Crankshaft Pulley Dimensions: Key Specs for Sourcing
Crankshaft pulley dimensions decide whether a replacement part will actually fit an engine with a fixed belt path, a compact accessory drive, or a specific accessory speed ratio. A usable sourcing decision requires more than outside diameter. Teams also need the hub bore and tolerance, pilot depth, keyway or spline geometry, pulley offset, groove count, belt profile, overall width, mounting face design, bolt pattern, face flatness, radial and axial runout, concentricity, and dynamic balance. Even a few tenths of a millimetre in offset can shift the belt centreline enough to increase rib wear or noise; a bore, pilot, or face error can create installation interference or front-end vibration. For procurement, the real question is whether the pulley matches the OE installation envelope and can pass first-article and incoming dimensional inspection, not whether it resembles the catalogue image. Driventus is an independent aftermarket manufacturer; brand names and OE references are used for fitment identification only. Our sourcing process verifies dimensions against samples, drawings, interchange data, and controlled measurement datums, then confirms material, finish, packaging protection, traceability, and balance requirements before shipment.
What buyers should verify first
For replacement and aftermarket sourcing, start by confirming that the crankshaft pulley matches the engine family, crank nose design, and front-end accessory drive layout. Price comparison should come after fitment risk is under control, because a pulley can look correct and still fail if the belt centreline, centre bore, mounting face, or groove geometry differs from OE.
Core dimensions to confirm:
Outside diameter and effective belt pitch diameter
Hub bore diameter, bore tolerance, roundness, and pilot depth
Keyway width and depth, spline form, locating slot, or interference-fit detail
Total pulley width, rib count, groove count, rib pitch, and groove angle
Offset from crank mounting face to belt centreline or first-groove datum
Bolt circle diameter, bolt hole diameter, fastener count, chamfer, and seating face style
Mounting face flatness, radial runout, axial runout, and bore-to-groove concentricity
Dynamic balance requirement, test speed, and acceptable residual imbalance
Material grade, hardness where applicable, coating type, and corrosion protection
The first technical decision is the datum scheme. Everyone involved must measure from the same reference face and axis. One supplier may quote offset from the rear mounting face to the centre of the belt track, while another measures from a front hub shoulder to the outside groove. Those values are not interchangeable. A useful RFQ states the reference face, measurement axis, measuring tool, nominal value, and tolerance for each critical dimension.
If the application uses an OE cross-reference such as OE 06A107065, treat it as a fitment reference and confirm the measured crankshaft pulley dimensions against a known-good sample, technical drawing, or approved first-article report. This matters even more when accessory loads, serpentine routing, air-conditioning equipment, alternator position, crank damper integration, or engine-code variants change within the same vehicle family. A shared OE-style reference can identify the application family, but each part still needs to be checked before approval.
Typical dimension set for crankshaft pulley sourcing
The table below shows the crankshaft pulley dimensions procurement teams normally request on a quotation sheet, first-article inspection report, or incoming QC checklist. Using a consistent dimension set makes supplier comparison easier and reduces the risk of approving a pulley that fits one engine variant but not another.
Dimension
Why it matters
Typical buyer check
Outside diameter
Affects accessory speed ratio and belt wrap
Measure maximum OD and compare with OE sample or drawing
Effective pitch diameter
Determines the actual belt operating radius
Verify against belt profile, groove depth, and rib geometry
Groove count / belt profile
Must match belt type, rib spacing, and belt seating
Confirm V-belt, multi-rib, serpentine, or custom profile
Centre bore
Controls fit on the crank nose or pilot
Measure bore diameter, roundness, surface finish, and tolerance
Hub length / pilot depth
Affects seating and crank engagement
Check depth from mounting face to bore shoulder or stop face
Offset / stack height
Sets belt alignment across the accessory drive
Check from mounting face to belt centreline or first-groove datum
Overall width
Controls packaging clearance
Compare against timing cover, belt guard, and adjacent components
Bolt circle / fastener count
Ensures mounting compatibility
Verify PCD, hole size, chamfer, counterbore, and seating type
Keyway / spline detail
Provides angular location or torque transfer
Measure width, depth, flank form, orientation, and edge break
Runout
Impacts vibration, noise, and belt tracking
Inspect radial and axial runout on defined datums
Dynamic balance
Reduces rotating imbalance and NVH risk
Request balance grade, residual imbalance limit, or test report
Mass and material
Affects inertia, durability, and torsional behaviour
Confirm cast iron, steel, aluminium alloy, or bonded damper structure
Coating thickness
Protects the part without disturbing fit
Inspect corrosion finish and masked critical surfaces
</tr></thead><tbody> </tbody></table>For many engine programmes, the acceptable tolerance band comes from the OE drawing or customer standard rather than a universal rule. In practice, buyers often treat bore, pilot, offset, groove geometry, and runout as critical-to-fit characteristics and hold them tighter than exterior reference dimensions. Small-diameter pulleys, bonded damper pulleys, and high-speed accessory drives can require tighter control because small dimensional errors become belt-tracking problems at operating speed.
