A Weiss CV joint is a ball-type constant velocity coupling that transmits torque between two intersecting shafts using four load-carrying balls seated in curved grooves machined into matching stub yokes, with a fifth centring ball locating the pivot point. The Willys MB jeep front axle ran Weiss joints under every wartime steered front wheel. The geometry forces the balls to sit in the bisecting plane of the shaft angle, so the output shaft tracks the input speed exactly through articulation angles up to about 30°. That eliminates the 2/rev velocity ripple a Hooke joint would feed into a steered driveline.
Weiss CV Joint Interactive Calculator
Vary joint angle and shaft phase to see the ideal Weiss constant-speed condition and the single-Hooke speed ripple it avoids.
Equation Used
The ideal Weiss joint keeps its four driving balls in the plane that bisects the shaft angle, so the output speed ratio remains 1.000. The Hooke-joint equation is included as a comparison to show the twice-per-revolution speed ripple that the Weiss geometry eliminates.
- Ideal Weiss groove geometry keeps the balls in the bisecting plane.
- No slip, compliance, backlash, or friction losses are included.
- Hooke comparison is for a single universal joint at the same shaft angle.
- Joint angle is kept within the typical Weiss working range.
The Weiss CV Joint in Action
The Weiss joint solves a specific problem — how to drive a wheel that also steers. A simple Hooke (cardan) universal joint will pass torque through an angle, but the output shaft speeds up and slows down twice per revolution as the angle grows. On a steered front axle that velocity ripple beats the tyres, the kingpins, and your fillings. Carl William Weiss patented the fix in 1923, and Bendix licensed it for production. Four hardened balls sit in curved grooves cut into the inner faces of two yokes, one on the input stub shaft and one on the output. The grooves are arcs of circles whose centres lie equal distances on either side of the joint centre. When you tilt the joint, the geometry forces the four balls into the plane that bisects the shaft angle — that is the kinematic condition for constant velocity. A fifth ball sits in a central socket and locates the two yokes, taking thrust and keeping the joint indexed.
The critical tolerance is groove form. Each groove must be a true circular arc, ground to within roughly 0.01 mm of nominal radius, with surface finish around Ra 0.4 µm. If the radius drifts, the four balls no longer lie in the bisecting plane and you get exactly the velocity ripple the joint exists to kill. Heat-treat is just as fussy — case depth on the yoke faces around 1.0 to 1.5 mm at 58-62 HRC, because the balls run on a small contact patch and brinell easily under shock load. The most common failure modes are groove spalling from contaminated grease, centring-ball wash-out which lets the joint clatter axially, and outright cage-free ball escape if a yoke cracks. You will hear a tired Weiss joint before you measure it — a rhythmic clunk on tight-lock turns under power is the textbook symptom.
A Weiss joint is not a plunge joint. It cannot accommodate length change, so the half-shaft assembly always pairs it with a separate sliding spline. Articulation angle is the other hard limit. Beyond roughly 30°-32° the balls climb out of the working portion of the grooves and the joint locks or skips. That is why Rzeppa joints displaced Weiss joints on passenger front-wheel-drive cars from the 1960s onward — Rzeppas comfortably handle 45°+ on the outboard side.
Key Components
- Input yoke (driving fork): Forged alloy steel fork with two opposing curved grooves machined into the inner faces. Groove radius typically matches a circle whose centre sits about 25-40 mm offset from joint centre on production automotive sizes, ground to ±0.01 mm.
- Output yoke (driven fork): Mirror-image fork carrying the matching pair of grooves. Input and output grooves cross at the joint centre, and the four balls sit at the four crossing points. Both yokes are case-hardened to 58-62 HRC with 1.0-1.5 mm case depth.
- Four torque-transmitting balls: Hardened bearing-grade balls, commonly 3/4 inch (19.05 mm) on a jeep-class joint, that carry the entire torque load through line contact in the grooves. Ball-to-groove conformity is tight — typically 52-54% of ball diameter — to spread Hertzian contact stress.
- Fifth centring ball: A single larger ball seated in a central socket bored through both yokes. It locates the joint kinematically, takes axial thrust, and holds the four torque balls indexed in the bisecting plane during articulation.
- Locking pin or retainer: A small cross pin or set screw retains the centring ball during assembly. If this pin shears or backs out, the centring ball walks and the joint loses its bisecting-plane geometry — that is the failure that produces the classic on-power steering clunk.
Who Uses the Weiss CV Joint
Weiss joints belong to driven steered axles, period. Anywhere you need to put torque through a wheel that also turns left and right, and where the articulation angle stays under about 30°, the Weiss is a workable solution. The design dominated military and utility 4×4 front axles from the 1930s through the 1970s, and you still find it in restoration parts bins and in some heavy-equipment steered drive axles where simplicity and field-rebuildability matter more than maximum angle.
- Military vehicles: Willys MB and Ford GPW jeep front axles used Bendix-Weiss joints on both half-shafts. The Dodge WC series and the M37 3/4-ton truck ran the same joint family at larger ball sizes.
- Civilian 4×4: Land Rover Series I, II, and IIA front axles used Bendix-Weiss joints as standard until the switch to Rzeppa-pattern joints in the late Series IIA / III production.
