CUMMINS 4995266 CYLINDER KIT
Product Specifications
Product quality
OEM Equivalent Grade
Wholesale price USD
$11.47
Wholesale price CNY
¥77.76
bolt MOQ (Minimal order)
30 pcs
local_shipping Production time
30 days
package_2 Shipping Weight:
—
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Application (cross references) 1
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| CUMMINS | 4995266 |
Overview & Operating Principle
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The CYLINDER KIT is a complete repair kit containing all the sealing, dust protection, and hardware components required to overhaul a disc brake caliper in-situ without replacing the caliper body — restoring the caliper's hydraulic integrity and mechanical freedom of movement to as-new condition at a fraction of the cost of complete caliper replacement. A standard caliper repair kit comprises the piston seal — a square-section EPDM rubber ring seated in a machined groove in the cylinder bore that seals hydraulic pressure between the piston and bore and retracts the piston by a precise amount when pressure is released to provide the running clearance between pad and disc — the piston dust boot that excludes road contamination from the piston-to-bore interface, slide pin rubber boots that seal the slide pin bores from road salt and moisture, slide pins themselves where worn, and anti-squeal shims and hardware clips for the pad mounting. On rear calipers with integrated electric parking brake mechanisms, the kit additionally includes the thread seal for the EPB motor shaft and any seals for the parking brake spindle bore.
This unit — CUMMINS 4995266 — is manufactured to OEM-equivalent specifications: piston seal cross-section diameter and compound hardness, dust boot inner and outer diameter and profile geometry, slide pin boot profile and material, slide pin diameter and surface finish tolerance, and all hardware dimensions are matched to the original caliper's specifications. Supplied as a complete kit with all components required for a full caliper overhaul. Available wholesale from 11.47 USD, MOQ
Caliper seal kits are the correct repair intervention when a caliper shows brake fluid weeping from the piston area or dust boot, a piston that does not retract correctly after pad compression, or a caliper that binds on its slide pins causing uneven pad wear — provided the caliper bore and piston surfaces are confirmed free of corrosion pitting and scoring that would prevent the new seals from maintaining hydraulic integrity. A cylinder bore with deep pitting or a piston with surface corrosion cannot be resealed reliably and requires complete caliper replacement; always inspect bore and piston condition before committing to a seal kit repair.
Symptoms & Diagnostics
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Brake fluid weeping from behind the dust boot or visible wet staining on the caliper body at the piston face — the piston square-section seal has failed, allowing hydraulic fluid to bypass the piston and migrate past the dust boot; the brake fluid level in the reservoir will be dropping slowly; the affected wheel's braking force is progressively reducing as fluid is lost from that circuit.
Brake pedal that slowly sinks to the floor under sustained moderate pressure with no external fluid leak visible — the piston seal is bypassing internally under sustained pressure, allowing fluid to flow past the piston without external weeping; this internal bypass fault requires caliper overhaul or replacement and is confirmed by a brake pedal that firms up immediately when pumped but sinks again under steady hold pressure.
Caliper piston that does not retract when the pad is pushed back with a piston retraction tool, or that requires excessive force to retract — the piston seal has hardened and lost its rollback elasticity, or road contamination has entered the bore through a torn dust boot and corroded the piston-to-bore clearance; inspect the dust boot for tears before forcing the piston back as driving a corroded piston damages the bore.
Uneven brake pad wear — inner pad significantly more worn than outer, or one side of an axle more worn than the other — seized slide pins are preventing the caliper from floating correctly; the piston-side pad carries all the braking load while the opposite pad barely contacts the disc; inspect the slide pin boots for tears that have allowed salt contamination to seize the pins in their bores.
Torn, split, or collapsed dust boot visible on inspection — a damaged dust boot has exposed the piston bore to road water and grit; inspect the piston surface and bore for corrosion before fitting a new boot; a piston with surface pitting will destroy the new piston seal within a short operating period even with a new boot fitted.
Brake drag at one corner — wheel noticeably harder to spin by hand than the opposite side — combined with the affected corner running hot after normal driving — the caliper piston is not retracting fully after brake release due to a hardened piston seal or contaminated bore; the constant light pad contact overheats the disc and accelerates pad wear; confirm by loosening the bleed nipple slightly to release hydraulic pressure and checking whether the drag reduces.
Logistics & Customs
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International HS Code
8708.30
EAEU Customs Code (TN VED)
8708 30 910 0
Typical Net Weight
Country of Manufacture
China
Standard MOQ
30 pcs
Production Lead Time
30 days
Always verify the exact 8-digit or 10-digit subheading with your customs broker for the destination country, as tariff schedules and duty rates vary by jurisdiction.
Installation Tips
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- Bleed the brake circuit and retract the piston fully before removing the caliper from the vehicle — open the bleed nipple slightly before pushing the piston back to allow the displaced fluid to exit rather than being forced back through the ABS modulator; fluid forced through the ABS modulator dislodges valve seat deposits that can block the modulator's solenoid valves, causing ABS and ESC fault codes that require specialist flushing to resolve.
