Oil Seal Size Charts & Selection
Oil Seal Size Charts & Selection
Oil seals (shaft seals, radial lip seals) are sized by three dimensions: shaft diameter (ID) x housing bore (OD) x width. Texas Belting stocks 2,700+ metric and inch oil seals and shaft repair parts from our Durus line in Houston, TX, with most stocked sizes shipping same day.
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On this page: How to measure · Size chart · Seal profiles · Materials · Shaft repair · Installation · Mistakes · FAQ
How do you measure an oil seal?
Measure three dimensions with calipers: the shaft diameter where the seal lip rides (the seal ID), the housing bore diameter (the seal OD), and the seal width. Sizes are always listed ID x OD x width: a seal marked 35 52 7 fits a 35 mm shaft in a 52 mm bore and is 7 mm wide.
- Shaft: measure the shaft OD on an unworn section next to the seal path, twice at 90 degrees. Readings that disagree by more than a few thousandths mean wear or out-of-round – see wear sleeves.
- Bore: pull the old seal and measure the housing bore ID after cleaning it. The seal OD equals the bore diameter.
- Width: measure the old seal's width, or the bore depth if the seal must sit flush.
- Markings: stamped numbers on the old seal face (for example 35 52 7 TC NBR) give size, profile, and lip material.
Shaft condition matters too: published guidance calls for a plunge-ground finish of roughly 10–20 microinch Ra with no spiral lead. A grooved lip track needs a Durusleeve wear sleeve before a new seal goes on.
Metric oil seal size chart
The metric sizes below are among the most commonly stocked ISO/DIN-pattern sizes, listed shaft x bore x width in mm with decimal-inch equivalents. Every row links to our metric oil seal collection; most sizes come in nitrile (NBR), many in Viton (FKM).
| Seal size (mm) | Shaft ID (in) | Bore OD (in) | Width (in) |
|---|---|---|---|
| 20x35x7 | 0.787 | 1.378 | 0.276 |
| 25x40x7 | 0.984 | 1.575 | 0.276 |
| 25x47x7 | 0.984 | 1.850 | 0.276 |
| 30x47x7 | 1.181 | 1.850 | 0.276 |
| 30x52x7 | 1.181 | 2.047 | 0.276 |
| 35x52x7 | 1.378 | 2.047 | 0.276 |
| 40x62x8 | 1.575 | 2.441 | 0.315 |
| 45x65x10 | 1.772 | 2.559 | 0.394 |
| 50x72x8 | 1.969 | 2.835 | 0.315 |
| 60x85x10 | 2.362 | 3.346 | 0.394 |
| 70x90x10 | 2.756 | 3.543 | 0.394 |
| 80x100x10 | 3.150 | 3.937 | 0.394 |
| 90x110x12 | 3.543 | 4.331 | 0.472 |
| 100x125x12 | 3.937 | 4.921 | 0.472 |
If your shaft measures a clean fraction of an inch (1.000, 1.250, 1.500 in), start in the inch oil seal collection instead – near-miss metric sizes are not drop-in substitutes.
TC vs TB vs SC: which oil seal profile do you need?
The letter code on an oil seal describes its construction. First letter: lip arrangement – T is a spring-loaded lip plus a dust lip, S is a single spring-loaded lip, V is a single lip with no spring. Second letter: outer case – C is rubber-covered, B is exposed metal OD. A 2 suffix (TB2, SB2) marks a reinforced-case heavy-duty version.
