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

[SeeeeeYa]

My car is currently up on jack stands, and I filled the rear diff bushings with the 3M Windshield poly crap that comes in a caulk tube to see if that eliminates the growling noise. I call it crap because it takes a scotchbrite pad and brake cleaner to get this stuff off your skin.

 

If you try this, get some latex gloves and wear a long sleeved shirt. No pictures were taken either; I was way to dirty to pick up my camera.

 

I’m going to let the car sit for at least 24 hours before I drive it. It has been cool hear in the AM, so I will post up in a few days when I know for sure that the growl is gone. I am going to a track day next Saturday and Sunday so I went ahead and did this while I was changing out the brake pads and flushing the brake fluid.

 

Great! And you're right about the mess. That stuff has to wear off.

 

After seeing how the rubber I'd previously mentioned that I stuck into the rear diff bushing's 'holes' was distorted, I'd decided to make the mod permanent.

 

I cut the aforementioned PVC pipe into quarters, resulting in four 1 1/2" long and 1 3.8" across sections. By putting the car on ramps and loading the suspension I could get to the top openings in the diff. A little prying down on the diff (those bushings are soft!) and the top holes were exposed adequately.

 

Using that 3m WS poly goop I liberally covered one half of a PVC piece and shoved it into one of the top holes. I repeated for the other side. Then I filled in the remainder of the openings with the poly, the PVC insert took care of most of the opening but the poly squished into what was left and smoothed across the top half of the bushing sealed it all up.

 

For the bottom holes I just put my jack under the diff and raised it until the lower holes were readied. Using the PVC inserts and poly I repeated the top procedure.

 

There is so much torque on those bushings, evidenced by the crushing of sections of tough mining belt I'd had in there, that I decided the PVC inserts would center the diff mount and along with the poly firm them to the point they would give very little.

 

The car then wasn't moved for about eighteen hours.

 

The rear lower control arm bushings are going to be harder to do. I had previously been able to do the above procedure on the rearmost opening but the fronts are inaccessible. I'm going to have to take the LCA loose to get to them properly. I'll be doing this soon.

 

Where before it sounded like the car was (and it was) being beat to death back there things have totally changed. That winding up and releasing was making the drive shaft go nuts with its flexible center bushing, the rear diff was banging around, and the LC arms were alternately jumping back and forth. Terrible noises. AND IT ATE MY REAR DIFF!!! While there is still noise under extreme power it is nothing like that anymore .

 

The banging of the driveshaft is gone, for example. And what remains is a small, non threatening, thing. When my transmission mount insert is installed (shortly) and the rear LCA bushings are done properly (only the one insert now instead of two, so there is that play left) I am convinced the overwhelming majority of the problem we have been plagued with will be gone.

 

Waiting on the aftermarket, like I've previously outlined, is futile. For even if they do come to market with a nice bushing...... I cannot imagine the difficulty in replacing it. Trust me. Just replacing that diff was eyeopening enough. But doing that would be almost child's play compared to removing that crossmember and replacing those bushings. And why? Doing it this way isn't that difficult. Its messy but not difficult at all.

 

Again, when I used to accelerate even from a low speed the noise was bad. Leaving at full throttle from a stop was traumatic and could be heard by anyone nearby. It was scary and embarrasing. But no longer. Today I did a 2500rpm 0-60 (and got my usual 4.7 ) with nothing but minor noise from the car. No banging, no thumping. Testing it turning hard rights and lefts under power produced none of the previous scary, irritating, damaging, and embarrasing noises..... other than what my car sounds like being illegally demonstrative .

 

After replacing one diff I'm not going to beat on it like I used to, but I no longer worry about whatever occasional 0-60 or stop light thrashing I want to do. This is a viable improvement and relatively easy to do. As soon as more people do these things and expand and improve on it a major headache will be cured.

[NewScooby]

So far so good on filling the bushings. I was WOT in first and second many times this morning with no thumping, vibration, etc. Just smooth acceleration.

