My car starts shaking really bad at 70mph. Yet it will go away but will eventually fade back in and start shaking yet again. I do notice some vibration at 60-65 but not much very little.

The vibration seems to come from the rear. I have checked the u-joints they seem fine. I do have a rim with a bent lip in the rear, but not sure if it might be the problem.

I haven't checked to see if the driveshaft is out of balance, i wondering if this maybe it.

Could someone help shed some light on this please?

 

bent rim from a curb? might check that axle...tao

 

Had a worn out transmission mount cause issues like this in the past. Also keep in mind that a miss could cause vibrations. Try running the engine up to 2000-2500 RPM for a couple seconds in park to see how the motor reacts. I had a miss that caused vibrations at about 75-80 but would settle out at 95.

 

I was getting a good vibration out of mine around 80mph... Changed out the torque arm bushing and it made a world of difference.

 

When did it start shaking? I had issues with mine bad! Turns out I had a bent rim
on the front (jacked it up and spun the wheel by hand) and found it. After I replaced the rim I also found the tire on the same rim was out-of-round (had it replaced pro-rated). I still had a slight vibration and found a rim with the bead bent and replaced it. After seeing it run smooth on the balancer, put it on the car, jacked it up, and started the engine, dropped it in first and noticed a slight wobble. I had to replace the right axel and now everything is smooth again.
If you have the WS-6 susp. the front can feel just like the rear. When I first bought the car it had vib. problems then and I swore it was the rear but turned out to be the front. If I were you I'd check the front first.

 

I guess i should have mentioned that the rims where changed shortly after getting it. I could replace the rear rims with the old ones a find out.

 

I had the same problem- aluminum driveshaft solved it for me.

 

This could be a number of things as shown in the post above. Also, it could be as simple as an out of balanced tire & wheel assembly. maybe you thru off a balance weight.

I like the driveshaft idea. Back a few years ago, I layed down a great patch but on a rough concrete surface, the rear end started to bounce, well, after getting on the xway, I had a new vibration. It turned out to be a bent aluminum driveshaft.