Drive line noise

Brandon Diagnostician Arizona Posted   Latest   Edited  

Hello all , looking for some ideas on how to isolate noises from a drive line. Example: recently rebuilt a front end on a GMC Yukon after hear noise from the front end on acceleration, removed the front shaft (from transfer case to front axle) test drove again and the noise was gone. Short of using chassis ears what other methods could I have used to diagnose the transfer case as the problem. I'm not 100% sold that the both transfer case and front axle were making noise.

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Tony Owner/Technician
Missouri
Tony
 

First of all: “Caster Replacement”? Where did the caster go and what does it have to do with this post? Secondly: “short of using Chassis Ears”… I mean, that's the first step if you want to locate a difficult noise… If you want to do something that's more difficult you could master NVH, which still uses microphones.

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Brandon Diagnostician
Arizona
Brandon
 

Caster replacement was auto populated, i missed that. Thanks for pointing that out . I don't own chassis ears so yes I'm asking if any one had another method for locating a noise other than using mics. Thank you Tony.

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Alan Owner/Technician
Kansas
Alan
 

If this is an AWD model take a close look at tread depth on all tires.

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Glenn Owner/Technician
Texas
Glenn
 

Hello Brandon, Look on Amazon or Ebay for piezo sensors. Get a couple of them and glue a magnet to the back or a way to attach them to a housing. Then use alligator leads attached to a scope and capture the signals. Move the sensors around until the scope signal has the highest peaks. That will confirm where the issue is. This was likely a front pinion bearing issue. The same can be done with…

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Cody Diagnostician
Illinois
Cody
 

Chassis ears are hard to beat, being able to test for noises dynamically. They are used enough and specialized enough, I'd put them high on the priority list for your next purchase.

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Benjamin Owner/Technician
Georgia
Benjamin
 

I agree, Chassis Ear is a must to own. I have the wired ones. I’ve never used the wireless ones and never bought them because others have stated they have static noise that can be irritating and more batteries to have to keep up with instead of just one 9v.

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Randall Owner/Technician
Michigan
Randall
 

If “rebuilt” did not include new ring and pinion, the noise may still be from the diff. Been burned by that more than once, but not again. In our shop, R&P are included in all estimates for diff repairs, where noise is the complaint. We do more rear diffs than front, and both times we got burned on a rear diff. My 01 F150 developed exactly that kind of noise at 60k on the clock. Sold the…

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Sadel Owner/Technician
Ohio
Sadel
 

Just to chime in, as others have stated, possibly the best way to do this without incorrect diagnosis is to use a set of chassis ears. They are not expensive at all and now with the ability to use them on a scope as opposed to trying to catch the noise on the right channel at the right time audibly thru headphones is a game changer. Hook up as many channels and drive, then simply stop the…

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William Diagnostician
Texas
William
 

Bosch has a free app called iNVH for your phone. Records data while you drive. Won't replace chassis ears or scope based NVH set-ups but I've found it useful on some test drives and the price is right.

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Richard Technician
New York
Richard
 

I use the wired version of the chassis ears. I bought it used on ebay. Thats really the only way I can think of to be sure.

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Jesse Owner/Technician
Georgia
Jesse
 

I will put an assistant in the car on the lift, run it and use a mechanics stethoscope to listen for the noise, Pull the driveshaft and do it again see if the xfer case makes same noise or different, Some noises respond better when the car is on the road with weight on it, but you got to find the noise, and strapping your assistant to the bottom of the car is frowned at..

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Brandon Diagnostician
Arizona
Brandon Resolution
 

Thank you all for the response, conclusion is I NEED to purchase the right tool for properly diagnosing noise complaints. THanks again.

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Rich Technician
Florida
Rich
 

Get a roll of vacuum hose and put a hose on the vent of each component. Run them into the cab and listen while driving. Hook up to a stethoscope tube if you like. It will be easy to isolate the issue.

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Randall Owner/Technician
Michigan
Randall
 

This is what I love about this industry, I am always learning, and forums like this make sharing possible. I have never tried this, never even had a hint of a thought of doing this, but right out of the gate, it “sounds” like it would work quite well, and it's simple, reasonable quick and cheap. Thanks for sharing All of the great tips like this , I share with my 30 somethings (and a two…

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