Hi, not a question, only an answer:
the typ 20 so stiff because it's made and recommended for pulleys with diameter more than 160 mm.
That's why the shortest belt length is 900 mm, shorter you don't get it over 2 pulleys with diameter 160 mm.
On your TRs smaller pulleys are fitted, so actually typ 20 it is the wrong type of fan belt.
Anyway I use a typ 20 for ages and it works very well, but I use the more flexible, notched one from the producer "Flennor".
Sometimes there are some on eBay, I can recommend it.
Typ 17 is made / recommended for pulleys with diameter 112 mm,
Typ 13 for diameter 71 mm and typ 10 for diameter 50 mm.
Edited by Z320, 29 June 2018 - 06:58 AM.