| Profile | Outer case | Dust lip | Garter spring | Best for |
|---|---|---|---|---|
| TC | Rubber-covered | Yes | Yes | Default for dirty or outdoor duty (ag, construction, wash-down); rubber OD seals slightly imperfect bores. |
| TB | Metal OD | Yes | Yes | Dusty duty where a rigid metal press fit in a clean machined bore is preferred. |
| TB2 | Metal OD, reinforced case | Yes | Yes | Heavy-duty dual-lip service; extra case rigidity on larger seals. |
| SC | Rubber-covered | No | Yes | Clean indoor duty: gearboxes, pumps, motors. Lower friction and cost than TC. |
| SB | Metal OD | No | Yes | Clean environments needing a firm metal-to-metal bore fit. |
| SB2 | Metal OD, reinforced case | No | Yes | Heavy-duty single-lip service on larger diameters. |
| VB | Metal OD | No | No | Springless grease retention at low speeds; slingers and dust exclusion. |
Two rules cover most replacements: around dust, dirt, or moisture, pay for the dust lip (TC/TB); if the old seal leaked at its outside diameter, the bore is likely scarred, and a rubber-covered case (TC/SC) conforms to minor bore damage a bare metal OD will not. And standard lip seals are low-pressure parts – typical published limits are around 7 psi (0.5 bar); above that you need a pressure-rated design, so ask us first.
Oil seal material selection: nitrile vs Viton
Nitrile (NBR) is the default lip material for petroleum oils and greases at everyday temperatures; step up to Viton (FKM) when the seal runs hot, fast, or in synthetic oils, fuels, or chemicals. The ranges below are typical published elastomer ratings.
| Lip material | Typical temp range | Good with | Watch out for |
|---|---|---|---|
| Nitrile (NBR) | About -40 to +225°F | Petroleum oils and greases, hydraulic fluids, water | Hardens and cracks above its range; limited with hot EP additives |
| Polyacrylate (ACM) | About -20 to +300°F | ATF and EP gear oils at elevated temperature | Poor cold-weather flexibility; not for water service |
| Silicone (VMQ) | About -60 to +350°F | Wide temperature swings; crankshaft seals | Poor abrasion resistance; no dry running; check oil compatibility |
| Viton (FKM) | About -20 to +400°F | Synthetic oils, fuels, EP lubes, most chemicals, high surface speeds | Highest cost; stiffer at low temperatures |
The old seal tells you why it failed: a hardened, cracked lip cooked in service – move up to FKM; a lip grooved by grit means contamination – add a dust lip (TC); oil weeping at the seal's outer edge points at the bore – use a rubber-covered case.
Grooved shaft? Fix it with a Durusleeve wear sleeve
When a new seal still leaks, the usual culprit is a groove worn into the shaft by the old lip. The fix is a thin-wall stainless wear sleeve pressed over the worn track. Typical published wall thickness for this sleeve type is about 0.011 in (0.28 mm), so the seal size does not change – the original-size seal fits over the sleeved shaft.
- 1. Measure and clean. Size the sleeve off an unworn shaft section, then clean and deburr the seal track.
- 2. Press the sleeve on. Drive it squarely over the groove with the included installation tool – no machining, no heating.
- 3. Fit the original seal size. Remove the install flange if it interferes, lubricate, and fit a new seal of the original ID x OD x width.
Our Durusleeve line covers 270+ shaft repair sleeve sizes; sleeves of this type are published for shaft diameters from roughly 0.5 to 8 in (about 12 to 203 mm). Fitting a different-width seal so the lip rides beside the old groove is a stopgap; a sleeve restores a true sealing surface.
Which way does an oil seal face? Installation tips
The spring side of the seal faces the lubricant being retained. On a gearbox or pump, the garter spring and primary lip point inward toward the oil, and the dust lip (if any) faces the atmosphere. Installed backward, the seal pumps oil out along the shaft.
- Lubricate the lip and shaft with the system's oil or grease – never install a lip dry.
- Cover keyways, splines, and threads with tape or an install cone so sharp edges cannot slice the lip.
- Press square, near the OD with a driver or flat plate on the seal case. Never hammer the seal face.
- Seat to depth – flush with the housing face unless the assembly calls for a set-back.
- Check the garter spring stayed seated in its groove; a popped spring is a guaranteed leak.
Oil seal supplier in Houston, TX
Texas Belting & Supply stocks metric and inch oil seals, Viton seals, and Durusleeve shaft repair sleeves. Most stocked sizes ship same day from our Houston, TX warehouse. We serve the Texas Gulf Coast and ship nationwide. Call (888) 203-2358 to confirm availability.
