Weld-In Chromoly Housings for Spherical Bearings

Uniball Cups — Weld-In Spherical Bearing Housings

Q: Which bearing fits which cup?

Use the cup pairing table: UBC8 fits COM8 / FKS8 / COM8-SS; UBC12W fits WPB12T; UBC16W variants fit WPB16T; UBC20 and UBC24 fit HCOM20 and HCOM24.

Q: Is the snap ring included?

Yes. The retaining snap-ring groove is part of the cup and the retainer is included.

Q: Do I need a separate spherical bearing?

Yes. The cup is the housing; install your spherical bearing into it. See the spherical plain bearings page.

A uniball cup is the machined weld-in housing that holds a spherical (uniball) bearing in a control arm, knuckle or chassis mount, retained by a snap ring. SYZ cups cover 10 sizes, fit COM8–COM12, WPB12T–WPB16T and HCOM20–HCOM24 bearings, use 4130 chromoly with mild steel optional, and include the snap ring.

Browse Uniball Cup Sizes ↓ Request a Bulk Quote

4130 chromoly

Mild steel optional

Weld-in

Snap-ring groove

COM8–HCOM24

Bearing families

10 sizes

Configurations

ISO 9001:2015 Quality

Overview

What Is a Uniball Cup?

A uniball cup (uniball housing) is a machined cup that retains a spherical “uniball” bearing and welds into a control arm, knuckle or chassis mount — the snap-ring groove holds the bearing in place. It’s the housing half of a uniball suspension joint: weld the cup, install the spherical bearing, retain with the snap ring. Use it where you want a serviceable, high-misalignment pivot built into fabricated suspension.

Weld-In Bearing Housing

The cup is the fabricated housing that receives the spherical bearing and snap ring, so its real job is to make a custom suspension pivot possible.

Bearing-to-Mount Match

Cup bore, snap-ring groove and weld-in OD all need to match the bearing and the fabricated mount together, not just one nominal size callout.

10 Standard Sizes

Uniball Cup ↔ Spherical Bearing Pairing

Open Interactive Spec Selection →

Select the cup by its internal B bore and weld-in D, then pair it with the corresponding spherical bearing family. Every cup row links to the cup record and the bearing column links to the spherical-bearing range.

Cup	Cup bore B	Weld-in OD D	Fits spherical bearing	Retention
UBC8	1.0000″	1.250″	COM8, FKS8, COM8-SS	SR8 included
UBC10	1.1875″	1.500″	COM10, FKS10, COM10-SS	SR10 included
UBC12	1.4375″	1.750″	COM12, FKS12, COM12-SS	SR12 included
UBC12W	1.3750″	1.750″	WPB12T	SR12W included
UBC14W	1.6250″	2.000″	WPB14T	SR14W included
UBC16W	2.1250″	2.625″	WPB16T	SR16W included
UBC16W-1	2.1250″	2.625″	WPB16T	SR16W included
UBC16W-2	2.1250″	2.625″	WPB16T	SR16W included
UBC20	2.3750″	2.875″	HCOM20	SR20 included
UBC24	2.7500″	3.500″	HCOM24	SR24 included

Build the Complete Kit

Quote the cup and bearing together

Add a matching spherical bearing and misalignment spacers for a complete uniball joint kit. The cup is the weld-in housing; the bearing is the replaceable articulating element.

Uniball cup, bearing and misalignment spacer kit

Request a Complete Kit Quote

Engineering Guide

Selection Guide

Match Cup Bore to Bearing OD

Match the cup bore to your spherical bearing’s outer diameter; confirm the weld-in OD suits your mount wall.

Choose Material for Duty

Choose 4130 chromoly for suspension strength; mild steel for general/cost use. The cup is structural and permanent.

Confirm Snap Ring Fit

Confirm the snap-ring groove matches your bearing’s retention ring — the groove and retainer are included with the cup.

