Please be aware that the HEL braided brake pipes sold on Ebay do not work with the E31 rear calipers, despite stating they do.
http://www.ebay.co.uk/itm/2212…geName=STRK%3AMEBIDX%3AIT
The BMW calliper has a recessed hole for the brake pipe fitting. The HEL pipes have a very narrow stainless "nut" on the fitting. When the brake pipe is screwed into the calliper, the nut is partially hidden inside the recess and you cannot get a spanner on it to tighten sufficiently to prevent leaks. This is even after fitting the copper washer. I am having to enter a return request with the supplier. Fortunately I had removed the original rubber hoses carefully so could refit them. I then flushed the system with DOT 5.1 fluid.
8er.org/forum/index.php?attachment/30754/