Common oil seal selection mistakes
- Measuring the old seal instead of the shaft and bore. A used lip is distorted; the machined surfaces are the true dimensions.
- Skipping the dust lip outdoors. A single-lip SC seal in ag or construction duty lets grit eat the lip; spend the extra dollar on TC.
- Installing the seal backward. Spring side faces the lubricant; backward seals pump oil out and fail within days.
- Reusing a grooved shaft. A new seal riding in the old wear groove leaks from day one. Sleeve the shaft.
- Treating a heat failure as a wear failure. A hard, cracked NBR lip will fail again in NBR – upgrade to FKM.
When to call
Some jobs need a human. Call when:
- You only have an OEM, National, or CR part number to cross-reference to an in-stock size.
- The seal sees pressure above about 7 psi, vacuum, or a split housing.
- The media is unusual: aggressive chemicals, fuels, food-contact, or steam.
- The shaft measures between standard sizes or is worn beyond sleeve repair.
Call (888) 203-2358 or send us what you have – the numbers off the old seal or a caliper photo is usually enough.
Frequently asked questions
How do I measure an oil seal for replacement?
With calipers, measure the shaft diameter where the lip rides, the housing bore diameter, and the seal width. Sizes are listed ID x OD x width - a 35x52x7 seal fits a 35 mm shaft in a 52 mm bore and is 7 mm wide. Measure the shaft and bore, not the old seal, which distorts in service.
What do the numbers on an oil seal mean?
Seals are stamped with size, profile, and material. A seal marked 35 52 7 TC NBR fits a 35 mm shaft and 52 mm bore, is 7 mm wide, with a rubber-covered dust-lip case and garter spring (TC) and a nitrile lip (NBR). Inch seals often carry a part number instead, which we can cross-reference.
What is the difference between TC and SC oil seals?
Both have a rubber-covered case and a spring-loaded main lip. A TC seal adds a dust lip that blocks dirt and moisture from the sealing lip, suiting agricultural, construction, and outdoor equipment. An SC seal has a single lip with slightly lower friction - the economical choice for clean indoor gearboxes, pumps, and motors.
Which way does an oil seal face - spring side in or out?
The spring side faces the lubricant you are keeping in. On a gearbox, the garter spring and primary lip point inward toward the oil; the dust lip faces outside. Installed backward, a seal pumps oil out past the lip. Only a pure contaminant excluder gets mounted the other way.
Can I use a Viton oil seal instead of nitrile?
Yes - Viton (FKM) is an upgrade. Typical published ratings run about -20 to +400 F versus about -40 to +225 F for nitrile, and FKM resists synthetic oils, fuels, EP lubes, and most chemicals at higher surface speeds. The reasons to stay with nitrile are lower cost and very cold service.
What is the difference between an oil seal and a grease seal?
Lip loading. Oil seals use a garter spring to hold the lip on the shaft because thin, hot oil is hard to contain. Grease seals are often springless single-lip designs, such as VB, since thick grease needs less lip force. A spring-loaded seal retains grease fine; a springless one should not hold circulating oil.
How do you fix a shaft that is grooved where the seal rides?
Press a thin-wall stainless wear sleeve over the worn section. Typical sleeves have a wall of about 0.011 in (0.28 mm), so the original seal size still fits. Clean and deburr the shaft, drive the sleeve squarely over the groove with the supplied tool, then install a new seal of the original size.
Are metric and inch oil seals interchangeable?
Rarely. A 25 mm shaft measures 0.984 in, so a 1 in seal runs loose on it and a 25 mm seal runs tight on a 1.000 in shaft. Lips are engineered around a specific nominal shaft diameter; forcing a near-miss size shortens lip life. Measure precisely and buy the system your equipment was built to.
Related products and guides
Need help sizing or cross-referencing an oil seal?
Send dimensions, the old seal's markings, or the OEM part number. Our Houston team will match it to in-stock Durus seals and sleeves.
Request a Quote Call (888) 203-2358Last updated: July 2026