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

[SeeeeeYa]

FWIW I put in my WhiteLine Diff insert.

 

I still get the noise.

 

What is the complete list of your mods addressing this issue now? In reading over these past posts I do not see anything about the REAR LCA FRONT bushing. While I sure wish that WL diff insert were around a couple years ago when I was working on this, making light of what was a messy job however effective.... without a similar modification to the REAR LCA front bushing you're only removing flex in HALF the equation in the rear.

 

I'll say it again, anyone who drag raced one of the muscle cars in the past knows that one of the FIRST things you did was replace/modify/augment or otherwise FIX the lower control arms that located the rear axel. While the modern independent rear suspensions introduce a lot more areas of flex compared to a solid rear axel, the fact remains that without an almost solid lock on the positioning of the two rear wheels relative to themselves and the chassis.... you are going to have the two rear wheels acting independently under power! This breaks things. It also makes noise, your alert that 1) you're losing traction, and 2) keep it up and you will break something.

 

In the end, even with each and every little rubber bit tightened with kits and inserts and rubber, depending on horsepower and the violence of the launch, there will still be the "noise" everyone is trying to get rid of. Get over it. There is only ONE way to end it, solid metal bushings. But since these are street cars no one wants that.

 

Therefore, address ALL the bushings to the degree you can tolerate and live with the remaining flex. In doing so you will have moved the "problem" (one you created by giving your LGT more power than it was designed for, and operated in a manner it was not designed for ) high enough up the scale that it won't be a problem except in extreme abuse.

[SBT]

^ And if you do install a hard front bush in the rear LCA say goodbye to any significant camber back there as that is where most would be getting it. Short of installing top camber plates.

 

As Uncle Mat says, camber via the rear LCA is hack.

[Guest]

^ And if you do install a hard front bush in the rear LCA say goodbye to any significant camber back there as that is where most would be getting it. Short of installing top camber plates.

 

As Uncle Mat says, camber via the rear LCA is hack.

 

No camber plates in the rear possible, it's multilink not strut setup there.

[SBT]

No camber plates in the rear possible, it's multilink not strut setup there.

 

Exactly - left that off of my comment above.

[rao]

You could always switch to a live rear axle

[Guest]

Btw, I run at least 50% more whp now, and haven't heard the noise yet in 50F weather, which I did before while being stock (on lowered suspension). I put Group N engine mounts, so I'd say they must be helping. Edited October 10, 2008 by unclemat

[whitetiger]

camber via the rear LCA is hack.

 

 

not true. adjusting camber by changing thedistance between the knuckle and rear subframe with adjustable rear LCAs is not a hack. thats how rear toe is adjusted from the factory.

[SBT]

You could always switch to a live rear axle

 

@ rao

[SBT]

not true. adjusting camber by changing thedistance between the knuckle and rear subframe with adjustable rear LCAs is not a hack. thats how rear toe is adjusted from the factory.

 

Note my "significant" camber qualifier. You can't get very much negative camber with the factory setup.

[Leonardo]

Btw, I run at least 50% more whp now, and haven't heard the noise yet in 50F weather, which I did before while being stock (on lowered suspension). I put Group N engine mounts, so I'd say they must be helping.

 

Like SeeeeeeYa said a good number of pages back, it's all part of the puzzle: Engine mounts, tranny mount, and diff mount.

[Guest]

Like SeeeeeeYa said a good number of pages back, it's all part of the puzzle: Engine mounts, tranny mount, and diff mount.

 

I know. So was LBGT reporting engine mounts helped. I'll see how it does it this winter. Next step I guess I'll replace the lower diff support bushings with Group N ones. If that does not work I'll try the rear ones since I'll be replacing the diff with a R180 next spring anyway.

 

I don't want tranny mount, I believe it makes NVH much worse. As for engine mounts, I could not tell they are any different than stock NVH wise.

[SBT]

I don't want tranny mount, I believe it makes NVH much worse. As for engine mounts, I could not tell they are any different than stock NVH wise.

 

Was just going to ask this. Good to know. Anyone upgraded their pitch stop too to see if this contributes to the driveline-alignment (growl issue)?

[SeeeeeYa]

^ And if you do install a hard front bush in the rear LCA say goodbye to any significant camber back there as that is where most would be getting it. Short of installing top camber plates.

 

As Uncle Mat says, camber via the rear LCA is hack.

 

The idea isn't to install a hard bushing in the rear arm, but to eliminate the "air pockets" just as is done for the diff bushings. Actually removing and replacing that bushing would take effort significantly greater than the worth.

 

I have eliminated the "air pockets" in those bushings just as I did in the diff bushings, with PCV inserts and 3M Poly goop. It would be difficult to apply a fix similar to the WL inserts for the rear diff bushings. That is, if there are any inserts that would fit. But it is necessary to address them somehow, in a similar manner, if control of the rear tires is desired.

 

With all the bushing modifications plus the transmission insert/bushing I have NO NOISE under almost all conditions. Once, on a bad surface, with torque brakeing to 3200rpm I had one event.... once. Otherwise I can take off at 4.2 to 4.5 0-60 times all day long without any noises whatsoever. ALL the car does is leap forward.

 

As for alignment, camber or otherwise, that rear arm bushing doesn't control it, nor is the rear alignment adjustable. By centering the bolt/bushing in the rubber bushing with inserts, then solidifying them in with the 3M poly, the rear tires stop having the ability to try and outrun each other, back and forth. Also, after coilovers and lowering, plus firming all the aforementioned bushings as well as installing the poly front LCA bushing (an almost necessary mod IMHO), my tire wear has been perfect through two sets of tires. I added a little front camber on purpose. with the adjustment bolt.