- Half-track and tracked carriers: M3 Half-track front steered axle used Weiss joints to drive the front wheels while the rear ran tracks.
- Agricultural and utility tractors: Older mechanical front-wheel-assist tractors — for example certain MFWD axles on 1960s-70s International Harvester and Case machines — used Weiss-pattern joints in the steering knuckle.
- Heavy off-highway equipment: Some articulated graders and small wheel loaders used Weiss joints on steered drive axles where the articulation envelope stays modest and field rebuild without specialist tooling matters.
- Restoration and aftermarket: Companies like Crown Automotive and Omix-ADA still supply jeep-pattern Bendix-Weiss joint assemblies for MB and CJ-2A through CJ-5 front axles.
The Formula Behind the Weiss CV Joint
The useful number for a Weiss joint is not torque capacity in isolation — it is whether the joint stays inside its kinematic working window across your steering range. The articulation angle θ between input and output shafts sets where the four balls sit in their grooves. At small angles the balls live near the centre of the groove arc with plenty of contact area on both flanks. As θ grows, the contact patch migrates along the groove and the effective torque arm of each ball changes. Below about 10° the joint is under-worked and the balls hammer one spot — fine for occasional steer, bad for continuous misalignment. Around 15-25° is the sweet spot where load distributes cleanly across all four balls. Above 30° you run out of groove and the joint binds. The torque capacity scales with ball count, ball-to-groove pitch radius, and the cosine-of-half-angle term that tells you how much of the input torque actually reaches the output through the bisecting-plane geometry.
Variables
| Symbol | Meaning | Unit (SI) | Unit (Imperial) |
|---|---|---|---|
| Tout | Torque transmitted through the joint at articulation angle θ | N·m | lb·ft |
| n | Number of torque-transmitting balls (4 in a standard Weiss joint) | — | — |
| Fball | Allowable tangential load per ball, set by Hertzian contact stress in the groove | N | lbf |
| Rp | Pitch radius from joint centre to ball centre | m | in |
| θ | Articulation angle between input and output shafts | rad or ° | ° |
Worked Example: Weiss CV Joint in a restored Willys MB jeep front half-shaft
You are rebuilding the front axle on a 1944 Willys MB and want to know what the Bendix-Weiss joint can pass to the wheel at full lock during a low-range crawl. The joint runs four 3/4 inch (19.05 mm) torque balls on a pitch radius of 32 mm. Hertzian analysis on the case-hardened groove gives an allowable tangential load per ball of 4,500 N. You want Tout at 5° (nearly straight-ahead crawl), 22° (typical trail-driving steer angle), and 30° (full lock).
Given
- n = 4 balls
- Fball = 4,500 N
- Rp = 0.032 m
- θlow = 5 °
- θnom = 22 °
- θhigh = 30 °
Solution
Step 1 — compute the constant ball-load term that does not change with angle:
Step 2 — at the nominal trail-driving angle of 22°, apply the cosine half-angle factor:
That is roughly 417 lb·ft at the wheel — comfortably above what a flathead Go-Devil 134 cubic inch engine can deliver through the T-84 gearbox and Spicer 18 transfer case in low range, so the joint is not the weak link in the driveline.
Step 3 — at the low end, near-straight-ahead at 5°:
Almost the full ball-load term. The joint is barely articulated, the four balls sit near groove centre, and the load distributes cleanly. The catch is that the same four contact points see every revolution under power for hours of straight-line driving — that is what brinells the grooves on a road-driven jeep that never steers hard.
Step 4 — at full lock, 30°:
You have lost about 3.3% of capacity versus straight ahead. That is small in absolute terms, but at 30° the balls sit near the end of their working groove length, contact patch shifts to one flank, and Hertzian stress on that flank rises by 15-20%. Above 30° the balls climb the groove ramp and the joint either binds, skips, or pops a ball — which is why the original MB steering stops are set to 29° at the knuckle.
Result
Nominal output torque at 22° articulation is 565 N·m (about 417 lb·ft) — well above the 240 N·m the MB powertrain can deliver in low range, so the joint runs with healthy margin in service. Across the operating envelope torque capacity barely moves (575 N·m at 5°, 565 at 22°, 556 at 30°) — the cosine term is gentle because half the steer angle stays small, but the real story is contact-patch position not raw capacity. If your rebuilt joint clunks under power on a tight-lock turn, the three usual culprits are: (1) a worn or backed-out centring-ball retainer pin letting the fifth ball walk axially, (2) groove brinelling from years of straight-line road driving on hardened balls running in one spot, and (3) contaminated grease — water ingress past the felt seal etches the groove surface and you lose the Ra 0.4 µm finish that keeps Hertzian stress in line.