 

I agree with Seeeee Yaa, even if bushings come to market, they will be a bear to install. Not an easy job for a weekend do it yourselfer, like myself.

 

For those interested in trying out the poly filler method, if replacement bushings do come out, the filled bushings will not be any harder to remove than stock ones. Also, the rear diff can also be removed just the same as stock. Other than costing a few bucks and being a PITA to clean up, I see no drawbacks so far to using the windshield poly to eliminate the growling rear end issues.

 

After looking at the rear Lower control arm bushings I decided to leave those for another day.

[Turninconcepts]

So far so good on filling the bushings. I was WOT in first and second many times this morning with no thumping, vibration, etc. Just smooth acceleration.

 

I agree with Seeeee Yaa, even if bushings come to market, they will be a bear to install. Not an easy job for a weekend do it yourselfer, like myself.

 

For those interested in trying out the poly filler method, if replacement bushings do come out, the filled bushings will not be any harder to remove than stock ones. Also, the rear diff can also be removed just the same as stock. Other than costing a few bucks and being a PITA to clean up, I see no drawbacks so far to using the windshield poly to eliminate the growling rear end issues.

 

After looking at the rear Lower control arm bushings I decided to leave those for another day.

 

I've got two GC style rear subframes here that I've been using to take measurements for these (GC and LGT use the same bushing). One of the big hold-ups in all of this is how to get the old bushings out. That's going to be the most difficult part of all this.

 

Even with a trick split design it's that teardown that's killing me.

 

Oh - did you find that the lower diff carrier bolts were put on by a gorilla when you did yours?

[Guest]

I keep hearing "lower control arm"... correct me if I am wrong, but I think the rear suspension has "trailing arm" and "lateral links"... no control arm anywhere.

 

Which is the one you are refering as lca?

[NewScooby]

I keep hearing "lower control arm"... correct me if I am wrong, but I think the rear suspension has "trailing arm" and "lateral links"... no control arm anywhere.

 

Which is the one you are refering as lca?

 

I'm talking about these, which look to be very nice quality, but these can be built equally as good for under $100. I'm just not sure I want/need them at this time.

http://www.jscspeed.com/lgt/lgt_base.html

[Turninconcepts]

I'm talking about these, which look to be very nice quality, but these can be built equally as good for under $100. I'm just not sure I want/need them at this time.

http://www.jscspeed.com/lgt/lgt_base.html

 

Thank you for the clarification. I thought you were talking about something else as well. Specifically these:

http://www.turninconcepts.com/product_info.php?products_id=335

 

On those arms - you're looking at tube, tube ends (one side left hand threaded), good rod ends (one side of each left hand threaded, and be sure to buy GOOD rod ends - Aurora as a minimum, FK for better), jam nuts, and you're going to need to mill some high misalignment spacers to fit the cleavis, and make up the angles that you may need.

 

Overall, very simple parts, but most folks don't have access to the equipment to make the small bits that they need.

[Guest]

I'm talking about these, which look to be very nice quality, but these can be built equally as good for under $100. I'm just not sure I want/need them at this time.

http://www.jscspeed.com/lgt/lgt_base.html

 

These are lateral links (adjustable unlike stock).

[NewScooby]

Thank you for the clarification. I thought you were talking about something else as well. Specifically these:

http://www.turninconcepts.com/product_info.php?products_id=335

 

On those arms - you're looking at tube, tube ends (one side left hand threaded), good rod ends (one side of each left hand threaded, and be sure to buy GOOD rod ends - Aurora as a minimum, FK for better), jam nuts, and you're going to need to mill some high misalignment spacers to fit the cleavis, and make up the angles that you may need.

 

Overall, very simple parts, but most folks don't have access to the equipment to make the small bits that they need.

 

I've already got the SuperPro bushings, I bought them from you. Great product, good price, and quick shipping BTW:lol:

 

Thanks for the info on the arms.

