68155868AB Spline Quantity: How to Count and Verify Hub Splines
Spline quantity on the 68155868AB front wheel hub assembly is the number of internal spline teeth cut into the hub bore that engage the outer CV joint stub shaft and carry drive torque from the driveline to the wheel. It is a fitment-critical number, and it is fixed by the part drawing and a physical sample rather than by the OE number alone. HJDP, the brand published at jnhjdp.com, treats spline quantity as one entry in a full spline data set that also covers major diameter, minor diameter, spline length and pressure angle.
What Does Spline Quantity Mean on a Wheel Hub Assembly?
Spline quantity is the total number of teeth in the splined bore of a hub flange, and it sets how many engagement surfaces share drive torque between the hub and the outer constant velocity (CV) joint. On a driven wheel position, the CV joint stub shaft passes through the hub bore, the axle nut clamps the joint face against the hub face, and every unit of torque delivered to the wheel crosses that toothed interface.
Clamp load and spline engagement do different jobs and are checked separately. The axle nut generates clamp load, which holds the joint against the hub and keeps the assembly stiff; the splines transmit torque and permit the small angular movement built into the joint. A hub with the right tooth count but a worn or under-torqued joint will still move under load, so spline quantity is a starting point for fitment, not a complete answer to it.
Where the splined bore sits in a third-generation hub unit
A third-generation wheel hub unit is a sealed assembly in which the bearing races, flange, wheel studs and ABS encoder are combined into one part; it bolts to the steering knuckle and cannot be repacked or re-adjusted in service. The splined bore runs through the rotating inner rings, so the same component that carries the vehicle weight also carries the drive torque. That is why spline condition and bearing condition have to be judged inside one non-serviceable unit: a worn bore and a worn raceway are found in the same inspection, and both end the life of the part together.
Why the count alone does not prove fitment
Two hubs can show the same spline quantity and still refuse to fit, because a tooth count says nothing about tooth height, flank angle or engagement depth. Buyers who look up the 68155868AB front wheel hub assembly usually hold one number in hand and need the rest of the data block before they can compare suppliers honestly. The count tells you which family of CV joint the hub belongs to; the diameters tell you whether that joint will actually enter and seat.
How Do You Count the Splines on a 68155868AB Hub Correctly?
Counting splines correctly means counting every tooth once around the full circumference of the bore, starting and ending on the same marked tooth, then recording the result together with the diameters that give the count its meaning. The counting itself takes under a minute. The marking, the lighting and a second check are what make the number trustworthy enough to put on a purchase order.
A four-step counting method
- Clean the bore. Wipe out grease, rust film and paint; a partially obscured tooth is the most common reason two inspectors report different quantities for the same part.
- Mark a reference tooth. Put a paint pen or marker dot on one tooth at the top of the bore so you can see where the circle closes.
- Count each tooth once, all the way round. Count teeth rather than gaps and say the number out loud as you pass each one; on straight-sided splines the tooth count and gap count are equal, but naming them prevents an off-by-one result.
- Record the count with its supporting dimensions. Note major diameter, minor diameter and spline engagement length from the same part, and photograph the bore with a steel rule in frame so the next shipment can be compared against the same reference.
Straight-sided splines and involute splines count the same way but fail differently
Straight-sided, or parallel, splines have flat flanks and a constant tooth thickness, so quantity plus the two diameters describes the pattern almost completely. Involute splines have curved flanks generated from a pressure angle and a module or diametral pitch, which means the same tooth count can be produced at different pressure angles with different contact patterns. When two drawings carry an identical quantity but different flank data, the parts are not interchangeable even though the number matches.
Counting errors that produce a wrong quantity
- Counting a quarter of the bore and multiplying by four when the tooth pattern is not perfectly symmetric.
- Counting both teeth and gaps and reporting the sum, which roughly doubles the true quantity.
- Counting on a heavily worn bore where tooth tips have been hammered into ramps and no longer read as separate teeth.
- Accepting a catalogue figure that was published for a different application of the same OE reference.
- Counting on a photograph instead of the part, where glare flattens the tooth form.
What Other Spline Data Must Match Besides the Quantity?
