32308C bearing: complete specifications & equivalents
The 32308C is a ISO 355 radial bearing sized 40 x 90 x 35.25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 40 mm |
| Outer diameter D | 90 mm |
| Width B | 35.25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 122 kN |
| Basic static load rating C0 | 140 kN |
| Limiting speed (mechanical) | 4200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1100 g |
| Manufacturer designation | NTN 32308C |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 32300-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 1.388 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in 32300-series | 20 mm |
| Largest outer diameter in 32300-series | 460 mm |
| Width range across 32300-series | 22.25–154 mm |
| Bore position in 32300-series (smallest first) | 6 of 30 |
| Bore above smallest 32300-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32308C | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 32308C model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the NTN order number 32308C denotes the extra-heavy 32300 family of metric tapered roller bearings, 40 mm bore, 90 mm outside diameter and 35.25 mm assembled width T (1.575 × 3.543 × 1.388 in) to the ISO 355 boundary plan. The last two digits 08 are the ISO bore code, ×5 = 40 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 35.25 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. NTN grades 4T metric bearings as open bearings without integral seals; at 40 mm bore the application supplies the seals and the grease fill or oil supply to the 5FD ISO 355 assembly. The two speed columns differ by a factor of .75 (grease/limiting 4,200 vs oil 5,600 r/min); heat generation at the cone rib decides which lubrication a real 32308C arrangement can sustain. Open 4T bearings need application seals; without them the grease at the cone rib of 32308C washes out and the rib/roller-end contact smears on the first wet or dusty shift.
Typical equipment & failure modes
Common applications
- pump and compressor drive shafts carrying combined load
- machine-tool gearbox and headstock shafts
- axle final-drive and differential positions
- construction-equipment wheel and pivot hubs
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- cage damage from a mounting blow delivered through the roller complement instead of the ring face
- rolling-contact fatigue after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 40 mm bore class are commonly adjusted in pairs; verify end play against the axle drawing and re-torque after bedding-in rather than trusting the initial preload on 32308C.
- The extra-heavy 32300 family at 40 mm bore (90×35.25 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 5,600 r/min oil ceiling.
- Back-to-back and face-to-face arrangements react differently to shaft bending: pick the pair orientation for the moment load before locking the 40 mm shoulder geometry, because retrofitting flips the cups.
- Back-to-back and face-to-face arrangements react differently to shaft bending: pick the pair orientation for the moment load before locking the 40 mm shoulder geometry, because retrofitting flips the cups.
- The 25.0 mm section leaves little room for an oversized shaft fillet; check the mounting-chamfer table for 32308C or the ring will bottom out on the radius instead of the shoulder face.
- The 122/140 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32308C (ISO 355 5FD); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 32308C?
32308C is a metric 4T tapered roller bearing to ISO 355: 40 mm bore, 90 mm outside diameter and 35.25 mm assembled width T (1.575 × 3.543 × 1.388 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 122 kN, C0 140 kN (2203E prints no Pu for this size), grease limiting speed 4,200 r/min, oil speed 5,600 r/min, mass about 1100 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32308C?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (32308C); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32308C designation encode the 40 mm bore and what is 5FD?
last two digits 08 are the ISO bore code, ×5 = 40 mm (codes 00–03 use the 10/12/15/17 exception table). The 90 mm OD and 35.25 mm assembled T follow the ISO 355 dimension-series plan. 5FD is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does 32308C list two speeds, 4,200 and 5,600 r/min?
The lower figure, 4,200 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32308C at 5,600 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32308C mean?
Suffix reading on 32308C: the trailing A/C/D (or E1) letter marks an NTN contact-angle or internal-design revision of the base number, not a seal or clearance code; the suffix is part of the order number and the variants are not interchangeable articles.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.