Driveshaft falling out

my driveshaft keeps falling out when I brake hard first time it fell out not much damage was caused I changed the rear u-joint and put it back in and this time it fell out and the whole driveshaft is messed up does any know the reason for it to keep falling out

Because it wasn’t repaired properly.See an independant mechanic if you want this repair to last.

Because driveshafts are held in with punctuation? lol, I kid, I kid… We do not know what vehicle we are discussing, nor what work was done to the driveshaft in the first place that warranted its removal. These are important details we need in order to begin to try and assist you with this issue.

Driveshafts are rather serious business, much more serious than many guys give them credit. Essentially they need to be perfect before installation, perfectly straight, perfectly balanced etc…

We need more details.

I’m wondering if something is broken or loose in the rear suspension causing it to shift during the hard braking.

Has anyone ever let a needle drop to the bottom of a u-joint cup… and left it there? If so I’m sure that you know the result of that error. I wander if @Damian_Rivera has learned just how important that 1/16" is when installing the joint.