Shaking \ vibration

Regarding a 96 Grand Am GT 3.1:

Today I was driving my car to work, and I noticed when I started going over 80km/h (50 miles per hour) my car starts to shake, very rhythmatic, almost like you're using a jackhammer - just not as strong.

The slower I go, the less I notice the vibration. But when I'm going that fast, and I accelerate, it almost sounds like a knocking sound at the front of my car. Could anyone tell me what this could be? Or what I should check?

Thanks!

Hello,

I'm having the same problem... you may notice my posting a little below yours (fmd1979). Feel free to check it out. So far, I've been told it may be the overdrive.

Cheers

So it has nothing to do with the tires, possibly the wheel bearing getting ready to fall off? lol

Whens the last time the car had an alignment and wheel balancing? This will also cause the shaking vibration your speaking of. Some other things to consider is a tire issues such as a bad tire, or possibly the brakes maybe a caliper slightly sticking If your wheel bearings were going you would hear a humming noise, coming from the front wheels. Good Luck

I dont' remember the last time I had a front end alignment, but the wheels were balanced when I bought my winter tires about a month ago, so I doubt it's that.... but could the front end alignment cause this? Very strange, as this is the first this happened, I drove the car yesturday and everything was fine.

As for the brakes... I did notice that at the beginning of the drive today, I had stronger than normal brakes... with the slightest touch, it was almost like I was slamming them on. So You're suggesting I get a front end alignment?

A wheel Alignment probably couldn't hurt at this point since your not quite sure when you had one last, Also check and make your you didn't lose any of the wieghts off the wheel, if you knew where they were.

since your saying the brakes were grabbing a tad bit harder then normal, it's possible that one of your front calipers are locking up a little bit this will cause the shaking vibration your speaking of. I personally never had this happen on the front, someone else may be able to give you more advice on this possible culprit.

Actually, it feels like the back brakes doing this, as when I touch them, it felt like the back end of the car sank. Do the drums on Grand Am's have problems like this?

As for the front end alignment, I actually have a free coupon for one, so I guess I could get that done sooner than later.

Actually, it feels like the back brakes doing this, as when I touch them, it felt like the back end of the car sank. Do the drums on Grand Am's have problems like this?

As for the front end alignment, I actually have a free coupon for one, so I guess I could get that done sooner than later.

the back brakes are a very common problem on the G/a's with locking up, that's either a caliper issue or a spring kit needed.

Free alignments are always a good thing!

It's not the first time the back brakes were touchy, so this would cause some of the problems I'm experiencing?

As for the Wheel alignment, I'll get that done asap, definately good when it's free. :)

This may seem kinda simple, but since you mentioned you just had tires put on a month ago .... have you checked your lug nuts? if you have aluminum rims its common to have lugs loosen up, I watched the guy torque mine twice, 2 -3 weeks later they were loose again. Should be torqued to 100 ft lbs, you will know if you find a loose one with a tire iron.

Have you been having rain? my brakes always get touchy after a rain, until I get all of the rust off the drum.

I forgot to give you guys an update. I found out what the problem was. We had a snow storm on the weekend, and my car became a snow drift, either way, this all happened after I dug my car out. That being said, someone mentioned to me the other day, that it could be 'snow in the rims' Doubtful at first, but willing to try, I took a pressurewasher to all 4 rims, and what do you know... it worked!

Very strange. The snow\ice must have been throwing the wheels off balance. Thanks to you all for your help!!

glad to hear that it was an extremely easy fix, no money required, always a good thing!