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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > General E90 Sedan / E91 Wagon / E92 Coupe / E93 Cabrio > Tension/ Traction Strut (Hydro)



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      05-01-2024, 02:50 PM   #1
gbalthrop
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Tension/ Traction Strut (Hydro)

History:
A) 3/2007 build 328xi E91. VA Safety inspector failed "suspension" simply 'cuz it "clunked" (HIS description) when brake applied at 1-2 mph. Didn't even jack vehicle or do "9 & 3 o'clock" or 6 & 12 o'clock shake tests, or inspect bushings. I was standing by vehicle when he Tested. NO noise/clunk, and there NEVER has been any issue with "clunk" or handling in 7 years I have owned vehicle. Steering/ Suspension is "Tight": NO Wander or steering looseness, & Nothing happens when brakes applied. It has always had "Hair-trigger" brake at last MPH to full stop, which I attributed to Vacuum Pump.

Background:
I'm requesting CONCEPTS/ Recommendations from ANYONE who has replaced front E9x suspension components, particularly bushings. I have replaced bushings & ball joints on many vehicles, have tools, shop space, etc., but am currently away from shop & have NOT jacked vehicle & inspected. My initial impression is that if ANY actual issue, first suspect is Rear "Hydro" bushing on Tension or Traction Strut. I have had NO issues with suspension in 7 years of ownership, & AFAIK, ALL is original; 141,000 miles.

Questions:
1) Which Component(s) are prime suspect if wheel torques or moves rearward slightly when wheel rotation is stopped by brake application?

2) Is Rear Bushing (where Tension Strut attaches to Subframe) liquid-filled (Hydro)? Item #9 in this Link:
https://www.realoem.com/bmw/enUS/sho...diagId=31_0740

3) If/when that bushing fails, is "Tell-tale" oil/fluid likely on bushing? OTHER signs/clues of failure?

4) ANYONE replaced bushing at rear of that Tension Strut? TIPS/ Recommendations?

5) If that is what appears indicated by examination, the "Repair would appear to me to be simply change those "Hydro" bushings (press out old & press in new). I would do BOTH sides at once. Anything to replace at FRONT of Tension Strut where Ball Joint is located?

6) Autohaus AZ has Lemfoerder bushings (2) for $46; Any reason to pay more? If so, got LINK? NOT going to pay $600+ for Turner "BLUE".
https://www.autohausaz.com/pn/3464402

6a) Bentley says "Bushings may only be replaced once". ANYONE know WHY, or HOW you can tell if prior replacement?

7 ANYONE with other advice on subject? Other things to inspect while I'm there? I do my own work, so NOT inclined to repair MORE than obviously-worn bushings at the moment, but DO want to assess everything in area "while there".

Thanks,
George
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      05-01-2024, 02:58 PM   #2
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My experience is with RWD, so YMMV.

The control arm bushings on my 09/08 build 335i failed at 80K miles. There was noticeable play, wandering at speeds, and some vibrations while braking. I personally did not observe any noticeable clunking, however.

My current 10/11 335i has all original suspension components and is nice and tight. But it’s an ex-California car, so I suspect it’s had a much easier life than my old 335i (ex-Va and GA car).

I am under the impression that Xi models have steel control arms with a different design wrt RWD, so I don’t know why the Bentley manual says you can only replace the bushings once. It’s my understanding that disclaimer is for Aluminum control arms (since Al can be more easily warped by pushing the bushing out).

I’d go for the Lemforder bushings. They’re hydro filled, and will leak a black goop when they’ve perished (I know mine did, on my both my E90 and my old E46 330Ci).

I’d also inspect the struts in the front, especially the bump stops. They’re foam and disintegrate (indeed my 10/11 335i’s bump stops are starting to show the first signs of disintegrating).

Any chance you can get the car re-inspected? Perhaps at a better place? Sounds like everything is just fine…
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      05-01-2024, 03:31 PM   #3
gbalthrop
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Quote:
Originally Posted by Hoody007 View Post
... It’s my understanding that disclaimer is for Aluminum control arms (since Al can be more easily warped by pushing the bushing out).
Any chance you can get the car re-inspected? Perhaps at a better place? Sounds like everything is just fine…
Thanks for taking the time to share your knowledge.
I'll examine the Tension Struts for any sign of tool marks at the rear bushing ring, & use Magnet to see if Ferrous. Unless "Bummed-up", I'll probably just replace bushings using Press.

I'll INSPECT/Examine the bushings & Ball Joints myself, and replace Hydro bushings if signs of "goop", either new or old. This is 2nd inspector who told me "these cars are KNOWN to do this". First Inspector didn't scrape old sticker, just told me what he "found". Neither mentioned a specific bushing, or any "leaked liquid". Both referred to "Lower Control Arm Bushing". VA Safety Inspections tend to be 10-15 minute inspections by folks who take their job seriously.

This makes one wonder: Did VA State Police/ Inspections put out a Memo about BMW Bushings? They (the two mentioned ;-) seem to be looking for something, but WITHOUT actually KNOWING how the front suspension & Bushings work. I "cross-examined" both about "fluid-filled bushing" leak. NEITHER seemed familiar with the concept or identified a specific Bushing/ Location that had failed.
Thanks again,
George
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      05-01-2024, 03:43 PM   #4
335i54n
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imo If your car has more than 60k on an open-style or fluid-filled tension bushing, it's worn. Most don't notice it and just Put Put around. Pretty easy to tell, like the inspector said, drive slowly and hit the brake hard. You can feel and see the wheel move. They aren't scamming you, but actually notice or are aware of the BMW chassis dynamics (even most techs aren't aware or care).
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      05-01-2024, 03:53 PM   #5
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*NEVERMIND, I see you have an AWD and M3 arms don't apply, sorry for the oversight* When my "hydro-bushings", as the shop called them, failed I just went with M3 front arms. They replace the fluid filled bushings with a much larger, solid rubber one. I figured this would eliminate the need for the bushing press and tools in my kit going forward. If you already have those shop tools, you may want to replace the bushings. Both of mine had leaked the fluid out and the passenger side had a "clunk" to it, fyi.

Last edited by BRG_N54; 05-01-2024 at 05:37 PM.. Reason: Missed the 328xi part
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      05-01-2024, 05:15 PM   #6
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It's been said but the tension strut (#8) handles fore-aft movement while the wishbone (#15) deals with lateral movements. The tension strut bushing (#9, 31126768818) is fluid filled and like all hydrobearings, fail and leak overtime. It's true that you don't really notice the degradation in handling as it is so gradual. The smoking gun is when it starts clunking under braking.

It looks like Lemforder is OE and is still made in Germany fortunately. A lot of their production moved to other countries with a drop in quality (M359 Restorations won't even use Lemforder anymore). It might be cheaper to replace the arms if you don't have access to a press

Arms: $160 for both
https://www.fcpeuro.com/products/bmw...rm-31126768983
https://www.fcpeuro.com/products/bmw...rm-31126768984

Bushings: $50
https://www.fcpeuro.com/products/bmw...nt-31126768818
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      05-01-2024, 05:20 PM   #7
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Quote:
Originally Posted by gbalthrop View Post
This makes one wonder: Did VA State Police/ Inspections put out a Memo about BMW Bushings? They (the two mentioned ;-) seem to be looking for something, but WITHOUT actually KNOWING how the front suspension & Bushings work. I "cross-examined" both about "fluid-filled bushing" leak. NEITHER seemed familiar with the concept or identified a specific Bushing/ Location that had failed.
There's no conspiracy, this is a very common issue with all fluid-filled bushings and not specific to BMWs
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