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Old 09-24-2017, 11:35 AM   #1
rgunlock
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Help identifying front-end noise

I'm just finishing up restoring my 78 K15 and during test drives I'm hearing a noise from the front end I haven't been able to identify. Its kind of a "swish-swish-pause-swish-swish..." noise. The tempo increases/decreases with the speed of the truck. I got a ChassisEAR setup and listened around and it seems to be coming from both front wheels.

Figured brakes. I'd already replaced rotors and pads so I went ahead and replaced the calipers as well. Still have the sound, but realized that it doesn't go away when I press the brakes. If it were pads hitting high spots on the rotor I figure it would stop when the pads grab.

Only thing left that I can think of is something in my locking hubs, but I've also replaced wheel bearings and lubed everything up several years ago before this became a restoration project. Can't think offhand what's in there that would make this kind of noise. Seems really loud when I drive past a solid fence along the road.

Any suggestions on what to look for? Both hubs are in the free position - haven't tried locking them in yet.

Thanks, Rick
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Old 09-24-2017, 12:09 PM   #2
mongocanfly
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Re: Help identifying front-end noise

wow..that's a sharp truck.....have you jacked up the front end yet and spun wheels by hand to listen for the noise?
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Old 09-24-2017, 12:56 PM   #3
Stocker
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Re: Help identifying front-end noise

Does it have a rubber or plastic air dam underneath the front bumper? The center part can detach with both ends remaining attached, and they kinda flap in the breeze. Looks funny meeting a vehicle with that piece flapping.... your description of the sound made me think of it.
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Old 09-24-2017, 03:57 PM   #4
rgunlock
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Re: Help identifying front-end noise

Quote:
Originally Posted by mongocanfly View Post
wow..that's a sharp truck.....have you jacked up the front end yet and spun wheels by hand to listen for the noise?
Thanks! Did 99% of this myself. I did spin the wheels when I thought it was the brakes, but need to do it again.

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Originally Posted by Stocker View Post
Does it have a rubber or plastic air dam underneath the front bumper? The center part can detach with both ends remaining attached, and they kinda flap in the breeze. Looks funny meeting a vehicle with that piece flapping.... your description of the sound made me think of it.
It originally did but I haven't put it back on.
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Old 09-24-2017, 05:16 PM   #5
Stocker
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Re: Help identifying front-end noise

With the hubs in the free position, the front driveshaft will sometimes rotate slowly. Maybe there's something about that driveshaft that's making the sound. Try driving it with the hubs locked (and the t-case in 2Hi). If the noise changes, goes away or speeds up, I would suspect the front driveshaft.

Another way to check for a front DS issue is to use one or more sturdy plastic ties to keep the DS from rotating -- only in 2Hi with hubs in free position of course.
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Old 09-24-2017, 08:23 PM   #6
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Re: Help identifying front-end noise

Thanks for the suggestions guys. I'm pretty sure I got this figured out today. I will chalk it up to a rookie troubleshooting exercise. Turns out the wheel weights from getting the tires balanced was rubbing on some high spots on the dust shield. Ground them down some in 2 spots (only got picture of 1) and problem appears to be gone.
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Old 09-24-2017, 09:36 PM   #7
andrewmp6
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Re: Help identifying front-end noise

You might want to look in to balacing beads they do work great and you could install them through the valve steam if you pull the core out.
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Old 09-25-2017, 02:37 PM   #8
Stocker
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Re: Help identifying front-end noise

Now that is interesting -- glad you found it!
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Old 09-25-2017, 08:42 PM   #9
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Re: Help identifying front-end noise

yep...sometimes its the simple things...
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Old 09-26-2017, 02:26 AM   #10
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Re: Help identifying front-end noise

Gonna have to get your wheels rebalanced now.

-Brad
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