Growling/Clunking noise in rear while accelerating hard in 1st or 2nd ??

Almost 1000 posts and no solution. I'm amazed that we have people that can swap the 2.5L for a small block V8 but we can't solve a noise issue.

 

Anyway.... I have information to add to the discussion.

 

When I have 3 or more people in my car, I have the clunking noise regardless of how fast I take off. It's really bad when I start off on a hill. The extra weight really adds stress to the problem. The noise duration also increases as I pick up speed.

 

clunk.............clunk..........clunk.....clunk....clunk..clunkclunkclunkclunk

 

That is pretty much 0-35mph^^

FWIW, my LGT had two reasons for these "noises," one was the common one that thunks. But there was one that SNAPPED... that one turned out to be a CV joint that had fractured half-way through. It was revealed during a 0-60 one day when it finalliy finished breaking and began flopping uselessly.

 

Most people probably don't break their CV joints, however, and have noises from the suspension due to the common reasons... RUBBER SUSPENSION PARTS. Instead of spending a lifetime looking for The Culprit, people should spend a little time and money upgrading their rubber suspension components... which are many. The older the car and the more it has been used, the more the NOISE will evidence itself... because the rubber parts are degraded. You are not going to find a single culprit. ALL the rubber suspension components contribute to the issue, just some more than others.

 

Ben Franklin said, "light a candle, instead of cursing the darkness." Get under your cars, and work. Your car will be in the crusher before you find any magic solutions in a forum thread.

Edited January 3, 2013 by SeeeeeYa

Hmmm... CV joint? I've had the noise in my 05 wagon for the past couple years. A couple shops have looked at it but don't see any issues. I thought it was just a problem with my car until I saw this thread a couple days ago. My noise sounds a lot like a CV joint going out on a front wheel drive car only it comes from the right rear on my wagon. Wonder if it's a CV joint waiting for an opportunity to break or a rear axle CV joint design issue that surfaces under heavy loads and rapid acceleration when the back end squats under acceleration.

Add me to the list.. (didn't have time to read the posts, time to go home, sorry). And didn't find this before (I've been on here for 5 years :-O )

 

I've mostly noticed it on one right-turn onramp that's uphill on the way home from work. If I gun it there before straightening out, it clunks. And more recently (been colder in the Bay Area), when car is cold, really gunning it (getting cut off in traffic) has done it a few times when going straight.

 

It definitely sounds like it's coming from the driver's side at the back. I've always written it off as the exhaust banging around (so I wouldn't worry myself to death).

 

'05 LGT 5EAT, stage 2/3 (bnr16g, injectors, fuel, gutted pipes), Cobb sways on soft, Koni shocks around medium, stock springs.

Good lord. I read for the first 15 pages and thought maybe if I just skipped to the end I can read about the solution sooner... nope! People have been having this noise happen for years and nobody has managed to isolate the issue?

 

That's absolutely wild!

Is this common on wrx or other subarus?

no

Given the different rear geometry in the Legacy platform, this must have something to do with the trailing arm setup. I think many are having this issue once lowered, and rear adjustable camber arms are installed.

Wow, add one more with this issue. I've noticed lately a rapid clunk sound coming from the rear of the car. Only when accelerating hard from a stop or low speeds. Y pipe hitting RSB? Doubt it but just a guess.

Changed out my rear lower links and thought that would fix it, but nope. Actually sounds like spring-squirm under hard left or right acceleration, but there's definitely a clunk....

sub just in case a solution occurs.

been hearing it whenever it drops below freezing

FWIW, I no longer have any trace of the noise, no matter how cold, and I put down a lot of more power than when I had the problem (I had the noise with VF40 @ stage1, now I am stage 3 with 300+ whp). I tightened my entire setup when I went with 6MT swap:

 

1. Group-N engine mounts

2. Group-N tranny mount

3. Group-N rear diff bushings (all four, including diff crossmember and subframe)

4. SpecB trailing arms and upper lateral links

5. AVO rear endlinks

 

One or more of these solved the problem, who knows which contributed the most. I remember we were speculating it was the trailing arms with the SpecB bushings.

 

I know rear lower lateral links do not matter (or not much), since I have had the JDM STI ones with spherical bushings for a very long time, and still had the noise issue.

FWIW, I no longer have any trace of the noise, no matter how cold, and I put down a lot of more power than when I had the problem (I had the noise with VF40 @ stage1, now I am stage 3 with 300+ whp). I tightened my entire setup when I went with 6MT swap:

 

1. Group-N engine mounts

2. Group-N tranny mount

3. Group-N rear diff bushings (all four, including diff crossmember and subframe)

4. SpecB trailing arms and upper lateral links

5. AVO rear endlinks

 

One or more of these solved the problem, who knows which contributed the most. I remember we were speculating it was the trailing arms with the SpecB bushings.

