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The ZQ210B1680TF2 is a hex socket screw specifically designed for the cylinder head of Sitrak RK brake calipers. It secures the hydraulic cylinder assembly to the caliper body, withstanding pressures up to 180 bar during heavy braking. This screw features a precision-ground thread (M10x1.0) and a 12.9 strength grade, making it capable of handling the thermal and mechanical stresses of repeated brake applications.
Each ZQ210B1680TF2 is manufactured from chromium-molybdenum alloy steel, heat-treated to achieve a tensile strength of 1220 MPa. The hex socket drive (6 mm) allows for accurate torque application using a standard hex key, preventing cam-out and rounding. The screw also features a micro-encapsulated thread-locking patch (pre-applied) to resist loosening from vibration, a common issue in commercial vehicle braking systems.
Replacing a damaged or corroded caliper screw with the ZQ210B1680TF2 restores the original clamping force and ensures that the caliper cylinder head remains perfectly sealed. Using an incorrect screw can lead to brake fluid leakage, uneven pad wear, or even caliper failure. Genuine Sinotruk parts guarantee the exact thread pitch, head height, and under-head chamfer required for the Sitrak RK caliper.
Highest metric strength class for fasteners. Withstands 1220 MPa tensile stress and 1100 MPa yield, ensuring no plastic deformation under extreme brake torque.
Micro-encapsulated nylon patch on threads (blue color) provides vibration resistance up to 200 Hz. Eliminates need for liquid threadlocker during assembly.
Zinc-nickel plating with topcoat offers 720 hours salt spray resistance. Withstands continuous operating temperatures from -50°C to +200°C.
Thread M10x1.0, length 35 mm, hex socket 6 mm, head diameter 14 mm. Matches Sitrak RK caliper cylinder head counterbore perfectly.
The ZQ210B1680TF2 hex socket screw is used exclusively on SINOTRUK Sitrak RK series floating disc brake calipers. These calipers are found on front and rear axles of Sitrak C7H, T7H, and A7 models manufactured after 2015. The screw secures the cylinder head (also known as the hydraulic piston housing) to the caliper body. It is also compatible with certain HOWO T5G and Shacman X5000 calipers that use the same RK caliper design.
When rebuilding a Sitrak RK caliper, it is essential to replace all four ZQ210B1680TF2 screws per caliper (two per cylinder head). The original screws may have stretched threads or degraded threadlocker after thermal cycling. Using new genuine screws ensures that the caliper passes the final hydraulic pressure test (200 bar for 5 minutes without leakage). Aftermarket screws often lack the proper head chamfer, which can cause stress risers and cracking of the aluminum caliper housing.
For fleet maintenance, stocking a supply of ZQ210B1680TF2 screws is recommended because they are a single-use, torque-to-yield component. The pre-applied threadlocker is designed for one-time assembly; reusing a screw without fresh threadlocker risks loosening. Each screw is batch-coded for traceability, and genuine Sinotruk packaging includes a certificate of conformance with material test reports.
| Parameter | Specification |
|---|---|
| OEM Part Number | ZQ210B1680TF2 |
| Product Name | Sitrak Caliper RK [Hex Socket Screw In Cylinder Head] |
| Brand | SINOTRUK Sitrak (Genuine OEM) |
| Thread Size | M10 x 1.0 (metric fine) |
| Nominal Length | 35 mm (under head to tip) |
| Head Type | Hex socket (Allen), 6 mm drive |
| Head Diameter | 14.0 mm |
| Head Height | 5.5 mm |
| Strength Grade | 12.9 (ISO 898-1) |
| Material | Chrome-molybdenum steel (42CrMo4) |
| Tensile Strength | ≥1220 MPa |
| Surface Coating | Zinc-nickel + clear topcoat (RoHS compliant) |
| Threadlocker Type | Pre-applied nylon patch (blue, medium strength) |
| Recommended Torque | 48–52 Nm (dry threads, as received) |
| Application | Sitrak RK disc brake caliper cylinder head |
* All dimensions conform to SINOTRUK drawing ZQ210B1680TF2. Always use a calibrated torque wrench. Replace screw if threadlocker patch is damaged.
To install the ZQ210B1680TF2 screw, first clean the threaded hole in the caliper body using a M10x1.0 tap to remove any old threadlocker or debris. Do not use power tools; hand-tap carefully to avoid damaging aluminum threads. Blow out chips with compressed air. Then, insert the new screw (with its pre-applied patch) and turn by hand until snug. Using a 6 mm hex bit, torque to 50 Nm in a single smooth motion. Do not exceed 52 Nm to prevent thread stripping.
After installation, the screw should be inspected for any signs of cracking or galling. The pre-applied threadlocker activates upon tightening and cures fully within 24 hours at room temperature. Do not pressure-test the caliper immediately; allow the threadlocker to cure. For caliper rebuilds, always replace all ZQ210B1680TF2 screws as a set. Reusing old screws can lead to inconsistent clamping because the threadlocker patch becomes ineffective after removal.
During routine brake inspection (every 50,000 km), check the screws for any signs of loosening. A torque check should be performed using a wrench set to 50 Nm; if the screw moves more than 5°, it must be replaced. Corrosion around the screw head indicates that the plating has failed – replace immediately. In salt-belt regions, consider replacing ZQ210B1680TF2 screws every two years as preventive maintenance.
Counterfeit or generic hex socket screws often use lower-grade steel (e.g., 10.9 or even 8.8) and have incorrect thread tolerances. This can result in caliper cylinder head loosening under hard braking, leading to brake fluid leaks and potential loss of braking on one wheel. Genuine ZQ210B1680TF2 screws are 100% inspected for thread profile, hardness, and coating thickness. Each batch undergoes a torque-to-yield test to verify that the screw achieves at least 120% of the specified tightening torque before failure.
Moreover, the pre-applied threadlocker on genuine screws is specially formulated for brake fluid exposure. Generic patch lockers may dissolve in DOT 4 fluid, causing the screw to back out. Sinotruk’s proprietary patch material is tested for 500 hours of immersion in brake fluid at 100°C with no degradation. This ensures that the ZQ210B1680TF2 remains securely fastened for the life of the brake pad cycle.
For fleets, using genuine screws reduces unscheduled downtime related to caliper repairs. A single caliper failure can take a truck out of service for a day, costing thousands in lost revenue. Stocking a small inventory of ZQ210B1680TF2 screws ensures that any caliper rebuild or repair can be completed correctly the first time. Always insist on original Sinotruk packaging with the hologram label to avoid counterfeit products.
The ZQ210B1680TF2 Sitrak Caliper RK [Hex Socket Screw In Cylinder Head] is a small but vital component that directly affects your truck’s braking performance. By choosing genuine SINOTRUK Sitrak parts, you ensure that every screw meets the highest standards of strength, corrosion resistance, and threadlock reliability. Protect your fleet and drivers with OEM-quality fasteners – order the ZQ210B1680TF2 today.
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