Clanking noise/rumbling coming from rear?

[Doobaru]

I recently bought a Subaru, and on the way home from driving it, I felt an odd wobble coming from what I thought was the back right wheel. It shook the whole rear of the car, but eventually tapered off. The wobble returned on higher speeds (65-75mph). I thought they were just the junk tires on them, but was diagnosing some other things at the shop and am lead to believe it's a bad drive shaft going into the rear differential.

 

The car is an automatic, and I noticed it also kicks when shifting as it gets up to speed, especially up hills. I jacked the car up on all fours and turned it on, put it in drive and tried to replicate the sound. It's like a clanking sound.

The one forum I found on this type of stuff was this: http://www.ultimatesubaru.org/forum/topic/128947-loud-banging-noise-felt-vibration-from-tunnel-area/ but before I try all of their troubleshooting I was going to see if anyone could pick out the sound first.
 

Is the clanking sound happening because the car is moving with no force against the tranny, and it's in a sense, looser? Or is it the U-Joints making the noise because they're worn?

Any help would be appreciated, I like this forum a lot and could see myself learning a lot from you guys, any help is appreciated!

Thanks,

Robert
 

Suby.wmv

[Doobaru]

Does any one have any input? I uploaded the footage to YouTube because I thought UltimateSubaru would emb it in the post, so here it is in a more accessible format:

Play close attention to the gravel like sound right before the wheels turn.

I had one more question, could the driveshaft be fully inspected without taking off the exhaust, or is there parts in between the yokes that are under the exhaust piping?

-Robert

[Fairtax4me]

Probably gonna be a u-joint.

They're fairly easy to check and if one is bad enough to make a clank/clunk sound it will be pretty obvious.

 

The exhaust isn't in the way too much but the front half is above the large heat sheild bolted under the center of the car. Its tricky to remove with the exhaust still on, but doable. Slide the heat sheild out of the way so you can inspect all 3 u-joints and the carrier bearing and mount.

[nipper]

A bad U-Joint it my bet. 

[Doobaru]

Sooberoo,

I took your advice tonight and got the heat shield out of the way. Very simple 6-bolt removal! Glad it worked out. So far I have diagnosed a bad carrier bearing, and from what schematics I've looked at and posts I've read, I know that the U-joints aren't serviceable, but does that mean the carrier bearings aren't as well? I haven't found any in auto parts catalog.

2 More Issues I've noticed and could use advice on:

1) Tiny pulses in break pedal while breaking under normal circumstances (While I was doing diagnoses in the shop, the car was raised and put into gear with no load on the wheels, and as I tried to break to put it back in Park, the ABS kicked in and was tripped out, could I have broken/blown something doing this?

 

2) Car pushes very strongly while in D and at a stop light (like I'm brake boosting it or something for all you turbo folks), and sometimes does a bit of a shudder?

It might seem like I'm a hypochondriac about my car, but I'm just paranoid about it getting me through Ski season, so I wanna get all the kinks worked out before the temps go way down,

Thanks for all the help guys!


 

[Doobaru]

Correction: I did find this carrier bearing from Fort Wayne Clutch

http://www.fortwayneclutch.com/index.php/driveshaft-parts/carrier-support-bearings/light-duty-car-truck/foreign/subaru/carrier-bearing-1996-1999-subaru-legacy-outback-rear-driveshaft-center-support-propshaft-carrier-bearing-assembly-sku-9980-45.html

It doesn't specify if it can be used with a 2.2L automatic though.

[Fairtax4me]

Did you spin the bearing by hand? Is it rough/sandy sounding? Is the rubber cushion torn? Did you see the carrier move and make the noise when putting the car in gear?

Some movement in the rubber cushion is normal and is not indicative of a problem.

 

The carrier can be replaced but it has to be pressed on.

 

 

Free-wheeling freaks the ABS out because it sees drastically different readings from the wheel speed sensors. With all 4 wheels off the ground the ABS will pulse when you hit the brake because one wheel will always stop sooner than the others.

Despite being AWD, the wheels will never free-wheel at the same speed due to differences in wear and drag from the brakes, axle, bearings associated with that wheel.

 

Pulling hard at a stop, sounds like it may be idling too high.

Idle speed should be around 750 rpm. Any higher and it will try to pull itself away like an old Buick.

[Doobaru]

Thanks for the advice guys. I found a serviceable driveshaft / propeller shaft on RockAuto for $385 after shipping. It was made by Dorman (who I'm not a big fan of), but the quality looked good. Greasable bearings and U-Joints that can be depressed and repressed (though I do think that the life of the driveshaft will out live the car, so I think Dorman will be just fine). It slipped in just fine.

