About 3 or 4 years ago I had a replacement driveshaft installed on my 97 D1, the old one had destroyed the u-joint and subsequently the yokes. Mechanic shop had to cut the bolts to get it out and installed the new one. fast forward to yesterday, My son is using it for a bit and called to tell me about a vibration at speeds above 35-40 mph. I questioned tire pressures, etc and he heard a loud bang... He was turning a corner driving slowly (luckily) and it wouldn't move. He pushed it into a parking lot and it was in Park while he was pushing it. He looked underneath and said a long thing was hanging down. Driveshaft!! I asked if there was any fluids pouring out and he said no.

Bolts holding the driveshaft flange to the front pinion flange were gone. He found what was left of them in the street. I looked at them and there were no marks on the head, meaning they were a grade 3 or less. They were replaced with Grade 8 Bolts and it runs smoother now. WHY would a reputable shop put lightweight bolts on a drive train and not use at least a grade 5?? I am amazed it lasted as long as it did, and thankful the shaft did not do a helicopter and take out the motor, trans or transfer case. The sway bar kept it from hitting the pavement and luckily it didn't happen at highway speeds.

And people wonder why I do my own work on my vehicles...

 

Yikes! Good thing nothing too horrible happened.I’m going to go check both of mine now. A mechanic should know better than too use crappy bolts on something like that.

Where’d you get your high grade bolts at?

 

ACE Hardware was about 2 miles down the road.. As long as they have the grade 8 markings, they should be good. luckily it happened at slow speeds and the sway bar kept it from hitting the road. When I recall all the times and situations over the years, I am surprised it didn't break sooner.