I am seeing a lot of flex disk failures on the 70s and 80s daily driver 114, 115, 116, 107, 123 and 126 chassis. The disk that usually fails is the front one, and when it does the front short section of the drive line flings around under the car and causes other damage in its wake.
Problem & Solution
Common among these chassis:
In two cases the internal transmission shift rod was so badly twisted that the transmission had to be repaired/replaced (major). In one case the parking lock cog inside the transmission was broken, in another the speedo cable was destroyed, and in another the whole shift mechanism was severely damaged. One of the cars was driving down a major street when the disk let loose, The loose drive line end wrapped around the emergency brake cable and brought the car to a screeching halt. It was very difficult to get the car off the road and when it came to my shop we found it was so tightly wrapped around the drive line, we had to cut the emergency brake cable. In that particular instance I had told the owner that the flex disk needed replacing but he didn't want to spend the money..... He ended up having to replace his transmission!
Get under your car and inspect the rubber drive line flex disks located at both the front and rear of the drive line. Remember, these rubber parts are getting old. If you find the rubber is cracked then replace one or both. Don't take the chance. They are not that expensive and will last another 15 - 20 years!