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Pilot Bushing? Throwout Bearing? Need Definite Answer


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Okay, I've searched all around about this noise and about 50% of the results I've found are POSITIVE that it's from the pilot bushing. The other 50% are POSITIVE it's from the throwout bearing. I have not a clue how the 280Z transmission related to other manual transmissions, so I have no clue which it is. Here's my car and the symptom.

 

Stock 78 280Z, 5-speed. When in neutral or in gear and the clutch is engaged (pedal released), there is a whirring noise from the transmission. The noise increases in pitch with RPMs. The noise vanishes when the clutch pedal is depressed to the point where clutch disengagement happens. The noise does NOT cease by merely touching the clutch pedal. If the clutch pedal is pushed in, the engine is revved up, and the clutch is released (all the while, the transmission is in neutral) the sound will increase in pitch to match the revs once the clutch is engaged.

 

I should note that so far, the sound is merely annoying. I haven't had any particular problems shifting the car.

 

So, what do you guys say?

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Sounds like a bearing inside the tranny, possibly the input shaft one.

 

Think of it this way, in neutral, clutch pedal out, it makes noise, the input shaft still spins in neutral. Clutch pushed in, the input shaft no longer spins, and no more noise.

 

A worn pilot bushing can make for choppy clutch engagement as the input shaft deflects a little bit. A worn throw out bearing makes noise when the clutch pedal is pushed as that is the only time it is spinning (when it contacts the PP).

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The noise is from inside the transmission. Pilot bearing and throwout bearing noise comes when the clutch is engaged. If the noise increases with engine RPM, not road speed, then its from something on the input shaft.

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The noise is from inside the transmission. Pilot bearing and throwout bearing noise comes when the clutch is engaged. If the noise increases with engine RPM, not road speed, then its from something on the input shaft.

 

Definately agree with John. I have 5 speed from an autowrecker with the same symptoms. Except mine sounds more like its full of rocks in neutral. Dropped my back-up 4 speed in, used same pilot bushing and throwout bearing, absolutely silent now.

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