E32- 750IL-1991 1) replacing with not self leveling rear shock absorbers& 2) stiff break

I have 750il -1991-E32.
1) My rear shock absorbers are leaking oil. So, I am trying to replace those. But it seems quite expensive for the 2 pieces. So, I am thinking
replacing them with non-self-leveling aftermarket shock absorbers. I once read that I have to do something with the electrical circuit not to complain/malfunction/malwarning when I replace with those of not self leveling. Would anyone send me the tech giude for the replacement procedure? if possible, photo might be good or any web link which shows the procedure all.
2) Another problem is very stiff break pedal. Usually OK, which means I have soft hydrauric softness of berak pedal when I press the pedal. However, some times( I can not tell the exact situation of occurring), I have to press the break pedal really hard to stop the car. Then ABS kicks in. It just like I am stopping the car by mechanical break rather than with hydrauric power. So, I consulted mechanics and their opinion is varied as below. a) I might need to lubricate the master break cylinder --? b) I might need to resurfice the break disk smoothly c) I might need to replace break accumulater ball. d) break oil air breeding. Shoul I do all of these 4 or any one? Even others? What is your opinion?
Thank you in advance.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There's an e32 group somewhere. www.e38.org might have links to it or even have the e32 info itself.
As for the brakes it sounds like the "accumulator" or something related to it. The other suggestions don't sound right to me. It could be that some part of the system has gotten stuck (like a caliper or collapsed rubber hose) and that's why you're also getting ABS kicking in as the other wheels lock up.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.