Spline quantity is one of several dimensions that must all match before a driven hub will seat and carry torque cleanly; the rest are the two diameters, the engagement length, the tooth form and the axle nut interface. A supplier who quotes only a count has given you a family reference, not a specification.
| Drawing parameter | What it controls | How a buyer checks it |
|---|---|---|
| Spline quantity (number of teeth) | How many engagement surfaces share the torque load | Count teeth around the bore and compare with the approved drawing |
| Major diameter | Whether the CV joint stub can enter the bore at all | Caliper or micrometer across opposing tooth tips |
| Minor diameter | Root clearance and how the stub sits in the bore | Caliper across opposing tooth roots |
| Spline engagement length | Contact area available under peak torque | Depth gauge from flange face to spline end |
| Tooth form and pressure angle | Contact pattern and rotational lash in service | Compare against the drawing data block or a profile gauge |
| Lead-in chamfer | Whether the joint starts squarely without cross-threading | Visual check plus drawing callout |
| Axle nut thread and seat face | Clamp load retention and joint preload | Thread gauge and visual check of the seat |
How to read the spline data block on a drawing
The spline data block is the small table on the drawing that defines the tooth system: tooth count, module or diametral pitch, pressure angle, class of fit, and the major and minor limits. Read it as a set rather than line by line. A metric drawing and an imperial drawing can describe a similar joint in modules and in diametral pitch, and mixing the two units is the classic reason a buyer believes two parts match when they do not. Ask for the drawing revision that was used for the sample you approved, and keep that revision number on the purchase order.
Why an OE reference is not a specification
An OE number such as 68155868AB identifies an assembly for an application, not a set of tolerances, and it does not by itself publish a spline count that a buyer can rely on. Running changes, supersessions and different suppliers of the same reference all mean the physical part must be confirmed. For HJDP hub assemblies, the spline quantity used in production is the one shown on the part drawing and confirmed against the approved sample, which is why both steps are part of the quotation process.
Which Hub Generation Uses Which Spline Arrangement?
Splined bores appear on driven wheel positions regardless of bearing generation; what changes between first-, second- and third-generation units is how the bearing is mounted, retained and serviced. Generation tells you how the part is fitted to the vehicle, and the spline data tells you whether it fits the driveline.
| Hub generation | What is integrated | How it mounts | Service implication |
|---|---|---|---|
| First generation | Double row bearing only; hub flange is a separate part | Pressed into the knuckle and retained by a circlip, flange pressed into the inner ring | Needs a press and correct seating; bore and flange condition checked separately |
| Second generation | Bearing with a flange on the outer ring; hub still a separate item | Bolted to the knuckle, hub shaft drawn in by the axle nut | Flange runout and bolt condition matter as much as the splines |
| Third generation | Bearing, flange, wheel studs and ABS encoder in one sealed unit | Three or four bolts to the knuckle; splined bore through the inner rings | Replaced as a complete assembly; no repacking or adjustment |
Driven and non-driven positions behave differently
A front hub on a front-wheel-drive vehicle is driven and therefore has a splined bore. A rear hub on the same vehicle is usually non-driven and carries a plain bore or a spindle with a nut, so there is no spline quantity to confirm at all. All-wheel-drive and four-wheel-drive vehicles are driven at both ends, and their rear hubs do carry splines. Getting this wrong at the catalogue stage produces an order for a hub that cannot accept the vehicle’s joint.
What a parts catalogue must record
A usable catalogue entry for a driven hub needs the generation, the spline quantity with both diameters, the ABS encoder type, the stud thread and the flange dimensions. Number of teeth on its own is a filter, not an identification. Importers building a private-label range through the HJDP hub assembly listing for this reference should decide which of those fields appear in their own catalogue before the first order, because the fields drive what has to be inspected on every later shipment.
What Goes Wrong When Spline Quantity or Spline Fit Is Wrong?
A wrong spline quantity causes an immediate assembly failure at the vehicle, while a correct count with incorrect diameters or flank geometry causes a slow failure through lash, fretting and tooth wear. The first is caught in the workshop within minutes; the second is caught by the driver weeks later, which is why it costs far more to resolve.
Problems that appear during installation
- The CV joint stub will not enter the bore, because the count differs or the major diameter is undersized.
- The stub enters part way and stops, which usually points to minor diameter or spline length rather than tooth count.
