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Mudguard / Penny Washer
Large outside-diameter mudguard (penny) washers, a wide face for a small hole in soft or thin material.
About the Mudguard / Penny Washer
Mudguard washers, also called penny or fender washers, have a big outside diameter for a small hole, to spread the load on trailer and vehicle mudguards, thin sheet, plastic and fibreglass panels, and to cover slotted or oversized holes. We carry DIN 9021 washers in 304 and 316 stainless and natural or black nylon (M3 to M20), hardened zinc flake ISO 7093 washers for high tensile bolts, Bumax stainless, large and extra large flat washers in galvanised, plain, zinc plated and stainless (M6 to M48), imperial zinc plated from 1/8 to 5/8 inch, and large OD Nord-Lock washers. Choose above; the guide below covers sizes and finishes.
Also called penny washers, fender washers or large OD washers.
Features
- Large OD for a small hole
- Spreads load on softer materials
- Metric and imperial
- Zinc and stainless
Applications
- Trailer and vehicle mudguards
- Thin sheet metal, plastic and fibreglass panels
- Covering slotted or oversized holes
- Electrical distribution (extra large washers)
What a mudguard (penny) washer does
A mudguard washer is a flat washer with a much larger outside diameter than a standard washer for the same bolt. Hobson describes the large OD as spreading the load more evenly on softer materials, protecting the surface from damage and covering slotted and oversized holes. The names mudguard, penny and fender washer all mean this large-OD flat washer.
Common jobs: fixing trailer and vehicle mudguards, thin sheet metal, plastic and fibreglass panels, soft timber and boards, and bolting through slotted or oversized holes. Hobson publishes no load rating for these washers; for structural timber or steel connections, use the washer size, thickness and finish the designer or span tables specify.
How to choose a mudguard washer
- Bolt size: a metric washer is named for its bolt, so an M10 washer fits an M10 bolt. Imperial washers are named for the bolt in inches.
- Outside diameter and thickness: bigger and thicker spreads the load further and bridges a bigger slot. For the same M10 bolt we carry 27 x 2mm (Supa), 30 x 2.5mm (DIN 9021) and 38 x 3mm washers.
- Hardness: with high tensile bolts use the hardened zinc flake 300 HV washers, which Hobson rates for bolts up to class 10.9. Hobson publishes no hardness for the plain mild steel, DIN 9021 stainless and nylon washers on this page.
- Finish for where it goes: see the finishes section. Exposed outdoor work such as decks, pergolas and trailers needs hot dip galvanised or stainless.
- Insulation: nylon washers separate dissimilar metals and insulate electrically.
Metric mudguard washer sizes (DIN 9021 and ISO 7093)
DIN 9021 and ISO 7093 washers have an outside diameter of about three times the bolt size. Select a row to open that washer in the selector.
Outside diameter x thickness in mm, from the selector. Hobson's black nylon sheet gives measured sizes a little under these nominal DIN 9021 sizes (for example M12 36.4 x 2.7mm). Zinc flake sizes are from Hobson's Did You Know sheet and Bumax 88 sizes from Hobson's dimension table. Min. order is the pack quantity; Bumax washers can be ordered from 1. Tap a number to show it in the selector above.
Large and extra large flat round washers (M6 to M48)
Hobson's large flat round (Supa) washers run from M6 to M48 in hot dip galvanised, plain and zinc plated mild steel. The extra large flat round washers come in the AS 1237.1 pattern (M10 to M24) and as heavy 5 to 6mm thick washers in M12 and M16, which Hobson lists as spacers, and the 304 ones for electrical distribution work.
