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Discussion Starter · #1 ·
have a 93 ltz caprice, sometimes when slowing down car shakes eratically, doesnt happen all the time, thats why i dont think its warped rotors, i think the abs is malfuntioning?? any thoughts? thanks
 

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have a 93 ltz caprice, sometimes when slowing down car shakes eratically, doesnt happen all the time, thats why i dont think its warped rotors, i think the abs is malfuntioning?? any thoughts? thanks
If tires are same size on all 4 corners, start by rotating front to back and see if condition remains (brakes, suspension) or dissipates or increases (out of round tire, bent rim, balance issue).
 

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Discussion Starter · #3 ·
If tires are same size on all 4 corners, start by rotating front to back and see if condition remains (brakes, suspension) or dissipates or increases (out of round tire, bent rim, balance issue).
i dont thinks its a balance issue because sometimes itll be fine then all of a sudden it shkaes like the cars having a seizure!!! maybe 1 out of 8 times when braking
 

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It may be a bad front caliper,if only one closes/brakes it would cause shaking or pull hard to one side...

Do you have drums or discs in the back??
 

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Check all of your steering and suspension components. It may be something worn, and when it starts, a harmonic makes it get worse. Steering and shocks are my first guess.

You can look at the tires for tread wiggles, it could be a broken belt.
 

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Discussion Starter · #6 ·
drums in rear, whats weird is that it comes and goes, i thought maybe caliper as well but doesnt pull to either side when it does it!!! i may just unplug one of the abs sensors and see what happens
 

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have a 93 ltz caprice, sometimes when slowing down car shakes eratically, doesnt happen all the time, thats why i dont think its warped rotors, i think the abs is malfuntioning?? any thoughts? thanks
Assuming the problem is not determined to be a suspension or steering related condition, here's some food for thought:

Can you isolate the shaking during braking to front (felt in steering wheel) vs rear (felt in seat/body)?

If you're not sure, and if the park brake is working, take the car to a safe location (large empty parking lot, road with no traffic--ie. late night/early morning), get the car up to speed above where the problem is occurring, put the car in neutral and at the same time, apply park brake ONLY (not the service brakes)--not to lock the wheels, but to apply rear brakes only. What you're trying to determine is whether the rear drum(s) may be out-of-round, causing the shake/shudder condition. Depending on condition of the drums, they can be turned or replaced--brake shoes probably need to be replaced too, if new drums are installed.

If it's in front, you can call it warped or anything else you want--rotor thickness variation is what you're dealing with, and it can create quite a bit of shake as the thick part of the rotor(s) comes around to push through the pads. Most of the time, the thickness variation is the result of pad material transfer onto the rotor surface. This happens when the brakes get hot, and then the driving conditions may result in sitting for an extended period with the brakes holding the car...the heat saturation from rotor to pad actually makes the pad "gooey" enough to result in more than the normal molecular-thin film of pad material to end up sticking to the rotor in one spot--making it thicker. Once the rotor cools, the pad buildup sticks, making the front shudder under braking. The fix is to turn or replace the rotors and install new pads.

Rotor temperature can make the condition more or less severe, which may explain--if the problem is in front--that the symptoms can change in severity every time they show up.
 

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Discussion Starter · #8 ·
ok its deff the front, just tried the rear brake only and no prob, i also unhooked the2 front abs sensors and it got better, but problem is still there, so i jacked car up gave the tires a good shake and no give so looks like balljoints, steering seem ok, so i guess its rotors??
 
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