Bellcrank & shock rubbing/wear - ideas?

[Lane]

In my quest to try to rid the car of the most annoying rattles (at least 95% there!), I found that the rear shock assemblies can twist and move 5 to 10 degrees.  Not only is that enough to make noise, I found the classic wear on the shock end that others here have described.



What it looks like when it twists and the sound it makes (mostly from the springs) can be seen in this vid clip: http://www.evilatom.com/forum/shock_noise.wmv

I flipped the position of the helper springs so they're closer to the rear of the car to keep the spring separator from binding on the end of the shock during travel.  But I would like to do something to address not only this noise, but also the wear if possible.  I'm thinking that the twist of the shock body coming into contact with the edge of the bellcrank while it moves sort of 'slices' away at it, which is made more effective by the sharp edge of the bellcrank meeting the shock body end at an angle.  What I'd like to do is fit a spacer on each side so the shock body won't twist as much.  In doing so, I realize that the contact will still take place, but it will be more parallel and not angular.  Taking up this space should address the clank noise as well.

If done carefully to prevent any chance of binding, does anyone see any specific problems with this that I do not see?  As for materials, poly washers would be an option.  They'd probably wear and need to be replaced every so-often, but they're slippery and soft enough to not let anything bind.  I mocked this up around the existing spacer, although the washer should be a bit larger diameter:



Or, how about even two thin fender washers with grease between them? 

I'm just throwing out a few ideas as I'm not sure what the best way is to address this for the average driveway mechanic, or if it should just be left alone.  Any thoughts are appreciated.  I have seen the thread identifying a bearing that goes between a spring and its perch to allow twist, but it's tough to think that there isn't a simpler solution.

[positron]

I've found that if you make adjustments to the springs and not "center" the entire mass between the bellcranks after cranking and locking them they tend to lay in a bind (action/reaction of rotating the spring assy).  My guess would be that, looking on to your pic, the last adjustment of the spring was anticlockwise. Just a slight clockwise adjustment would center the mass. Once the car weight is on them they don't seem to be free oscillate otherwise they would give way during bellcrank movement.

Certainly spacers would help center and buffer metal to metal with something sacrificial between them.

Similarly, when I adjust any of the rod ends I make sure they are parallel to each other and free centered.

I've also started rotating the major spring to where it looks like it is more centered about the barrel hoping to give most possible clearance during travel.

[rfmarz@frontiernet]

THAT, like fourfather said, is the "click" that I have been hearing. It's the one that so many said was coming from the brake pads sliding in the caliper.

[Lane]

When everything was pulled apart, it was easy to see that the edge of the spring separator was making contact under compression and possibly causing some bind.  This was from the spacer in its stock configuration where it rode above the shock rod.


After swapping the springs around so the spacer now rode above the threaded part of the shock body, there was more contact.  So, I took a few mm off of the inner diameter of the aluminum.  Before and after:


This was very effective and it virutally eliminated all rub noise.  I can now only faintly hear it when pushing/pulling on the rear end at rest so I doubt it will be audible when driving.



Here's what I ended up doing with the washers on the ends of the shocks.  Poly were used to fill the gap on the forward end just to minimize the ability to twist.  On the rearward end, two stainless fender washers were used and took up most of the gap on the driver's side and reduce the aluminum 'slicing'.  There is just enough clearance left in there to be able to spin the washers when the car is at rest.  Yes, I know the bolt is in backwards in the photo - I fixed it afterward.  Weirdly, the shock to bellcrank angle on the passenger side showed more of a misalignment than the driver's side (as reported here by others as well) and also less twist play.  I attempted to use washers on that side as well, but it ended up being too tight so I will run without them.  Besides, the wear on that side was relatively minor compared to the driver's side.

After a 45 mile test drive on some local roads that do a good job at exercising the suspension, I can report that the rear end of the car is absolutely silent in a straight line.  I haven't yet had a chance to run it hard through some corners on a less-than-even surface to see if the silence holds.  I will be keeping very close tabs on these modifications going forward to make sure they cause no ill effects.  Now, only thing left to figure out is one persistent rattle on the forward driver's side suspension but I'm pretty confident I'll eventually find it.

[Lane]

[quote="Spanky"]
Did you find any signs of the driver's side rear shock had been rubbing on the black plastic intake tube that feeds air to the driver's side of the supercharger?
[/quote]

I'm assuming you're talking about the newest design smooth plastic intake tube.  Mine had at least 1/2" clearance between it and the black spring.  After I swapped spring positions, there's now about a quarter inch between the red spring and the intake tube.  No rub marks were visible.

If you see evidence of rubbing, have you tried undoing the worm gear clamps over the coupler connecting the black tube to the inlet?  Doing so may allow you to reposition the tube end further into the coupler in order to move the tube away from the spring.

[bolus]

[quote="Spanky"]
Lane,

  Your parts look exactly like mine in they way that have worn on each other. Did you find any signs of the driver's side rear shock had been rubbing on the black plastic intake tube that feeds air to the driver's side of the supercharger?
[/quote]

The shock can tub on the corrugated hose (older style) intake but the smooth intake should have some clearance.