[boostsr20]

So did I miss the How-to on this I am starting to get the noise now and want to try the window weld mod. Can someone postpics and a quick how to?

[TRS]

I get the "growl" on hard acceleration from a stop or slow speed when it's cold out, but when it's mild it only happens on hard acceleration while turning tightly. I did a version of bushing inserts yesterday to see if it would help limit movement of the rear differential.

 

I took a pair of spare rubber sway bar bushings...

http://i23.photobucket.com/albums/b380/TRS60586/Misc%20Legacy/DSCN0188.jpg

 

...cut the flat portion off of them...

http://i23.photobucket.com/albums/b380/TRS60586/Misc%20Legacy/DSCN0189.jpg

 

...and cut the remaining two semicircle parts in half to make four inserts.

http://i23.photobucket.com/albums/b380/TRS60586/Misc%20Legacy/DSCN0190.jpg

 

To widen the openings in the top part of the rear differential bushings I pried down on a mounting bolt by placing the hole in the end of a breaker bar over the tip of the bolt and then jacking up on the other end, using the brace (with the arrow on it in the picture) for leverage. I then worked the inserts into the top openings (silicone spray helped).

http://i23.photobucket.com/albums/b380/TRS60586/Misc%20Legacy/DSCN0199.jpg

 

Then I jacked up on the differential to open up the bottom opens in the bushings...

http://i23.photobucket.com/albums/b380/TRS60586/Misc%20Legacy/DSCN0196.jpg

 

so I could work the lower two inserts in.

http://i23.photobucket.com/albums/b380/TRS60586/Misc%20Legacy/DSCN0203.jpg

 

They haven't totally eliminated the noise but have made a significant reduction in it. Next, I'll upgrade to poly inserts to stiffen it up some more.

[SeeeeeYa]

^^^ That's how I started, with similar results, although your inserts are a better idea than what I first used. And those results prompted the final version with the PVC inserts and 3M WS poly which really made a difference.

 

IMO this bushing is the major contributor to the problem. Yesterday I installed the Rallitek transmission mount insert. I'll be testing today to see if it did anything for our rear noise issue.

 

That mod of yours with that bushing is a good first approach, putting similar pieces in those top holes would have given even better results I think. Remember, when that diff twists the top of one side goes UP as the other side goes down. For people who don't beat on their car like I do they might even be enough, along with the 3M poly to keep them in place. But for those who rip and tear, like I do sometimes , IMHO the PVC insert along with the 3M will provide the most stiffness.

 

Excellent pictures BTW.

[TRS]

I'll cut the other sway bar bushing into two more inserts, pull out the lower ones, try putting some in the top bushing openings, then reinsert the lower ones. It looks like the raised shoulders will keep the inserts from coming out on their own for now while I experiment.

[boostsr20]

So where does the PVC insert go? Is it filled while its off the car then inserted similarly to TRS's swaybar bushing fix?

[SeeeeeYa]

So where does the PVC insert go? Is it filled while its off the car then inserted similarly to TRS's swaybar bushing fix?

 

 

I used a section of PVC plumbing pipe as follows:

 

PVC pipe with 1 1/2" I.D. and 1 7/8" O.D. with a 6" circumference.

Cut off a section that measures 1 1/2" long,

Cut that piece longitudinally into 4 equal segments which will measure 1 1/2" long and 1 3/8" wide (the curved part).......these are the 4 INSERTS

 

Then read the preceding page, post #326.

[boostsr20]

Gotcha. Thanks! So the window weld is fairly thick and will stay in without too much leakage? I'm going to try and get it done this week.

[NewScooby]

Gotcha. Thanks! So the window weld is fairly thick and will stay in without too much leakage? I'm going to try and get it done this week.

 

It's thick stuff, I had no drips.

 

Looking for the ultimate hold, I cleaned the bushings with a toothbrush and brake cleaner prior to "Operation Polygrip"

 

I considered making an insert. The reason I didn't was that I was able to fill the bushings with the windshield poly flush with the bottom of the nut holding the bushing over to the outside metal ring of the bushing on both sides, creating on sold glob of material going from one side of the bushing thru the middle to the other side.