 

I know rear lower lateral links do not matter (or not much), since I have had the JDM STI ones with spherical bushings for a very long time, and still had the noise issue.

 

Great to hear you solved it! As I'm sure you remember, I solved mine and outlined the fix five/six years ago. Got a lot of flack saying I was mistaken... LOL. The thread has since gone on for years with people still asking for a solution. We will see if it ends now.

 

I still miss my LGT. Her picture hangs above my desk, mid-turn on the Dragon. It is good to see you're still caring for yours in the best of ways, as always.

Solved it 5 years ago myself but I don't remember updating this thread...

 

And, yep, with all the work and money I put into the car(s), I can't see myself parting with them. Besides, there aren't any worthy replacements anyway. I could add to the stable, though. Thinking about C7...

 

Edit: I did update it few years back... Oh, well.

Edited December 26, 2013 by unclemat

Solved it 5 years ago myself but I don't remember updating this thread...

 

And, yep, with all the work and money I put into the car(s), I can't see myself parting with them. Besides, there aren't any worthy replacements anyway. I could add to the stable, though. Thinking about C7...

 

Edit: I did update it few years back... Oh, well.

 

I thought you had. But people think it's something addressable with a kit, not the comprehensive elimination of drivetrain compliance. The thread likely won't end here, your fix is too expensive and mine is too back-yard. Anyone serious can find it all in the thread's pages.

 

I agree, the '05 LGTs have an elementally artful, timeless elegance that doesn't come around very often. With the mechanical upgrades you've done it's irreplaceable. You have an enviable car(?).

I thought you had. But people think it's something addressable with a kit, not the comprehensive elimination of drivetrain compliance. The thread likely won't end here, your fix is too expensive and mine is too back-yard. Anyone serious can find it all in the thread's pages.

 

I just went and read most of the pages (over 2 days), and my head's still spinning a little. It definitely seems like it requires the replacement of 2-5 different bushing sets/mounts (which you self-fabricated), and even then, it only gets progressively better with each thing replaced.

 

This makes it hard to "plan" what to replace, other than "everything", and as you say "everything" is too expensive for most people.

 

I live in NorCal, and yes, with a somewhat colder winter, I notice it more. And, as has been mentioned over and over, it's easier to reproduce when turning (especially a right-hand turn for me - I've almost never had it in an left-hand turn), and with passengers in the car. But, even now that it's a little worse than 2 or 3 years ago (although basically same drivetrain/suspension setup), it's happening a little more. Suspension mods: Koni springs, Cobb sways front and back, WL LCA bushings, steering rack bushings and upgraded endlinks (endlinks made no difference).

 

The big question I have: how dangerous is it? Are we wearing out part of the drivetrain each time this happens, or is it just something that sounds horrible, but isn't really going to matter as far as overall wear (other than maybe tires)?

 

Lately, I've had a burning oil/grease smell that I haven't had time to fully track down (right after the major coolant leak in this car AND our other one, all within a month of each other). Thought it might be the passenger-side front CV boot again (had it done 3-4 years ago), but after reading this thread I'm wondering if maybe the U-joint grease is leaking/burning??

 

Ahhh.. Ignorance really is bliss

I just went and read most of the pages (over 2 days), and my head's still spinning a little. It definitely seems like it requires the replacement of 2-5 different bushing sets/mounts (which you self-fabricated), and even then, it only gets progressively better with each thing replaced.

 

This makes it hard to "plan" what to replace, other than "everything", and as you say "everything" is too expensive for most people.

 

I live in NorCal, and yes, with a somewhat colder winter, I notice it more. And, as has been mentioned over and over, it's easier to reproduce when turning (especially a right-hand turn for me - I've almost never had it in an left-hand turn), and with passengers in the car. But, even now that it's a little worse than 2 or 3 years ago (although basically same drivetrain/suspension setup), it's happening a little more. Suspension mods: Koni springs, Cobb sways front and back, WL LCA bushings, steering rack bushings and upgraded endlinks (endlinks made no difference).

 

The big question I have: how dangerous is it? Are we wearing out part of the drivetrain each time this happens, or is it just something that sounds horrible, but isn't really going to matter as far as overall wear (other than maybe tires)?

 

Lately, I've had a burning oil/grease smell that I haven't had time to fully track down (right after the major coolant leak in this car AND our other one, all within a month of each other). Thought it might be the passenger-side front CV boot again (had it done 3-4 years ago), but after reading this thread I'm wondering if maybe the U-joint grease is leaking/burning??