Outside diameter x thickness in mm, as listed in the selector. Where Hobson's Did You Know sheets give slightly different figures: 304 M12 45 x 5 and M16 51 x 5; 316 M12 and M16 5.75mm thick. Min. order is the pack quantity. Tap a number to show it in the selector above.
| Range | Bolt | OD x thickness (mm) | Finishes | Min. order |
|---|---|---|---|---|
| Large flat round (Supa) | ||||
| Large flat round (Supa) | M6 | 19 x 1.6 | Hot dip galvanised, plain, zinc plated | 200 |
| Large flat round (Supa) | M8 | 22 x 1.8 | Hot dip galvanised, plain, zinc plated | 200 |
| Large flat round (Supa) | M10 | 27 x 2 | Hot dip galvanised, plain, zinc plated | 200 |
| Large flat round (Supa) | M12 | 32 x 2.25 | Hot dip galvanised, plain, zinc plated | 100 |
| Large flat round (Supa) | M16 | 38 x 2.75 | Hot dip galvanised, plain, zinc plated | 100 |
| Large flat round (Supa) | M20 | 45 x 3 | Hot dip galvanised, plain, zinc plated | 50 |
| Large flat round (Supa) | M22 | 50 x 3.5 | Hot dip galvanised, plain, zinc plated | 50 |
| Large flat round (Supa) | M24 | 55 x 4 | Hot dip galvanised, plain, zinc plated | 25 |
| Large flat round (Supa) | M27 | 60 x 4.5 | Hot dip galvanised, plain | 20 |
| Large flat round (Supa) | M30 | 65 x 5 | Hot dip galvanised, plain, zinc plated | 15 |
| Large flat round (Supa) | M33 | 70 x 5.5 | Hot dip galvanised, plain | 10 |
| Large flat round (Supa) | M36 | 75 x 6 | Hot dip galvanised, plain | 10 |
| Large flat round (Supa) | M42 | 83 x 7 | Hot dip galvanised, plain | 10 |
| Large flat round (Supa) | M48 | 90 x 8 | Hot dip galvanised | 10 |
| Large flat round (Supa) | M48 | 95 x 8 | Plain | 10 |
| Extra large flat round, AS 1237.1 | ||||
| Extra large flat round, AS 1237.1 | M10 | 30 x 2.5 | Hot dip galvanised, zinc plated | 500 |
| Extra large flat round, AS 1237.1 | M12 | 37 x 3 | Hot dip galvanised, zinc plated | 200 |
| Extra large flat round, AS 1237.1 | M16 | 50 x 3 | Hot dip galvanised, zinc plated | 200 |
| Extra large flat round, AS 1237.1 | M20 | 60 x 4 | Hot dip galvanised, zinc plated | 150 |
| Extra large flat round, AS 1237.1 | M24 | 72 x 5 | Hot dip galvanised, zinc plated | 25 |
| Extra large flat round, heavy (HEC) | ||||
| Extra large flat round, heavy (HEC) | M12 | 43 x 6 | Hot dip galvanised | 100 |
| Extra large flat round, heavy (HEC) | M12 | 44 x 5 | 304 stainless | 100 |
| Extra large flat round, heavy (HEC) | M12 | 44.5 x 6 | 316 stainless | 100 |
| Extra large flat round, heavy (HEC) | M16 | 54 x 6 | Hot dip galvanised | 100 |
| Extra large flat round, heavy (HEC) | M16 | 50 x 5 | 304 stainless | 50 |
| Extra large flat round, heavy (HEC) | M16 | 57.2 x 6 | 316 stainless | 50 |
Imperial mudguard washers (1/8 to 5/8 inch)
Imperial mudguard washers are sold as bolt size x outside diameter x gauge. Gauge is the sheet thickness: the higher the number, the thinner the washer. Thickness in mm from Hobson's washer gauge conversion chart.
Bolt size x outside diameter (inch, with mm by arithmetic) x gauge (with Hobson's mm equivalent). Min. order is the pack quantity. Tap a number to show it in the selector above.
