I recommend you to search this forum. Choose ”Advanced Forum Search”, scroll the ”Forum(s) to search” to ”Technical-Prewar”, begin to choose 1916-1922 (Model 490 only) and print ”clutch leather” (Note: don’t forget the ”...”:s) in the ”Keyword Search Terms”, then ”Searth Entire Posts”. On ”Date Range, choose ”Newer than 20 years. Klick ”Search forums” and you’ll get a handy number of posts (I got different numbers, between 24 and 43!), many of them from the same thread. Choose one post, go to the first post in that thread and often you will find a lot of good information. Sometimes different opinions on the same subject. In some of these threads you will find links to other threads, or tips of different kinds.

1 How long time?
I have no idea. Depends on the mechanic's knowledge and experience.
I replaced the clutch leather, during the winter 2006/2007, with extremely lot of help from a good friend, not a professional mechanic but with a lot of knowledge and quite a lot of experience from restoring and reparing older cars on hobby basis. At that time I was not a member of the VCCA, and i did not have the excellent ”Chevrolet Repair Manual 1918-1924”, third edition January 1923, which I one year later bought from Gary Wallace.

2 Some problems?
In my opinion: a lot. Depends on the mechanics knowledge and experience.
For me alone it had been an impossible job.
One example: How to remove the gear box without removing the rear end? I got the information from a man who was restoring a 490.
Another example: How to construct and make a ”Clutch Puller”? My friend succeded! And he did that without the instructive picture of the tool in the Repair manual mentioned above.

3 What other parts?
I cannot remember if we replaced some other parts.
I used leather, and I recommend that. After the replacement the clutch has worked for more than 11 000 miles, so far without issues.
The six expanders are crucial, mine were quite good.

4 Any advice
I have quite a lot of pictures from the replacement, also from the check of the clutch leather I did one year later, when I had to make an engine overhaul.