Rotational crunching sound while slowing down

[AZ-Dan]

 I have a sound coming from the front end of my 2005 Silverado 4x4 that happens only after it has been driven 10-15 Miles (Hot) and sounds like a rotational crunching sound (some could call a clicking or maybe popping) It seems to only happen while I am at Low speeds coming to a stop only.  I don’t seem to hear anything abnormal while accelerating or cruising and when I begin to brake there’s no issue (brakes feel/work great) but only when I get down to around 10 miles an hour (crunching 2-3 times per tire rotation) It’s really hard to pinpoint what side of the truck but it sounds to be about the same from both sides. I have done a bunch of work including replacing front CV axle’s, front brakes, front differential service, transfer case service, lubed rear slip yoke, inspected/tested actuator for front differential engagement, and spent hours attempting to diagnose and inspect the entire Front end and drivetrain. The crazy thing is I got the Sound to go away completely after The night I had replaced the front CV axle’s, and brake pads and then put about 300-400 miles on it (took camping loaded up and drive and brakes worked fantastic) and now the sound has come back!?... I really am getting very confused and discouraged on where to go next? I guess I was thinking of getting it to act up and then removing the front driveshaft to see if the sound continues and I guess that would help determine if its a possible driveshaft or u-joint issue or maybe front differential or transfer case issue?  Sorry for the long post I just want to put as much info as I can and THANK YOU ?? in advance for any help I can get I really appreciate it! I have good videos of the issue but the files are too large to upload on this post but I could email them to somebody if they’re willing to watch? THANK YOU! 

[tbarn]

Without hearing the noise, I can guess based on experience. First thing comes to mind is rotors with excess lateral run-out. What you may be hearing is the calipers moving back and forth. Another problem I've seen is bad tires. They usually do at slow speed but not necessarily with brakes on. Pump up tire well above normal. If it is still there it's probably not tires.

[mjm-1957]

Are you sure the abs isn't activating from a bad wheel speed sensor? Install a Tech 2 and go to abs data and watch the wheel speeds as you come to a stop. If your having a problem with a sensor you will see the speed drop out compared to the good one.The one thats dropping out is your problem.

[Colossus]

I heard crunching noises from the back axle on my 99 silverado when the G80 diff let go..

[crankman]

I agree check the rotors they can make clicking noise, does it stop when you apply the brake?

[AZ-Dan]

6 hours ago, tbarn said:

Without hearing the noise, I can guess based on experience. First thing comes to mind is rotors with excess lateral run-out. What you may be hearing is the calipers moving back and forth. Another problem I've seen is bad tires. They usually do at slow speed but not necessarily with brakes on. Pump up tire well above normal. If it is still there it's probably not tires.

Ok it does make a little sense that could be rotors because it does it when it is hot and after the heat up I suppose things could change. I did just take it camping with new OEM brake pads and everything worked great even with a fair load in the bed so it’s a little hard to believe but makes sense. If I’m coming to a stop and lightly applying brakes at low speeds that’s when it happens but if I firmly apply brakes it will grip and stop great....

 

I will also try pumping the tires up maybe 20 pounds past recommended pressure and drive after the sound starts to happen to test.

 

Thank you! 

 

[AZ-Dan]

6 hours ago, mjm-1957 said:

Are you sure the abs isn't activating from a bad wheel speed sensor? Install a Tech 2 and go to abs data and watch the wheel speeds as you come to a stop. If your having a problem with a sensor you will see the speed drop out compared to the good one.The one thats dropping out is your problem.

Tech 2 is one of those nicer scan/ diagnostics tools correct?  I wonder if I can rent one somewhere?  I definitely don’t have any ABS or brake light coming on or anything but i’m sure that doesn’t necessarily mean the sensors are good. 

 

 Thank you for your advice I will look into finding one of those tools. 

[AZ-Dan]

6 hours ago, Colossus said:

I heard crunching noises from the back axle on my 99 silverado when the G80 diff let go..

 I just did a front and rear diff service and everything looks great.  The rear gears looked great when removing cover and no chunks found in either of the fluids. ?...  I will keep plugging away at it but thank you for you insight. 

 

[AZ-Dan]

5 hours ago, crankman said:

I agree check the rotors they can make clicking noise, does it stop when you apply the brake?

 Do you guys know if there’s anything visually I can look for on the rotors to see if the issue is there?  I suppose they’re pretty cheap I can swap them out and re-test.  I really wish there was a way I could upload a small 5 second video that you can hear the sound pretty well on but apparently it’s too large of a file?...

[tbarn]

If pedal pressure makes a difference it's probably not an ABS issue. Mostly I have heard what I would call a rotational scrunch noise with light or moderate pedal pressure. Although generally with this noise you feel at least some brake pulsation sometimes. As far as visual inspection goes, rotor run-out and thickness variation can be measured but requires special tools. Check for loose bearings, and for dirt or rust between the hub and rotor.

[AZ-Dan]

14 minutes ago, tbarn said:

If pedal pressure makes a difference it's probably not an ABS issue. Mostly I have heard what I would call a rotational scrunch noise with light or moderate pedal pressure. Although generally with this noise you feel at least some brake pulsation sometimes. As far as visual inspection goes, rotor run-out and thickness variation can be measured but requires special tools. Check for loose bearings, and for dirt or rust between the hub and rotor.

Yeah it seems that pedal pressure does not make a difference.  But I would say the description of rotational scrunching noise  would be accurate.  And the brakes do feel and work fantastic.  I just replaced the driver side hub assembly Friday night and there was quite a bit of rust and dirt that was needed to be cleaned out before installing the new one. Passenger Side hub assembly was replaced before I bought the truck roughly 6000-8000 miles ago and I would assume they clean the rust and dirt out on that side (either way the sound seems to be equal from both sides).  I can send you a quick video take a listen. 

 

Thanks for your help! 

[AZ-Dan]

 And one more thing I guess I forgot to mention is it seems to have some high pitched squeaking sounds that once started turns quickly into the scrunching/crunching sound I’m concerned about. 

 

Thx ??

[Brianibew]

Sounds like a universal joint failing.

[AZ-Dan]

 I’m picking up some rotors at lunch and I’m going to swap those out tonight and update the post.  If the rotors don’t do it I’m leaning more towards a possible U joint/drivetrain issue Because I am hearing the scrunching/crunching sound three times per tire rotation. 

[AZ-Dan]

 I do have a short 15 second video that shows the sound very well if anyone is interested shoot me a message with your email address and I will send it over. ?? 

But after talking with some of you it’s sounding like it’s more likely to be a sound somewhere in the drivetrain. most likely U joints.

 

 

Thank you!