Pair with Spherical Bearing

The cup is the housing only — pair with a spherical plain bearing as the articulating uniball element.

Industrial Uses

Applications

Fabricated off-road suspension (control arms, knuckles), uniball upper mounts, chassis pivots, and any weld-in housing for a spherical bearing.

Fabricated Suspension Control Arms

Weld the cup into upper or lower control arm tube ends for a serviceable, high-misalignment pivot that survives repeated suspension travel.

Off-road & motorsport

Uniball Upper Mounts

Replacing OEM rubber upper mounts with a weld-in uniball cup and spherical bearing for improved camber response and serviceability.

Coilover & strut builds

Chassis Pivots

Weld-in cups at suspension link chassis mounts, skid plate pivot points and any structural joint that must articulate under load.

Custom chassis fabrication

Knuckle & Hub Assemblies

Integrated into fabricated knuckles or hub carriers where a weld-in housing provides a precision-located bearing seat.

Full custom suspension

Technical & Fabrication Guide

How a Uniball Cup Builds Into a Joint — Without Ruining the Bearing

The cup is the housing half of a serviceable uniball joint. Weld it first, let it cool, then install the bearing and retainer.

Fixture the empty cup square to the control arm, knuckle or chassis tab; tack in at least three spots to control distortion.
Complete the weld with the bearing removed. Heat from welding can damage the bearing, liner or heat treatment.
Let the cup cool fully, then check the bore and press in the matched spherical bearing.
Seat the included snap ring in the groove and confirm the bearing rotates freely without bind.

Match the interface: cup bore B to bearing OD, weld-in D to the mount wall, and snap-ring groove to the supplied retainer.

Maintenance Guide

Service & Failure Modes

A uniball joint is built to be serviced: the snap ring lets you replace just the worn spherical bearing and keep the welded-in cup — a major advantage over a sealed joint on a vehicle you’ll maintain.

Symptom	Cause	Prevention
Bearing won’t press in / binds	Cup bore distorted by weld heat	Tack first, weld cooled, keep bore round; re-machine if pinched
Bearing spins in the cup / falls out	Wrong bore-to-OD match, or missing/under-sized snap ring	Match cup bore to bearing OD; confirm the included retainer fits the groove
Cup cracks at the weld	Poor penetration / wrong procedure on chromoly	Full-penetration weld; proper 4130 procedure (pre/post-heat as needed)
Premature bearing wear	Wrong bearing type for the load/dirt	Pick the bearing series (metal-to-metal vs PTFE vs sealed) to suit the duty

Material choice: 4130 chromoly cups for suspension-strength fabricated joints; mild-steel cups where cost matters and loads are moderate. The cup is structural and permanent; the bearing inside is the wear/replaceable part.

FAQ

Common Questions

Which bearing fits which cup?

Use the cup ↔ bearing table above: UBC8 fits COM8 / FKS8 / COM8-SS; UBC12W fits WPB12T; UBC16W variants fit WPB16T; UBC20 and UBC24 fit HCOM20 and HCOM24. Open the spherical plain bearing range →

What material are SYZ uniball cups?

Machined from 4130 chromoly for suspension strength, with a mild steel option for general use.

Is the snap ring included?

Yes — the retaining snap-ring groove is part of the cup and the retainer is included.

How do I size a uniball cup?

Match the cup bore to the spherical bearing outer diameter and confirm the weld-in OD fits your mount. The catalog spans 1.0000–2.7500 inch cup bores across 10 sizes.

Do I need a separate spherical bearing?

Yes — the cup is the housing; install your spherical bearing into it. See the spherical plain bearings page.

Engineering Tools

Tools for Cup & Bearing Selection

Interference Fit Calculator

Estimate the press-fit relationship between bearing OD and cup bore.

Spherical Bearing PV Calculator

Check pressure-velocity limits for the paired spherical bearing.

Buyer Guides

Buyer Guides for This Product Family

Uniball Cups

Factory Direct

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