OK - I finally decided tday was the day to change the rear end oil to see if I could eliminate the whine. I used GM lube and addative. BVut the noise is still there. I'm starting to question if it's actually the carrier or if it's rear wheel bearings.
I did have the rear end re-shimed last summer and it's always made this sound before and after.
It's a medium to medium-high toned whine. It only appears after 50 mph and gets worse with increased speed. I can hear it upon acceleration or deceleration but it is much louder if held at a constant speed.
Can wheel bearing make this sort of sound or does it have to be the rearend?
Thanks!

 

Is this a new sound that it's making or just a whine thats been there? Reason being my brother has a 78 and my buddy and I have 79's and they all have a whine to the rear ends you can hear around 45 or 50mph. Just curious!

 

It's been there as long as I've had the car. But that's not that long.

 

might i ask what a "re-shimmed" rear end is????? ...redvetracr

 

LOL - not my term. Inside, there are disk shaped shims that have a slight dish to them. I did not want them to replace the gears. When they setup the rear they had to add a couple of these shims in there. I've never rebuilt a rear end but I'm starting to think now may be the time to learn.

 

ttt - anybody?
Let me state that I did search the forum and read the articles at Randy's and a bunch of other places before I posted. None of these had a definitive answer. So I'm not being lazy and just asking before doing any research!
Please?

 

No answer to your question, but another question. My vette's got a whine in the rear and I figure I ought to change out the oil in the rear end as well. What did you do to drain the rear? Some sort of pump?

 

No, but a pump or turkey baster might be faster. I used a 1/4" hose (Just a gas line - could have been 3/8"). I stuck it down in as low down inside the carrier as I could. Then I squirted some new oil out of the bottle through the line to fill it. Then I put the end of the line down lower than the carrier and into a gallon jug. Then waited about an hour for it stop draining. Got a couple quarts out so I figure most of it must be out. Oh - I took it for a short drive first so the oil would be thinner. Wasn't too bad.

 

Typically when a rear end has developed a whine, it can't be eliminated without changing the ring gear and pinion. Once a rear end has developed a wear pattern it should not be changed, otherwise it will whine. Running one low on oil can set up a different wear pattern on a good ring and pinion and it will whine from now on though it may run for another 200000 miles. Clearances are very important in a differential and once a wear pattern has developed they are best left alone.

Phlash 72 BB Roadster :seeya

 

Have to agree, the pattern is the most important thing.
I disassembled my diff, changed out all the bearings and seals, took apart the positraction, cleaned the shims, assembled it BUT
bruought it to a shop to ALLIGN it.
They use chalk on the pinion and rear gear to figure out the right pattern, there are several books out there that show how to do it. My book is a very old one that I got from my father, it´s probably as old as I am, but it shows our type off diff. Nevertheless I let them do their job and let me give a warranty against failure and whining starting from the time when my car is ready and insurance begins.

My advice: Take off the backplate of the diff and check the gear visually.
Maybe you can see a strange pattern on it. Then I guess it´s time for replacing. Unfortunately I have no scanner to show you the right pattern which is in my book, but if you´re patient I will visit a friend of mine who has the equipment to do it.
Markus

Yep I forgot to answer aour second question....
Wheel bearings can make a whine too, but you can easily identify where it comes from.
If the whine only occurs during cornering or gets louder when cornering then it´s the bearings!!
If it ´s all the time.....Sorry=>rear gear.
Then again, I´m not so sure if it´s not even easier to replace the rear gear instead of the rear wheel bearings!!
Did both and rear wheel bearings are not fun! Of course it can be the front wheel bearings too, this is what I hope for you.



[Modified by MARKUS_P, 6:00 AM 1/11/2002]

 

Thanks Guys!

I think you are correct that it's the rear end and most likely the gearing. I would think a wheel bearing noise would be heard at lower speeds too. I'm just trying my best to not have to rebuild it! One of the projects for this winter (if we have one) is to tear out the rearend and suspension. I figured if I could get it quiet now then I'd skip the new gearing.
I do have the diagrams of correct engagement patterns so this time I can check it myself. Thanks!

 

My gears whine too. Only under no load cruise. Not under acceleration or decelleration. Only at that in between state.

Keep in mind that the rear diff is bolted directly to the frame in these cars. This has a tendency to amplify noises that would otherwise not be heard in other types of vehicles such as Camaro or Chevelle.


[Modified by Jvette73, 7:47 AM 1/11/2002]

 

That's almost what mine do. A slight whine/hum that is only present when you're off the throttle. Just touching the throttle makes it disappear. It is present under braking, though...