| Bolt | Outside diameter | Gauge | Finish | Min. order |
|---|---|---|---|---|
| 1/8 inch | ||||
| 1/8 inch | 1/2 inch (12.7mm) | 20 gauge (0.89mm) | Zinc plated | 200 |
| 3/16 inch | ||||
| 3/16 inch | 3/4 inch (19.1mm) | 18 gauge (1.26mm) | Zinc plated | 200 |
| 3/16 inch | 3/4 inch (19.1mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 3/16 inch | 1 inch (25.4mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 3/16 inch | 1-1/4 inch (31.8mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 1/4 inch | ||||
| 1/4 inch | 3/4 inch (19.1mm) | 18 gauge (1.26mm) | Zinc plated | 200 |
| 1/4 inch | 3/4 inch (19.1mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 1/4 inch | 1 inch (25.4mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 1/4 inch | 1-1/4 inch (31.8mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 1/4 inch | 2 inch (50.8mm) | 16 gauge (1.59mm) | Zinc plated | 100 |
| 5/16 inch | ||||
| 5/16 inch | 3/4 inch (19.1mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 5/16 inch | 1 inch (25.4mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 5/16 inch | 1-1/4 inch (31.8mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 5/16 inch | 1-1/2 inch (38.1mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 5/16 inch | 2 inch (50.8mm) | 16 gauge (1.59mm) | 304 stainless | 100 |
| 5/16 inch | 2 inch (50.8mm) | 16 gauge (1.59mm) | Zinc plated | 100 |
| 3/8 inch | ||||
| 3/8 inch | 1 inch (25.4mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 3/8 inch | 1-1/4 inch (31.8mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 3/8 inch | 1-1/2 inch (38.1mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 3/8 inch | 2 inch (50.8mm) | 16 gauge (1.59mm) | Zinc plated | 100 |
| 3/8 inch | 2 inch (50.8mm) | 12 gauge (2.52mm) | Zinc plated | 100 |
| 1/2 inch | ||||
| 1/2 inch | 1-1/4 inch (31.8mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 1/2 inch | 1-1/2 inch (38.1mm) | 14 gauge (1.99mm) | Zinc plated | 200 |
| 1/2 inch | 2 inch (50.8mm) | 16 gauge (1.59mm) | Zinc plated | 100 |
| 1/2 inch | 2 inch (50.8mm) | 12 gauge (2.52mm) | Zinc plated | 100 |
| 9/16 inch | ||||
| 9/16 inch | 1-1/4 inch (31.8mm) | 16 gauge (1.59mm) | Zinc plated | 200 |
| 5/8 inch | ||||
| 5/8 inch | 2 inch (50.8mm) | 16 gauge (1.59mm) | Zinc plated | 100 |
| 5/8 inch | 2 inch (50.8mm) | 12 gauge (2.52mm) | Zinc plated | 100 |
Large OD Nord-Lock washers
Large outside diameter Nord-Lock wedge-locking washer pairs are in this range too, for bolts that must not vibrate loose on slotted holes or softer surfaces. How Nord-Lock washers work, and the standard sizes, are on our Nord-Lock and safety washer page.
Large OD Nord-Lock washers we carry; every size is in the selector. 316L stainless washers can be ordered from 1. Tap a number to show it in the selector above.
| Material | Metric sizes | Imperial sizes | Min. order |
|---|---|---|---|
| 316L stainless | M3.5 to M30 | 1/4 to 1 inch | From 1 |
| 254 SMO stainless | M4 to M16 | None | 100 to 200 |
| Delta Protekt (zinc flake) hardened steel | M3.5 to M36 | 1/4 to 1 inch | 25 to 200 |
Which finish for where?
- Zinc plated and plain: zinc plated is about 5 microns with low corrosion resistance, for indoor and non-corrosive environments; plain washers are uncoated (lightly oiled). Inside and under cover only.
- Hot dip galvanised: about 50 microns, high corrosion resistance. Hobson's corrosion guide lists hot dip galvanising or stainless for exposed fixings such as decks, pergolas and outdoor frames, away from seaspray and pools.
- Zinc flake silver and Delta Protekt: zinc flake coatings, rated high corrosion resistance, applied without electroplating so there is no hydrogen embrittlement risk.
- 304 and 316 stainless: for exposed work; Hobson's corrosion guide gives 304 or 316 in seaspray zones and 316 within 2m of a pool edge. Neither 304 nor 316 is made to sit in seawater.
- Nylon: natural or black UV stable (nylon 66 with carbon black for outdoor weathering). Hobson notes nylon absorbs moisture, which lowers its strength and stiffness; use it where insulation, surface protection or separating dissimilar metals is the point.
