Disabling Anti-lock Brakes?

[Doug Johnson]

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I'm looking for advice for a friend and her '90 coupe quattro.
It was in for timing belt and water pump last week, and the discussion
turned to the ABS.
When it's disabled, she's got halfway decent brakes, but when ABS is left
on, she's got virtually none.
Also, when she applies the brakes with ABS enabled, even gently, she gets a
serious CLUNK.
The mechanic, who has taken care of my 4kqs, and my urq, mentioned that the
205/50-15 tires could contribute to her troubles.  Does that make any sense?
If all else fails, and to stay away from a second mortgage, is there any
chance that we could disable the ABS by removing a fuse or relay?
If so, can someone please direct me the specific fuse or relay?
All advice is appreciated, since I'm far too simple-minded to understand
new-fangled cars.

TIA!

 ~ Doug

BTW, I was just pre-qualified for a car loan....up to $60k!  Any
suggestions?

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