- Inspect the caliper bore and piston surface thoroughly under good lighting before proceeding with the seal kit repair — insert the removed piston into the bore and rotate it while pushing to feel for rough spots; use a bore light to examine the bore wall for pitting, scoring, or deep corrosion marks; any pitting deeper than 0.1 mm or scoring visible to the naked eye means the caliper body cannot be reliably resealed and must be replaced — continuing with the seal kit on a pitted bore produces a repeat leak within a short period.
- Clean the bore, piston, and all seal grooves with dedicated brake system cleaner — never use petroleum-based solvents, brake cleaner containing petroleum distillates, or compressed air to dry a cleaned bore as these leave residues that degrade the new EPDM seals; use only isopropyl alcohol or dedicated brake component cleaner and allow to air dry completely before fitting new seals.
- Lubricate the new piston seal and bore wall with clean brake fluid of the correct specification before assembly — apply a thin film of brake fluid to the seal groove and seal outer surface only; never use petroleum-based grease, silicone grease, or copper grease near any brake hydraulic component; use the brake assembly lubricant supplied with the kit for slide pin bores and boot seating surfaces only.
- Install the new piston seal in its groove without twisting — the square-section seal must sit flat in its groove with no spiral twist; a twisted seal produces inconsistent rollback behaviour, causing either brake drag from insufficient piston retraction or excessive running clearance from over-retraction; press the seal into the groove uniformly around the full circumference and confirm it sits flush before inserting the piston.
- Install the new CYLINDER KIT (CUMMINS 4995266), refit the caliper, bleed the brake circuit until no air bubbles are present at the bleed nipple, pump the brake pedal firmly to seat the piston against the new pads, confirm pedal height and firmness are correct, check for fluid leaks at the caliper and bleed nipple under firm pedal pressure, and road test with several progressive stops from moderate speed before returning the vehicle to service.
Tools: piston retraction tool (C-clamp or wind-back tool for EPB rear calipers), brake bleed kit, bore inspection light, brake component cleaner, brake assembly lubricant from kit, torque wrench for caliper bolts and bleed nipple.
Frequently Asked Questions
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When is a seal kit repair appropriate and when should the complete caliper be replaced instead?
A seal kit repair is appropriate when the caliper bore is smooth and free of pitting, the piston surface is clean and undamaged, and the caliper body casting shows no cracks or distortion. Complete caliper replacement is the correct repair when the bore shows pitting or scoring visible to the naked eye, when the piston surface is corroded or pitted, when the caliper body casting is cracked, or when the caliper has been overheated to the point where the aluminium body has discoloured — heat distortion of the bore geometry prevents a reliable seal regardless of seal quality. As a general rule, seal kit repair is cost-effective on vehicles below 150,000 km with good brake maintenance history; caliper replacement is more appropriate on older high-mileage vehicles where bore condition is uncertain. ok.parts supplies seal kits and complete calipers at wholesale MOQ from 11.47 USD per unit.
Should both calipers on the same axle be overhauled simultaneously when only one has failed?
Overhauling both calipers on the same axle simultaneously is strongly recommended when the failure is due to seal age or moisture contamination rather than a specific damage event. Both calipers share the same age, the same brake fluid degradation, and the same road salt exposure — if one has developed a seal failure, the opposite caliper's seals are at the same wear stage. Overhauling both during the same brake service eliminates a repeat axle bleed within a short interval and ensures matched piston retraction behaviour on both sides, which is important for balanced braking force distribution.
How does the OEM-equivalent aftermarket unit compare to the genuine OEM part?
OEM-equivalent units in this catalogue replicate the current OEM design geometry and material specification. Quality is verified against OEM cross-reference data. When ordering in bulk, confirm with our team that the specification matches the latest OEM revision for your application.
Is white-label or custom packaging available for wholesale orders?
Yes. ok.parts works directly with the manufacturing facility and can accommodate neutral white-label packaging or fully branded packaging with your company logo, part numbers, and barcode. Minimum order quantities and lead times for custom packaging may differ from standard stock. Contact the team via the inquiry form to discuss your specific requirements.
Frequently Replaced Together
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| Part | Reason for Combined Replacement |
|---|---|
| Brake Pads Axle set, OEM ref. varies | Caliper overhaul requires retracting the piston fully to access the bore — this is the definitive opportunity to inspect pad thickness and replace the pads if they are at or approaching minimum thickness. Fitting a newly overhauled caliper with worn pads means the piston will need to be retracted again within a short service interval, unnecessarily stressing the new seals. Always replace pads simultaneously with any caliper seal kit service. |
| Brake Fluid DOT 4 or DOT 5.1 per OEM specification | Caliper overhaul requires opening the brake hydraulic circuit and bleeding the caliper, making this the mandatory time to assess brake fluid condition. Moisture-saturated fluid with a high wet boiling point depression degrades the new EPDM piston seal by promoting corrosion at the piston-to-bore interface. Replacing the brake fluid simultaneously with the seal kit service maximises the service life of the new seals and restores the circuit's full high-temperature braking capacity. |
| Brake Disc OEM ref. varies by axle position | A caliper that has been dragging due to a seized piston or slide pins will have overheated the brake disc, causing heat stress cracking, surface hot spots, and thickness variation. A disc that has been subjected to extended drag overload should be measured for runout and minimum thickness and replaced if either measurement is out of specification — fitting new pads and a freshly overhauled caliper to an overheated disc produces immediate brake judder and uneven pad transfer. |