I finally popped the c-clip off to check my spherical bearing inside my HMS strutmounts and discovered that this set of bearings is still in perfect shape (Upperend Aurora bearings, not the stock COM-12's they came with- but same exact dimensions). What I have discovered is that the knocking noise I am getting is excessive play between the bearing and the c-clip that was never there before. The clip is not bent. What has happened is the aluminum has fatigued and stretched from the compression and rebound forces of the strut and this upper lip of the groove that retains the c-clip has bent upward ever so slightly- but enough to make a fairly loud knocking noise going down the road.

I am curious if anyone else is experiencing this problem with the HMS or even the Spohn aluminum strut mounts? I am going to have to have a shim made to slip underneath the bearing to take up the play that has formed. Hope this doesn't get worse.

 

It will . A property of aluminum that makes it bad for long term suspension components without a softer intermediary (like a rubber bushing). Even then aluminum will still stretch, only the slop won't cause rattles like it is in your case.

 

My thoughts exactly, thats why i posted this info. Now that I have fully done the testing on these units, we know they are not going to withstand long term use under higher damper loads. Time for someone to make them out of steel. And I hate to say it, but I would not recommend anyone buy these style unless that bearing retention desiogn is improved upon.

Ps- Its not a rattle (rattle sounds so crappy) its a knock just like a bad rodend will make.

 

Ah man...if your mounts are rattling then I can just imagine if had those mounts. Cause I push the suspension to it's limits like crazy. O_o I guess the stock ones are the best option...

 

GM doesn't spend $$$$$$$ on their designs for nothin. Everything has it's pros/cons. This just so happens to look awesome under the hood and preform with the least amount of bind but it's design is high maintenance. If not kept up there is slop and slop in the strut of a mcpherson style suspension is a major issue.
I still like my idea of just "spacing" the stock mounts to get the same effect.
You might want to try and install some paper gaskets/spacers first to see if it's really knocking. Then measure how many sheets went in to get rid of the knock and make the spacer/shim that thick. Do NOT make the spacer/shim out of aluminum .

 

Like I baby my car

 

first off, you guys are blowing this out of proportion. We are talking .003" of a shim I need in there after a year and a half of hard abuse. I run a very lightweight nose with wvery heavy rate springs (I run stiffer spring than just about every V8 car here) and I run Koni yellows on full adjustment) An I run this car hard on roadrace courses. I don't think many here do more than parking lot slides.

 

Yes, I have a set of HMS that had the same problem...I shimmed it and it`s been quite..How long have you had them on your car..Miles?

 

Things don't get loose and just get slightly worse over time. If there is any slop it'll exponentially get worse.
I was blowing the slop out of proportion but once it becomes audible it's serious in my book. Then again the FSAE car's I've built never had ANY slop and adjusted for the lowest possible hysteresis. So yeah, I'm a stickler for tight things.
Not but a few months ago was one of my LCA bolts rusted loose! Damn thing sounded like the rear of my car was going to come flying off! Believe it or not, it DID make a difference in the cars stoplight launching. New bolt, no slop but more hysteresis = happy predictable launchs...
What would be interesting is having your car go to the NJ DMV and getting the front shock test done. It's pretty annoying but cool at the same time.

 

I/m guessing about 15,000 miles on them. The first Com-12 bearings I wated in about 1 1/2 months. It was definately the bearings on both side the first time that were the problem. I put the new stronger Aurora bearings in there and it has been fine until about a month ago( been in there 1 year exactly). I am not so certain that it POSITIVELY will get worse. I may, it may not. The metal has compressed. and in my opinion, it will only compress so much. Its not like its bending and will eventually break off. WIth a car as solid as mine, it doesn't take much of a very small gap to create noise. This car is far from the cadilac ride of a WS6 V8- and I'm not being sarcastic when I make that comparison. The suspension doesn't move when I try and bounce a fender, only tire flex- again this car is solid so any knock is going to travel through it and be heard and felt. My springs are larger than the WS6 springs and I have them on a lighter weight V6 car.

 

Welcome to the wonderful world of aluminum suspension parts. I figured that the c-clip would wear the slot larger over time, just not so quickly. Now we are getting some hard data. Of course you're wasting bearings so it only stands to reason that you'd get wear before most who aren't as hard on their cars. Even with a shim, the grove will expand. The aluminum is starting to fatigue, check for stress cracks.