[ian240z]

Hi guys,

I have a vibration in my car that's driving me nuts. It only comes in around 65 - 70mph and dies off around 90. Doesn't matter if in gear or clutch depressed.

So far I've had new diff & tranny mounts, brand-new drive shaft, new wheel bearings, new tie rods, replaced the bushings up front, wheels balanced both off the car and on. Rear drive shafts seem ok with no play.

Any other ideas?

Thanks & regards,

Ian

 

[mark71z]

I have the same problem with my 71. One problem I have is a slight amount of play in my steering rack. The other is that my wheels balance out fine but one wheel is very slightly out of round. Mine doesnt vibrate til i get over 70. Have you checked your rear suspension and front suspension for the slightest bit of play yet? Good luck Mine has been a constant battle for the past two years. Laterzzz Mark

 

[chastryan]

I think you covered just about everything. I know this sounds like a reach, but did you check to see that all of your wheels are "true". I was thinking that a condition like that might not show up during balancing. But a slight side to side shimmy could show up at certain speeds, and if were slight enough, you might not really notice it unless you were really looking for it. For that matter, a little bump or slight expansion in one of your tires could cause the same thing and not show up while balancing.

If you have a buddy with a Z, a quick wheel swap will let you know right away if you should even be concerned with the wheels.


Good Luck,

Chas

 

[Son_of_Z]

I had the same problem recently with my 70. I replaced all of the u-joints (6) and had the main drive shaft balanced and trued. They found a small irregularity in it and it was out of balance. Also, replaced the Mustache Bar bushings and the front differential mount. This seams to have fixed the problem but have only had the car up to 90 mph so far.

 

[yo2001]

I have that too. new polyorathane rack bushing helped a little. I think balancing the tire would help too

 

[JR]

You might have already done this, but try putting exchanging the front wheels with the rears. If the vibes change or go away, it's you wheels. If they stay the same, it's likely something else.

 

[tyco1983]

These guys are correct, it is most likely your wheel. I have Ultra Light Racing Panasport wheels on my '70 240z which are too "soft" to be driven on the street. They are made out a lighter metal compound than the street wheels which make them more suseptable to being bent. I guess somewhere along the line i went over railroad tracks too hard or hit a speed bump, but I started getting vibration from the back. I replaced u-joints in the halfshafts, driveshaft-Then one day while the rear was jacked up, i spun the wheel with the halfshaft removed and noticed that the wheel seemed out of round, BAD. It starts to vibrate bad near 60 miles/hr and on.

 

[johnh240]

I had a similar problem after having all new ujoints, bushing etc done in the rear. Bothered me for a couple of years. Even had and occasional CLUNK as I went around a corner and accelerated, but only in one direction. Found a dribbling rear wheel cylinder on one side. After replacement of both rear cylinders and new shoes the problems went away. Figured out that the dribbling was causing a brake drag on one side just enough to cause some stickiness and vibration and also something of a lock up which was causing the clunk on one way turns. All better now.

 

[jcool78 2plus2]

Re: Vibration

I like all of the above ideas, but I've had such bad luck with tires over the past years that I always think they are the problem.

Tires are so poorly made, like a sandwich at the deli, that about one out of four is "bad" somehow or gets bad (like a shifted belt) over time. Right now I have a set of Bridgestone's on that were a matched set, but one will balance OK but gives a slight vibe, so I keep it on the rear so I won't notice it. Even cubes can be balanced.
The worst tires have been Pirelli's - never again!

 

[ian240z]

Thanks Guys

Thanks so much for all your input. As I said, I have had the wheels balanced "on-car" but after reading your posts, have taken it back to the workshop. Apparently, they only did the on-car balancing to the BACK wheels, the front were balanced off the car! Dumb muthers! I've left the car with them overnight and asked them to do a proper job on the balancing (Night out with the guys last night so didn't want to drive back anyway!) So I'll see what they've managed to do to solve the problem this morning. It's 7:00am now so Idon't have long to wait!

Thanks again, I'll let you know if that solves the problem.

Ian

BTW - Tyco1983 - do you work for Tyco?