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1996 Chevrolet Suburban:
Clunking Noise/Drivetrain Slack

By
Alex Steele
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seen in Truck Trend

Question:

 

I recently bought a 1996 Chevy Suburban 1500 4x4 with 18K on it, and it is one of the best vehicles I've ever had!

 

When I let off the accelerator at low speeds (10-20mph) and coast, and then apply the throttle, there is a clunking noise from the limited slip differential. I can feel what seems to be drivetrain slack. The dealer, of course, claims this is normal and due to the limited slip.

 

Answer:

 

A 4x4 driveline includes a lot of parts between the engine and the rear wheels. These parts are assembled to make up the transmission, transfer case, drive shaft and rear axle. Unfortunately, all these items are not welded together. That's why there's a necessity for specified "clearances" along the way. When you decelerate, all this slack is taken up in one direction, and then upon acceleration the slack is taken up in the opposite direction. This can produce a slight and, yes, normal clunk.

 

Excessive backlash between the ring and pinion gears or various worn out items within the rear axle can produce unreasonable clanking. However, the limited slip aspect of the differential would have little to do with this type noise. A clicking on turns would be another story.

 

Also, the problem may be way up front, but due to a "funky" audio transfer principal it sounds like it's coming from the rear.

 

If you truly feel the noise is beyond normal and the technician is missing something, then ask to go for a ride in a similar vehicle and compare clunks for yourself. If your clunk is noticeably louder than the other clunk then there's more work to be done. On the other hand, if your truck sounds just like the test-truck, it's probably a normal characteristic.

www.realworldautomotive.com

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Chevrolet | Noise | Differential | Driveline
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Comments:

Latisha
19 Mar 2016, 05:00
Do you have more great arieclts like this one?
Administrator
20 Mar 2010, 16:52
You should fully inspect the driveline to be sure nothing is worn out and producing the noise, such as a U-joint, the rear axle, or a loose transmission mount.

Then, assuming it's not normal 4x4 driveline slack producing the noise, Jeep technical service bulletin 03-004-07 may apply.

This TSB deals describes "A ringing, snapping or popping sound coming from the drive line when the transmission is shifted from forward to reverse or reverse to forward. The sound may also occur when the brakes are released after shifting into or out of Drive or Reverse."

The fix involves "replacing the transmission output flange on certain vehicles, and applying "Stud N Bearing Mount Adhesive" to the transmission output shaft flange splines."

Check your VIN number at a local dealer to see which applies to your vehicle. They should also be able to verify the output flange being the problem, or not, and give you a price on parts and labor accordingly.
Fantie Loots
20 Mar 2010, 15:07
I have a 2006 Jeep Cherokee 3.7l Auto with 55 000 Km that sometimes makes a load "Clunk" when in 4x4 low range and changing from D to R, especially on inclines. Is this serious?
Administrator
20 Jan 2010, 19:08
The Suburban's automatic and manual transfer cases are two different systems -- but both use electronic inputs and commands, including activation of the front axle actuator.

You really gotta scan the system for trouble codes and correct readings, before evaluating the mechanical elements.
Jim
20 Jan 2010, 18:23
my transfer case is engaged and won't disengage. its a 2000 suburban lt. The front diff. is not engaged, only when you put it in 4 wheel drive.???
Alex
25 Aug 2009, 21:32
Hey James,

It all depends on the specific application, but the 4x4 light flashing typically means there was a fault detected in the transfer case, front axle or related components.

The system then shuts down to protect from further damage, and a trouble code is stored in the control module's memory.

You really need to get it to a technician with a scan tool, and take it from there.
James Brekhus
25 Aug 2009, 21:12
I noticed this similar clunk as there is a sudden change of acceleration or deceleration. But now I am faced with yet a new dilemma. Now my 4x4 high or low will not engage. I hear a clunk and the light keeps blinking and never fully engages. What is the possible fail point in this scenario? Please advise.

 

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