Where no drawing is available, request measured samples, agree the inspection method, and identify critical dimensions before tooling release or bulk order approval. A controlled sample approval process is especially useful when sourcing aftermarket parts for multiple export markets where build years, engine codes, air-conditioning options, and OE supersessions overlap.
Material, finish, and balance requirements
Crankshaft pulleys are commonly produced in cast iron, steel, or aluminium alloy depending on belt load, packaging, damping requirement, and cost target. Material choice affects stiffness, corrosion resistance, mass, machining stability, and how the pulley behaves under belt tension and changing engine speed. It also influences which crankshaft pulley dimensions need the tightest process control during machining and coating.
Common sourcing points
Cast iron: good mass and damping, often used where inertia and vibration control are beneficial
Steel: suitable for compact, high-strength designs with thinner sections or higher belt loads
Aluminium alloy: lower mass, but requires careful control of wear surfaces, coating adhesion, and balance
Bonded damper designs: require verification of rubber compound, bond line, indexing, outer-ring alignment, and post-cure dimensional stability
Surface finish is not only cosmetic. Phosphate, e-coat, zinc-based protection, black oxide, paint, or other anti-corrosion finishes can affect storage life, installation fit, and belt contact surfaces. Confirm coating thickness and masking requirements. Bore diameter, belt grooves, bolt seats, pilot diameters, and mounting faces may need to be masked or finish-machined after coating because excess build-up can change fit, offset, or runout.
Balance should be specified for pulleys that operate at higher engine speeds, include a heavy outer ring, integrate a damper, or support sensitive accessory drives. The RFQ should state whether balance is required on every part or by sampling lot, and whether the report must show residual imbalance, correction method, correction location, test speed, and acceptance criteria. Many buyers specify residual imbalance in g-mm or use a balance quality grade such as ISO 21940 guidance when the customer drawing does not provide a dedicated limit.
For export programmes, buyers commonly add salt-spray expectations, anti-rust oil requirements, packaging protection for machined faces, VCI bag or paper use, carton drop strength, and label traceability. Driventus manufactures under IATF 16949:2016 and ISO 9001:2015 controls, with process records that support lot traceability, inspection review, and dimensional release.
Dimensional inspection and validation tests
A practical inspection plan reduces disputes during incoming QC and after field installation. The plan should combine physical measurement with functional checks, and it should define measurement datums before production begins. Without a shared datum, two inspection teams can measure the same pulley and report different offset, width, concentricity, or runout values.
Recommended validation steps:
1. Measure outside diameter, effective pitch diameter, bore, hub length, overall width, and offset with calibrated gauges. 2. Check groove profile, rib spacing, belt seating width, groove depth, and groove angle against the specified belt type. 3. Confirm bore-to-groove concentricity, radial runout, and axial runout using the agreed bore, pilot, or mounting face datum. 4. Verify bolt pattern, PCD, hole diameter, chamfer, counterbore, thread condition, and face flatness where applicable. 5. Inspect keyway, spline, locating slot, or press-fit feature for width, depth, orientation, flank condition, and burr control. 6. Review balance specification, sample weight, correction marks, and residual imbalance report if supplied. 7. Inspect coating thickness, corrosion finish, masked surfaces, belt contact surfaces, and defects that could affect installation. 8. Compare the part against drawings, a known-good OE sample, or an approved first-article inspection report. 9. Confirm packaging prevents dents, corrosion, and abrasion on machined faces, belt grooves, and coated surfaces.
Incoming inspection should separate critical-to-fit dimensions from general reference dimensions. Bore, pilot depth, offset, belt groove geometry, bolt circle, face flatness, and runout usually deserve tighter sampling or 100% checks during launch because they directly affect assembly and belt tracking. Less critical exterior features can move to normal batch sampling once process capability is proven.
