What Causes "Howling" Rear Gears?

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pastortom1

pastortom1

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I know some of the things that can cause rearend gears to howl or sing in an annoying way, but I wanted to put this out there for you guys to comment on......

It's a common problem I've run into when restoring old Mopars, and was wondering if we could lay out some of the MOST COMMON causes for rearend noise........(OK comics......stick to the mechanical aspects please).

How about a little input as well on the effectiveness of additives (like the Mopar lube) on actually cutting down on some of the common noise from old or worn rears..........

I'd like to hear what you'se guys have to say in general from your experiences.
 
Good day Tom, I will be first :happy10: Pinion bearing wear has dun this to me years ago and it went away that day we replaced it.

Know we will hear from our tec's here, I would like to learn more


Good thread :happy10:
 
OK, a few things.

worn/ rough/ pitted bearings

worn/ rough/ pitted/ damaged ring and pinion

With original tapered axle bearings, if not adjusted correctly. Won't be long for this world

Metal touching metal. Remember that original spring hangers were rubber bushed. If you install "harder" modern heavy/ race/ "improved" bushings, this may well transmit more noise into the cabin

Various add--on traction devices. Any installed metal links can transmit more noise into the cabin This might even include a pinion snubber if it uses a minimal rubber.

"low" rears (higher numeric) spin faster and are generally more noisy

Don't forget tires---some tires are produce much more road noise than others
 
Make it howl, then let off the gas; if howl quites down- internal.
If it stays the same-tires, axle bearings, u joint.
 
Improperly set up gears can howl also.

Rarely does any additive help with howling. The only time I've seen the noise cut down is when thicker lube was installed and that was just a band-aid fix.
 
Most of the time I find that it is the seals that cause the problem.

Well at least the start of the problem, cuz once the seals start leaking then the oil goes by by then the gear wear out and make noise.

How often do you check your rear-end oil level ?
How grimy is your rearend ?
 
Wrong viscosity oil.
Someone before you or you yourself replaced the pinion or ring gear and not it's partner. Gears develope a wear in pattern over time and don't much like having one replaced and not the other. Bearings, lash and bearing preload, housing saddles are out of align to each other, some numskull used heat on the ring to carrier bolts to remove them causing a wobble. The hardness on the gear set is all wrong from new.
 
One more thing. Mismatched gears will do that too. Taking a used pinion and ring from different housings and using them together will howl as well,ene if properly installed and likely not last long.
 
......Pinion depth........its the biggest killer......ever checked a factory set of 391s?.......usually not even close........and how much backlash did they have.....usually .020-.030.........u just cant correct that............kim..........
 
SAW DUST! :D

Now that is technical....

I think you guys named just about every moving part connected to the rear...That really narroweded it down for him...lol.

Normally look to the carrier or pinion bearing. Biggest cause of a failed pinion bearing is the NUT backs off the yoke. which in turn makes the pinion loose changing the preload which prematurely wears the pinion bearings.

LOW fluid level will be the next biggest culprit of bearing failure.

Good luck on the search for your HOWL. :) Jim :thumbup:

If it is the GEARS that are HOWLING and NOT a bearing issue the gears are set -up wrong (meaning backlash could be wrong spec - too tight or too loose, pinion depth wrong too shallow or too deep.)
If they just started to howl ...they are warn out , tooth chipped off and has a shape edge lastly a old rear that was sitting for a long time a had rust build up on the face of the teeth and this will cause the howling too...rough surface.
 
Just about every part in a rear end has been listed here as a possibility.
I just took my car out tonight for the first time since swapping in an 8 1/4. It has 3:55 gears & a Trak Lok unit. I had a guy in town set it up for me that has been doing axles & transmissions for almost 50 years. He replaced every bearing, seal & race. He took the Trak Lok apart, inspected everything & reassembled it. Topped it all off with gear lube & sure grip additive. 2 different guys said that the ring & pinion looked fine. First trip down the road it sounded fine under acceleration but as soon as I took my foot off the gas it started to roar, howl, whine, whatever you want to call it.
My guy is telling me that it is the ring & pinion that are bad, he could hear it over the phone when I called him. Some research is pointing towards possibly being set up wrong.
Any advice? Where should I start? Second opinion maybe? Have I ruined it by driving it 2-3 miles? Any help is greatly appreciated. Funds have been drained this winter & spending $200 +/- for new gears & then more for set up again is not sounding good not to mention more than likely having to pull the rear end out to make everything easier. Thanks
 
If your running an Eaton Truetrac, they say don't take it apart and run straight mineral oil and no additives or synthetic, not sure if that's what you have or not.

You might want to check that fluid level again, I would.
 
If it howls under accel only or decel only the ring gear pinion depth is WRONG. PERIOD.
 
Strokerscamp is correct. And also the more you drive it in the wrong set-up the worse it will get and you will NEVER get it to go away.

The combination of the pinion depth being to depth or too shallow with wrong backlash will make this a noisey rear.

SO very slight whine could be present on a normal set-up or one that is close but not absolutely perfect...BUT a heavy howl is just plan wrong.

We would need to see a pattern of the gear with marking compound to get some I dea as to how far off it is. Jim

PM me and I can send you marking compound and if you are willing to do some labor will check that pattern on line ...Ok? Jim

330 659 7117
J D Race
 
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