[TR] Vibration at Speed

[Bob Rochlin]

Hi Everyone,     Over the summer I got a new set of Michelins for my TR6. The old tires were 15 years old and were causing some shimmy vibration as well as being well past safe.  This was in connection with getting my wire wheels straightened and trued.  The wires guy, New England Wire Wheel, mounted and balanced the tires with a Snap-on static balancer . When I got the wheels back on the car I went out for a ride and felt a definite vibration between 65 and 75 MPH.  I concluded that the wheels needed to be rebalanced with a dynamic balancer.  I found a shop who could balance the tires correctly and had them rebalanced.  The tires were little better, but there was still a pronounced vibration in the seat and body at 65 to 75 MPH.  I brought the tires back to the tire shop and they graciously first checked the tire balance and then rebalanced them.  They said that the balance was of about a 1/4 oz. , and that two of the tires seemed to be a very slightly out of round.  I mount those tire on the rear, but again the same problem.      I've moved the tires from front to back thinking if the offending tires were on the front wheels the vibration would be through the steering wheel and not the frame.  No joy.  My thought is that there is something in the driveline causing the vibration, perhaps the rear brake drums worn out of balance.  The drive shaft was balanced 5 to 6 years back.  Over the years i've replaced all the universal joints.  As far as I can tell the rear drums are original to the car, as are the half shafts.      Before I start pulling the driveline apart I thought I see If anyone has had a similar problem of a suggestion of where to go next.  I'd appreciate the input.    Bob    72'TR6 		 	   		  
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