odd noise

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7duster4

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Lately I have been having a strange noise coming from the back of the car. I noticed this about a month ago. Although when I first heard it, it was the first time I drove the car with the windows up. With them down it's almost impossibile to hear. So this may have been going on all summer. Anyway there is a groaning type of sound. Sounds like it's coming towards the rear of the car. Sometimes but not all when I accelerate like normal from a stop I can hear the noise then goes away as I keep on accelerating. It dosn't do it for long. It's not too loud but noticable especially with the windows up. Over a year ago I had some rear end work done. It's a 8 1/4 with 3.21 sure-grip. I haven't had any issues with it. We had a minor leak in the past but thats been fixed. I really hope this wouldn't have to do with the rear end. Could this be a vibration of some sort? Maybe in the suspension? This has been going on for at least a month or so. I typically drive it every weekend and it has been doing fine. The more I think about it dosn't seem like it has been doing it as much now as it did in the past. So I guess thats a good sign. Am I just over-reacting?

Any info is appreciated. Thanks
 
Did you put a can of sure grip additive in the rear when you filled it up? Sounds to me like you don't have any in the rear.
 
Yes we did use kendall sure-grip additive. I beleive the oil is valvoline 80w-90. You think maybe I should put some more additive in?
 
Exhaust clearance? Should have at least an inch everywhere. Look for shiny spots on mufflers/pipes. This shows up with age as the rubber in the mounts gets soft and allows a little more slop. Just throwing out ideas.
 
New axel bearings were replaced when the rear-end was done. Maybe he didn't do the best job. Is it a good or bad sign that it dosn't make the sound as much as in the past? I would assume good but im no mechanic. I would rather it be bearings than my rear-end going to crap.

Thanks guys for all your feedback
 
Axle bearings aren't the only bearing in the rear that can make noise. There's pinion and carrier bearings also. Sometimes noise can change for the better with temperature changes due to the oil staying thicker. It sounds like you need to get it up in the air and run the drivetrain to determine where it's coming from.

BTW: My old 93 Dakota's rearend starting making a slight growling noise at about 75,000 miles. I ran it until it had a little over 90,000 on it and sold the truck telling the guy that it needed rearend work. He said he'd drive it until it quit and finally at 124,000 miles it gave out. He said it ended up being a carrier bearing. That's an extreme case of lasting a long time after starting to make noise but just though I'd ad it.
 
If I have time this weekend i'll jack it up and try that. Should defenitly be able to pin point it and determine where in the rear its coming from. Thanks for the tip "fishy68"

I take it to replace those bearings the whole rear end has to come apart?
 
7duster4 said:
If I have time this weekend i'll jack it up and try that. Should defenitly be able to pin point it and determine where in the rear its coming from. Thanks for the tip "fishy68"

I take it to replace those bearings the whole rear end has to come apart?
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Your welcome and yeah unfortunately it means tearing it all down to replace them. Check the U-joints good while you have it up in the air. Most of the time U-joints don't growl but you just never know.
 
What type of axle bearings did you install, the green bearings or the OE style tapered bearings? Although usually considered a superior design, the green axle bearings have no side load protection and will wear out quick if used for a street application. They are really designed for straight line performance applications. I have seen them go out in less than one driving season due to cornering in a street application. My rear end guy always uses the OE style tapered bearings for street car applications!! Just throwing out ideas here too!! Good luck with the diagnosis and report back your findings, Geof
 
cosgig said:
What type of axle bearings did you install, the green bearings or the OE style tapered bearings? Although usually considered a superior design, the green axle bearings have no side load protection and will wear out quick if used for a street application. They are really designed for straight line performance applications. I have seen them go out in less than one driving season due to cornering in a street application. My rear end guy always uses the OE style tapered bearings for street car applications!! Just throwing out ideas here too!! Good luck with the diagnosis and report back your findings, Geof
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To be honest I don't know what type of bearings they were. This is the kit I purchased from randys ring and pinion. I bought the axel bearings separate. They are timkin and I used what was in the catalog for a 8 1/4. I would assume OEM style but I'm almost 100% positive they are not the green bearings. It was a reputable mechanic that did all the work. So I thought...

http://www.ringpinion.com/ProductDetails.aspx?ProdID=1457

Over the summer I had to get the pinion seal replaced as the rear end had a leak. Even after all this work was done. But it was a different guy that I went to. He is very good with old cars. Anyway he was concerned about the pinion nut. He said the guy who did the rear end work tighten it too much. It was real tough to get loose to replace the seal. But he got it. Hasn't leaked since. But also noted the nut being that tight could cause some problems but I would have already notice them if something was wrong. The pinion seal was replaced almost a year after the gears/carrier were changed. The seal was replaced this past summer. It wasn't until October that I noticed the present sound. If it turns out to be the bearings i'll probably go back to this guy. Im just hoping I don't have to do anything until after winter. I probably won't drive it but a couple times before storage so I guess I should be okay.

Thanks for your feedback.
 
fishy68 said:
Your welcome and yeah unfortunately it means tearing it all down to replace them. Check the U-joints good while you have it up in the air. Most of the time U-joints don't growl but you just never know.
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As far as the u-joints go what should I look for? Would they just be real loose and have lots of play if there going out?
 
7duster4 said:
As far as the u-joints go what should I look for? Would they just be real loose and have lots of play if there going out?
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Most likely it's not the U-joints by your description but I always check them anyway if I have the rear up in the air so that's why I mentioned it. You just basically check them for play and make sure they are grease good.

BTW: It's normal for a pinion nut to be hard to remove as they are torqued down to at least 150 lbs. Most I take apart I have to use my 3 foot cheater bar on my 3/4 drive breaker bar. I don't know enough about the 8-1/4 to know if it uses a crush sleeve or spacer with shims but if it is a crush sleeve type they are very tricky if not impossible to reuse and when the last guy replaced the pinion seal he might have crushed it down more than it should have been and caused the pinion bearings to burn up which could be the noise. It's also possible the original guy did that. The crush sleeve can be reused most of the time if your extremely careful but as I said it's real tricky because you have to make sure and not over torque the pinion nut and cause too much bearing preload but at the same time you have to get it tight enough to stay on.
 
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