- The stub enters but rocks visibly before the axle nut is torqued, indicating rotational play that no amount of clamp load will remove.
- The nut reaches its torque before the joint face contacts the hub face, so the assembly runs with no clamp load and the splines take the full load alone.
Symptoms that appear after weeks or months
| Symptom | Likely cause | What to check first |
|---|---|---|
| Click or clunk when drive torque is applied | Rotational lash at the spline joint | Tooth count, major diameter, axle nut torque |
| Hum or rumble rising with road speed | Raceway damage or false brinelling | Raceway condition, seal integrity, fitting method |
| Rust staining around the joint to hub interface | Fretting corrosion from micro-movement | Spline fit, clamp load, seal at the joint face |
| ABS warning light after replacement | Encoder ring damaged during fitting | Inboard seal face and sensor air gap |
| Visible play at the wheel with the vehicle raised | Bearing end play or a loose axle nut | Axial play measurement and nut torque |
Fretting is the failure that buyers underestimate. Small rotational movement inside a spline joint that should be locked by clamp load polishes the flanks, breaks down the protective oxide layer and lets corrosion start; the teeth then wear thinner and the play grows. By the time a driver hears it, the hub and the joint are both beyond recovery, so the first inspection point is always the nut torque and the fit, not the bearing.
How Should Importers Verify Spline Quantity Before Ordering and at Goods Receipt?
Verify spline quantity twice: once against the drawing and approved sample before production, and again on the inspection bench when goods arrive. A spline mismatch cannot be detected from a packing list or a photograph, so the second check has to be physical and has to follow the same method every time.
Before the order: drawing and sample confirmation
Send the OE reference together with a sample of the part currently in use, or the original drawing if one is available. The supplier then returns a drawing showing the spline data block and a sample confirmation against the physical part. This is the point at which a discrepancy is cheap to fix; after tooling and production it is not.
At goods receipt: a practical inspection sequence
- Match the carton label, part number and drawing revision on the documents to the purchase order before opening anything.
- Take the agreed sample size from the shipment and clean one bore on each sampled part.
- Count the teeth using the marked-reference method and compare against the approved drawing quantity.
- Measure major and minor diameter at two positions 90 degrees apart to catch ovality as well as size.
- Check spline engagement length and lead-in chamfer against the drawing callouts.
- Trial-fit a CV joint stub or a spline gauge where one is available, and feel for rotational play by hand.
- Inspect the ABS encoder face, the seal lip and the flange for handling damage, since these fail in transit more often than the splines do.
- Record each result, photograph the bore, and keep one confirmed sample sealed as the reference for the next shipment.
These steps fit an ordinary goods-in bench and need no special equipment beyond a caliper, a depth gauge and a paint pen. Importers who repeat the same sequence on every shipment build a comparable record, and that record is what settles a dispute about fitment far faster than correspondence. The same 68155868AB front hub assembly reference can then be re-ordered with confidence that the spline data has not drifted between batches.
FAQ: Spline Quantity Questions Buyers Ask
How many splines does a 68155868AB hub have?
The quantity is defined by the part drawing for that reference and confirmed against a physical sample, not published reliably by OE number alone. Ask the supplier for the spline data block and count the bore on the approved sample before ordering. HJDP confirms spline quantity by drawing and sample before production, and the confirmed figure is what appears on the inspection record.
Can two hubs share the same spline quantity and still not fit?
Yes. A matching tooth count only confirms the joint family. If major diameter, minor diameter, spline length or pressure angle differ, the stub will either not enter, not seat to the correct depth, or enter with rotational lash. All of those dimensions have to match, which is why a count on its own is a filter rather than a specification.
Is the hub spline quantity the same as the tooth count on the CV joint?
The two must be equal, because they are the two halves of one joint: the CV joint carries an external spline and the hub bore carries the matching internal spline. Equal counts are necessary but not sufficient, since the diameters, spline length and fit class on each side also have to agree with the drawing.
Do rear hubs need a spline count as well?
Only driven rear positions do. On a front-wheel-drive vehicle, the rear hubs are non-driven and normally carry a plain bore or a spindle, so there are no splines to count. On all-wheel-drive and four-wheel-drive vehicles, the rear position is driven and its hub carries the same kind of splined bore as the front.
