So I am running a nine inch in a car I bought already done,i haven't run nine inches before so I don't know a whole lot about them. When driving at 45-50 or higher I get a hum coming from the rear, I put the car on a lift and put it in gear , with no weight on the tires I got no noise. I also have a really really small leak from the third member seal. My question should I be looking at carrier bearings or axle bearings? I was thinking an axle since with no weight on the tires it doesn't make noise.
Rough axle bearing? "Already done" to me means going through it anyway, esp. if it came from a swap meet... BTW, your subject line is pretty funny! Tom
..that's what HE wished she said.... I would look up the noise on a standard rear end diagnostic chart. Most old car manuals had them in them somewhere. I'm sure you can dig one up onlline. Bob
I dunno... I'd describe the noise that I hear from my 9 inch is more of a moaning than a humming noise. I'll have to pay a little closer attention next time.
If your pinion seal is leaking maybe you should be thinking about changing the seal. As for the HUM me not being privy to your noise descriptions, I am going to have to say that what you are hearing is tire noise. Put it on a rack and spin it the noise goes away.
Humming on acceleration that disappears when you take your foot off the gas pedal is usually the Pinion bearing. I have the same problem with my daily driver RWD Lincoln.
It depends........ Does it change pitch when... You steer/sway from side to side - axle bearing Under load - bad ring & pinion, performance ring & pinion or bad pinion bearing All the time - carrier bearing To just say that you have a noise coming from your 9" (which by the way is fuckin' funny as hell) is like saying my engine makes noise!
oh, man, what a vivid imagination could make out of this string......LOL Moaning, 9", sway from side to side, Humming, small leak, hey to fix that small leak change brands of ..... uh,,, thingies ! get a smaller size so it fits better... LMAO !
I had a '75 ford van that had a humming rearend at speed. The oil was way low, and after changing it to the right level the humming stopped. This one leaked out of the axle all over the brakes. A lucky fix. TP
Here's a pretty good diagnostic article. I would first rule out tire noise and low lubrication as Zibo posted. You have to get the vehicle through a series of conditions to really pinpoint the source of the noise. http://www.summitracing.com/experta...ow-to-Diagnose-Differential-Driveline-Noises/ Bob
Just to clarify it may be nine inches but six of the inches are root,lol anyways I forgot to mention that the noise is only on acceleration and goes away when I let off the gas.how big of a pain is it to change the pinion bearing? And how long can it go before I f%#k something up ?
I did check the oil,it's a small leak .puddle maybe 2 inches in diameter after sitting for 10 + days. I checked the oil first assuming that was the problem but it was only about a quarter to half a quart low.
Not long. For what it's worth, I had the same exact thing going on in my pickup truck. I was sweating bullets at having to replace the pinion in my only daily driver. I called my buddy who's a mechanic, and he said, "Look, before you get all flipped out, change your u-joints." Guess what- turned out to be a spent u-joint. Went away immediately once I changed them.
OK we have gone from a hum to a whine. Get it off the ground, drop the drive shaft and grab onto the yolk and give it a shake. Does it have any play either up and down or in and out? if your pinion shaft bearings are gone or going you can feel it. You should have zero slop. There are 3 bearings on the pinion. Two within the pinion support with a crush sleeve between them. there is a third a needle bearing on the inside end of the pinion shaft, I have seen those be shot while the rest of the rear is in good shape. Usually the cage fractures. The only way that I know to check that bearing is to drop the piion support, the pinion will come out intact, then you look inside real good to see if you see pitting in the rllers/needles or a busted cage. if that is the case it is an easy repair more or less, you just drop the chuck, pull the carrier out and and change the brearing, then you have to set the gear lash and go with it. If the bearings on the pinion itself are toast you will have to remove them from the pinion shaft, press new bearings on and go through the steps to set up the pinion then finish setting up the rear. To set up the pinion you first get the inner bearing on then the crush sleeve, then the outer bearing, now tighten the yolk down until you have no play, after that you torque it to about 25 inch pounds and run with it. That is overly simplified but you can snag a manual and follow the steps. I personally belioeve that you can do it, it is not majic but it is a matter of you believeing that you can do it.
Great info porknbeaner , I will drop the driveshaft and check it out as soon as I get home from work,thanks a ton.
I had this problem once. Under acceleration it sounded fine but when I lifted off the gas there was a slight vibration and a hum from the rear end. The problem I found was that the pinion nut was just about finger tight...so I tightened it up and problem solved.
yea when they whine under decelleration it means the gears are hunting, that can only happen of you have a loose pinion. well I guess it could mean that your carrier is moving back and forth.
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