 

Just one of likely many effective ways of getting rid of the Growl

 

 

Also, there is enough to do at least 3 or 4 cars in each tube.

[LittleBlueGT]

I couldn't find the product in Canada, but found a similar product called Proform.

 

I did it last night and will be driving the car tomorrow.

[boostsr20]

Are any of you guys getting NVH from doing this? I seem to be getting a little more Vibration through the gas pedal with my temporary solution (old sway bar buchings like posted above).

[SeeeeeYa]

After modifying mine I almost immediately installed the Rallitek tnsmission support bushing insert ...... now we're talking increased drivetrain feedback! However, even in this case the increase in NVH primarily occurs during periods of high engine load and is simply not an issue during 'normal' driving. I just put several hundred miles of mountain roads on the new bushing mods and all is great.

 

The overall results have been to slowly remove my apprehension about hammering the throttle. Where before about anything I did led to histrionic suspension/drivetrain reactions I can now nail it and expect nothing but acceleration effects. Living with that nasty "growling" noise, which was far more than that in my car, was intolerable and I'd have accepted any NVH problem that was part of the solution. As it stands I believe the rear bushing modifications alone have tamed the problem and the stiffening of the tranny bushing just adds more strength where it was needed to resist the torque windup of the drivetrain.

 

Petal to the metal now draws attention because of the vicious sound and fury of a fully tweaked VF40 on meth. Before that everything was compromised by hammering, banging, thumping, 'growling' madness from the drivetrain. Soon I'll find out what difference a bigger turbo makes to all this...........

[boostsr20]

How hard was the Rallitek insert

to install?

[SeeeeeYa]

How hard was the Rallitek insert

to install?

 

In its own way a messy little bitch. But as long as you have a nice vice, a good toolbox, and some patience no problem. Go here to read some informative posts:

 

http://legacygt.com/forums/showthread.php?t=68567

 

When you look at the mount and that insert side by side you will think, 'no way!' But when you smear whatever slimy lube they send with the insert on both the insert and the hole in the stock tranny mount, and align them carefully in your vice, you can get it done ok. It's an optical illusion thing as the edges of the insert are larger than the center in order to hold it in.

 

Talking with t0ad neither of us can put our finger on what it feels like, but we like it . You can definitely feel, and hear, the engine grunt against the car, and there is the impression that it goes better somehow. Almost like motion that was once lost in twisting against those flexible bushings now goes immediately into forward motion. Add in the increased sound and the overall impression is that pressing on the accelerator makes the car go forward NOW, and that things are happening faster than you expect. I haven't actually logged and analyzed them yet so this is mostly subjective, butt dyno, impressions. Experience at drag racing tells me that MY car post bushing insert would beat MY car without it, but those differences may only be quantified at a drag strip.

 

It is part of the overall nature of my car for that insert to be there, as are the poly LCA and anti-sway bar bushings, CBE, coilovers, and all the rest. While it is a pleasureable and comfortable ride on a trip, day to day it feels and acts like what it has become since those early quiet plush times.

[Beanboy]

I skipped a lot of pages, but the last few warm my heart. Homemade inserts are nice!

 

Avoided diving in, but after three years, everything is loosening up. Time for a complete bushing overall. The AWD aspect makes for huge drivetrain movin' and shakin'. So much damn slack...

[boostsr20]

I got the Race trans mount in and the diff bushings fix. So far it has cured the straight line aspect of the noise (for now, maybe not when really cold). I do still get it on right handers from teh stop sign if I go half throttle. That fades as the diff fluid warms up though.

[nismoz]

Subscribed. I am not even going to Stage 1 before this issue has perfect solution.

[HansGT]

few cold mornings in a row now....high 30's. don't notice it yet this season, but again I'm on Bilsteins now...dunno if that's the diff for me or not.