I'm At A Loss... Weird "popping" Noise In Rear End

[MTBwrench]

I'm only starting a new thread as a last resort, because I am seriously at a loss when it comes to this issue.... My wagon is making a horrid popping noise from the rear driver's side when I:

 

-Make a swift left turn

-Get on the throttle

-Hit large bumps or divots in the road

 

Also keep in mind that so far I have replaced:

 

-All rear end suspension bushings, except for the trailing arm bushes.

-Toe and camber arms with the Whitline KTA124 Kit

-The driver's side rear axle

-Diff bushings

 

The pop seems rotational and driveline related, as it's not always just one, but can be multiple pops which are directly related to vehicle speed in frequency. The pop is not just audible either, you can feel it through the subframe, as if someone is tapping the unibody with a rubber mallet. It also appears that suspension loading on that specific tire(rear driver) plays a big role in this. If I put 200lbs in the rear seat, the noise gets worse/louder. Loading the rear up is even worse/louder still, to the point that 50% throttle in a straight line is guaranteed to make the noise. On the opposite side of all that, I can make as aggressive of a WOT left turn as possible, which with my Dunlops is pretty aggressive, and absolutely ZERO noise. I can do figure 8's all day, forwards and backwards, no noise as well. I've even gone so far as to back the rear driver's tire onto a ramp, purposefully flexing it, to inspect for loose/dangling/binding components and everything is fine.

 

Has anyone ever had or dealt with an issue like this? Any insight would be greatly appreciated... because I am at a loss.

[solidxsnake]

Have you checked the strut assembly? I'm wondering if maybe your springs are shifting under load, or if for some reason the tophats aren't torqued properly. I recall someone else having similar problems with front suspension where the springs weren't seated on the perch correctly, so they would rotate and pop occasionally until they were re-seated correctly.

 

And of course, like any one of these threads, <obligatory nagging about video/audio because internet diagnosis is, like, hard, maan>

 

Also, some threads that may be of interest:

 

http://legacygt.com/forums/showthread.php/please-help-popping-noise-259481.html

http://legacygt.com/forums/showthread.php/rhythmic-click-hard-left-255864.html

[Gex]

Bad U Joint. But after re-reading your post maybe strut problem... Didn't you just get new control arms/suspension work?

[KRM]

Sway bar making contact with anything? Have locks on it? Just a thought because I had a similar issue in the past

[MTBwrench]

Time for me to rebuke everything... But I have arrived at a new hypothesis which I will detail at the end of this post.

 

Have you checked the strut assembly? I'm wondering if maybe your springs are shifting under load, or if for some reason the tophats aren't torqued properly. I recall someone else having similar problems with front suspension where the springs weren't seated on the perch correctly, so they would rotate and pop occasionally until they were re-seated correctly.

 

And of course, like any one of these threads, <obligatory nagging about video/audio because internet diagnosis is, like, hard, maan>

 

Also, some threads that may be of interest:

 

http://legacygt.com/forums/showthread.php/please-help-popping-noise-259481.html

http://legacygt.com/forums/showthread.php/rhythmic-click-hard-left-255864.html

 

I went through the same process, I even removed the shock assembly and inspected it, then re-torqued everything. Sadly, no issues found. Also, with how much the popping noise happens (sometimes dozens of times), I'm not quite sure a suspension part would be flexing that rapidly. I thank you for the threads though, the second one may prove to be helpful!

 

Bad U Joint. But after re-reading your post maybe strut problem... Didn't you just get new control arms/suspension work?

 

I've also suspected this... I removed the driveshaft from the diff and spun all the joints. Buttery smooth, carrier bearing too. I did get all new control arms, and an alignment, which will lead me to my hypothesis at the end of this post.

 

Sway bar making contact with anything? Have locks on it? Just a thought because I had a similar issue in the past

 

I've also tried this... no change. I've removed the swaybar/links, and even my catback, in an attempt to see if it was a clearance issue. Nothing. I've also inspected the entirety of the rear end for rubbing/wear marks etc. Nothing.

Now for my hypothesis: Axle Bind Due To Being Too Low

 

This issue has been getting progressively worse over the last few months, and, became twice as bad when I installed the adjustable control arms. Then, even worse still when I got the proper alignment. Here's my theory: Since I'm lowered, and quite a bit by Outback standards, my axles are already at a negative angle. On top of that, the suspension compression and having a proper alignment mean the control arms are drawing the hub closer to the diff. This shortens the axle length thus reducing the axle's maximum angle of flex before binding. To add to all of this, my front position trailing arm bushings are walking themselves out (I wish I had known this before I got an alignment...). This means that there is a possibility the toe and camber arms needed to be shortened significantly(more than normal) to achieve zero toe, also drawing the hub closer to the differential and creating the same issue. When all of this is combined that the fact that the differential in my Outback is also 1" lower than a Legacy due to the subframe spacers, I have created for myself a potentially unhealthy drivetrain situation where the axle is flexing at extreme enough of an angle that it is rubbing against the inner cup and "popping" over each of the six ball bearing channels machined into the cup.

 

Now the real question is.... why only on the driver's side?

 

Either way, I spoke to Subtle Solutions today and have 1" aluminum rear shock spacers on order to replace my 1/2" spacers, and new front position control arm bushings on order as well. I have another alignment scheduled for next week as well. I swear I'm going to really kick myself if this is all of my own accord and lack of attention to suspension geometry.

[Max Capacity]

Why drivers side, because, how heavy are you ?

 

I also seem to recall from the Honda day's people were talking about noises when the cars were really low.

[MTBwrench]

Why drivers side, because, how heavy are you ?

 

I also seem to recall from the Honda day's people were talking about noises when the cars were really low.

 

I thought so as well, I'm around 175lbs. To test this, I had two ~200lb passengers sit on the passenger side(front and rear). There was no noise on the passenger side, still only the driver. To that end, if extreme axle angle is really the culprit, we're still working with a 225k mile vehicle here so inconsistency is entirely possible.

[NotYourAvgSpec.B]

Could be a cracked cage in the rzepa(cv) possibly driver's side only cause it travels a longer distance around most typical turns... Also lowering your ride may have put the inner triod cv joints at there max cause them to bottom out inside their housing..

 

Lol sorry, just read you post... Yea your on the right track... But It would take alot for the balls bearing to skip in their grooves.. unless of course a damaged cage wasn't holding them properly