 

Ahhh.. Ignorance really is bliss

 

Yes, it can be dangerous... although others have, not too many Subies have wrecked from it but it is dangerous to your car's parts.

 

Your reading must have revealed that my car suffered a number of failures in the suspension and drivetrain. I'm fairly sure the infamous "noise" broke the diff and axel. The tranny is a different story. As you note, your car makes the noise now more than it once did, that's because the underlying little buggers responsible have become softer with age and use.

 

And, yes, to fix the noise you have to address more than one or two things. That's because more than one or two things are involved. To get a better idea of what the "noise" is and how to work toward its elimination look at what has worked for those who've been successful in this thread.

 

Researching the root cause, wheel hop, will further explain. Here is a start: http://www.mc2racing.com/tech/20061012a/

Yes, it can be dangerous... although others have, not too many Subies have wrecked from it but it is dangerous to your car's parts.

 

Your reading must have revealed that my car suffered a number of failures in the suspension and drivetrain. I'm fairly sure the infamous "noise" broke the diff and axel. The tranny is a different story. As you note, your car makes the noise now more than it once did, that's because the underlying little buggers responsible have become softer with age and use.

 

And, yes, to fix the noise you have to address more than one or two things. That's because more than one or two things are involved. To get a better idea of what the "noise" is and how to work toward its elimination look at what has worked for those who've been successful in this thread.

 

Researching the root cause, wheel hop, will further explain. Here is a start: http://www.mc2racing.com/tech/20061012a/

 

(first, sorry for the long post)

 

Thanks for that link - I read that page, and it explained it quite clearly. So, it says to check shocks too. I have Konis (around 50k miles ago), and I think they are still working, although the driver's rear has been bottoming out more than before when loaded, going over speedbumps (i.e. not a common situation, but it didn't use to bottom out then either). But, AFAIK, that's more springs than shocks.. And the clunking is definitely driver's side rear - could there be something else that has worn out? I haven't seen any major leak from the shocks, and the "stand on bumper" test seems fine - I have them set quite firm, and in general, they seem ok too. I'll be doing the rear brakes soon, so I'll be "in the area" - anything to look for? Not very good at telling if a shock is worn or not..

 

Looking at unclemat's list, I've already done rear endlinks (not to address this problem, but at least that's off the list).

 

Could I expect the problem to "get significantly better" (maybe not go away entirely, but get a lot better), if I told the shop to

-take off the rear trailing arms

-is there a rear frame piece holding the trailing arms? Take that off too?

-replace all bushings involved with OEM (or upgraded, if not too much $$)

 

How much work is involved in that (removing the rear trailing arms/rear frame piece)? Could I do that on a Saturday, take it to a shop to press out/in the bushings, and re-install the next Saturday? Do I just have to support the rear axles/diff? Or do I have to totally disassemble the rear axles/diff as well?

 

I'll also have to look at replacing the exhaust hangers with stronger ones - is there a good source for decent exhaust hangers I could try?

 

Again, sorry for all the rambling..

In my car this same noise is caused by bad u-joints in the driveshaft, check them people I've replaced a lot of driveshafts already

All on your Subaru(s)? U-joints aren't replaceable. Whole propeller shaft or send it out to a shop for whole shaft refurbishment. Particularly onerous that the center bearing is also part of the shaft.

^^SBT is correct about the joints being an un replaceable part of the oem shaft. a few companies make a shaft that's repairable like it should be..Dorman comes to mind

have you done some research into the topic? Or possibly just removing the turbo and going nat aspirated? That is a fairly hot topic now.

This has to be the longest one-topic thread in history. I got my wife's 2005 Outback XT back from the dealer today. Symptoms were strong growl/vibration when accelerating, and constant above about 50 mph. At about 70 mph, the growl reduced when backing completely off the pedal. The drive shaft assembly was replaced today (part #27111AG16A, since it can't be repaired) and problem solved. Done.

^ Back from the dead!

 

Also an update from me, my growling went away after I replaced my clutch and had to remove the driveshaft to drop the transmission. Perhaps I relieved some kind of factory slack, alignment, or bolt torqueing issue?

 

I *think* I tightened up everything back the same, but I did not use a torque wrench. (Yes, I've checked the bolts repeatedly since) No growling for 2 winters now.

^^SBT is correct about the joints being an un replaceable part of the oem shaft. a few companies make a shaft that's repairable like it should be..Dorman comes to mind

 

 

Dorman 936-955 is the 5mt driveshaft.

 

936-954 is the 5eat's.