A jolt type 'clunk' that is getting worse on my automatic 89 Civic wagon ( real time drive)with 161,000 miles, coming I think from back of car? Hear /feel it more at higher speeds but once it starts, it becomes more frequent and occurs at lesser speeds too (not associated with shifting). Local Honda shop says possibly Viscous Coupler needs to be replaced. Could this have been caused by the 4th tire (not matched) that the tire guys put on a couple of months ago when flat was not fixable? Car pulls hard to left since this replacement. If so, could I stop the problem, or slow it down by simply buying 4 new tires, allowing me time to find a used car? Mechanics advise little use of the car for potential safety reasons. Shop has only replaced these a couple of times in their history. Otherwise, a $400 repair that may not even be the problem. And I'm thinking it's time to move on.