I Need help with rear end knocking noise - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jcloud6 · 02-16-2011, 08:07 PM

I searched the post but could not find any help with my truck rear end problem. The rear end started this loud thumping/knocking type noise. I put on jack stands, started the engine and put it in drive. With the rear wheel spinning I was able to pin point the location of the noise. Its the 1981 C10 orginal factory non-posi rear end. The oil level is good, however I did notice the rear pinon yoke had a small wobble while the rear wheels spinning. Is it possible the front and rear pinon bearing is worned out and the wobble is causing the noise?

Any assistance will be helpful

Thanks

LONGHAIR · 02-16-2011, 08:21 PM

If you have a noticable pinion wobble, there is a bigger problem lurking. If the pinion is loose enough to move at the yoke end, it has definately damaged the ring gear's teeth too. There is a very precise alignment required with these parts and any "movement" causes improper wear. It will be noisy and the normal rate of wear is greatly accelerated.
Over-all not an easy fix. Simply replacing the bearings (assuming that this is the original problem) will not cure it.

spudz · 02-16-2011, 08:27 PM

your pinion nut prolly backed off and chipped some teeth off the ring gear. if you grab the pinion flange can you move it at all? Like its loose? Either way, pull the cover and look inside.. 3 quarts of 80-90 gear oil and a gasket is cheap enough.

jcloud6 · 02-16-2011, 09:14 PM

Spudz and Long Hair

Thanks for your prompt reply and valuable information, Base on your feedback and my limited mechanical knowledge Its probably a good idea for me to replace the Rear end. My Local cash of clunker salvage yard currently have a desent selection of C10 pickups. Since I am going to replace the entire unit I may as well look for one with posi-traction because most parts their are sold at a very reasonable price.

Thanks again

spudz · 02-16-2011, 09:20 PM

before you do that.... make sure that you dont just have a bad u-joint. if it was a rear ujoint it may look like its the pinion joke moving.

James McClure · 02-17-2011, 08:41 AM

Hay guys, just my 2 cents and a quick thought. IF the pinion is loose enough for you to see it wobble the the pinion seal should be leaking like crazy. I think Spudz is probably right. "U" joints fail a lot more often than rear ends do. jim

Goldfinger · 02-22-2011, 01:10 PM

I've had a knocking sound i thought came from the rearend it was an exhaust leak. hope this will help.

02-16-2011, 08:07 PM	#1
jcloud6 Registered User Join Date: Oct 2010 Location: Clarksville, TN Posts: 37	I Need help with rear end knocking noise I searched the post but could not find any help with my truck rear end problem. The rear end started this loud thumping/knocking type noise. I put on jack stands, started the engine and put it in drive. With the rear wheel spinning I was able to pin point the location of the noise. Its the 1981 C10 orginal factory non-posi rear end. The oil level is good, however I did notice the rear pinon yoke had a small wobble while the rear wheels spinning. Is it possible the front and rear pinon bearing is worned out and the wobble is causing the noise? Any assistance will be helpful Thanks

02-16-2011, 08:27 PM	#3
spudz Registered User Join Date: Oct 2005 Location: Branchville SC Posts: 1,647	Re: I Need help with rear end knocking noise your pinion nut prolly backed off and chipped some teeth off the ring gear. if you grab the pinion flange can you move it at all? Like its loose? Either way, pull the cover and look inside.. 3 quarts of 80-90 gear oil and a gasket is cheap enough. __________________ 2004 z71, 96 z71 on 38s, 88 Chevy k5 blazer, 4in lift. 84 swb project, 82 SWB project , 84 chevy 4x4 lwb project, 88 Jimmy beater/highschool ride. 79 c30. 99 tahoe 4x4 project. and a bunch of parts trucks..

02-16-2011, 09:14 PM	#4
jcloud6 Registered User Join Date: Oct 2010 Location: Clarksville, TN Posts: 37	Re: I Need help with rear end knocking noise Spudz and Long Hair Thanks for your prompt reply and valuable information, Base on your feedback and my limited mechanical knowledge Its probably a good idea for me to replace the Rear end. My Local cash of clunker salvage yard currently have a desent selection of C10 pickups. Since I am going to replace the entire unit I may as well look for one with posi-traction because most parts their are sold at a very reasonable price. Thanks again

02-16-2011, 09:20 PM	#5
spudz Registered User Join Date: Oct 2005 Location: Branchville SC Posts: 1,647	Re: I Need help with rear end knocking noise before you do that.... make sure that you dont just have a bad u-joint. if it was a rear ujoint it may look like its the pinion joke moving. __________________ 2004 z71, 96 z71 on 38s, 88 Chevy k5 blazer, 4in lift. 84 swb project, 82 SWB project , 84 chevy 4x4 lwb project, 88 Jimmy beater/highschool ride. 79 c30. 99 tahoe 4x4 project. and a bunch of parts trucks..

02-17-2011, 08:41 AM	#6
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: I Need help with rear end knocking noise Hay guys, just my 2 cents and a quick thought. IF the pinion is loose enough for you to see it wobble the the pinion seal should be leaking like crazy. I think Spudz is probably right. "U" joints fail a lot more often than rear ends do. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

02-22-2011, 01:10 PM	#7
Goldfinger Registered User Join Date: May 2010 Location: laurel hill Fl Posts: 645	Re: I Need help with rear end knocking noise I've had a knocking sound i thought came from the rearend it was an exhaust leak. hope this will help. __________________ 1985 C10 Custom Deluxe LWB 305/700r4 [ Goldfinger ] 1999 k3500 crew cab dually 6.5tdi/4l80e



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