Help! Is my car bent? Bad vibration at speed!

[Guest Confederado120]

I am experiencing a bad vibration in steering wheel at 55 MPH.

 

I have done the following things (checks). Wheels balanced, tires are in good shape, alingment just done. Ok(alingment) they didn't try to sell me anything. So, I hope those area's are ok.

 

As for the vibration. Can feel it mildly at about 35 MPH. Gets worse up to about 55. Still have it at higher speeds. Downhill deceleration at high speed it's worse. Car tracks straight, no bad wear patterns in tires.

 

Anybody have any suggestions. I am thinking my car may be bent.

 

Thanks, Walt

[auxilary]

replace steering coupler with either urethane unit or abs plastic unit, replace steering rack bushings with urethane ones

[Tim240z]

Keep in mind that most alignment places (at least in my experience) are like assembly lines and don't do a thorough job. A good alignment shop should take at least 15 minutes on the car before even putting the sensors on it. (I was an alignment tech for years, so I know of what I speak). You should raise the front of the car and check for play in All areas and in ALL directions. If you do that you will find the problem.

Probably is what Alex mentioned, but could also be wheel bearings, ball joints, etc.

 

Tim

[Guest Venture-Z]

Check you're U joints, if they go bad they can cause a nasty shake.

[johnc]

As Tim said regarding most alignment shops. Basically, all they do is "get it in the green" and call it done.

 

FYI... Tuesday I took my Z to Erik Messley at EMI Racing to get it aligned. Started at 8:30am and was done at 10:00pm. That's the kind of effort it takes to get a racing 240Z properly aligned.

[auxilary]

If you want good professional alignment in bay area, there's a good shop called Roger Kraus Racing, and they will do custom alignment, coilover adjustment, corner weights, etc. They did my car for $105, and that included coilover adjustment. They're in Castro Valley

 

http://www.rogerkraustires.com

[Guest Confederado120]

Thanks for all the suggestions. I will try the coupler and bushings. Planning on a frontend rebuild in the future anyway. Just trying to get to the source right now. I totally didn't think of RogerK. Not to far away from me. A friend of mine mentioned on car wheel balancing. Any thought's? I am running old slot mags. They are in good condition, no scrapes gouges.

 

Walt 73 240Z

[technicalninja]

Swap tires front to back and see if vibs change. It is possible to have belt delamination which seriously affects ride without showing on outside of tire. Also check front dif mount (pry up between dif and crossmember with large screwdriver-if you have prob it will move more than 1/8-1/4 inch). Good luck.

[Guest 240hybrid]

When was the last time you had or put brake pads on the car. I put pads on a honda (not rice, just daily driver) I used to have and didnt get the rotors turned when I did it. Soon after this, I ended up with some wicked wheel shake/wobble. It had the exact same symptoms that you listed, and felt like the car was going to shake itself apart. I got the rotors turned/resurfaced and the problem went away.

 

Also you might want to jack the front end of the car up, lock the steering wheel, and grab and shake the front wheels to see how much play is in them. This is a good ole boy way of see if the tie rods are worn out.

[Tim240z]

A friend of mine mentioned on car wheel balancing. Any thought's? I am running old slot mags. They are in good condition' date=' no scrapes gouges.

 

Walt 73 240Z[/quote']

 

On car balancing is good if you get a small vibration at high speed. Many will tell you that it takes into account the rotors etc in teh balancing process, but this is generally not a factor. You will still need to get the wheels balanced 'off the car' to be sure that the static balance is correct, and that the dynamic is close to true. On the car balancing is just a bit more accurate. Off the car balancing will get the dynamic balance to within about 5 grams of perfect. On car balancing will be accurate (depending of course if the operator is competent....sometimes unlikely) to within 1 gram. If your vibration actually shakes the steering wheel, and the wheels have been balanced already (off the car), then likely not a balance problem. make sure that one or both of your front wheels haven't thrown a wheel weight. Also, did you watch them balancing the wheels? Are the rims true or out of round?

Also, driving with excessive wheel vibration will eventually damage the wheel bearings.

 

Hope that helps.

Tim

[Guest Confederado120]

Update,

 

Well I've found two problems. My rear driveshaft u-joint bolts were so loose, it was scary. Second, my left front control arm bushing was shot. So much for a professional alingment from shop I took it to. Looks like its major suspension overhaul time. Bushings, Balljoints, Tie rods and Struts. My struts are shot to.

One other item. Someone (PO) I think has installed lowering springs. They are pale blue in color. And when front suspension is unloaded, they are not seated in springs. They will flop around (slack). Is this normal?

 

Thanks everyone for all your help,

Walt