Noise on deceleration - TCCoA Forums
 
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post #1 of 10 (permalink) Old 08-17-2006, 09:31 AM Thread Starter
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Noise on deceleration

When driving at highway speeds, the bird is driving pretty well 'normally', considering all 245, xxx kms on the OD.

When I go down a hill, and lift my foot off the skinny pedal slightly, in order to maintain a constant speed, I'm getting a loud, low rumbling sound from the back end.

When I open the throttle back to its cruising level (either continuing downhill or flat), the noise drops back to its 'normal' level.

Does this sound like a worn gear set in the differential?

How can I check the gear set for play?

What amount of play would be considered acceptable?

Thanks

Kevin
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post #2 of 10 (permalink) Old 08-17-2006, 11:14 AM
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Sounds like something in the differential is worn to me. Put the transmission in park and hold the yoke firmly. Also hold one wheel firmly. Then move the other wheel. If ti moves more than 1 inch at the ouside the backlash is too high which would indicate it being worn out.
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post #3 of 10 (permalink) Old 08-17-2006, 11:43 AM
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I wonder what is your exhaust system like?
is it stock or modified? no holes in it?

I got no mufflers and 3rd cat -> I get exactly what you just described. when you coast down the hill the rmp drops down slowly and makes that sound due to no mufflers present.
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post #4 of 10 (permalink) Old 08-17-2006, 01:10 PM
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I am having the exact same problem in my Honda Passport, except mine was preceded by a bunch of smoke coming from the differential where the driveshaft goes in. But I have the same thing. When I am accelerating, its fine, but when I let off the gas, and there is any strain on it, I hear a moaning sound, and when i hit the gas I hear a little *clunk* from the driveshaft

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post #5 of 10 (permalink) Old 08-22-2006, 10:04 PM Thread Starter
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The exhaust system is still stock. Yes, I'm amazed that a stainless system has survived 245xxx kms of winter conditions in southern/central ON, no holes or leaks yet...

I will be checking the gearset tomorrow as indicated. I know there is some play, will be measuring it.
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post #6 of 10 (permalink) Old 08-22-2006, 10:11 PM
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I had the same symptoms in my 94 LX. It turned out to be worn out diff mount bushings. Replacing them with new poly diff mount bushings cured it.

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post #7 of 10 (permalink) Old 08-22-2006, 10:34 PM Thread Starter
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Hi Rod,

I don't think its the differential mounting bushings, I changed them some time back, and the noise issue was unaffected. I noticed the unit seems to be more stable since, but no improvement in the noise dept.

BTW, looking forward to the RSTB arriving... any day now...

Regards

Kevin
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post #8 of 10 (permalink) Old 08-22-2006, 10:41 PM
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In that case, it probably is a worn diff.

Let me know when the RSTB arrives. It should be there toward the end of this week/early next week.

-Rod

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post #9 of 10 (permalink) Old 08-23-2006, 09:24 PM Thread Starter
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I measured 1.75" of play in the differential. I suspect I will be replacing the gear set shortly.

Is anyone aware of a thread on this board that explains what to expect if I change the axle ratio?

If I change from 3.27:1 to 3.55:1 or even 3.73:1, what is the effect on driveabilty, fuel economy, performance, etc?
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post #10 of 10 (permalink) Old 08-23-2006, 09:36 PM
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Changing the gears will mean you need to change the speedo gear or get a speedcal. From what I've read on here, 3.55's will be a mild increase over the 3.27's. Enough to notice a difference and not too hard on gas mileage at all. Most people will probably recommend 3.73's. They'll give you a pretty decent launch and your MPG will suffer maybe 2-3. But that's only if you don't run WOT all the time with those new gears!

FYI, with 3.73's here's what you will experience:
70 MPH = 2300 RPM
80 MPH = 2640 RPM
(Info taken from this TCCoA Tech Article)

In any case, no matter what you do put in a T-Loc.

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