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Vibration under deceleration


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Had something weird happen yesterday. Was on the freeway and had a pretty nasty vibration come on when I left off the accelerator. It almost felt/heard like something was clanking. When I accelerated again, it went away.

 

It seemed to go away, because it doesn't seem to do it....however I haven't really gone on the freeway again....

 

Only thing I can think of is cv axle or diff/trans.

 

The axles were rebuilt in 97......they should've been replaced......they have been making clicking under acceleration......I think they've just come to the point where all the inards are toast.

 

Any ideas/comments?

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Maybe your auto-trans is getting tired? Do you work it hard??

 

Doesn't sound like a driveshaft problem, for which I would expect a clonking on low speed tight turn manouvres, and only a single clonk at throttle on or off.

 

It COULD be a badly balanced driveshaft, and during deceleration you hit a spot where it was able to resonate.

 

 

I hate these kinds of intermittent problems, you replace something and think everything is fine 'cause you can't provoke the problem back. Then, like two days later ....clonk..drone...splutter!

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How about a bad engine mount on the [right side???] non-torque drive side? Deceleration torque could cause the engine to vibrate, would be more apparent at highway speeds.

Can you reproduce it by revving up in a lower gear and releasing the gas at a slower speed?

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It's very possible the auto trans is getting tired.....and yah I probably am a little harder on things then most.

 

I mentioned cv axles because they were rebuilt, and really should have been replaced. They did click after being rebuilt and within the past months I do get clicking under acceleration and turning. It still however may not be the cause of the problem, just an additional one.

 

It really felt/sounded like something was hitting/banging.

 

As for driveshaft.....I don't have one, FWD.

 

Just replaced engine mounts with sti engine mounts 2 weekends ago.

 

It did do it at slower speeds, but was no way near as bad, and after I stopped and looked at the car and everything, I couldn't reproduce it. It is definitely speed dependant, not engine rpm dependant.

 

It felt like a vibration (out of balance tire) as well as the noise I mentioned earlier.

 

As mentioned I have new engine mounts, tranny mount looks fine, I have a new one I will be putting in shortly, but I don't think that is the cause.

 

 

Steering rack bushings just got replaced last weekend with the whiteline poly bushings.

 

Tires are wearing fine. I've jacked up the front and rear of the car and everything seems fine, nothing loose.

 

Draining fluid in the diff and trans are about the only way I can think to check them.

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Actually the term axle would be correct :)

 

Yeah it's possible one of them is out of balance. I just don't know why it would do it, then go away, and now not do it any more.

 

I'll be driving up to the airport tomorrow, so I'll see if it does it again.

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Josh! In my own private world of automotive terms:

 

Driveshaft/half-shafts provide drive from a diff to a wheel. A propshaft provides drive between diffs, or engine and a diff.

 

Axle is anything cylindrical that might rotate or facilitate the rotation of something mounted to it :D

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Something got temporarily caught up on a half-shaft... and then came off again?

 

I'd think you'd feel that more or less constantly though, instead of just on decel.

 

Just trying to add to the thought process.

 

Commuter

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Did you feel it in the steering wheel? Did it seem 'up and down' side to side' - anyqualifiers might help.

 

Any pulling/drifting off track?

 

The noise - was it high pitched and tinny of low pitched and knocy/clunky (usually the low pitched noises are trouble).

 

We need some hypnotic regression to bring your suppressed memory to the surface.....you're getting sleepy...sslleeeeeeeppyyyyyy.............

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this test.

 

Open your hood while the engine is running and stand on the brakes while slowly revving up the engine in drive and then try it in reverse. A bad mount would let the engine torque up off the seated position. I've done this with a V-8 and watched it look as if it would jump out of the engine compartment because the mount was totally broken in half!

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