Driving around surface streets seems to be fine, however...

Once I hop on the freeway at get to about 65-70mph, a carwide (it seems) vibration starts to occur.

I don't believe it is directly related to the clutch, but I'm not sure. When it happened, I immediately pressed the clutch in - the vibration continued until I slowed down. Could it just be tires, or possibly the rear end? I'm due for new ones, and it's the stock(original) rear.

 

Could be the driveshaft. When people change to the alluminum driveshaft it seems to go away.

 

If you have a polyurethane trans mount, that might be it, Just a guess

 

Since you need new tires anyway I'd do that first. Only time my car has ever vibrated it was the tires.

 

that happened to me....it turned out that i threw a wheel weight just a thought

 

Can you drive through the vibration?? (I mean, speed up beyond 70 mph, and the vibration may go away). If so, that's almost definitely tires.

 

It's not a poly mount - just put a new one in a couple weekends ago, standard stock replacement.

I haven't tried to accelerate through it however. Last time the vibrations got pretty bad, and the SES light came on - after driving it a couple times at street cruising speeds it went away on it's own and hasn't come back. My next purchase is tires. We'll see if that fixes it, and they will rebalance the wheels at that point anyway. Has to be done anyway so let's hope for the best on that I suppose.

 

I had this thought too, however I've never had a problem before at these speeds, and most people have always had the vibration. This one just came on out of the blue. Still think it's possible?