If the clutch releases properly there should be no grinding as such, but you will be aware of the unsynchronised gears engaging.
If the clutch is not releasing fully, then yes, they will grind, can't really say it should be worse when hot though.
Try this:
With everything warmed up, select 2nd and then 1st immediately.
Then select neutral and engage the clutch.
Then release the clutch, and with the pedal held down, select 2nd, and then neutral and count to 5 and then first. see i8f it grinds worse than selecting immediately.
Then try with a 10 second and 15 second delay.
The object is to try and tell if the clutch is dragging.
Here's the old school way to tell if your clutch is releasing..
(copied from a recent thread)
Ok, here's the scoop on how to test if your clutch is releasing properly.
With the engine running, without pressing on the clutch, slowly and carefully move the shifter towards reverse until the gears can just be heard to make the slightest contact - do not attempt to engage the gear. Hold the shifter so that the grating can be heard. Press the clutch pedal down and stop when the grating stops (the clutch has released). Then press the pedal all the way down, making a judgement on the relative distance between clutch release and when the clutch pedal stops moving.
This procedure should tell you if:
1, The clutch releases cleanly and there is plenty of movement after release (the ideal situation).
2, The clutch does release but the pedal is on the floor (time to make an adjustment or check lever lengths and ratios if a non stock linkage).
3, The pedal is on the floor and the clutch still has not released.
If you have situation number 3, then either there is something wrong with lever lengths etc ( in a non stock situation) or the clutch linkage is adjusted incorrectly, or the clutch pressure plate has theoretically released the clutch disk, but it has not released due to sticking due to contamination or warpage or some other reason.
Mart.