[SBT]

The idea isn't to install a hard bushing in the rear arm, but to eliminate the "air pockets" just as is done for the diff bushings. Actually removing and replacing that bushing would take effort significantly greater than the worth.

 

I have eliminated the "air pockets" in those bushings just as I did in the diff bushings, with PCV inserts and 3M Poly goop. It would be difficult to apply a fix similar to the WL inserts for the rear diff bushings. That is, if there are any inserts that would fit. But it is necessary to address them somehow, in a similar manner, if control of the rear tires is desired.

 

With all the bushing modifications plus the transmission insert/bushing I have NO NOISE under almost all conditions. Once, on a bad surface, with torque brakeing to 3200rpm I had one event.... once. Otherwise I can take off at 4.2 to 4.5 0-60 times all day long without any noises whatsoever. ALL the car does is leap forward.

 

As for alignment, camber or otherwise, that rear arm bushing doesn't control it, nor is the rear alignment adjustable. By centering the bolt/bushing in the rubber bushing with inserts, then solidifying them in with the 3M poly, the rear tires stop having the ability to try and outrun each other, back and forth. Also, after coilovers and lowering, plus firming all the aforementioned bushings as well as installing the poly front LCA bushing (an almost necessary mod IMHO), my tire wear has been perfect through two sets of tires. I added a little front camber on purpose. with the adjustment bolt.

 

There are some that are running rear adjustable lower control arms, which enables a lot of negative camber dial-in, at the expense of torquing the rear LCA bushing. Hardening (removing the air space) the rear front LCA bushing would prohibit this for those going this route.

[SeeeeeYa]

There are some that are running rear adjustable lower control arms, which enables a lot of negative camber dial-in, at the expense of torquing the rear LCA bushing. Hardening (removing the air space) the rear front LCA bushing would prohibit this for those going this route.

 

Off topic, but could you point me to some links... for both that adjustable arm as well as words by those using it? I'm curious, as I don't see how that bushing could possibly influence camber one way or the other. That is one heck of a component to be replacing, it looks like a forged piece and holds the entire rear wheel/brakes/etc. One would think such a performance piece would come with significantly better bushings than the POS (performance wise, not NVH) stock ones.

[Guest]

Off topic, but could you point me to some links... for both that adjustable arm as well as words by those using it? I'm curious, as I don't see how that bushing could possibly influence camber one way or the other. That is one heck of a component to be replacing, it looks like a forged piece and holds the entire rear wheel/brakes/etc. One would think such a performance piece would come with significantly better bushings than the POS (performance wise, not NVH) stock ones.

 

He is talking about front lower lateral link that allows adjustment of camber.

 

Btw, Subietonic, the cast piece in the rear is trailing arm not control arm (LCA).

[Leonardo]

Wonder if the JDM STi parts for the Legacy from the catalogue have stiffer bushings.

[SBT]

He is talking about front lower lateral link that allows adjustment of camber.

 

Btw, Subietonic, the cast piece in the rear is trailing arm not control arm (LCA).

 

Correct on both points. I had just replaced my front LCA bushings and all I had in mind was the physical similarity (round and soft) between the rear front TA bush and the front LCA bush. Sorry for any confusion

[Leonardo]

Well, added the "race" trany insert and it took care of the remaining noise from the diff. I can even hear the tire screeching in the hard right handers from a stop.

 

Yes, the rear lower control arm bushing would be great but I have more reason to believe that the mount under the diff would benefit from harder bushings (would have to be pressed in) as unlike the STi, ours are solid but soft.

 

Another thing is my drive-shaft U-Joint (near the rear diff) is leaking a bit of grease so they ordered a new assembly under warranty.

[LittleBlueGT]

I would say yes. Did hear it just a light "tad-tad" but I think the lower inserts we can't use are part of the equation and also I yet to install the auto trany insert.

 

I am pushing down alot of power and lowered so I believe the problem will be fixed for at least 95% to 98% of the people here.

 

Was out for a little bit (breaking in the rotors for the front Brembos) so I'll do a more extensive test later on. I wonder if the whole STi lower brace will fit the Leg GT (looks lighter than ours) since the Impreza suspension is based on the LegGT. I will see if in the dealer I can get them to take out one and try it on my wagon.

 

 

There is also the part from Beatrush to consider though the bushings will be a cheaper alternative:

 

http://www.japanparts.com/images/ImageFromDB.php?base=1&no=15720

 

Anybody know where to buy this thing?

[LittleBlueGT]

Found it:

 

http://www.machiii.net/contact.html

 

I think I will order it.

[chuckzul]

I had the same problem,exactly, it turned out to be the rear wheel beraings were shot

[LittleBlueGT]

I had the same problem,exactly, it turned out to be the rear wheel beraings were shot

 

Did the noise only present itself in hard acceleration? Or did it show up as a steady noise the faster you drove?

[LittleBlueGT]

I thought I did everything. I guess I am wrong.

 

I have the Beatrush support on order (will be a few weeks).

 

 

Here is some stuff from Rallitek that you guys may be interested in, anybody try them:

 

http://www.rallitek.com/avogemobu1.html

http://us.st12.yimg.com/us.st.yimg.com/I/yhst-49187380673845_2028_1856864

[Turninconcepts]

I thought I did everything. I guess I am wrong.

 

I have the Beatrush support on order (will be a few weeks).

 

 

Here is some stuff from Rallitek that you guys may be interested in, anybody try them:

 

http://www.rallitek.com/avogemobu1.html

http://us.st12.yimg.com/us.st.yimg.com/I/yhst-49187380673845_2028_1856864

 

 

tranny crossmember bushings. One needs to be either thicker or a spacer bushing run as the 05+ LGT and 08 Imprezas have one bushing that is a bit thicker than the older setup. If this kit has a bushing that is a little thicker then it's good. If it's a kit for the older car setups then it won't work.