Snapped drive shaft

True. Ever since I bought my own truck, I crawl under it once a week and grease all u-joints (truck and PTO) and check everything for slack. That's usually plenty. Any more often than that would be a waste of grease, in my opinion.

I've had u-joints go bad before and have always been able to catch them before they leave me stranded because I could hear/feel the slack when getting on/off the throttle. Usually comes with a slight vibration as well. I always listen carefully to the sounds my truck is making and any change in the way it sounds causes me to check things out the first chance I get. You can't always catch everything, but it sure saves time and money when you can.

 

My first driving job I found a bad u joint and a cracked brake shoe in South Dakota while I was greasing the truck. Told the owner about it and said that I would nurse it home. Was pulling brand new side dumps from the factory.

Day after I get home was told to clean out the truck, it was leaving. Little Weasley did not even have the balls to fire me. So I went to moving heavy machinery and two weeks later it let go and he was blaming me for it.

 

That's why I like my open frame. I can see the shaft all the way from the transmission back to the diffs merely by looking in between the rails.

 

BAD.
BAD DRIVER !
BAD.

 

A previous company I worked for was having a rash of u-joint failures on the Internationals that was traced back to their shoddy mechanics. As the trucks were frequently coming back on the hook for other issues they weren't torquing the driveshaft back in properly and twisting them off.

 

Hum, I was tagged and came here too late. Most everyone had my thoughts already.

If you twisted the shaft that means the forces were greater than the deliberate design failure of the shaft strength, like a giant fuse, cheaper to replace shaft than a final rear ends.

U joint bolts would be next to look at. I don't know too many people crawl under there to take a look at em. 4 bolts to a U joint. If you are down to three it's going to snap.

Shifting and clutch work is the third. Ive torn out finals where the long machined gear that is about 14 inches long by about 2 to 5 inches wide inside the axles itself had a bite taken out of it where the abused power shock traveled right to it along the shaft. The shaft did not break and the forces kept going back until it found something to bite into and break. It did that day. It was a old Brigader on a traffic light US 40 north and east of Joppa on a freaking upgrade. I was not doing well, forced the thing to get moving in low, jammed first slamming it and SNAP. That was that. Container was a bejeesus heavy. Which is why I call myself heavy.. ugh...

I had a problem with new shafts designed to fail at 1300 pounds torque it does not take much to snap em, twist em etc when trying to slide tandems in a scalehouse somewheres. I like my shafts somewhat more beef in them. Come on engineers are you actually trying to stabotage truckers? Or is it the companies too cheap to spec and order properly strong shafts?

4th, I would take a look at you, your shifting when you start off. You have to take off in a gear low enough so that everything gets moving without bucking or fighting. If you had to take off in low, that is what it's for. If you tried to take off in say 3rd instead of low because of that heavy load... it's not good.

Im the last person to be virtuous about this subject. Ive raced a 93 COE with a 500 detroit on a rockwell 9 forcing it to take off in 6th high from start, it poured black and brown from the clutch and was at 45 plus before I put her into 8th and stood on the hammer. She leaned and did not stop pulling until 90 then the top gear took her into 115 plus until the fuel pump quit feeding at 125 or so. She was still leaning from the power being applied. I don't race big trucks anymore because all that computer stuff works against me now. It was one of the enjoyable things to do. There is a awful lot that can go wrong when you abuse the trucks like that.

 

On my 4wd tahoe i recently changed the u joints and i use solid u joints NON greasable because they are much more stonger then the greasable ones. And i only buy made in USA like Moog brand. The chinese made u joints are made with cheap steel and needle bearings.