Quote From DrJeckyll:
I would say it is too long.
If a PhD is 6 main chapters plus introduction and conclusion, then each main chapter should be around 10.000 words (did a science PhD, maybe it is different in other disciplines). I broke my methodology into two chapters of 10K.
Does it really matter though if you have some chapters longer than others? Mine aren't going to be of equal length because some have more data than others. So far one of my data chapters is 30 pages, 10,000 words and the other is 50 pages, 15,000 words. I know of other people who have 5000 word chapters.