SITRAK ZQ151C1880 BOLT
Product Specifications
| SITRAK | ZQ151C1880 |
The BOLT is an automotive threaded fastener — a hexagon-head, Torx-head, or socket-head steel bolt manufactured to a specific OEM grade, length, thread pitch, and head configuration for a defined attachment position in the vehicle's chassis, powertrain, or body structure. Automotive bolts are not interchangeable hardware items but precision-engineered components whose property class (typically 8.8, 10.9, or 12.9 in the metric system), thread geometry, shank length, head drive type, and surface treatment are each specified for the joint's clamp load requirement, the bolt's reuse profile, and the corrosion environment at the installed position. The bolt's primary function is to clamp two or more components together with a precisely calibrated axial preload that exceeds the maximum service load the joint will experience, preventing relative motion between the clamped components under operating loads — vibration, thermal cycling, and mechanical impact. The preload is established during tightening through a combination of bolt elastic stretch (in conventional bolts) or controlled plastic deformation (in single-use stretch bolts), with the final preload value determined by the torque applied to overcome thread friction and create the desired tensile force in the bolt shank. Single-use stretch bolts — increasingly common on critical joints including cylinder head bolts, main bearing caps, connecting rod bolts, and hub nuts — are specifically engineered to operate beyond their elastic limit during tightening, producing a precisely controlled plastic deformation that gives the joint a higher and more repeatable preload than conventional bolt design allows.
This unit — SITRAK ZQ151C1880 — is manufactured to OEM-equivalent specifications: thread diameter and pitch, shank length and gripped length, head drive type and across-flats dimension, property class for the required tensile strength and proof load, surface treatment for corrosion protection (zinc-flake coating, geomet, dacromet, or as-blackened), and single-use or reusable designation as applicable are matched to the original part. Supplied individually or in sets matching the joint's bolt count. Available wholesale from 1.18 USD, MOQ 1 pcs, production lead time 60-120 days.
Automotive bolts require replacement following any single-use joint disassembly where the bolt has been torqued to its plastic deformation range — reusing a single-use stretch bolt produces a clamp load significantly below the joint's designed preload, causing joint loosening under service loads and eventual fastener fracture or component separation; following corrosion that has reduced the bolt's effective cross-section, particularly on underbody bolts exposed to road salt; following thread damage from cross-threading or galling during a previous installation that prevents the bolt from achieving its rated torque; and following any service operation where the bolt's surface coating has been damaged, breaching the corrosion protection and accelerating subsequent corrosion under service exposure.
- Confirm the bolt's single-use or reusable designation from the OEM service data before disassembly — single-use bolts include cylinder head bolts on most engines, main bearing cap bolts, connecting rod bolts, hub nuts, wheel bolts on some applications, certain suspension fasteners, and various structural joints; the OEM service procedure identifies single-use bolts explicitly; reusing a single-use bolt risks joint failure under service load; order new bolts of the correct part number before beginning any disassembly that involves single-use fasteners.
- Match the new bolt to the original specification in every dimension — thread diameter and pitch, head type and across-flats size, shank length, property class (marked on the bolt head), and surface coating must all match the OEM specification; substituting a higher-grade bolt for a lower-grade does not improve the joint and may cause incorrect preload at the OEM torque value; substituting a longer bolt may bottom in the bore and prevent proper clamping; never substitute on critical joints.
- Clean the bore threads before installing the new bolt — bore threads accumulate old thread lock compound, corrosion products, and debris that prevent the new bolt from achieving the correct torque-to-tension relationship; chase the bore threads with a thread chaser tap (not a cutting tap) to clean without removing material; blow out the bore with compressed air to remove debris before fitting the new bolt.
- Apply lubrication to the bolt threads and underhead bearing surface as specified by the OEM — most modern bolt torque specifications assume lubricated threads — applying engine oil, anti-seize compound, or the specified thread lock compound to the threads achieves the torque-to-tension relationship the OEM specified; tightening dry threads to the same torque produces a clamp load typically 20–40% below the lubricated value, leaving the joint inadequately clamped; consult the OEM procedure for the specific lubricant required at each joint.
- Use a calibrated torque wrench for all critical fasteners — torque-to-yield (single-use stretch bolts) require a torque wrench plus an angle gauge to achieve the OEM-specified torque-plus-angle tightening sequence; conventional bolts require torque-only tightening; never estimate torque by feel on any safety-critical joint; verify the torque wrench calibration annually or before any critical engine assembly operation.
- Install the new BOLT (SITRAK ZQ151C1880) with the correct lubricant on the threads, follow the OEM tightening sequence for multi-bolt joints — typically a star pattern in progressive stages — apply the specified torque value or torque-plus-angle sequence with a calibrated wrench, mark the bolt position with paint marker for visual confirmation that the bolt has not loosened in service, and verify final torque after the first heat cycle on critical engine joints where bolt relaxation may occur.
| Part | Reason for Combined Replacement |
|---|---|
| Matching Nut and Washer Set Application-specific — OEM thread and grade | Where the joint uses a nut as well as the bolt — through-bolted suspension joints, U-bolt clamps, and many subframe attachments — the matching nut is typically a single-use component for the same reason as the bolt: its locking feature (deformed thread, nylon insert, or castellation) deforms during initial tightening and cannot reliably maintain the specified torque on reinstallation. Replace the nut and any captive washers simultaneously with the bolt to ensure the complete joint is renewed. |
| Gasket or Sealing Element OEM ref. varies by joint type | Bolts that seal a flange joint — cylinder head bolts, exhaust manifold bolts, intake manifold bolts, water pump bolts, valve cover bolts — operate alongside a gasket that compresses under the bolt's clamp load. Replacing the bolts without replacing the gasket reproduces the same gasket compression set that contributed to the joint loosening; replacing the gasket simultaneously with the bolts ensures the new bolts achieve their designed preload against a fresh, undeformed gasket and the joint sealing capacity is restored to its designed condition. |
| Component Being Fastened Bracket, arm, or component receiving the bolt | When the bolt has fractured in service due to fatigue or has been over-torqued to thread damage, the component being fastened — the suspension arm, the engine bracket, the body panel — may have sustained damage at the threaded bore or at the bolt-head bearing surface. Inspect the receiving component carefully before fitting the new bolt: damaged bore threads require helicoil repair before the new bolt can be installed; cracked or deformed bearing surfaces under the bolt head indicate component fatigue that may require component replacement alongside the new fastener. |