weird abs/ brake noises

[no1of consequence]

ive got some funny brake noises + i wonder if anyone might know whats up..

when backing down a steep + slippery [snowy or rainy] hill, driveway, etc 
and if i  brake adn the tires slip [i can feel them slip and feel the abs 
start to work] i get groans and pangs from the vicinity of the MC - it 
sounds kinda like hitting a failling power steering pump with a coil spring. 
=)

its only ever when i back up. forward the brakes work great.  i just did new 
pads, rotors, a caliper, lubed the ebrake cables, and flushed the lines with 
new juice. it made the noises before i did any of this.

is it a sign of a bad mc or abs pump [or whatever contraption it is that 
drives the abs]?

thanx all. happy holidays,

jim

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