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bkhess
New User
May 10, 2010, 7:33 AM
Post #1 of 4
(2039 views)
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ABS unique problem
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1998 Buick Century. Drive side noise. No ABS codes.
When ABS system engages(when braking on slippery road and ABS engages.) it makes a sound like a loose tooth getting knocked around by a gear.
Also when starting car (before putting it in gear) it makes a weird clunk sound. Sometimes it does not do it when starting car, it waits until you put it in gear. Other times it will wait to make clunk sound until you move after putting it in gear.
Everything is solid on driver side.
There is no recurring time/situation of when this happens, it happens differently most times. Meaning it may make the noise when putting it in gear but next time it will make it when I start car and before putting in gear.
When ABS engages does it do anything to tranny? Meaning does it disengage drive axle so brakes can work on their own?
Not sure what would cause this sound.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 10, 2010, 8:26 AM
Post #2 of 4
(2035 views)
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Re: ABS unique problem
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ABS in this car is sensing how fast the wheel is rotating and when out of parameters of the other wheels that are not slipping will lower pressure to that brake, frequently a rapid fire pulse of braking action and non action like pumping brakes but at faster speeds than you could do with your service brake. The idea is capable of maximizing possible traction in certain cases. Does feel like something is wrong sometimes but probably normal.
The clunk while just starting the car (hopefully you aren't even moving) could be a motor/trans mount. I'll venture the guess that if a mount is that bad that while ABS is actively working the symptoms/feelings/noises could be more that if there wasn't an issue.
"Is this hard on the transmission" > Probably no worse if just ABS working.
If you are experiencing ABS operating and the conditions don't really call for it such as really slippery conditions or hard stops there could be a problem OR tires that are very worn or uneven, brake problems alone or mismatched would aggravate it too.
So far my guess is mostly a motor/trans mount has gone bad. With a helper you can see which one (stand to side of car) just shifting (park to reverse, to neutral then reverse) and looking at them with brakes applied watching the mounts to see if they move too far,
T
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bkhess
New User
May 10, 2010, 9:23 AM
Post #3 of 4
(2028 views)
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Re: ABS unique problem
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Pretty sure mounts are not bad.
All the sounds come from driver side tire/axle area.
Never heard the sound of a loose tooth getting knocked around by a gear before. Comes from driver side tire when ABS engages.
Other clunking sound also comes from driver side wheel area. Also makes a small clunk sound when put into gear but what is really weird is sometimes when you turn the key and start car (before shifting into ANY gear) it makes this sound from driver side wheel.
Also has wobble feeling on that side, assuming it needs ball joints, struts. It has 105,000 miles(not bad for a 1998) on it and never been worked on other than regular maintenance.
May be too much for me to figure out, garage may be next.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 10, 2010, 10:16 AM
Post #4 of 4
(2024 views)
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Re: ABS unique problem
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OK: All this that can happen both stationary and moving suggests either two issues at once or one common item/problem that can cause both.
Now there's noted wheel wobble so this is a safety issue and needs immediate diagnosis and repair. Trying to save a nickle now is of no use if an accident happens over delaying proper fix.
This list of maybes is so long I'm at a loss except to default to get help,
T
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