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Low pitched whine from driveline. What is it? #470322
09/16/09 09:00 PM
09/16/09 09:00 PM
Joined: Sep 2006
Posts: 1,161
Los Angeles, CA
JF_Moparts Offline OP
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JF_Moparts  Offline OP
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Joined: Sep 2006
Posts: 1,161
Los Angeles, CA
All,

I mentioned a while back that my rear driver's wheel fell off while I was driving (someone tried to steal the wheel). Since then, I've been replacing parts in the rear to get everything back to normal.

Well, a low pitched whine starting happening when I got the car back on the road (mainly at highway speeds, 60+), and even though we've replaced almost everything, it's still there, although it's quieter.

Here's the details:

Wheel falls off the car.
Car goes to shop where we replace driver's spring perch and shock. We install new axles (Yukon) and bearings on both sides. And we rebalance the driveshaft.

I buy and install new wheels and tires.

Next, I start driving the car and after 200 miles or so the low pitched whine starts. Here's when it happens:

- After the car heats up, after roughly 5 min of driving or so.
- Initially, only at highway speeds. I first notice it at 70 mph, but as I get used to the noise I realize that I can hear it at speeds as low as 30 and as high as 80. Above 80 it's quiet.
- Only when my foot is moderately on the gas. If I'm coasting or braking, the noise is gone. Also, if I'm flooring the car, the noise is gone. It's only when I'm accelerating moderately.

We diagnose it as the ring/pinion gear. We get a brand new 3rd member and install it. The old one looks good, but we figure that not all problems can be visually identified.

Now I'm driving the car and it has 300 miles on the new 3rd member. I've driven it like a granny, no hard acceleration at all. I took it on the freeway for the first time this weekend and lo and behold, at 70 mph the whine is there, although quieter. The whine starts at about 65 and ends at 80mph. Same symptoms - it's only there under moderate acceleration.

So now I'm stumped. Could it be that the axle housing is slight bent from when the wheel fell off, and the axles are connecting with the 3rd member at a slight bad angle?

Any ideas? I'll do anything to fix this. This is the car I drive my 3 year old in, and I want it to be a safe ride.

Thanks in advance for any suggestions.

Jim

Re: Low pitched whine from driveline. What is it? [Re: JF_Moparts] #470323
09/16/09 09:45 PM
09/16/09 09:45 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert Offline
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Lincoln Nebraska
Quote:

Any ideas?


You might slip a pair of 2 or 4 degree tapered shims on the housing perches between them and the springs(not sure which way to tilt it, might try both ways) & see if it's a ujoint angle problem


live every 24 hour block of time like it's your last day on earth
Re: Low pitched whine from driveline. What is it? [Re: RapidRobert] #470324
09/17/09 01:33 AM
09/17/09 01:33 AM
Joined: Sep 2006
Posts: 1,161
Los Angeles, CA
JF_Moparts Offline OP
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JF_Moparts  Offline OP
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Los Angeles, CA
Quote:

Quote:

Any ideas?


You might slip a pair of 2 or 4 degree tapered shims on the housing perches between them and the springs(not sure which way to tilt it, might try both ways) & see if it's a ujoint angle problem




Thanks Robert. So you're thinking it's the angle of the driveshaft/u-joint? Do you think it's possible that it could be a bent rear end?

Jim

Re: Low pitched whine from driveline. What is it? [Re: JF_Moparts] #470325
09/17/09 09:48 AM
09/17/09 09:48 AM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert Offline
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I wouldn't think they could have changed the angle of the housing since they welded on only 1 perch but stranger things have happened. You have replaced the 3rd member/axles/bearings & (re)balanced the driveshaft so yes that does pretty much does only leave the housing. I'd think if the housing end was bent/cocked enough to cause the noise that it would be noisy all the time. the ujoints were replaced(or checked) during the balancing?


live every 24 hour block of time like it's your last day on earth
Re: Low pitched whine from driveline. What is it? [Re: RapidRobert] #470326
09/17/09 12:14 PM
09/17/09 12:14 PM
Joined: Sep 2006
Posts: 1,161
Los Angeles, CA
JF_Moparts Offline OP
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JF_Moparts  Offline OP
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Yes, there are new u-joints in there.

I am running a Gear Vendors unit, which does shorten the driveshaft and increase the u-joint angles, but I'va had that unit for 3 years and this noise just started.

Jim

Re: Low pitched whine from driveline. What is it? [Re: JF_Moparts] #470327
09/17/09 12:23 PM
09/17/09 12:23 PM
Joined: Jan 2003
Posts: 543
Indiana, Just Off I-70
BradD Offline
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Indiana, Just Off I-70
It may be the axle bearing if the housing warped on the end when they welded on it!


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