How To Tell if e34 Subframe Bushings are Bad?

[VonRiesenberger]

Hey everyone! So first time poster, but lonnnng time lurker. My apologies for the belated arrival but I finally found something...or I guess in this case, the lack of, something that someone hasn't asked or answered.

So I recently started getting a significant rear twitchy/floaty/wandering feeling from the rear. It's mainly apparent during highway driving and on long sweeping turns at 45-65 mph and the onset of this was very sudden. My first suspect was the rear subframe bushings and search results confirmed those thoughts. However, getting under the car and taking a look at them (pics below), they seem to be in visually good shape but when I pry at them with a flathead screwdriver, the entire subframe moves quite effortlessly. When I say pry, I mean very gently and softly...like not what I was anticipating to happen to the frame at all. I should mention this was done with the rear end up in the air and with no load. There are a few small surface cracks on the rubber, but nothing that has me convinced they need to be replaced. I was under the impression that rear subframe bushings rarely go bad?

And this goes without saying but I've never installed or held new/used subframe bushings...are they normally suppose to be this soft? My eyes tell me one thing and my touch tells me another. So, in the longest way possible, is there any definitive way to tell if subframe bushings are bad or not?
That's my first question...


Second question...if they turn out to be perfectly good, what could be going on here?

Other helpful information you might need...
-128k miles on the car, and no idea about what has been serviced and not.
-If you're thinking not enough miles for bushings to go bad...you'll want to know when I purchased the car...pretty sure still with its original Dinan struts and springs...it felt like I was driving on one of those dirt roads that gets those tiny washboard bumps but....literally the entire time, on perfectly flat roads and at any and all speeds. Baffles me that anyone would let something get to this point but there's kinda a weird back story and just couldn't pass it up...anyway.
-Replaced struts/springs with catuned coilovers, and replaced thrust arms, control arms, and sway-bar ends.
-Car sits low but not too low.
-Right rear has more than usual negative camber and the coilovers are adjusted at equal height.
-Brand new tires and balanced as of yesterday.
-Wish bones replaced 10k ago.
-Rear trailing arm bushings look fine....but what the hell do I know at this point.


Screen Shot 2019-02-17 at 3.47.14 PM.jpgScreen Shot 2019-02-17 at 3.47.26 PM.jpg

Thoughts? Thanks!

[shogun]

Looks like you need new beer cans, failure/faults as described are typical for this.
Failure syndromes:
• Rear clunk noise when you disengage the clutch on an upshift / down shift; especially an upshift. when accelerating; the subframe is pulled away from the chasis via the wheel torque. when you push the clutch in, the subframe unloads and hits the chassis creating the thunk.
• The rear of the car feeling like it steers itself. Probably best to do the rear pitman arms first before the subframe bushings if you have a self steering rear. or, at least have them inspected. If the pitman arms are good then this means the bushings are soft. No real way to inspect the bushings visually. however, if you support the subframe, you can easily remove the arm covering the bushing and see how torn it is.
http://www.bmwe34.net/E34main/Mainte...ameBushing.htm

Pitman arms "Dogbones"
Failure syndromes:
• The rear of the car feeling like it steers itself. Probably best to do the rear pitman arms first before the subframe bushings if you have a self steering rear. or, at least have them inspected. If the pitman arms are good then this means the bushings are soft. No real way to inspect the bushings visually. however, if you support the subframe, you can easily remove the arm covering the bushing and see how torn it is.
http://www.bmwe34.net/E34main/Mainte...PitmanArms.htm

dogbones are easy to replace, maybe you start with that and test. But buy good quality ones, not the cheapo stuff. Lemforder is worth the money. I have tried cheap ones before, did not last very long.

[bigsixe34]

You won't get much visual cue on the subframe bushings like Shogun said unless they're total trash. But 128k is enough for them to fail, especially if the rest of the suspension was in such poor standing.
When you put your passenger wheels over a drain or dip do you hear a knock back there as the weight is shifting quickly?
I changed out the original set at 145k and they were beyond dead. Every irregularity toward the shoulder would prompt a loud thunk. They should be replaced before that starts happening. Mileage was in the northeast on a daily driver. I'm sure bushings last a little longer in Georgia.

[jehu]

when they're failed the center separates from the rest so they lose stability and this is not evident without removing the covering plateAttachment 645906

Its been my experience when you find the rear end clunking during shifting this is the sign they're failed. Its something you might overlook being otherwise engaged with driving but if you are not getting anything like that the other parts like dog-bones appear the better place to begin.