If the pulley is part of a regulated application, buyers may also request material declarations for REACH (EC) No 1907/2006 compliance and documentation aligned with the destination market. For durability programmes, related belt-drive or corrosion exposure tests may reference customer standards or procedures such as SAE J2527 where appropriate, although the exact validation plan should follow the application, material, and customer requirement. Where the crankshaft pulley includes a rubber damper element, validation may also include bond integrity, heat ageing, ozone exposure, torsional performance, outer-ring slip checks, and visual inspection for separation or cracking after cycling.
How to compare suppliers on dimensional control
Dimensional control is not only a machining issue. It reflects incoming material control, casting or forging consistency, fixture stability, CNC process capability, tool wear management, metrology discipline, coating control, balance correction, and final inspection handling. A supplier that can hold crankshaft pulley dimensions consistently should be able to show how critical characteristics are controlled from raw material through packing.
Compare suppliers on the following points:
First-article inspection reports with measured values, not only sample photos or catalogue drawings
Tolerance records for bore, pilot depth, offset, runout, concentricity, and groove profile
Process capability data for critical dimensions when volume production is planned
Batch traceability, heat or lot coding, and inspection record retention
Gauge calibration status and measuring equipment suitability, including CMM, runout fixtures, height gauges, bore gauges, and profile gauges where needed
Control plan coverage for machining, deburring, coating, balance, final inspection, and packing
Handling of OE cross-reference updates, supersessions, and market-specific engine variants
Packaging method for machined faces, belt grooves, coated surfaces, and export transit protection
Ability to support drawings, samples, reverse engineering, private label, and PPAP-style documentation where required
Lead time, minimum order quantity, service part continuity, and document response speed
A strong supplier should be able to explain how a first sample is measured, how the production fixture locates the part, which dimensions are checked in-process, and how nonconforming parts are contained. For pulleys with tight offset or runout requirements, ask whether the supplier inspects from the same datum used in assembly. This avoids a common sourcing problem: a part passes an internal shop-floor check but fails the customer's fitment inspection because the measurement reference was different.
If you need alternate designs or private label programmes, use custom manufacturing to define target dimensions, material, surface finish, balance, packaging, and validation requirements before release. For standard parts, review our catalog and quality system for available families, documentation structure, and inspection controls. Driventus serves aftermarket distributors, OEM / Tier-1 supply chains, and repair networks across export markets.
Specification checklist for a request for quote
Before sending an RFQ, prepare a specification sheet that removes measurement ambiguity. The goal is to give the supplier enough information to confirm fit, quote tooling or production cost, and define inspection coverage without repeated clarification. For crankshaft pulley dimensions, a clear RFQ should identify both nominal values and measurement references.
Include these items:
Engine code, vehicle application, model year range, fuel type, and market region
OE cross-reference, interchange number, or current supplier reference if available
Sample part availability, drawing revision, 3D data, or measured inspection report
Annual volume, order frequency, forecast, target lead time, tooling expectation, and launch schedule
When drawings are not available, send photos with scale references only as supporting information, not as the main specification. Photos help identify the part but cannot replace measured crankshaft pulley dimensions. A physical sample, CMM report, or complete dimensional inspection sheet is more reliable, especially for offset, bore tolerance, runout, and groove profile.
For programmes that need a non-standard design, request a quote with drawings, samples, or target measurements. If the part is part of a broader engine programme, you can also review engine components for related sourcing options. The more complete the dimensional brief, the faster the supplier can confirm manufacturability, inspection coverage, tooling requirements, and stable supply.
Frequently asked questions
They control belt alignment, accessory speed, crank nose fit, and front-end accessory drive stability. Small errors in offset, bore, groove profile, bolt pattern, or runout can create vibration, belt wear, noise, or installation failure.
You can start with an OE cross-reference, but you should still verify bore, pilot depth, offset, groove count, belt profile, bolt pattern, runout, and balance requirement. OE numbers guide fitment; they do not replace dimensional inspection.
Ask for a dimensional inspection report, material declaration, finish specification, balance confirmation where required, lot traceability, packaging specification, and confirmation of IATF 16949:2016 and ISO 9001:2015 controls where applicable.
If you need a verified dimensional match for your next programme, send your drawing or sample details and we will review the specification with you. Start here: /contact.html
