rear end suspension

[bgriff]

84 ltd lx, 5.0 sefi, t5. I hope to have 3.73 gears in my replacement 8.8 rear end next week. Since I am doing the replacement, I figure I should upgrade the upper and lower control arms and shocks. I am not sure about the springs or sway bar. I would appreciate any advice and suggestions.

[Ruffi]

Pretty sure if your doing springs you want to do them in sets, front and rear. I found the stock sway bar fine for me on my 85 although all of this depends on how fat your wallet is.
GL

[ukravit]

I went with Mustang GT suspension parts, except for springs. Mustang springs act differently.
Changing rear springs made the fronts seem odd so all were changed. well worth the effort in ride quality and performance.

[BadZ]

A buddy just updated his LTD LX with tubular uppers and lowers with urethane bushings. Stock sway bar and springs. And I must say it works very well. Just has bad wheel hop on launch since the T5 swap.

Lon

[bgriff]

Any particular brands of control arms and shocks?

[FoxChassis]

Urethane bushings .... NO. They do not allow the axle assembly to 'articulate' (move up/down/side-to-side/rotate) like it is supposed to do. Either stick with rubber bushings or go with heim joints. Do not use urethane bushings.

[BadZ]

Any particular brands of control arms and shocks?

The control arms were something on sale at CJ Pont Parts. The shocks are parts store cheapies at this point. He just got lowering springs (CJ's store brand which is Eibach). So new shocks are coming as well. The rear end has heim joints at the axle housing. I know how people feel about the urethane bushings causing limited movement. But I feel a "properly" installed set with lubricated bushings work very well in most circumstances. If you are looking for all out corner carving, heim ends are the way to go. Pretty rough on the street though. The suspension has limited travel with lowered springs and stiff sway bars anyhow and it doesn't need full articulation like an off-roader would need.

Lon

[JACook]

The reason we say urethane bushings don't belong in the rear of a Fox is simple. They're just plain too stiff.
Doesn't matter how much you grease them, because the control arms do not -ever- operate in a straight arc.
Not even the lowers. Simple urethane bushings in simple tubular arms, like what's in that CJ Pony Parts kit,
create suspension bind. Lubrication doesn't enter into it. Nor does installation technique. It's all about the
geometry of the triangulated 4-link type of rear suspension (what's under the rear of our cars).

In any triangulated 4-link, the geometry has exactly one position where it wants to be. If you were to put
solid aluminum bushings in those tubular arms, you could literally remove the rear springs and when you
put the rear wheels on the ground, the suspension would not move much at all. This is because all four of
the rear control arms always operate in compound arcs, even if the suspension is only moving straight up
and down. In order to move, the triangulated 4-link suspension has to include some means to allow the
control arms to deflect from the arc prescribed by the pivot point. These are not simple hinge joints.

The means to do that can be anything from rubber bushings to monoballs and heim joints. The latter are
not acceptable in a mass-produced automobile for a variety of reasons. So from a production perspective,
the balancing act with this type of suspension has always been about providing enough bushing compliance
for the suspension to move, vs making the bushings firm enough to keep the rear end where it belongs,
vs durability and NVH concerns.

And this is where much of the aftermarket gets things horribly wrong. Urethane is not compressible enough
to do the job without undesired side-effects. The compound angles the upper arms must deal with are simply
too large, even if you leave the rubber bushings at the axle end of the arms. The resulting suspension bind
combines with the rear spring and stabilizer bar rates in very non-linear ways, even before you introduce
body roll into the equation.

But worse than that is that the bind does not actually prevent the suspension from doing what it must do.
No, those arms just transfer a portion of the necessary compliance into the chassis structure, which was
never designed to tolerate such a high degree of repeated flex. This causes the torque boxes and the area
around them to work harden, and eventually fail.

Urethane-bushed tubular upper control arms have no place in a triangulated 4-link rear suspension. Ever.
The companies that make and sell those arms are either ignorant, dishonest, or some combination of the
two. Sorry if that sounds harsh, but there's really no way to sugar-coat this.

And while the lower arms do not have to deal with compound angles as extreme as the uppers do, I still
do not recommend simple urethane bushings there either. There are far more effective solutions available,
even without resorting to heim joints. Before anyone ever buys a set of those cheap arms, they should
spend some time educating themselves.

I don't like to shill for any brand, but Maximum Motorsports has a lot of good tech info on the Fox rear
suspension, and they also sell products that just plain work. Yes, you'll pay a bit more than $142 for the
set. But given what those $142 arms are going to cost you over the long term, it'll be worth every penny.

[bgriff]

What about shocks?

[JACook]

Fundamentally, the job of the shocks is to control the suspension, and that function ties directly to the spring
rates you're using. But beyond basic function there's several factors to consider up front.

The shocks you choose really depend on what else you've done with the car, along what you're looking for the
car to do. If your priorities favor straight-line weight transfer, the decision points are very different than if you
favor carving corners. Or different again if you're just looking for a daily driver with good road manners.