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Stemco · Brakes & Wheel End
MK42100S
In stock · ships from Knoxville
The MK42100S is an automatic slack adjuster for S-cam air brake systems on heavy-duty trucks and trailers.
Confirm the part fits before you buy. Applications and interchange numbers are researched and audited per part.
Verified fitment for 2 applications
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All confirmed applications for this part number.
Other applications
Other applications
Verify arm length, spline count, and clevis size (5/8-18" straight clevis) match your application before purchase. Always replace in axle pairs for consistent adjustment.
Part data verified against 5 catalog sources
Different year, make, or config? Get a confirmation against your truck in under a minute.
It automatically maintains the proper clearance between the brake shoes and drum as the linings wear, ensuring consistent and safe braking performance. Features include the Auto-Check™ stroke indicator for quick chamber stroke inspections, a Cam Guard lubrication system to prevent corrosion, and a clearance-sensing clutch that reduces maintenance. Typically replaced when the adjuster fails to adjust, seizes, or is damaged, restoring reliable brake function.
Part Number: MK42100S
AUTO SLACK ADJUSTER
Unit: ea
Dealer: Post Onsite
Compatibility, alternatives, and more
Parts commonly needed alongside brakes & wheel end
