[curls]

Hi - I'm new to my Subaru. I was lurking on this site the other day, but didn't expect to be back with an emergency so fast!

It starts & drives & brakes fine, but loud rapid thump, thump thump from rear. Any ideas? 1998 Outback 113k automatic

Reduces when on accelerator!

- I'm suspecting brakes, wheels, or something back underneath (but please don't hold me to this!)
- back of car is visibly shaking in rear view mirror
- faster with more speed. A little louder too
- vibration eventually started coming through floor pan
- Sounds much more distinct at very low speeds

At first driving was fine. Right before getting home, POSSIBLY seemed worse to left than right. Possibly less secure on road, especially after bumps (or it was my nerves giving out.)

Problem started a while ago (weeks at least), but was mild enough I thought it was these cars. Also it was intermittent, so I thought maybe the road I was on.

I'm told, this car has a history of scraping noise from back brakes that was never fully fixed. May have been a loose emergency brake. Maybe caliper. It went on for years & didn't effect driving or braking.

Any help would be great! Thanks!

 

[Boxxerace]

Sounds like a tire issue off of first description.

Other possibilities:
- Rear driveshaft (check for tightness - grab a 12mm wrench and check all four bolts!)
- Loose wheel - not joking. Torque them to 65 ft lbs!
- Crap caught in wheel?

I highly doubt the brakes in this case unless the vibration increases greatly when you brake.

Check these things and get back to us.

 

[curls]

On checking... what I see...

I don't think it's tires. They look fine, & were fine not long ago. Nothing done to them to change them or the torquing. Regularly rotated, etc (I'd have to look up when but it's more vibration & louder than tire thumping, is my sense.) If over toqured could it take 4 months to get this bad?

I'll look in the day. Unfortunately it's just me, so I can't have someone watch to see if there's any wiggle. If they are loose - that would make sense with this noise. But would it get less when pressing accelerator? It distinctly does.

It's vibrating the rear visibly through rear mirror, so it's not something caught in tires & it's dark but didn't see anything with flashlight.

Rear drive shaft? What would make that go loose? I'll look in the morning, but wouldn't know what I'm looking at. Would looseness possibly make a loud rapid thump?

Braking - it's not changing at all with braking.

Thanks!

 

[Boxxerace]

On checking... what I see...

I don't think it's tires. They look fine, & were fine not long ago. Nothing done to them to change them or the torquing. Regularly rotated, etc (I'd have to look up when but it's more vibration & louder than tire thumping, is my sense.) If over toqured could it take 4 months to get this bad?

It's vibrating the rear visibly through rear mirror, so it's not something caught in tires & it's dark but didn't see anything with flashlight.

Rear drive shaft? What would make that go loose? I'll look in the morning, but wouldn't know what I'm looking at. Would looseness possibly make a loud rapid thump?

Thanks!

You bet it could. I'm guessing you have another issue though. Consider rotating the wheels and see if the problem moves up front (after a thorough inspection of the tires.). Please go check your lug nut torque, I'm not kidding when I've seen wheels fall off.

There was this one time when my brothers wheel feel off in the middle of a busy street in Downtown Seattle. Heh, I had to go play traffic blocker with my truck while we re-attached the wheel to the two lugs not messed up. - Learn from this and avoid the hard way please!

That said, your tire could be out of round, it could just be a missing wheel weight that got flung off or something else. You don't have snow in your area right now do you?

P.S. I meant to indicate under-torquing, not over.

 

[curls]

That said, your tire could be out of round, it could just be a missing wheel weight that got flung off or something else. You don't have snow in your area right now do you?

Definitely I'll check into the tires in the morning. I don't have a torque wrench with me, so I'll have to bring it into a shop. Also would pressing accelerator reduce it?

It's been snowing & could be missing a weight, but this isn't a little shake or thump. It's distinctive, loud, rear is visibly shaking. A balance shake is nothing compared to this. (The ones I've ever had.)

The only recent work was:
- oil change a few weeks ago.
- tightened emergency brake cable 3 months ago.

Sounds like you had a fun day! That had to be something else.

 

[Boxxerace]

Any chance you went drifting in some deep snow and have snow and ice buildup in the wheel?

I have had wicked wheel wobble after a good snow drifting session.

 

[curls]

Any chance you went drifting in some deep snow and have snow and ice buildup in the wheel?

I have had wicked wheel wobble after a good snow drifting session.

Good ideas! It's been melting all day. And this started a while ago on days without snow.

I wish "thumping" was easier to search for. It brings up too many irrelevant results.

Why do you think it's not the drive shaft? (Not that I mind that not being it :29

 

[curls]

what parts are these - that are falling off?

