I have an alterktion and street lynx 4 bar under my GTX (5.7/NAG1)
While I enjoy driving it hard and it handles well, I am really annoyed at how "clunky" it sounds. I want to say it sounds like the shocks completely extend, then SLAM home when I go over even the slightest bumpiness.Consequently I hear the clunk on the up and down stroke of the shocks.
I am wondering if it is the QA1 shocks??? Has anyone had this experience? I just changed all the bushings on the 4 link...they were JUNK after only 6000 miles. Thinking that was the problem, I am surprised to hear the same clunking noises and I don't even have 100 miles on the new bushings.
Would Bilstiens be quieter??????? Any ideas/suggestions?

6000 miles to destroy a set of bushing is pretty poor...Aside from the shocks, is it perhaps a binding issue with the suspension design itself that is causing the clunky feeling? (and taking out the bushing so fast) Any metal to metal contact or binding under travel perhaps?

Do you have an old pair of shocks (assuming they use a similar to stock configuration?) that you can just toss on to go for a run for a few miles to eliminate that ?

Are the shocks a bushing mounting or a bearing setup ?

Did not notice any evidence of metal to metal where the links mount in the fittings. Street Lynx admitted a batch of bad bushings and sent me replacements for free.
The shocks are bushing mounted.
It may well be an alignment issue with the links but the system was designed for 68-70 B Bodies. That does not mean I don't have something slightly out of line though. I will have to take a closer look at that. I am going to try softening the shock setting two more clicks and see what that does.

The shocks are bushing mounted, and they hold the car up to? I think you just found your problem. They should have bearings not bushings.

Do all 4 links have bearings??? I have not seen that, not that I have made any kind of study on it.

I assume we are talking rear suspension here. A triangulated rear 4 link must have induced "bind" in roll, because of conflicting arcs of the links, That's physics, and is the case on every mustang, etc with a triangulated 4 link. In a drag situation, and or only bounce situation, it is workable, in a roll situation or one side bump, something has to absorb the arc bind with compliance, Mustangs for instance use flimsy/flexible control arms to allow motion and reduce bind in addition to varying compliance bushings. It is a very compromise solution. I have addressed this issue many times here on Moparts. It is common knowledge, easily confirmed online. When the bind happens one of the handling gremlins quickly apparent, is erratic snap oversteer, as the apparent spring rates quickly appears to approach infinity, makes driveability very exciting. This compliance if not designed into a triangulated 4 link puts huge stresses on all components, weakest likely show first decline, and in your case it sounds like the bushings, or bad bushings. I would say there is not an ideal solution.

Thanks JC. This makes sense to me, although I have NO CLUE how to deal with it at this point. I can relate to the "SNAP" , not so much as "oversteer" however. This becomes apparent when gears shift at fast rates of acceleration and when I go over a bump in the road at speed. When/as the rear end settles back in it will snap or jerk slightly to the left in the rear end. It does not feel like the front end wants to go anywhere I am not pointing it.

Along with all that, the length of the control arms will affect your roll center/instant center, etc, etc.

My Holden Torana, which use a triangulated 4 link from the factory have been road raced since day one and have been rung out every way you can think of in every sort of class from stock suspension to modified. Everyone who can goes to a 3 link (most often) with a watts link. Doesn't have the binding issues the triangulated 4 link does.

Very stiff bushing used in the control arms makes it worse as well, for when it comes to the binding issues and various stresses. Adding a panhard bar on (as some people have done) adds yet another binding point. (but people do it to help with side to side movement of the diff still even with the triangulated setup)

Just guessing the length of the arms in the lynx setup were optimized for packaging in the car and not maybe ideal for handling and what not.


That all said, I run the stock setup in mine (all though with boxed lower arm and adjustable length uppers that use rebuildable spherical end (the old Edelbrock ones actually) and it all is pretty good for what it is.

