That old "Boing" noise is still there!

[mlgraham at bmi.net]

Well, I'm at a loss now. Car is a 86 5000 CSTQ.

I had a front drivers side CV joint go bad and replaced it.  Every since, 
then with the Anti-Lock system on, when I step on the brake pedal, and
for some reason at low speeds - less than 10 mph., I get a loud "boing"
noise like a spring letting go from the pedal/dash area.  At first I
thought it was one of the rotors locking up, as it doesn't make this
noise when the ABS system is turned off.  I thought the rotor was
locking, and causing one of the front suspension coils to compress,
causing the "boing" noise. The new axle I installed was reported to be an 
86 Audi, and the teeth looked correct on the hub, but I failed to compare 
them, as I turned the old axle in for a core, before receiving the new
replacement from NAPA.  

I then though I may have damaged the ABS sensor, and have changed the
sensor out and installed a new albative cap. No change. It still makes
the "boing" noise.  If the ABS is switched off, it doesn't make the
"boing" noise. So I am thinking its got to be something related to the
ABS system.

I drove it a bit harder today.  Again, it makes the noise with the ABS
on, and only when coming to a stop at less than 10 mphs speed. I think I
can now feel the brake pedal drop towards the floor between 1/2 to 1"
after the "boing" noise.  I took the car out it out on a large parking
lot, and did a couple of lock the brakes up at 40 mph, and it appears
only the passenger side tires are locking up, or leaving rubber on the
lot.  My Hanes manual doesn't go into any detail regarding the ABS
system, and if no one has any ideas, I guess I will need to take it into
the dealer.  

Oh, no other problems indicated on the computer display.  The brake light 
doesn't illuminate, and I have a new pressure accumulator (Bomb) on the
car (as the old one was dead prior to the axle problem, and the "boing"
noise). I changed out the bomb after the axle replacement, but the
"boing" noise has existed prior to changing the bomb out and is still
making the noise with the new bomb in place. The master cylinder is also
new (within the last 3 years) so maybe its a bleeding issue or something
only the Audi dealership can diagnose?

Any ideas or thoughs would be appreciated!  The darn albative caps cost
me $1.90 each!  And it will probably be another 2 - 3 weeks before I can
get the car into the dealer!  So I have more time to play with it, but
really don't know what else to try?


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