I went to accelerate today and started off fine for about 20ft then I heard a clunk in the front end and the van stopped accelerating. I coasted it to the side of the road turned the wheel and saw that the axle shaft on the driver side had snapped just infront of the rubber thing in the middle of the shaft. The trans shifts in and out of gears alright as far as i can tell and the piece of shaft that was still inside was turnign fine while it was in gear. I pulled the broken shaft out and replaced but has anyone had this happen to them? Should I be looking for another problem or was it just a weak shaft that gave out. There didnt seem to be any twisting in the break on the shaft, it just seemed to have snapped like a candy cane. Any input? By the way I have a 98 GC with 3.3 and automatic.

 

Ck the motor mount on the same side, When the mount breaks or has a soft mount the inner boot will hit the lower control arm tear the boot, all the grease comes out and the axle comes out of the tripod housing. If the motor mount is okay, then the axle just broke.

 

Some of these have a round tuning mass about in the middle of the axle shaft. If yours has one, it is likely that corrosion at that point weekened the shaft and caused it to break. You'll probably be OK for another 10 years depending on where you live.

 

did you change your trans fluid after changing the shaft? I think that is how I got trash in mine and ended in a rebuild.

 

Wow! Snaped the shaft in half? The axle shaft, at least to my beliefs, is a harded steel bar aprox 1" thick. To snap this from crosion you would have to park the van in salt water for 10 years and then slam the trany in park while traveling down the freeway. I would check for further problems. Do you hear any weird noises, or feel any vibrations? It is possible your torque converter locked up or some other internal problem with the trany locked it up and snapped it.

 

I was thinking something bound up as well but it did not have a twist int he break or anywhere else in the shaft. I have seen some jeep axle shafts break and there is always some twisting that took place and you can see where the metal twisted before it broke and sometimes the splined section will have started to twist as well. The boots were fine on it, I actualy cut the tranny side boot open and pulled it all apart to make sure nothing inside had bound up but it was still sealed and had nice looking grease in it still. I will see if I can get a pic up of the old shaft later. I know the motor would jump a bit when you shift in and out of gear so I am thinking a bad mount may have been the culprit. I am going to go check itout in a bit.

 

Surprisingly, it doesn't take much to cause a weak spot on a shaft like that. It's very common for torsion bar springs to break after they get a little bit of damage on the surface from rubbing or corrosion. These axle shafts are just like a torsion bar.

 

I'll give you an analogy on how a shaft can break from the slightest scoring or corrosion. If you have ever cut glass or ceramic tile, all you do is score the surface and it breaks exactly where you scored it (usually). A spring, torsion bar, or axle shaft will do exactly the same thing due to what is called a stress riser. If you have about 150 ft lb of torque out of that 3.0 multiplied by a first gear ratio of about 2.8 and a torque converter ratio of 2.5 to one, that shaft sees over 1000 ft lb of torque under throttle. If you happen to spin the wheels on something, it can double! You should look at the end of the shaft where it broke. If it is twisted and looks like a pig's tail, it is due to over-torguing--if it is a relatively clean break, it is due to a stress riser.

 

I went and looked at the old shaft again, and noticed there was an old crack or chip out of the metal right where it broke. The chip had a coating of rust on it so it must have been there for a little bit. It was a pretty clean break with no twisting to it. I did happen to notice today that the mount that bolts up under the radiator ad to the engine/tranny is very well worn. Guess that is tomorrows project. Thanks for all the replies everyone!