I recently picked up some belt tensioners for the X and Y axis as I didn’t think I was getting them tight enough. When the printer took certain quick reactions I would hear some slop in movement yet I couldn’t seem to get them any tighter just by holding the bracket and screwing down at the same time. I ordered these off of Aliexpress and they took a bit over a month to get here but were very cheap compared to Amazon.
They replace the existing end bracket and add an adjustment nob for tension. This makes it much easier to adjust on the fly. It also came with another belt but had no crimped ends so not that useful. Each printer seems to need a different bracket combination so make sure you are getting the correct set. The link I posted about has multiple options within it for different Creality printers.
Installation is very simple. Just remove the existing bracket and install the new one on the X and Y axis. Then use the nob to adjust tension till it’s where you want. Material seems to be the spacers in between the bracket and wheel on the Y tensioner. There is some side-to-side play in the wheels but as long as there is belt tension that shouldn’t be an issue.
Left is the X axis and right is the Y axis with the new tensioner adjustment brackets installed. This is a cheap and easy modification that makes adjusting much easier. I highly recommend these.