Control Arm Washer with Fitting Position Front and Rear, Front for 2009 Pontiac G8 Base

A washer in a suspension joint is not a spacer or a packing piece. It is a structural component spreading several tons of clamping force across a bracket face.

Get it wrong on your Pontiac G8 and the joint loosens over months regardless of how accurately the bolt was torqued.

What a Washer Does in a Clamped Joint

Torquing a suspension bolt stretches it, and that stretch generates clamping force pulling the two faces together.

All of that force arrives at the bracket through whatever sits under the bolt head and the nut. Without a washer, it concentrates into the small area of the head itself.

A washer spreads it across a larger area. The pressure on the bracket face drops in proportion, which keeps the metal below the point where it starts to deform.

It also provides a smooth bearing surface for the nut or head to turn against. Friction there affects how much of your applied torque becomes clamping force rather than being absorbed in the joint.

On an arm pivot carrying braking and cornering loads, both of those jobs matter continuously rather than occasionally.

Hardened Washers and Why Softness Fails

This is the part that decides whether a joint holds.

A standard flat washer is mild steel, soft enough that the clamping force under a high grade bolt deforms it. It dishes slightly, cupping away from the bolt head.

That dishing absorbs some of the bolt's stretch, which means the clamping force drops. The joint is now held less firmly than the torque wrench suggested, and it continues relaxing as the washer deforms further.

A hardened washer resists that deformation almost completely. Specifications such as F436 for imperial applications and HV300 for metric describe hardness levels suited to structural joints, and a hardened flat washer stays flat under the load a 10.9 or Grade 8 bolt generates.

The rule here is straightforward enough to apply. A high grade bolt needs a hardened washer, because a soft one becomes the weak point in a joint that was otherwise specified correctly.

Substituting a hardware store washer under a suspension bolt is the same mistake as substituting the bolt itself.

Embedment and Why Joints Lose Torque

A clamped joint loses some tension in its first hours of service, and understanding why explains the retorque interval.

Microscopic high points on the mating surfaces carry the initial load, and under clamping pressure they flatten out. That is embedment, and it happens on every face in the joint.

As those surfaces settle, the bolt's stretch reduces slightly and the clamping force with it. On a well specified joint the loss is small and the remaining clamp is sufficient.

A soft washer adds a large amount of embedment because the whole washer deforms rather than just the surface. The joint loses far more tension, and it keeps losing it.

Painted or corroded surfaces behave the same way. Paint crushes under load, and rust scale crumbles, so a joint clamped against either settles considerably more than one on clean metal.

That is why the surface the washer sits on is worth cleaning rather than assembling over whatever is there.

Shim Washers and Alignment

Washers appear in a second role entirely on some applications.

Where camber or caster is adjusted by moving an arm's mounting position, shim washers stacked either side of the mount set that position. Move shims from one side to the other and the arm's pivot shifts.

That makes the washer stack part of the geometry rather than just the clamping arrangement, and the number and thickness of shims is an alignment setting.

Count and record the shims on each side before dismantling anything. Reassembling with a different stack changes the alignment, and the setting is not recoverable by eye.

Shim kits supply a range of thicknesses for exactly this reason, since the correction needed varies by vehicle and by how far the geometry has moved.

Have the alignment set afterward regardless, since the shim position determines the result.

Cupped and Conical Washers

Not every washer in a suspension is flat, and the shaped ones are doing a different job.

A cupped washer has a formed dish that locates and contains whatever it clamps. On a bushing or an isolator, that cup stops the material extruding sideways out from under the clamping load.

Conical or Belleville washers act as a spring, maintaining tension in a joint that moves or where thermal expansion changes the stack height.

These are not interchangeable with flat washers and a flat one in a cupped position loses the containment that was the point of the design.

Fit what came out, in exactly the same orientation. A cupped washer reversed clamps on its edge rather than its face.

Why Pontiac G8 Control Arm Washers Get Replaced

The case for new hardware extends to washers more than people expect.

A washer that has dished under load does not return to flat when the joint is released. Refitting it means starting with a component that has already absorbed some of the bolt's stretch.

Corrosion is the other common reason to replace one. A pitted washer face has less bearing area and an uneven surface, so the clamping load concentrates rather than spreading.

Galvanic reaction between dissimilar metals leaves a washer welded or seized to the face it sits on, and removing it damages both.

Washers cost almost nothing against the labor of reaching the joint, which makes reusing them a poor economy on any suspension work.

Sizing a Pontiac G8 Control Arm Washer

Four dimensions decide whether a washer does its job, and all four matter.

Inside diameter has to suit the bolt passing through it. Too tight and it will not seat, too loose and the washer can shift under load, concentrating the clamping force on one side.

Outside diameter sets how much area the load is spread across. A larger washer distributes better, and it has to fit within the bracket face without overhanging an edge, since an overhanging washer bends rather than spreading.

Thickness affects how well the washer resists dishing. A thin washer in a high load joint deforms where a thicker one of the same material does not.

Hardness is the fourth dimension, and it is the one not visible by eye. A washer that looks identical to the original can be made from entirely different material.

Measure the original with calipers rather than matching by appearance, and where the original is damaged beyond measuring, use the specification for the bolt grade it works with.

What Washers Do Not Fix

Worth stating, since they get used to solve the wrong problems.

An elongated bolt hole is not fixed by a larger washer. The washer spreads load across the bracket face while the bolt still moves within an oval hole, and the bracket needs repair or replacement.

A gap in the joint stack is not a washer problem. Filling it with washers means the wrong component is fitted somewhere, and packing it out leaves a joint that settles.

Insufficient thread engagement is not solved by removing a washer to gain length. The washer is doing structural work, and a bolt that is too short needs replacing with the correct length.

And a joint that keeps loosening is not cured by adding spring or lock washers to a high tensile assembly. Those are designed for lower load applications, and in a properly torqued suspension joint the clamping force itself is what prevents loosening.

Fitting and Orientation on Your Pontiac G8

A few details decide whether the washer does its job.

Clean both bearing faces thoroughly before you assemble it. Paint, underseal and corrosion all compress under clamping load and cost you tension.

Check which face of the washer goes against the bracket. Punched washers have a slightly rounded edge on one side and a sharp edge on the other, and the rounded side should face the bolt head.

Use one washer per face rather than stacking several to fill a gap. A stack settles more than a single washer and loses tension faster, and a gap needing filling usually means the wrong part.

Torque at ride height with the vehicle on its wheels where the joint includes a bushing, so the bush takes its set in the working position.

Retorque after the first few hundred miles on anything newly assembled, which is where embedment has done most of its work.

Find Control Arm Washers for Your Pontiac G8

Control arm washers sit within our nuts, bolts and screws lineup, with matching control arm bolt kits.

Select your Pontiac G8 to see the control arm washers and washer kits available for it. Match the hardness and dimensions to the original rather than substituting a generic flat washer, since the washer is carrying the same load the bolt is.