When replacing my rear brake shoes a few weeks ago, I noticed when I spun the rear wheel (axle on jack stands), I could hear the gears meshing together in the rear diff. Should this be noticible or quiet. I'm getting a howling noise, most pronounced at 40 mph, but also at 65 mph diminished some. I posted this howling noise before on here and narrowed it down to tire noise, but now I'm thinking something else. Can't really tell if it's coming from front or rear. I had the pinion bearing replaced about 80k ago, but if I remember correctly it was more of a low rumble then. Thanks for any suggestions.
howling noise
- Thread starter sawguy
- Start date
Register to hide this ad
bandman659
New member
I think hearing the gears mesh is pretty normal when you turn the rear wheels while it's in the air.
Can you tell if the howling is coming from the front or rear? If you've had the pinion bearing replaced (relatively) recently, the diff has enough oil, and you don't have blown axle seals, I would look at wheel bearings.
I had the pinion bearing go south on mine, so I know that particular low grumble/howl. Instead of replacing the bearing, I got a used 3rd from someone nearby parting out a 4runner with fewer miles than mine on YotaTech.
Can you tell if the howling is coming from the front or rear? If you've had the pinion bearing replaced (relatively) recently, the diff has enough oil, and you don't have blown axle seals, I would look at wheel bearings.
I had the pinion bearing go south on mine, so I know that particular low grumble/howl. Instead of replacing the bearing, I got a used 3rd from someone nearby parting out a 4runner with fewer miles than mine on YotaTech.
I don't think it's a wheel bearing. Jacked up the front and both front wheels have zero play up and down and side to side. Also spun the wheel and no noise or vibration whatsoever. When slowing down it sounds like very agressive tire treads. Sometimes you can actually feel it in the floorpan with your foot. I had these tires put on 4000 miles ago and didn't hear any noise at all. ( Cooper ATP's from Discount Tire. ) I am due for a rotation soon so maybe I'll see if that makes a difference.
Ginneta
New member
I just replaced my rear diff (yes I did it) last summer. It's not a difficult task, BUT before you spend the money on the parts. Physically check the rear diff for any give. Once you remove it turn the top gear and make sure they are in sync with the bottom. Should not be a whole lot of play between the two. I bought my truck used and had the same issues. Once I got to about 35 or 40 it almost sounded like a stick shift in reverse. I tried the method of draining the rear diff fluid to check for metal but mine was old (looked like it hadnt been changed the whole 160k miles) it was too hard to tell. I scored a rear diff for $250 from my uncle. He tows vehicles after being wrecked, had 12K miles on it, physically counted the grear notches to make 100% sure the ratio was exact. total switch out took me about 3 hours with out any help.
nevada
Senior Member
and what about the rear wheel bearings?
what you are describing does sound like a bearing, now to just figure out which one.
can you post a pic of your tires? are they cupped at all?
No cupping on tires. If I was to guess, it's up front since I can feel it in my foot on the floorboard. But that's only when decelerating at about 15-20 mph.
When I replaced the rear brake shoes everything was dry as far as axle seals. No leaking from the rear diff. ( dry as a bone). Maybe I should get it up on a lift and run it. Thanks for all the suggestions so far.
When I replaced the rear brake shoes everything was dry as far as axle seals. No leaking from the rear diff. ( dry as a bone). Maybe I should get it up on a lift and run it. Thanks for all the suggestions so far.
If you were just spinning one tire, you were hearing the spider gears. They are going to be louder than the ring and pinion because of the type of gear that they are (straight bevel). If you put it back up on jackstands, put it in neutral and have someone spin the other tire at the same time, you can hear the difference (or if you have a locker).
nevada
Senior Member
FYI, a bearing can be bad, and making noise without any discernible movement.
1985taylor1925
Senior Member
howling noise huh? Maybe you have a werewolf living in your 4runner
StreetCreeper
New member
I see you have Cooper ATP tires. I have the same tires and while I have zero complaints about them (great tires with about 8-9k on them), I too have noticed some "howling" noise especially when taking long sloping turns around 40 mph or so. Kind of an occilating hum.
I just figured it was tire noise as well...although in the back of my mind I've always wondered if it was something more.