I think that "free wheeling" the Subaru and getting that noise in the video above might be common. I was watching an EricTheCarGuy video and he did an Automatic Transmission Fluid/Filter change, and when he free wheeled his 1997 Legacy on jack stands, it did the same thing. And after I replaced the drive shaft the noise was still there, no where near as clanky and pronounced.

Here are some notes on this procedure if anyone finds this post years down the road and is bit lost. 

Disconnect your battery's negative cable.

After lifting the car -- Start with the rear metal bracket, 6 14mm bolts, to expose the rear U-Joints. Be sure to make an alignment mark where the flange meets the rear diff terminal so you can match up the 4-hole square plate on the new one exactly. Its a similar concept to camber plates if you've ever done a lower control arm.

The next step in my process, was I dropped the exhaust. Two 12mm screws into two 12mm nuts. It was too tight with the heat shields for me to get a socket in there, so I used two 12mm wrenches. . Mine were pretty badly seized, so I used a propane blow torch to heat the nuts up until they were orange, and they came off with a nice and steady torque applied to them. If you chose this method, do not place yourself directly underneath the bolts as they fall, do it beside where they'll fall. There was a 14mm bolt that threaded into a bracket into the exhaust piping itself, take out the bolt.  The bracket attached to two 12mm screws going into the tranny block -- if you're having a hard time getting your exhaust unstuck -- loosen the two top bolts so the bracket can unhook itself. Tapping the flange with a mallet helps too.

 

Dropping the exhaust -- removing it by the hangers -- After separating it from the flange, I took the exhaust off from the muffler forward. I did this because the hangers were very rigid and hard to slip off, so the easiest ones to get to were the two on the sides of the muffler. I dropped those first which allowed the exhaust to sink so it stretched the other ones down so they could slip off more easily.

With the exhaust sitting a bit lower now, take advantage of this space to remove the O2 sensor. It's much easier with the exhaust slightly lowered, because you're not cramming an O2 socket in there between the heat shield and that sharp metal. After the O2 Sensor is out of the way, take of the rest of the hangers. Once that is done, take off the heat shield, four 12mm bolts and two 12mm nuts.

Get the exhaust and heat shield  out of the way and set up camp near the rear diff. This process is going to be similar to exhaust, except the shaft rotates so you'll have to plan your screw/nut removal more cautiously. I also had to torch these as they were siezed. IF YOU CHOSE TO DO THIS, BE EXTREMELY CAREFUL, AS WHAT SITS AROUND YOU IS SEVERAL GALLONS OF GASOLINE. BE VERY CAREFUL WHERE YOU AIM YOUR TORCH, IF YOU TRIED PB BLASTER BEFORE AND SURRENDER TO THE TORCH METHOD -- BE SURE TO WAIT! Try to keep the torch focused on the nuts. Aim towards the front of the car, not up into the cabin or back towards the diff, as that can possibly ruin seals.

When the nuts were glowing red, I took the open end of a 12mm, and stuck it onto the hex head screw I was working on. Spun the driveshaft so it was wedged into the frame, then took the closed end of another twelve and loosened the nuts. Be careful doing this too, the wrenches heat up quick, it isn't a bad idea to have water laying around in a shallow tray to cool them off, just be sure to oil them afterwards.

Remove the carrier bearing -- two 14mm bolts. The easiest part of the process, and perhaps the most satisfying. Once it's removed you can slide the driveshaft back.

Line up the driveshaft next to the new one, turn it until it's identical on the floor. All U-Joints matching, Take note of the front splines -- how there's a section in the middle where there aren't any splines. Try to feel for that splice when you put it back in.

Slide it back in, then do the carrier bearing, holding the back part of the drive shaft up with your elbow. My carrier bearing bolts were way harder to thread back in, it's almost as if they're angled outwards or something. Be patient and don't cross thread.

 

Put some anti seize on the nuts that are mating the driveshaft, and finger thread them back in first, in the same order you'd put a 4-lug rim back on the hub. Be sure to tighten equally.

Re-assemble everything in a manner that best suits your mood at the time.


 

 

 

 

 

 

 

 

Edited October 11, 2015 by Doobaru

[Fairtax4me]

Really don't need to drop the exhaust to do this. That's just a lot of extra work.

Remove the bolts on the heat sheild and side it out of the way, then you can remove the bolts for the carrier bearing holder and just slide the driveshaft shaft toward the rear of the car and there is enough room to drop the carrier down between the exhaust pipe and the tunnel above. Keep in mind, the exhaust is moveable (its on rubber hangers), so if there isn't quite enough space you can just shove it or use a pry-bar to pull the pipe off the the side enough to get the carrier out.