Weiss CV Joint vs Alternatives
The Weiss joint sits between the cheap-and-angular Hooke joint and the smooth-but-complex Rzeppa joint. Pick it when you need true constant velocity, modest articulation, and field rebuildability without specialist tooling. Skip it when you need 40°+ steer angles or plunge capability in a single unit.
| Property | Weiss CV joint | Rzeppa CV joint | Hooke (cardan) U-joint |
|---|---|---|---|
| Maximum articulation angle | ~30° | 45-50° | ~30° but with velocity ripple |
| Velocity ripple at angle | None — true constant velocity | None — true constant velocity | 2/rev sinusoidal, severe above 10° |
| Torque capacity (passenger half-shaft class) | ~500-600 N·m | ~2,500-3,500 N·m | ~400-1,500 N·m depending on series |
| Plunge capability | None — needs separate slip spline | None on fixed type, full on plunge type | None — needs separate slip spline |
| Field rebuildability | High — replace balls and grease in hand tools | Low — needs press, cage timing | High — replace cross and bearings |
| Typical lifespan in service | 80,000-150,000 km on steered axle | 200,000+ km | Highly variable — 50,000-200,000 km depending on angle |
| Cost (single joint, 2024 aftermarket) | $80-180 (jeep MB pattern) | $60-250 | $15-90 |
| Best application fit | Light military 4×4 steered axle | FWD car outboard half-shaft | Two-piece driveshafts, PTO drives |
Frequently Asked Questions About Weiss CV Joint
Asymmetric clunk on one steer direction almost always means one of the four torque balls is undersized or one groove pair has worn deeper than the other. When you steer toward the worn side, that ball loses preload and slaps before it picks up torque. The diagnostic is to mic each ball — they must match within 0.005 mm — and dye-check the grooves for differential wear depth.
The other cause is yoke misalignment from a bent stub axle. Even 0.5° of stub-to-knuckle misalignment shifts the bisecting plane off centre and one direction of articulation runs the joint into the end of the groove sooner than the other.
No, and you will break the joint. The 30° limit is not a stop-block setting — it is the geometric end of the groove arc. At 32-33° the four torque balls climb out of the working portion of the grooves and onto the unhardened back-relief, which has neither the case depth nor the curvature to carry load. You will spall a groove or pop a ball within a few hundred miles.
If you genuinely need more steer angle, switch the outboard joint to a Rzeppa pattern. That is exactly why Land Rover moved off Weiss joints in the late Series IIA — the larger steer angles needed for tighter turning circles outran the Weiss working envelope.
Look at the ball count and the groove geometry. A Weiss has exactly four torque balls plus a fifth centring ball in a socket, and the grooves are open arcs cut into yoke fingers — you can see straight through the joint sideways. A Rzeppa has six balls held in a cage between an inner race and an outer race with closed cylindrical housing, and you cannot see through it.
If the joint is still in the housing, check the boot. Weiss joints on jeeps and Series Land Rovers run inside a kingpin housing packed with grease — no rubber boot. Rzeppas universally run sealed rubber or thermoplastic boots on a stub housing.
The closed-form cos(θ/2) result assumes ideal groove geometry, perfect ball-to-groove conformity, and no friction loss. In a real joint, especially a worn one, three things eat extra torque. First, sliding friction between balls and grooves rises with angle because contact patch migration introduces a small sliding component on top of rolling. Second, the centring-ball thrust load grows with angle and that interface is pure sliding. Third, packed grease churning losses scale with both speed and angle.
A healthy joint loses about 2-4% to friction at 25°. If you measure 8-10% loss, suspect dry or contaminated grease or a galled centring-ball socket.
Different problems. A Weiss sits at the wheel end and handles the steering articulation. A double-cardan sits at the transfer-case end of the front driveshaft and handles the pinion-angle offset that lifted suspension creates. You almost always need both, not one or the other.
If your question is really about whether to keep the original Bendix-Weiss outboard joints versus swap to a 297-series U-joint conversion (a popular MB/CJ upgrade), the trade is true constant velocity with 30° max angle (Weiss) versus higher torque capacity with velocity ripple above 10° (twin U-joints). For a stock-power flathead jeep that crawls, keep the Weiss. For a V8 swap that sees highway miles, the U-joint conversion takes more torque but you live with the ripple.
Notchiness at low speed with in-spec parts almost always points to the centring ball, not the four torque balls. The fifth ball runs in a socket that is supposed to be a smooth spherical seat. If the socket has fretted — common after years of small-amplitude steering inputs while parked or at idle — the ball drops into tiny detents at specific positions and you feel it as notchiness.
Pull the joint apart and inspect the centring socket under magnification. Polishing marks or a mirror finish are normal. Visible pits or a dull frosted ring means the socket is fretted and the joint needs the socket re-cut or the yoke replaced.
Weiss joints sit in a kingpin housing that runs hot from braking heat soak and sees small reciprocating motions during steering. Generic NLGI 2 chassis grease softens above about 80°C and the small-amplitude motion at the centring ball pumps it out of the contact zone, leaving a dry spot that fretts the socket within a few thousand miles.
Use a moly-fortified extreme-pressure grease with a dropping point above 200°C — Mil-G-10924 spec or modern equivalents like Mobil XHP 222 or Lucas Red & Tacky meet this. The molybdenum disulfide content is what protects the centring-ball socket during the boundary-lubrication condition that small-amplitude steering creates.
References & Further Reading
- Wikipedia contributors. Constant-velocity joint. Wikipedia
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