In stock trim, like my '07 Classic, one of the biggest of these issues is the stock steering system - it has a weakness that is best addressed sooner than later.

After much research I decided to fix the problem before it became serious and more expensive to fix. With just 3000 km on the clock I installed the GM 8-Lug Pitman and Idler Arm Support Kit from Cognito Motorsports.

Here's the why and the how:

Driver turns steering wheel which turns steering shaft (1) which turns steering box (2).

Steering box provides power assist and turns the Pitman arm (3) in an arc.

The relay rod (1) is connected to the steering knuckle (and therefore the wheel) via a tie-rod (2) and tie-rod end (3).

As relay rod moves left and right, the wheels are steered left and right.

Simple, eh?

Yes - BUT - there is one flaw in the way the system is designed and it concerns the joints between the relay rod and the Pitman and idler arms.

The next section explains the problem, it's cause and effects.

As mentioned, the problem stems from the rod-end joints that are part of the idler and Pitman arms (1) and join the arms to the relay rod (2).

These joints need to allow for rotational movement between the arm and the relay rod so that the relay rod can be steered left and right.

This view from below also illustrates, by way of the double-headed arrow, the undesired fore-aft movement between the arms and relay rod.

Recall that the wheels are mechanically connected like so: wheel - steering knuckle - tie-rod - relay rod - tie-rod - steering knuckle - wheel.

As the relay rod wobbles back and forth, front to back, there will actually be minute changes in the length of this mechanical connection. This is illustrated by the red lines drawn above the tie-rod-to-relay rod joint in the pic at left. Though grossly exaggerated, we can clearly see how a fore-aft motion of the relay rod changes the length of the wheel-to-wheel mechanical connection. This means that it is impossible to set, let alone hold, a consistent toe-in setting for front end alignment.

You can easily demonstrate this situation to yourself.

Jack up one front wheel, leaving the other on the ground.

While rocking the wheel, look under the truck at the steering linkage.

Observe the joint between the idler arm (yellow arrow) and relay rod (green arrow) and you'll see the relay rod moving back and forth, front to back (red arrow).

The kit consists of:

1 - A small quantity of Loctite 271 red high-strength thread locker
2- Two 3/4" bore x 5/8"-NF18 spherical rod ends (Heim joints)
3 - Two fine thread shank nuts
4 - Two coarse thread shank nuts
5 - Two 9/16" lock washers
6 - Four 5/8" jam nuts
7 - Idler arm bracket
8 - Pitman arm bracket

It isn't strictly necessary, but the installation is a lot easier if you jack up the front end of the truck and support it securely on jack stands.

Never work under a truck supported only by a jack.

If your truck has the factory plastic shroud, its removal is the first step.

Undo the four 15mm bolts and remove the shroud.

Moving the anti-sway bar out of the way isn't part of the instructions and isn't strictly required but I found that it makes the rest of the job much simpler.

Remove the four 10mm bolts holding the front anti-sway bar clamps to the frame...

With a 1-5/16" wrench, loosen the nut securing the Pitman arm to the steering box shaft.

I shot this pic before removing the anti-sway bar - you can see how it's in the way.

Place the Pitman arm bracket in place as shown here. Place a 9/16" lock washer in place on the Pitman arm stud as shown (red arrow); then simultaneously slide the large hole in the bracket over the steering box shaft and slide the bore of the rod end over the Pitman arm stud.

Holding the bracket in place, reinstall the lock washer and nut on the steering box shaft and finger tighten.

The Cognito kit comes with silver- and gold-coloured shank nuts. The shank nuts are inserted through the bores of the rod ends and tightened onto the studs of the Pitman and idler arms.

The gold-coloured shank nuts have a coarse thread and are for use with factory or OEM Pitman and idler arms.

The silver-coloured shank nuts have a fine thread and are for use with aftermarket Pitman and idler arms.

Depending on the brand or combination of brands of arms you have on your truck, you may need to use either the gold nuts, the silver nuts, or one of each - just match the thread of the nut to the thread of the stud. Vernon from Texas, reports: "I ended up having to use one silver and one gold to install the braces on my new Napa Chassis (made by Spicer) idler and pitman arms. "

As on the Pitman arm side, slip the idler arm bracket in place over the idler arm pivot and idler arm stud, making sure the 9/16" lock washer is in place between the rod end and relay rod (red arrow).

Apply some thread locker to the threads of a shank nut and thread it onto the idler arm stud to hold the bracket in place (green arrow).

Reinstall the bolts securing the idler arm pivot to its bracket and tighten to 73 ft/lbs.

Use a wrench or other support between the relay rod and frame (red arrow) to prevent the wrench on the nut from scratching the polished shaft of the steering stabilizer as you tighten the bolts.

Tighten the idler arm pivot nut to 85 ft/lbs.

Then, using a pair of 15/16" wrenches, tighten the jam nuts to 85 ft/lbs, jamming the Cognito bracket between them.

Here's how the kit works:

The Cognito bracket "captures" the relay rod in a "double-shear" mounting, meaning that the relay rod is supported on both sides. Also, the bearing in the rod end attached to the Cognito bracket rotates in its race, allowing the steering to move left and right, but cannot move fore and aft in its race.

Combined, these features mean that the relay rod no longer moves in the unwanted fore-aft plane as indicated by the red arrow.