Automatic Slack Adjuster 40010211

Automatic slack adjusters on S-cam foundations

Stroke creep on an S-cam axle rarely announces itself with drama. Linings wear, slack adjusters compensate until they cannot, and pushrod travel quietly crosses inspection limits. The Haldex automatic slack adjuster listed here is a maintenance replacement piece for fleets running common North American cam brake layouts.

Automatic adjusters reduce manual clicking during PM, but they do not forgive contaminated cam paths, seized bushings, or drums that were turned past spec. Replace an adjuster when manual intervention becomes routine or when internal gears show damage during inspection.

This card is for a single automatic slack adjuster body. It is not a complete brake shoe kit, drum, or chamber. Confirm arm length, spline, and clevis orientation against the removed hardware.

Interchange stamps to compare

Supplier catalogs also list related numbers including 40020211 and the ABA token for some cross-books. Treat those as research hints only. The authoritative match remains the stamp on the removed adjuster, clevis pin diameter, and arm hole spacing measured on the bench.

Published tractor examples include Freightliner, Kenworth, Mack, and Peterbilt in the fitment table. Verify every unit with VIN data when available and with photos if a vocational spec differs from over-the-road builds.

Email support@aonetruckauto.com or use the fitment guide when two adjusters look identical except for a half-inch arm variation.

Published weight and price

Listed ship weight is 4.2 lb. Card price is $64.25 USD before tax. Neither figure replaces a torque spec or stroke limit from the axle maker.

Freight handling choices are documented on the shipping policy. Read that page before you promise a bay date to a customer truck.

Stroke verification after adjuster work

Installing a new slack adjuster without measuring pushrod stroke is incomplete work. Set chambers at proper pressure, apply brakes, and measure travel with a gauge at the recommended angle.

Compare readings to the legal limit on the data plate or OEM chart for that axle. Out-of-stroke conditions require lining, drum, or cam investigation—not repeated adjuster swaps.

Installation discipline

• Cage spring brakes correctly before loosening clevis pins on live spring units.
• Clean cam and slack splines; light lubricant only where the axle manual allows.
• Torque clevis pins and lock nuts to spec; do not leave worn pins in service.
• Re-measure stroke after a short road test and again after the first loaded trip.

Log initial stroke on the work order so the next PM can trend wear honestly.

Receiving notes

Inspect splines and arm surfaces for shipping dents. A bent arm will bind under load and mimic adjuster failure within weeks.

Unused returns follow the returns and refunds policy. Installed hardware may be excluded once mounted on an axle.

Fleet purchasing tips

Photograph the old adjuster from both sides, capture stamp photos, and measure arm length before you multiply quantity in cart. Mixed fleets sometimes carry two arm families under similar cab badges.

Wear patterns on cam and slack hardware

S-cam head wear shows as uneven lining contact and stroke that grows faster on one side of the axle. Replacing a slack adjuster on a worn cam lobe buys time but does not restore geometry. Inspect cam rollers and bushings while the adjuster is off the splines.

Vocational trucks that drag trailers through quarries see contamination in slack mechanisms from dust that passes as normal PM grit. Blow-down is not enough when paste forms inside the adjuster body; replace or rebuild according to fleet policy.

When two adjusters on one axle measure different free play, look for bent pushrods or mis-drilled clevis holes before ordering another pair.

Fleet stock keeping

• Store adjusters by arm length label, not only by box color.
• Rotate stock so older cartons ship first.
• Keep clevis pins in matched grade bins beside adjusters.
• Separate core returns by stamp to speed supplier credits internally.

Stock discipline prevents grabbing a near-match arm during a night shift and discovering mismatch at stroke check.

Alignment between slack adjusters and ABS timing

Automatic adjusters influence how quickly brake apply feels at the pedal on some ABS platforms. While ABS modules do not replace stroke gauges, uneven adjustment sometimes appears as intermittent wheel speed faults under hard apply. Measure both sides of the axle after adjuster service and log results for the ABS history file.

Clevis pin wear is invisible until stroke grows; replace pins on a schedule tied to shoe jobs rather than waiting for oval holes. Pins are inexpensive compared with roadside citations.

Stroke verification after ABA install

Automatic slack adjusters still need measured stroke after install. Adjust, then record pushrod travel with brakes released and applied so compliance files have numbers, not “felt okay.”

Spline and arm geometry must match the removed adjuster. A Haldex ABA that looks right from the catwalk can still bind if the arm hole does not line up with the pushrod clevis.

If one wheel end shortens stroke while the mate grows, inspect S-cam bushings before condemning the new adjuster. Bent pushrods from curb strikes mimic adjuster failure.

Delivery methods and packaging notes live on the shipping policy. Unused-item rules are under returns and refunds. Reach us at support@aonetruckauto.com or the contact form.

A-One Truck Auto is operated by HEAVY TRUCK PARTS, INC. Manufacturer names indicate fitment language only.