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


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As usual..... The noise was non-existant all summer long and returned on the first cold morning. I took off hard in 1st and "thump thump thump" from the back.

 

I've adapted to the noise at this point but now I'm concerned with the hissing sound coming from the clutch area. :spin:

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Any possibility that this is spring-squirm? Coils (on stock or Bilstein shocks) compressed too tightly on each other at the rear and edging in and out, thumping/clanking on accel/hard turns from a stop?
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Any possibility that this is spring-squirm? Coils (on stock or Bilstein shocks) compressed too tightly on each other at the rear and edging in and out, thumping/clanking on accel/hard turns from a stop?

 

FWIW I ran on Bilstein/Pink setup for more than a year before I got the Stage2 done. No growling sound. The day I went Stage2 (BNR16 , CNT DP) I had GroupN MT mounts installed as well. This is when the growling sound came in. So I don''t think it's the springs. Besides in my case I only hear it when DEcelerating. Never at take off - even though it may be simply washed out due to other noise at that time.

2005 LGT Wagon Limited 6 MT RBP Stage 2 - 248K

2007 B9 Tribeca Limited DGM - 258K

SOLD - 2005 OB Limited 5 MT Silver - 245K

SOLD - 2010 OB 6 MT Silver - 205K

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LMAO. dude when its 0 degrees out here and im romping the piss out of it (yes its been driven for 30 minutes prior to this) my friends panic like WTF was that?!!?!. it sounds like a bunch of rocks are being tumbled in the rear end.

 

Im pretty sure the sound is mostly coming from the front diff. I dont have this sound in a straight line, only when turning and mostly only when the front tires are spinning...

 

also i almost always drive with TC off. Your rock tumbling analogy is dead on tho!

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No... it's definately from the back ... and is worse with more load (passengers,etc) in the rear of the car. It also gets worse with rear suspension squat (from acceleration, hard cornering, etc).

 

This appears to be an issue with the rear suspension geometry.

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About a week ago I replaced the stock rubber drive shaft center support bushings on my '05 LGT with solid billet aluminum ones from Torque Solution, purchased from FredBeanParts.com.

 

http://www.fredbeansparts.com/media/catalog/product/cache/1/image/5e06319eda06f020e43594a9c230972d/t/s/tscarrierbearing_1_1_1.jpghttp://www.fredbeansparts.com/media/catalog/product/cache/1/image/5e06319eda06f020e43594a9c230972d/t/s/tscarrierbearing2_1_1.jpg

 

While I'm recently just out of the 1000 mile break-in on my new build engine (ringlang failure of OE pistons) and still have not fully thrashed on the new engine, these did seem to add to the solution of eliminating the infamous "growl".

 

These are not a single solution to the problem. As anyone who has followed or read through the entire thread knows the fix is to eliminate as much of the built in "softness" of all of the drive train and rear suspension bushings. Remember, the Legacy was designed to be a "near luxury" sedan so the engineering, especially for the NOAM market, focused on limiting NVH as much as possible, thus the cushy bushings.

 

 

Other mods I've made to remove slop, and in the process eliminate the "growl", include:

 

RalliTEK poly AT mount insert

Beatrush rear differential front member

Whiteline rear differential bushing stiffening inserts

Spec-B rear lower arms (stiffer bushes than GT)

 

Updates? Did it solve the issue?

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Updates? Did it solve the issue?
While not totally banished, I can only produce it when it's cold out and I'm accelerating hard from a stand-still into a tight left or right turn. After all the various bushing mods and bracing I did, when it does occur it is now much less subdued; more like somebody knocking on the floorpan with their knuckle rather than hammering away on the unibody with a 5lb sledge.
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While not totally banished, I can only produce it when it's cold out and I'm accelerating hard from a stand-still into a tight left or right turn. After all the various bushing mods and bracing I did, when it does occur it is now much less subdued; more like somebody knocking on the floorpan with their knuckle rather than hammering away on the unibody with a 5lb sledge.

That's not what I'd call a growl. The only bang on shift I had was resolved by a rear diff bushing insert. Now it simply sounds like the diff is pinned up against the body or something under heavy torque/cold weather/passengers in the rear.

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  • 4 weeks later...

I just upgraded my clutch to an Excedy setup and a light weight flywheel. Now the clunking in the rear is much worse! Am I losing my mind?? It's a possibility.

 

I'm guessing the motor rev's a little quicker now with the LWFW and the clunking issue is not happy with it.

 

Last night the temp was 24 deg outside and I punched it from a stop. (turning right) The car launched hard and felt great but I thought the rear end was going to break!

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  • 3 weeks later...
  • 4 weeks later...

Man if you guys think it's loud inside the car......

 

I swapped vehicles with my mom this weekend and she likes to have fun in my car. I watched her take off in first gear and "SNAP SNAP SNAP SNAP." The end of my driveway is over 150 ft away and I heard it loud and clear.

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  • 9 months later...

I know this thread is old, but after reading through most of the posts, I'm still wondering if anyone has taken recording of their sound.

 

I just posted about a sound I'm having recently, as its gotten closer to freezing, but I'm still trying to figure out if its the same sound.

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  • 4 weeks later...

I don't have a smart phone or I would take a video for you.

 

It doesn't make the sound under normal driving. It's only when you are hard into 1st + 2nd gear and usually when the cold weather arrives. It's like a rapid clunking in the rear end.

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:lol: I've also been part of this crowd for years ugh :spin: but I have since then cut back A LOT on the boosting and aggressive throttle load on torque jumps from a start... Haven't heard it in years :rolleyes:

 

But yea this creaking is SO annoying! I don't have the time to read through 50+ pages of this thread at the moment, but it sounds like people are still trying to figure out what and where this grumbling,knocking,creaking noise is coming from huh? :confused:

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