What's this clonk?

[Kendo]

What is “releasing” u joints? I don’t remember doing that when I replaced mine, and they don’t clonk.

[Triton]

When replacing  a u/j   sometimes the joint can be tight in a certain position. A few taps around the joint will usually sort it. I don't think it would make a noise but probably a vibration......

[Kendo]

Is that because some of the roller bearings are not quite lined up? When I replaced my ujs, I worried about the bearings staying in place as I pushed in the caps.

[BDA]

It helps to smear some (more) grease on the pins when you assemble the U-joint. That way they are more likely to stick to the cup and not get caught by the cross when you press them together.

[Triton]

As  BDA says , I always press a bit more grease into the rollers.   If  a roller has fallen over i don't  think there would be room to get the circlip in but not 100% sure about that. It's always easier with another pair of hands.....

[BDA]

If a needle falls over or is bent when you press the cross into the cup, you'll know!! If it just falls to the bottom of the cup, you should be able to use it again but if you bent a needle and you have the old U-joint, you can steal replacement needles from it. If not, you can get by with one or two less needles in the short term (eg. you need the car on the road quickly) but I'd start getting ready to install a new U-joint at your next opportunity and I would drive it pretty gently till then.