Here's an example:
Glenrowan in r7 in syd
Going down several class from Group 3 to Welter - rises 8kgs in weight.

I think its 4 grades lower Welter-Flying-Quality-Listed-Group 3.

In fact that race r7 is a good example of class/weights - have a look at all the runners.

If you want info on handicapping in relation to class, wins etc go to the Victorian Racing site.

My Info says this race is 5.5kg easier than his last start making him porly weighted.

I believe just taking what a race is classified as to be its "class" is very dangerous as it is quite possible that two races with the same "class" can have vastly different quality fields.

Crossing the road is dangerous if you don't look at the traffic first.