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-   -   Clunking rear shock mounts: Solved? (http://www.focusfanatics.com/forum/showthread.php?t=157728)

CaysE 04-23-2008 07:36 PM

Clunking rear shock mounts: Solved?
 
I believe I may have stumbled on the reason that the rear shock mounts clunk when replacing the dampers:
Overtightening the top shock nut.

That's all. The top nut is a crush nut, meaning it will hold its place no matter how far down you tighten it... but when most people replace the shocks, they tighten them all the way down, crushing the inner sleeve of the rubber bushing and putting the steel plate almost in contact with the dust boot clips that stick out. Over time, suspension travel continues to damage and crush the inner sleeve and the steel plate contacts the dust boot clips, causing clunking.

I also understand now why Ford designed them this way in the first place: low speed comfort. On the highway, shock travel occurs quickly, leaving the top bushing mostly out of the picture. On the backroads, shock travel occurs slowly, leaving the top bushing to do all the work. Now that I put the delrin shims in, the rear feels VERY stiff when driving down my street, but feels great on the highway. Clunking is gone.

I may get new top mounts and replace them, leaving the shims out. The inner sleeve of the rubber piece is pretty messed up from the overtightening, otherwise I would just try it with the ones I have now.

Anyone with clunking top mounts want to try it out? You should only need to tighten the top nut down before the steel washer starts moving downward in the rubber bushing.

HaveBlue83 04-24-2008 12:34 AM

i never crank really hard on them....especially the fronts....I have KYB AGX...def not trying to snap off the adjustment tab.

loudfocus01 04-24-2008 02:03 AM

You are exactly right CaysE.
I overtightened mine before, and it caused a clunking noise.
So I loosened them up, and no more clunking.
Good post!

Egz 04-24-2008 06:49 AM

P-51 on fj used to make shims that you can put inside the rubber piece below the washer. No clunking, and solid action.

CaysE 04-24-2008 07:07 AM

LOL in case you missed it, I put the shims in, and will be ordering new top mounts to install without them.

Geezer 04-24-2008 03:00 PM

Any shock that has a shaft that uses a single nut and bushings above and below the upper shock mount should never be fully tightened. That fully compresses the two rubber bushings which can cause noise and doesn't let them do their job correctly. The top shock mounting shaft has to be able to move and not be bound up. Most install directions that come with shocks clearly indicate how much the top bushings are to be compressed. Most of the time there's even a graphic. In most cases you're suppose to "slightly" compress the bushings and then stop tightening.

CaysE 04-24-2008 04:50 PM

This has been an issue for years now; I'm surprised noone has brought this up.

loudfocus01 04-24-2008 11:20 PM

Yeah, all the "clunking suspension" threads over the years and you are the 1st one to bring this up. Good job CaysE. I came to your same conclusion a while back when my suspension was clunking in the back, but I never thought to post about it.

CaysE 04-24-2008 11:36 PM

Well negative rep for you, then! [hihi] j/k

WD40 04-25-2008 04:49 PM

On my recent Koni damper/spring install, I tried something completely different.
I ditched the factory parts and used poly bushings.
No noise, and nice and tight.

I don't have a pic, but this is what I used.
From top down:
1) Koni supplied lock nut
2) Washer
3) Poly bushing
4) Car body-shock mounting hole
5) Poly bushing
6) Koni supplied washer

The bushings are compressed about 1/8 inch each when torqued to 20 ft-lb.
I'm really liking this setup so far.
It got rid of a bunch of funky noises I had out back, and as mentioned, the suspension is really tight now.
It reacts very quickly to steering inputs.

If/when I can find a pic, I'll post it up.


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