Your focus on tire was on the right track!

Two lugs are left. Parts going to the tire are falling off. Any idea what parts these are? I'm waiting to hear back from an auto shop.

 

[Boxxerace]

It is hard to see what is loose in the photos but I see your rear swaybar, links, control arms amd the wheel.

Details on what you see is loose?

 

[curls]

It is hard to see what is loose in the photos but I see your rear swaybar, links, control arms amd the wheel.

Details on what you see is loose?

Last photo is the clearest. When I click on them, they're much bigger & it's easier to see. That triangular piece with the bolts is supposed to be at mid-tire level, not hanging down. The other side it's at middle of the tire.

 

[curls]

I'm going to attach more, hopefully one will be clear. (But I think only one is new.)

This first one shows that somethings sheared off.

I'm calling it triangular, but it's more that it's flat hunk, verse the rest that are pipes.

 

[curls]

I went out again, I looking more closely -- I think everything may be attached. It's just that the lug nuts are sworn off (3) and so they must have been put on too loosely.

What has to be replaced so nuts exist again? Is it expensive?

I'm wondering if I can drive the 3 miles into town or will need the $80 towing too. Sigh.

Thanks! You've been right on target.

 

[147_Grain]

Tire / wheel is likely out of balance. Check lugnuts, rocks or debris in tires, or the weights on the rim have fallen off.

 

[curls]

Thanks again. I've got towing coming. Hopefully it will just be the lugs. At most lugs & wheel.

One shop told me this is something Subarus do (lugs come loose). This side rear brakes were repaired in late Oct. So that was probably the start. But it's too long ago for it to be their mistake. Just natural to Subaru. That's my best guess at the moment.

 

[curls]

Tire / wheel is likely out of balance. Check lugnuts, rocks or debris in tires, or the weights on the rim have fallen off.

Grain - thanks! Now that it's daylight, I looked. 3 Lugs are sheared off.

It was much too big a noise & vibration for out of balance, in my experience of out of balances. Got worse suddenly - probably another lug fell off.

I was very lucky!

 

[Boxxerace]

Grain - thanks! Now that it's daylight, I looked. 3 Lugs are sheared off.

It was much too big a noise & vibration for out of balance, in my experience of out of balances. Got worse suddenly - probably another lug fell off.

I was very lucky!

Ah hah! The problem was found! Now, if you've always had a Subaru dealer or wheel / tire shop take the wheels off and you never have yourself, you may be in a situation where they can pay for your replacement parts.

In your case, you probably need a couple of parts replaced:
1. Unit bearing hub (which the lugs are attached too).
2. New lug nuts
3. Wheel inspected or replaced if damaged.
4. Possibly a new brake rotor if warped at all.
5. All the joints should be checked for damage and wear on the corner that had the loose wheel.

I'm glad you persisted and found the problem the easier way rather than at 75mph. Keep us posted on your repair!

 

[cardoc]

It looks like the sway bar may be close enough to the axle to be hitting on the boot.

Can you edit the photo and repost it with a circle or something pointing out the triangular part you are referring to?

 

[curls]

Ah hah! The problem was found! Now, if you've always had a Subaru dealer or wheel / tire shop take the wheels off and you never have yourself, you may be in a situation where they can pay for your replacement parts.

In your case, you probably need a couple of parts replaced:
1. Unit bearing hub (which the lugs are attached too).
2. New lug nuts
3. Wheel inspected or replaced if damaged.
4. Possibly a new brake rotor if warped at all.
5. All the joints should be checked for damage and wear on the corner that had the loose wheel.

I'm glad you persisted and found the problem the easier way rather than at 75mph. Keep us posted on your repair!

I have the car back - lugs replaced & tire is tight & fine according to the mechanic! Cost was $225 including the $80 tow. One hole is a little misshapen, but he says it's all tight enough & doesn't need the wheel replaced.

I need to have the joints checked, but he didn't say anything at this time.

This was't from a bad rotor situation in this case. It was the only tire removed 3 months ago for a repair. It wasn't put on properly & took time to loosen. Sigh. My dad had that repair done, & he's going to be none to thrilled...

The mechanic said often people will drive it until the tire goes flying by them, so I really did luck out that I stopped before that point!

Thank you again to everyone!!!! :17::29: I'm sorry my photos weren't very clear -- it looks so much better with my eyes, than through that camera!

Thanks especially ointing out the tire possiblity made it quick & easy for me to spot the problem once I looked... at the tire of course.

So yay! I'll be able to make my long trip tomorrow. It's a strange sense to think of the wheels falling off a car. Literally.

 

[Boxxerace]

You are welcome.

Cheers!