kbmb02

Upper Strut Mount - Failure

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</begin info-rant>

I removed a front subframe today to prep an engine bay for refinishing, left the struts hanging as I often do. Reached up casually to rotate a strut and it fell out in my hands, almost clunking me in the noggin. "Huh?" I stared blankly at it for a moment, then at the rest of the strut bearing still attached to the fender.

 

strut-fell-out-1a.jpg.619f169c346e44c8e9d81ac8f4c4213f.jpg

 

strut-fell-out-2a.jpg.8fcaa89ed254e4031e9e65b81633db27.jpg

 

strut-bearing-failure-1a.jpg.c67b16cb4f4d36b845d784ed412c6770.jpg

 

 

It was obviously a failure; inspection and a discussion with car owner (who installed the strut mounts) told this story, as I understand it:

 

- customer purchased aftermarket strut bearing from popular seller

- while installing, customer noted to seller the bearing wouldn't rotate freely; seller assured customer it was the correct part

- customer proceeded with install using diagram and the best information they had

 

What I observed: This aftermarket strut mount had a design/manufacturing defect, in that the ball bearing assembly was located 'too far inside' (from the bottom) of the mount; and while the customer installed all the OEM washers, sleeves and shims correctly, the lower OEM washer wasn't thick enough to provide clearance between the incorrectly-located ball bearing and the top of the upper spring hat (aka pocket). The core of the strut mount grabbed/rubbed on the hat, rather than rotating freely (you can see the large diameter witness mark). In short order - less than 100 miles since customer installed it - the inner section of the strut mount broke free from the rubber surround; when turning, it wasn't rotating on the ball bearings, but rather metal vs rubber.

 

This is the aftermarket part, after failure (shown upside down) - note how ball bearing assembly is pushed deep inside unit (it's down in there 4-5 mm).

 

strut-bearing-bad-part.jpg.62ecce5216be06d76e9038a9cf4b8020.jpg

 

 

This is how the ball bearing assembly should be located inside the strut mount.

 

strut-bearing-correct.jpg.946664bc6b73606ca08704fa54febfb6.jpg

 

 

That's the witness mark: guts of strut mount was grinding on spring hat, and eventually separated from rest of mount.

 

strut-bearing-witness-mark.jpg.41f4b2229be92e95365d461071d38ee4.jpg

 

I recognize selling aftermarket parts must not be fun. In this case, it would seemingly require knowledge of OEM spec, awareness of and paying attention to reported issues, subsequent inspection of each part, and/or writing instructions so that DIY repair people not overly-familiar with these cars could be assured a reasonable measure of success and safety. (In this instance, extra shims/washers between the bottom of the strut bushing and the top of the 'hat' would have allowed the bearing to move freely).

 

At minimum, I believe, a seller ought listen to feedback, and accept returns of defective / failed / poorly designed parts. In the meantime, installer and buyer beware. -KB

</end info-rant>

 

 

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Thanks for sharing that.  Nice photos too.

 

I have a similar situation/problem, in that the top of the spring caps are making contact with the underside of the strut mount bolt heads, (such as they are).  I recently lowered the assemblies enough to reach up and feel the tops of the caps and sure enough, I can feel where flat spots have been worn, where they stick up at the end of the springs.  I see similar wear in the last photo you posted.

 

I have been wondering whether adding another thick washer would be a suitable fix.  Your description makes it sound like it might be.

 

I don't think I am getting that contact in the center though.

This makes me want to pull things apart and take a closer look.

Well, it makes me think I should anyway... not that I want to, really.

 

Tom

 

 

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failure after a 100 miles due to an obvious manufacturing defect? I should think any seller of these should be worried about a lawsuit from the accident waiting to happen. 

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I've purchased strut bearings from BavAuto twice and they've always worn prematurely (1.5 years or so). They wouldn't honor a replacement after a year. 

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I ordered new strut bearings from Blunt about two years ago. At installation they seemed too flexible to me and I was concerned about possible deformation. I was reassured by a couple of mechanics nearby that once weight was added they would be fine. Still not comfortable I called Steve. He immediately said ship them back and he would replace them. The new ones were a lot stiffer. This is not something I would have noticed before unpacking them. I don't expect him or any other seller to unpack and inspect parts like this. I appreciate his quick action. The customer must inspect new parts for obvious or suspect problems. Comparing new to old parts etc. This is a scary story though so listen to spidey sense. Some new parts that are safety related deserve more critical inspection than others. Specially with the inconsistent quality we see and hear about today.

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(edited)

I replaced my mounts when I first got the car six years ago... along with the rest of the rubber up front (all of which I bought from Blunt).

 

It was a little disappointing to open the Meyle box, which had GERMANY written all over it and find a sticker saying made in China; but not that surprising.