I was talking about your SHOCKS/COILOVERS having bushings not your arms. The arms need compliance at the eyes.

Please define "compliance" as relates to this issue?? I have not heard that term used in this discussion before so I am curious ...remember...I am a kitchen and bath remodeler, so I am unfamiliar with some mechanical terminology.

My understanding is that "compliance" might mean that some allowable movement is allowed to account for differeing arcs of movement from unequal length control arms.
If two different arcs are travelled while somehow being paired together, a solid connection would result in a bind, limiting total travel. Using a softer bushing would allow greater travel before binding.

When using a poly or rubber bushing in a control arm, they have more "compliance" to not only twist but also axial and radial loading. As mentioned earlier the triangulated 4 link design has bind when cornering as a byproduct. Going away from poly or rubber bushings would INCREASE the bind. A Johnny joint or heim might be better to a point, until the axial and compressing forces need COMPLIANCE.

And in our world in of "cornering", "compliance" is usually the last thing we want, hence the compromise. Also, urethane even when available in different durometers, is still not thought to be compliant, and if forced to be compliant, I suspect its lifespan is greatly reduced, as the OP maybe finding out. Rubber, and rubber bushings that are larger then expected, and sometimes with holes cast in, is the direction compliance is normally found when needed, where lifespan is sought, such as OEM solutions.

When a suspension is designed, it is designed in a steady-state, with no movement of locations other than what is explicitly intended. In this state, the control arm, for instance, will move in the Z direction only [up and down]. However, when it is installed on the vehicle with rubber bushings, it will distort as it is loaded and will no longer travel only in Z.

That difference is a way to describe "compliance". Movement that is unintentional and is usually undesirable.

I think the attached pic of an OEM rear lower longitudinal link from a 5.0 Mustang with a triangulated 4 link shows the designed in compliance we are referring to well. It IMO is not a hard rubber bushing.

Here is the original diff out of my Holden (upgraded to a 9", etc) and can see they just use a normal round bushing, same idea as a Chevelle basically but with longer lower arms.

I used Aussie made poly bushing in it, but of course there are all durometers out there, these comply enough but no sloppy feeling. No issues with binding excessively from too stiff a bushing either that I can tell. Only different style bush in all the 4 arms are the uppers which I bought from here in adjustable to dial in the pinion angle. (The ones in the diff housing the upper arms mount too are the same Aussie ones in the lower arms)

That looks like a nice upgrade package. And to carry the discussion a little farther, in the LCA pic I included, I would suspect it is half the length of your Holden set up, which means it is torsionally a lot stiffer by being shorter then the longer Hodlen arms, and therefore needs greater compliance, somewhere. It is as I understand it, compliance is not needed in every connection, or there needs to a smaller amount of compliance spread between each connection, or some can be more in some and less then others. I would be curious as to what your pic doesn't indicate, are the longer LCA links boxed, or open u channels (ie very flexible)? Again as I understand it, compliance needed to prevent bind is not linear in use, and in small arcs may never be much of an issue (bind), but as some point, when suspension gets greater roll movement, say on hard cornering, the bind can occur very quickly, its results very obvious.

The factory lower arms are a U channel (there was a sway bar between them as well) boxing the lowers has been done since new basically though and I did as well. (I went to an adjustable differently mounted sway bar on mine, similar to what the race cars ran in the mid to late 70's, same for an adjustable front bar as well)

These cars were road racing cars from the onset basically, so plenty of time to work out how to do things and lots to read up on with them luckily at least as well.

They are somewhat short as well..with a 101" wheelbase. (and around 2500 - 2600 pound curb weight originally)

The bushings in my 4 link look similar to the ones in the front end of Oz's long bar on the new rear set. Street Lynx GAVE me a set of new bushings stating that in the time frame I bought it (07-08) They had a supplier that used "powder metal"??? their words exactly. I could not tell the difference looking at the old and new. I will see if I can take a pic of the ones that failed so you guys can see what happened.