Rear End Drone

[Chad]

Hi all. I just finished pulling my rear leaf springs, replacing the bushings, cleaning them all up and reinstalled. Took her out for a spin yesterday, and am getting a strange droning sound from what seems to be the rear end. Oddly enough, it only happens at lower speeds, say between 30-40 mph, and only when my foot is very lightly pressing on the accelerator. If I remove my foot and decelerate, it disappears. If I put my foot into the accelerator, it disappears. Again, only when I lightly press the pedal do I hear it. It’s more of a drone sound that reminds me when a truck goes by with larger tires, you hear that harmonic droning.

I did just perform a differential service, and although I typically put in two quarts of Royal Purple and call it a day, I do have a new diff cover that could be possibly expanding the volume of fluid that it holds. Could being a 1/4 to 1/2 quart low cause this?

I’ll have some time to give it some attention tomorrow, but figured that someone might know why I’m only hearing it under these circumstances. And by the way, it is a 10 bolt 8.2 posi rear end.

Thanks!

Topic

[Andrew Button]

Double check fluid level again…. if its full then do this…and you don;t have to take anything apart either…

Pull the cover off and pattern the gears with the appropriate yellow or white compound. Make sure the drive side of the pattern is not way to the edge of the ring gear. Google this one. Check backlash as well. Inspect all gear teeth including spider gears and other parts in there for bad things. Run a magnet through the gunk and see if you get chips… Its all different shades of brown in there and easy to miss stuff, so get a bright light. Then you will know.

Putting your foot into the accelerator is most likely loading the pinion and pushing it farther into the ring gear changing the meshing of the gears. The above stuff will tell you where the problem lies. Thats assuming that there isn’t a bigger problem like something else loose. Not space here for that part. Then you can put new fluid in as well and make sure the level is right

[Ingvar]

Are there words more commonly used to describe what “droning” noise is? Can it possibly be humming noise?
Also, what exactly is that drone that you are driving? A truck? A car with leaf springs? They are still around, you know.
I have 2 wild guesses for you.
1. you changed your rear end suspension. Now, your tires run at different path on the tarmac and what you hear, is lugs re grinding themselves.
2. have no idea. I had very similar humming noise on 99 Silverado. Boooooooooooooooooooooooooooooooooooo Very faint and coming from somewhere behind me, sitting in driver seat. Behind and below. It basically sounded like air coming through a narrow passage, except that were no air passages there. No influence on driveability, so I simply quit paying attention to it.,
Royal Purple makes gear oil for rear diff?
Now, should it be one of GM trucks, I wouldn’t be surprised with that humm being “normal”. Those things are made with axe and crowbar.

[Chad]

[quote=”ukrkoz” post=124781]Are there words more commonly used to describe what “droning” noise is? Can it possibly be humming noise?
Also, what exactly is that drone that you are driving? A truck? A car with leaf springs? They are still around, you know.
I have 2 wild guesses for you.
1. you changed your rear end suspension. Now, your tires run at different path on the tarmac and what you hear, is lugs re grinding themselves.
2. have no idea. I had very similar humming noise on 99 Silverado. Boooooooooooooooooooooooooooooooooooo Very faint and coming from somewhere behind me, sitting in driver seat. Behind and below. It basically sounded like air coming through a narrow passage, except that were no air passages there. No influence on driveability, so I simply quit paying attention to it.,
Royal Purple makes gear oil for rear diff?
Now, should it be one of GM trucks, I wouldn’t be surprised with that humm being “normal”. Those things are made with axe and crowbar.[/quote]

Thanks for the reply. My vehicle is in my profile…’67 Camaro. I described the noise and frequency as well as I can, and definitely not a hum. I’m going to start with the u-joints and work my way back. Pinion yoke might be loose. Highly doubt it’s the lugs grinding themselves. Royal Purple makes a great differential gear oil with the posi additive already included.

[Andrew Button]

if you pinion is loose and your crush is lost and you will have to redo the entire rear end. You cannot, under any circumstance torque it back down. Rear end settings, one setting changes, they all change. No room for error there, none.

[Lorrin Barth]

You might take a look at where the leaf springs are hung to see if anything metal to metal is transmitting normal road noise to the body.

[James O’Hara]

The sound is most likely your diff as andrewbutton442 is getting at especially if you did leaf springs. I am guessing that you did not take measurements off your old leaf springs and reposition the axle in the same spot it was in.

Check diff fluid level first and fill as needed. Drive for about 2 miles making lots of turns. Then recheck and refill. Then see if the noise goes away.
If not you can drain your diff and do what andrewbutton442 said. Or if you still have the old leaf springs laying around you can look at them and take as accurate as you can measurements loosen the U bolts and reposition the new leaf springs to the exact same position as the old. If you are withing 1/16-1/32 on either side for accuracy it should go away.

[Lorrin Barth]

If you get into the differential, look for any chunk style material. If you find it check the side bearings.

[James O’Hara]

Also did you install regular springs or lifted ones because if you installed lifted it may be drive shaft angle.

[Author]

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