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What was surprising was that I noticed a difference between the two mounts I'd installed, in that the one on the right side deformed a lot more, under the weight of the car.  I noticed it due to the fact that I was hearing spring cap/bolt contact and steering was not returning as it should.

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I sent these photos to Steve and he immediately sent me a replacement, which was like the flatter one.  No complaints with the service I received, which is why I continued to buy the rest of my parts through him.

 

The mounts I removed were marked with BMW emblems on the rubber.  I swapped them with the idea that fresher is better, but now am not so sure.  I saved those old ones, since they really looked to be in pretty good condition.  I may wind up putting them back in some day.  Maybe sooner than later.

 

There is not very much clearance between the mounts and spring caps.  Another concern I have read about is that the spring caps can deform over the years, mushrooming up in the center.  I will definitely be looking closer at mine, the next time I have it all apart.  I may need to beat them back to flat.

002.thumb.JPG.2f26815d09021f0d9794a230f2acf485.JPG

 

Zooming in on this photo shows evidence of rubbing with the original (stiffer) mounts.  I guess I'll interpret that as a need for flattening the center of the caps, as well as another thick washer on top of them.

 

Tom

Edited by '76mintgrun'02
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10 minutes ago, '76mintgrun'02 said:

Another concern I have read about is that the spring caps can deform over the years, mushrooming up in the center.  I will definitely be looking closer at mine, the next time I have it all apart.  I may need to beat them back to flat.

Tom

 

Tom: On the de-formed spring caps I've seen, they tend to flatten out (rather than mushroom 'up'). And thus the washer isn't sufficient to allow everything to turn freely, and possibly resulting in the reduced clearance you describe. -KB

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Thanks Ken.  I was thinking the center had pushed down, with the edges coming up.

 

Mushrooming was a poor word choice.  Although my photo hunting brought up pictures of some shaggy parasols I picked and they way they age, they flatten out, with the edges coming up!

 

008.thumb.JPG.69a1610cf35072e734d8cd73b623b4cd.JPG009.thumb.JPG.fe2545048dd4568d205bda4fa7452281.JPG010.thumb.JPG.b0de669232bc7fea6879f8d71c299029.JPG

YUM

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Tom

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(edited)

I gotta say, at this point, most of the aftermarket rubber things that aren't Lemforder 

are heading toward the quality category of "pure junk" these days.

 

They're not ALL junk- the problem seems to be that as demand for a part diminshes,

its quality of manufacture gets steadily lower.

So Brand X strut mount for an E90 might be quite good, while the E21 version from the same

manufacturer will be utter crap.

 

Plastic parts (of which we have few, thankfully) are going the same way.

 

get off my lawn!

 

t

 

Edited by TobyB

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KB--what brand were the mounts that failed?  

 

I noticed that when I replace the upper mounts on my '73--about 8-9 years ago as part of a front suspension refurbishment--that the rubber portion that is in tension when the car's weight is on it almost immediately showed small stress cracks--just about the same as the original mounts on my '69, that were nearly 40 years old at the time.  When I did the '69's suspension the following year, the same thing happened with my new strut bearing assemblies--small stress cracks appeared almost immediately.  I've had no problems--so far--with either car, but should I worry?  That's a task I'd prefer not to do on the roadside!

 

mike

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(edited)

 

 

 

 

Edited by BLUNT

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51 minutes ago, mike said:

I noticed that when I replace the upper mounts on my '73--about 8-9 years ago as part of a front suspension refurbishment--that the rubber portion that is in tension when the car's weight is on it almost immediately showed small stress cracks--just about the same as the original mounts on my '69, that were nearly 40 years old at the time.  When I did the '69's suspension the following year, the same thing happened with my new strut bearing assemblies--small stress cracks appeared almost immediately.  I've had no problems--so far--with either car, but should I worry?  That's a task I'd prefer not to do on the roadside!

 

Were the cracks in the rubber or the coating on the rubber?  Many bearing assemblies I've seen seem to have a clear coat or something on the rubber that does crack/flake.

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2 hours ago, John_in_VA said:

 

Were the cracks in the rubber or the coating on the rubber?  Many bearing assemblies I've seen seem to have a clear coat or something on the rubber that does crack/flake.

 

+1

 

my new ones appeared to be covered in black paint which immediately flakes off when touched. Pretty hokey production method I thought. 

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5 hours ago, John_in_VA said:

Were the cracks in the rubber or the coating on the rubber? 

It appears to be in the rubber itself, not the paint, or whatever that covers the new assemblies when you pull 'em out of the box.  I suspect it's overspray from when they paint the metal parts of the bearing assembly.

 

mike

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