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Old 12-29-2012, 05:43 PM   #30 (permalink)
California98Civic
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Join Date: Mar 2011
Location: Coastal Southern California
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Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

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Quote:
Originally Posted by Old Mechanic View Post
Try getting up to 30 MPH, shut off the engine, keep the clutch depressed. AS you coast down to say 10 MPH downshift from 5th to 1st and see if it changes the pitch of the noise. Let me know what you find out. Imput shaft bearing will go frrom not too noisy to very noisy as you go from 5th down to 1st.

regards
Mech
Wow. I have heard that first gear sound for a couple years. So, for testing sake, I ran the test you describe a few times and what happens is the usual bearing noise problem, which is a lower pulsing sound following the wheel rpm changes when I shift out of fifth and into first as the car gets down to around 10mph: a louder and higher pitched and more dry-sounding noise gets overlayed onto lower and quieter sound.

Quote:
Originally Posted by Rusty94cx View Post
The input shaft bearing is notorious for going bad. And it could be the noise you describe. I have also had wheel bearing that you could not test bad. The didn't feel gritty they felt tight they he'd no play or run out but yet under load they were bad that is the problem. You can test them under load. I tried o read all the posts but might have missed it does cornering change the noise if so probably wheel bearing. If not input shaft bearing.
The sound does change slightly when I make slight left-right movements with the steering wheel, but it changes little after that as I go into a corner. I am told however that that change in sound could be caused by changing pressures on the transmission bearings via the drive axles.

So I have to think this is most likely a bearing problem within the transmission, right? There is a remaining slight possibility that it's a wheel bearing--or both the tranny and the wheel--but the transmission is the most likely culprit, no?

Interesting to note that the higher pitched sound in first gear I have noticed for years--long before ecomodding. I have also occasionally heard a sound a little like it during stand still idle.
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See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.



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