen. It’s not a steady shake that’s caused by alignment or tire balance, there’s no noise when it shakes, and there’s no certain speed that I have to be driving before it shakes.
I’ve asked the Ford mechanic if the motor mounts were loose, and he said no. So I’m at a loss as to what it could be. Would Dr. Austin have any ideas?
Thank You in advance,
Hi there Rick
Hi, thanks for your email. I have more questions than answers.
You say “shake” does it do this when you are driving (usually freeway or slower speeds…on acceleration or just a steady speed or at a stop light)?
Get back to me and I will see what I can assist with.
Austin C. Davis
Thank you for getting back to me Austin,
The “shake” happens during both city & highway driving, it could occur during acceleration but no guarantee. On a scale of 1-10, ( 1 being least likely ) I’d give it a 2 for during acceleration. It never shakes when just idoling, I have to be traveling slow or fast, and it happens at random.
The only way I could describe it is this:
As if the car was on top of a big massge pad and it turned on at random times for maybe 10 seconds at a time.
I don’t notice an exact amount of time in between shakes either.
If you have any idea, that would be great.
I think this is one those times where I need someone to drive it for a week and feel it themselves.
Thanks for the clarification Rick
If you live in the Houston area I would be glad to take a ride with you and see if I can determine the problem.
If you have a shimmy or shake while you are driving it most likely is coming from one of these:
Wheel balance problem – usually the shimmy is always there because the tire is always out of balance, but hitting a pot hole can cause a shimmy for a few seconds until the wheel comes back into balance…or close to it. I would rotate and balance the wheels, moving front wheels to back and back to front.
Run your hands along the tread of the tires (this will get your hands very dirty) and see if you can feel any rough or high spots that might be caused from uneven tire wear. If you have a tire that has some high spots that you can see with your naked eye and feel with your hand…this will and can cause vibration problems.
Slight vibrations, but enough that will cause your coffee cup to shake when you have it in your cup holder. These rough and high spots will cause the tire to be out of balance just slightly and will be felt at certain speeds and on certain pavements, not all the time. So one day you might be just on the right pavement at just the right speed to feel it. Most vibration complaints I see are caused by rough and out of balance tires.
Rule of thumb – the more aggressive the tire I,E like a competition low profile tire which you probably have or a tall more off road tire like most SUVS the more you will feel a vibration than if you had some “grampa” highway radial tire that is soft and absorbs more of the road. The shorter the tire profile the more of the road vibration you will feel in the seat. Switch to a taller, highway type tread…and get a softer ride but less handling performance on turns.
Driveshaft or u – joint problem Again, this is an out of balance problem and once out of balance it is usually always out of balance, but checking the u- joints is easy to do. There should be no play in the joints or the driveshaft.
Steering stabilizer shock – Your car probably has this option. When you hit a pot hole the front end gets all shaky and squirrelly because the stabilizer shock is worn out. If you have one, and it is old….replace it as maintenance ….your car will handle better anyway with a new one even if you don’t solve the problem.
Worn or loose tie rod ends or worn control arms – if you have not had an alignment in awhile, get an alignment and have your mechanic “shake the front end down” to check for anything that is loose or worn in the steering and suspension system.
Austin C. Davis