Strut bearing loose

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acat2002

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Busy sorting out some minor issues with an otherwise great coupe.

The first thing I must do is resolve this clunking noise from right front strut. Only occurs over small bumps (and not on the compression).
Took the wheel off and noticed some significant play in the top of the strut (not the strut mounting plate with three bolts - that is secure), but the roller bearing and bearing race that you can see when you take off the rubber cover at the top of the strut. (see photo)


Both struts themselves are new (within past year and w/ relatively no mileage).

The underlying question is this.......can this top bearing be replaced without disassmbling the strut completely?
Or could the large center bolt need to be tightened more?
Has anyone run into this? could you solve it without dissassembling the entire strut?
[/img]http://www.flickr.com/photos/26376951@N06/2472960778/
http://www.flickr.com/photos/26376951@N06/2472960568/
 
You probably need to replace the strut bearing, but first try to work some heavy grease, like wheel bearing grease into it.

Second, check that the large nut that tightens the shocks into the strut is tight. I have seen several instances, especially with Bilsteins where the nut is loose and you get a knock in the front end. While it is kind of crude, I use a large pipe wrench on these nuts. The Bilstein 'wrench' only works if the strut is dissassembled and even then I find it is hard to use.
 
Thanks Bill

Grease was the first thing I tried, but all that did was make the knock a little more dull sounding (still there, just less metal-on-metal sounding).

I will try to tighten the large nut, but it seems like the inner bearing race is worn. I did not remove the bearing to really inspect it. I guess there is no harm in simply trying to tighten the nut first.

I'm not going to pretend that I'm an engineer, but I can't help but wonder why there is a ball bearing at the top of the strut. The part does not rotate. I understand that the strut does pivot slightly upon compression, but it seems like a thrust bearing or ball joint type of bearing would have been a better solution for a part that has constant compression force applied. Then again, what do I know I'm not an engineer.
 
Don't prematurely knock that strut bearing!

I have seen a number of "dried out" upper strut bushings, but that mostly includes the rubber drying out. Even though the bearings themselves are susceptible to wearing out, as with any part, I would be disinclined to assume yours are worn out. They just don't see the kind of wear and heat that say a wheel bearing might receive.

More to the point, a friend's E3 had a Bilstein knock and this was sometimes accompanied by a slight binding when turning the wheel when the front end was jacked off the ground. While it seemed logical that the large nut was too tight, just the opposite resulted. The threads were somewhat bungled, but greasing the bearings and then tightening to "just over" the recommended specs and the problem (clunking and steering binding) was gone!

Good luck.
 
Well, after tightening the large nut as far as it will go, still no luck - too much play.

Bearing is definately gone

Can I simply buy the strut bearing, is it typically sold as a unit with the strut mounting plate, or NLA? Local BMW stealership? or is this "special" like everything else E9-related?

Any suggestions?
 
Strut bearings are shared with e3's and possibly e12's. They're not the cheapest part, over $100, but you will never buy another set in your lifetime. You have to disassemble the strut to replace it; the big nut you tightened is the top nut of the strut.

Call Jim @ Mesa Performance, he can hook you up.
 
thanks

Sort of what I suspected, but didn't want to go ordering parts/replacing parts without a second opinion. Further inspection does indeed confirm a bad strut mount/bearing. I think I'll take the strut down to a local shop to install the new mount/bearing (have no interest in compressing the spring with a cheap mail-order compression tool).

On the bright side, diagnosing the knock involved eliminating almost every other front suspension component. Everything else is in good order, so that gives me a little more peace of mind.

It has been said on many occasions before on this board - these cars require CONSTANT attention!
 
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