Fix a Rear End Differential Problem – Rear End Making Noise?

So right around 40 miles an hour, lightly
accelerating, I can hear a howling noise that’s coming from the back of the vehicle. When I let off the gas, the noise goes away. When I step on the gas, it comes back. I can actually feather the gas pedal and make
the noise come back and forth. It’s pretty bad. What’s up, guys? I’m Andy from 1A Auto. In this video, I’m going to give you some
tips on how to diagnose a rear differential. If you need any parts for your vehicle, click
the link in the description and head over to 1AAuto.com. All right when you’re diagnosing the rear
end noise that you have, if it’s a noise that’s constant all the time, what you can do is
you can put the vehicle up on a lift and have someone driving. Be careful when you’re doing this. You want to stay away from this area because
this is going to spin real fast with the driveshaft and the yoke and stuff. But you can take a stethoscope and you can
check right here in this area. If it’s a real loud in this area, you’re going
to have a problem with your pinion bearing. If it’s real loud on the side, over here and
over here on this side, it’s probably your carrier bearings, and then also if you’re
only hearing it when you’re accelerating versus decelerating or vice versa. It’s probably your ring and pinion. Another thing you can check with is by using
chassis ears. You can actually attach chassis ears right
here and right here and over here. What chassis ears are are basically little
microphones that are attached to wires. Some of them are wireless and then you can
drive the vehicle around and listen to where the sounds are and see which sound is closer
to the actual noise you’re looking for. Another possibility is the bearings over here. Those could be making noise. It’s not as common to have these bearings
go bad. But it does happen. But generally, it’s the carrier bearings or
the ring and pinion bearings. I set up this dial indicator to check the
backlash before I take this completely apart. This isn’t normally what you would do. But my assumption with this rear end is it
was set up wrong and that’s why I’m getting a noise. So I just wanted to baseline it before I take
it all apart, and see how the backlash is. What the backlash is, is basically the play
between this gear and the pinion gear. There’ll be a little slot and they’re supposed
to be. They’re supposed to be about 8 to 12 thousandths
of backlash. Now what I do is I’m going to hold the pinion
with one hand, and then I’m going to just rotate the ring gear back and forth and see
how much backlash I have. And right there, I have almost 15 thousandths
of backlash, which is way too much. Now they have different setups for a dial
indicator you can use. They have some that have a magnet. That would be more ideal. This situation will work for us. It’s the best I have available right now. So I want to check the pattern on this gear
before I take it out. So I’m going to use some gear marking compound
and an acid brush. Just mark this gear. We’re going to mark both sides. What we’re doing is we’re going to try to
see where the pinion is actually riding on the ring gear because it needs to be in a
certain location. Otherwise, you’re going to get a noise or
it’s going to wear funny. So I’m going to take a pry bar, and I want
to pry in here. And I’m just going to put a little tension
on the ring gear so that it pushes down a little bit and spreads the gear marking compound. Once it goes that way, then I’m going to put
the pry bar on the bottom and I’m going to spin the pinion in the other direction. As you can see on this side, that’s where
the pattern is pushing on the ring gear from the pinion. The other side, it looks like it’s pushing
right there. So when we were checking our pattern in this
ring and pinion when it was still in the vehicle, this one side, which happens to be the coast
side, the pattern was actually pretty good. It looked just like this. It was right in the middle. It didn’t look too deep. It didn’t look too far forward or too far
back. But when we were checking the drive side which
is when we were accelerating, the pattern was way down here and way here. So there wasn’t a lot of contact touching
the ring gear, which isn’t good and that’s why we were getting a noise. So it should be right there in the middle,
a nice contact and we were getting it way on the outer edges and a thin line contact,
which is causing our noise and what we found is it’s probably due to lack of changing the
fluid and there was a seal that was leaking and it was low. So when the pinion was riding up against here,
it’s actually worn down. The ring and pinion are worn. So it’s not making good contact there. We replaced the ring and pinion, all the bearings,
and put in the correct shim. Okay, so we set this up again and put our
gauge on and we’ll just check in the backlash and we have about eight thousandths, which
is awesome. That’s exactly where we want to be. You don’t want to be too high. You want to be over 12 thousandths and you
don’t want to be much under seven thousandths. So eight thousandths is awesome. So we’re going to send it like that. In case you don’t understand what I’m talking
about when I’m talking about backlash and this measurement right here, what it is is
the ring gear and the pinion. There’s an air gap between the two and if
that air gap is too tight, then when all these components heat up, it’s going to bind up
and cause a lot of wear and then if the air gap is too loose, then you’re going to get
clunking while you’re accelerating and decelerating. So that is why it’s important to have this
adjustment adjusted properly. So we have the backlash set up. So we’re good there. So now we want to check the pattern. So I’m going to take some gear marking compound
and a small brush. Just mark this up. I’m going to mark it up on both sides of the
ring gear. Okay, now we’re going to check the pattern. I’m going to have a friend turn the pinion
while I use the pry bar, and I’m going to put a little pressure on it. And what the pressure is doing is making it
so the pattern’s going to spread a little bit better. Otherwise, if you just do it freewheeling,
then it’s going to have as good of a pattern. All right, you can stop. Now we’re going to go the other direction. So now I’m going to pry from the top. All right, go ahead. First, we’re going to look at this side. Now this area right here is where the pinion
was contacting the ring gear. Now this is the driver side. So when you’re accelerating and going forward,
this is where it is pushing on the ring gear. Now ideally, I would have rather it been closer
to the middle. But that actually looks pretty good where
it is. It’s a nice pattern. It’s nice contact. It’s oval. It’s not coming off the edge, which it looks
really good and then if I looked at the coast side. There’s a nice oval on this side as well and
it’s pretty close to where I want it to be. Ideal would have been closer to the middle. But that looks pretty good. All right, so we’re done. We finished our repair. We replaced the ring gear and we replaced
the bearings while we were in there too and it’s probably kind of hard to hear on the
camera. But the rear differential is nice and quiet. So we actually fixed our problem and we’re
good to go. Thanks for watching. Visit 1aauto.com, your place for DIY auto
repairs, for great parts, great service and more content.

Bernard Jenkins

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