Front Suspension Knock

Springs and shocks. What keeps your car tight around corners?
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Front Suspension Knock

Postby EBSF » Fri Oct 05, 2012 5:41 pm

So, I overhauled the struts on my E30 about a month ago, which hadn't been done since the car was new. New Bilstein HDs, new soft parts (upper/lower spring pads/shims, strut mounts/guide support assemblies), and new hardware, and keeping the stock springs for a variety of reasons. I hadn't done this job before but I am very handy, very careful, and had researched the topic extensively over a couple of months while I was figuring out my parts list. Other than some minor glitches (a broken brake caliper bolt and having to spend a day finding a better ball joint separator), everything went according to spec and to plan.

The immediate outcome was great. Cornering improved significantly, tire bounce going over road seams on the freeway was eliminated as was rocking when stopping abruptly, and the previously aggressive front-end shimmy when braking at speed is entirely gone. So far, so good.

The problem is this: The right side knocks badly when going over a road patch, pothole, or the curb lip into a driveway, although not on going over speed bumps more slowly or those plastic reflective lane markers. So, higher-acceleration bumps. I re-inspected externally and everything is seated properly, the mount nuts and ball joint lock nuts are torqued to spec, and the gland nut (the collar nut retaining the shock in the strut housing) also is tight.

The question is, what's up? Before I spend a weekend taking the strut assembly back apart, I thought I'd see if anyone had any thoughts about what I should be looking for. I'm guessing the shock may be loose inside the strut housing perhaps, or that the shock itself may be bad (although I wouldn't know how to determine that). Alternatively, some other suspension component may be involved that I am not thinking about. Of course, the real problem may be user error by a newbie. Any thoughts would be greatly appreciated.


**Problem aside, one lesson learned on the project: I highly recommend the Harbor Freight universal ball joint separator for removing the control arm and tie rod ball joints. A pickle fork will almost certainly shred the rubber boots, besides being a chore to use. Once I finally got the tool, I had all four joints off in less than ten minutes. Pelican also has a somewhat similar tool but it is more than twice the price ($46 cf. $19.99) and may not be versatile enough to work on the control arm joints.
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Re: Front Suspension Knock

Postby Yoshi » Fri Oct 05, 2012 5:50 pm

answered you on tech. got al ink for the balljoint separator?
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Re: Front Suspension Knock

Postby EBSF » Fri Oct 05, 2012 6:34 pm

I actually bought the ball joint separator at one of Harbor Freight's retail stores but to find it online, go to their site and input the item no., which is 99849, in the search box. It's called, '3/4" Forged Ball Joint Separator' and the brand is U.S. General, which is their house brand.
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Re: Front Suspension Knock

Postby Yoshi » Fri Oct 05, 2012 6:35 pm

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Re: Front Suspension Knock

Postby M20_fever » Fri Oct 05, 2012 7:10 pm

maybe answer him here also Yoshi, good reference for other members.
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Re: Front Suspension Knock

Postby ponycarman » Fri Oct 05, 2012 8:06 pm

I need to grab one of those one day. I have the old fork style. They are a pain to use lol.

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Re: Front Suspension Knock

Postby Yoshi » Fri Oct 05, 2012 8:11 pm

I think it's probably the gland nut loosening or not being tight enough or the shock nut that keeps it to the camber plate. I've had both of those happen before. Also brake calipers are possible but not as likely. MAYBE loose sway bar link. Something is loose.
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Re: Front Suspension Knock

Postby EBSF » Fri Oct 05, 2012 8:33 pm

Something's definitely loose. The question is what. I'm going to eyeball the strut nut in a minute and the sway bar links and locknuts over the weekend. I doubt it's the calipers because those were torqued to 65 ft.-lbs., but you never know and I'll check those, too, when I have the wheel off. I'll need to schedule a weekend to dismount and dismantle the strut to check the gland nut, though.
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Re: Front Suspension Knock

Postby M20_fever » Fri Oct 05, 2012 11:49 pm

did you remember to put the washer back on top of the strut top?
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Re: Front Suspension Knock

Postby EBSF » Sat Oct 06, 2012 1:55 am

All the small parts went back on in the right order, or at least that's my distinct recollection. I don't think it's the case that I missed this but we'll find out for certain in a week or two when I get the strut dismounted and disassembled. That of course will be one of several things I'll be checking closely.

I'm hoping to find at least some small glitch because I honestly can't think of what I missed along the way and my greatest fear is finding nothing.

The top "shock nut" on the end of the shock shaft is tightened down, by the way.
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Re: Front Suspension Knock

Postby Nsquared97 » Sat Oct 06, 2012 3:14 am

On sale for $16.99 now, going to have to pick one of those up soon. Keep us updated on what you find out too, I most likely will be going through all of that too in a couple months.
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Re: Front Suspension Knock

Postby EBSF » Sat Oct 06, 2012 6:14 am

Another hypothesis that has been posed is that it may be the control arm ball joint, because the control arm also is presumably original if the prior shocks were. I have what purport to be the complete service records and there is nothing to suggest any prior front suspension work, so this likely is true.

This also is consistent with my sense that I did get the strut assembly back together correctly. I may have muffed it somehow but I'm not certain that's the case and it won't do much good re-overhauling the thing if there is another explanation.

The first question is, whether removing and reinstalling the ball joint connector could have ruined it because the knock didn't occur before this strut overhaul. The second question is, whether this might simply be a case of not having reinstalled the ball joint correctly and if so, how to fix that. The third question is, how to test for a bad ball joint.

Thoughts?
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Re: Front Suspension Knock

Postby Nsquared97 » Sat Oct 06, 2012 6:32 am

So it's the original ball joint/LCA? IMO I would replace them then, you've done all that work, might as well get those taken care of too.
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Re: Front Suspension Knock

Postby Yoshi » Sat Oct 06, 2012 1:05 pm

I'd replace them but I don't think that's your issue. it won't make a knock that big. I think you didn't do the washer stack right on the sock where it meets the camber plate (what tony said). That's happened to me before. unfortunately, it's hard to tell until you get it all back off.
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Front Suspension Knock

Postby ten2doyle102 » Sat Oct 06, 2012 2:42 pm

Is it possible that the strut top itself it toast? Ive had those give me trouble before.

If you grab the fender and lift up and down on it, can you get it to make te same sounds? Maybe useful in narrowing the location of the clunks
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