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when should whine from rear end become a concern?

jz61

jz61

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been hearing a whine from the rear of my 65 Plymouth, 8 3/4 3,55 gears. gets louder as speed increases. no evidence or bearings getting hot, no performance issues. more of annoying thing. about 55 to 65mph has a pretty loud whine, as I let off gas and slow the noise goes away. should I really worry until I go thru whole rear and re-do the axels bearings? any way to tell axel bearing noise from center chunk noise?
 
really hard to tell for sure.you can find the whine by running it on jack stands or a rack.is the noise new?some gears make noise.(richmond)is the fluid topped off?is there any play at axle ends(side to side)or at the pinion?
 
will check all soon,like I said doest really seem to be a problem, don't know how much noise it SHOULD make! I know it is primitive set-up ,lots of metal to metal contact, more likely a product of my over active imagination, old cars make noises, new ones every day, some go away as soon as they come. thanx for the tips, will keep a eye, or ear on it!
 
Sounds like a ring and pinion noise. You have it on acceleration or constant load and it goes away when you coast or take the load off. Check the fluid condition. Need to check back lash but that is a pain obviously.
 
I have 2 cars with the 3.91 gears in them, and they both whine at certain speeds under load. Quiet on deceleration. They didn't do this before I changed the center section. The sound is most likely caused by a poor ring and pinion contact pattern. It wont hurt anything far as I know, just maybe your ears. Lol. I just drive mine and try to ignore the noise.
 
I guess first step is to check fluid level, am I correct in assuming that its full when I comes out the fill hole? glad my original radio still works, that AM static is just the right tone to mask the whine!
 
jz61 said:
been hearing a whine from the rear of my 65 Plymouth, 8 3/4 3,55 gears. gets louder as speed increases. no evidence or bearings getting hot, no performance issues. more of annoying thing. about 55 to 65mph has a pretty loud whine, as I let off gas and slow the noise goes away. should I really worry until I go thru whole rear and re-do the axels bearings? any way to tell axel bearing noise from center chunk noise?
Click to expand...

when should you worry? when it starts to sound like my ex-wife!!! HA!! (sorry couldn't resist). Assuming it's an orig. set, with several 10's of thousands of miles, and fluid probably hasn't been changed since Jesus owned the car, a fluid change will help. But it's probably (as mentioned) a lash problem due to wear. If you have the noise under load and not when off the throttle; you'll likely not hear it on Jack stands if it's lash but you may if it's bearings. Change the fluid first; cheap and easy. see what happens.

Let us know.

- - - Updated - - -

jz61 said:
I guess first step is to check fluid level, am I correct in assuming that its full when I comes out the fill hole? glad my original radio still works, that AM static is just the right tone to mask the whine!
Click to expand...

yes.
 
JZ, I don't know if this is relevant to your case or not, but I have a Ram 3500
Dana 80 that had a small whine. I drained the gear oil and replaced it with Amsoil
synthetic gear oil, added the limited slip additive and the whine disappeared.

Might be worth a try. Good luck!
 
It's pretty simple really. They're not supposed to whine. Something is wrong.
 
They can't tighten up so the bearings are worn causing the gears to be mis aligned... if it's the 741-742 shim style... Or the newer 489 has a crush sleeve... pull the center section get a kit for rebuilding and have it done by a shop that has experienced it....Or studie up on it and do it yourself but it's complicated.... the gears could be worn out as well... then good oil... Lucas or Amsol whatever and the additive in the oil for posi or shure grip as we call it on here... open diff takes a different 85-90.... always better to get a gallon of premix than having to mix separate bottles.
 
You do need to check the level, but if it has been low long enough to allow a whine to develop, then the gear teeth faces ofr bearings may well be effected. Plan on changing the oil to a synthetic; gear oil can and will break down over a long time, and needs to be changed. If it continues beyond the oil change, then this will need to be dissassmebled and checked sooner rather than later. You don't want it to progress; this is in the ring and pinion gears and/or their bearings, not the axle bearings.
 
the good news I guess is level was full, did change fluid with synthetic and additive. seems to be somewhat better, altho havnt gotten out on highway for a long drive.i wonder why they didn't put a drain plug lower on the pumpkin? this worked well for me, I got a transfer pump from advance auto for about 15$ used a empty gallon water jug pumped old fluid into jug. got another clean jug, measured how much came out, put same amount into clean jug by putting side by side and comparing, its just about 2qts, plus abit for the additive, then pumnped it back into housing. nice and neat , no fuss , no mess!worst part was the smell of the old fluid, smelled like a dead whale!
 
Set up is wrong, or you have bearing issues.

Richmond makes noise when they're set up wrong.

The only gear sets that have piss poor quality are those that are not lapped or run in, those are usually cheap copy versions or usa standard.
Motive/Richmond, US Gear, Precision, Nitro, AAM, Dana, Yukon (reboxes some listed) shouldn't make noise, if they do its the set up and the person believing they know what they're doing.

.
 
How many miles are on this rear end?? Were the gears set up recently? Taking a set of used gears and resetting them into another case can be tricky. On a new set up, gears that whine on acceleration generally have the pinion shaft set too shallow and noise on coast indicates the pinion is too deep. Also, these things were not designed for syn lubes but who am I to say anything since I have a Dana 80 full of STP :D Yeah that did make them much more quiet lol
 
Hemi Rebel said:
Sounds like a ring and pinion noise. You have it on acceleration or constant load and it goes away when you coast or take the load off. Check the fluid condition. Need to check back lash but that is a pain obviously.
Click to expand...


X2 with Hemi Rebel....
 
Hemi Rebel said:
Sounds like a ring and pinion noise. You have it on acceleration or constant load and it goes away when you coast or take the load off. Check the fluid condition. Need to check back lash but that is a pain obviously.
Click to expand...
Generally, if the fluid is so old that the gears started to whine, then they already have wear. Also, if the backlash is off enough to cause them to whine, resetting it won't help much if any.
 
^^^ Actually, I have had gear oil break down so badly in hard racing that it effected trannie operation; fresh gear oil fixed it all up. Probaly not the case here, but gear oil breakdown can occur without gear damage if caught quickly.

No drain plug is normal due to the infrequency of gear oil changes on live axles.

Dead whale smell? You need to spill some Ford friction modifier; that is a galactic-sized dead whale smell! LOL
 
Actually, we used to call the GM posi additive "whale oil". Got the impression that it had some in it, although that's probably not true.
 
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