Slotted and oversized holes
Hobson's application advice: most fabrication standards limit a bolt hole to 2mm over the bolt size (up to M24) or 3mm over (above M24). Where a joint needs slotted or oversized holes, the engineer and fabricator should put washers between the bolt head and nut and the joint surface, so the washer and the material are not overstressed or deformed. A large OD washer is the usual answer; in a structural joint the engineer specifies which one.
Mudguard washers in Adelaide
Allmat supplies mudguard and penny washers, extra large washers, bolts and nuts to builders, fabricators, trailer and vehicle builders, electricians and trade across Adelaide and South Australia. Add them to a quote with your bolts and nuts and we will price the lot.
Mudguard and penny washers
Mudguard washers, penny washers, extra large flat washers, bolts and nuts are available to order from Allmat for builders, fabricators, trailer and vehicle builders, electricians and trade across Adelaide and South Australia. Order through Allmat, we pick and pack it, then click and collect from the Allmat yard or have it delivered to site.
Goes with
Questions
What is a penny washer?
Another name for a mudguard washer: a flat washer with a large outside diameter and a small hole, used to spread the load on thin or soft material and to cover slotted or oversized holes. Fender washer is the same thing.
What size is an M10 mudguard washer?
It depends on the range: the DIN 9021 M10 is 30 x 2.5mm, the large flat round (Supa) M10 is 27 x 2mm, the AS 1237.1 extra large M10 is 30 x 2.5mm and the zinc plated mudguard M10 is 38 x 3mm. All fit an M10 bolt.
What does 1/4 x 1 x 16g mean on a mudguard washer?
A washer for a 1/4 inch bolt, 1 inch (25.4mm) outside diameter, 16 gauge thick. Hobson's conversion chart puts 16 gauge at 1.588mm.
Which mudguard washer for high tensile bolts?
The zinc flake silver 300 HV washers (ISO 7093, M10, M12 and M16). Hobson rates them as hardened washers suitable for bolts up to class 10.9.
Which mudguard washers for outdoors?
Hot dip galvanised or stainless steel. Hobson's corrosion guide lists hot dip galvanising or stainless for exposed fixings, 304 or 316 in seaspray zones and 316 within 2m of a pool edge. Zinc plated and plain washers are for indoors or under cover.
Are nylon washers waterproof seals?
No. Hobson lists nylon washers for separating dissimilar metals, electrical insulation, protecting a surface and absorbing shock and vibration. For a weather seal under a screw head, use a sealing washer.
Where can I buy penny washers in Adelaide?
Order through Allmat. Order ahead by phone on 1300 03 03 63 or send your list for a quote, then click and collect from 25 Kapara Road, Gillman, or have them delivered to site.
Mudguard / Penny Washer: sizes and finishes we supply
166 lines by type and finish. Pick one above for its product code, pack sizes and dimensions.
| Type | Finish | Sizes | Lengths | Lines |
|---|---|---|---|---|
| Mudguard | Zinc Plated | 1/8, 3/16, 1/4, 5/16, 3/8, 1/2, 9/16, 5/8 | x1-1/2x14g to x3/4x18g (9 lengths) | 27 |
| Standard | Galvanised | M6, M8, M10, M12, M16, M20, M22, M24, M27, M30, M33, M36, M42, M48 | x19x1.6 to x90x8 (21 lengths) | 21 |
| Standard | Delta Protekt | M3.5(#6), M4(#8), M5(#10), M6, M8(5/16), M10, M12, M14(9/16), M16(5/8), M18, M20, M22(7/8), M24, M27, M30(1-1/8), M33(1-1/4), M36(1-3/8) | x9.0x1.8 to x63.0x6.6 (14 lengths) | 17 |
| Standard | 316L Stainless | M3.5(#6), M4(#8), M5(#10), M6, M8(5/16), M10, M12, M14(9/16), M16(5/8), M18, M20, M22(7/8), M24, M27, M30(1-1/8) | x9.0x2.2 to x58.5x6.8 (13 lengths) | 15 |
| Standard | Steel | M6, M8, M10, M12, M16, M20, M22, M24, M27, M30, M33, M36, M42, M48 | x19x1.6 to x95x8 (14 lengths) | 14 |
| Standard | Zinc Plated | M6, M8, M10, M12, M16, M20, M22, M24, M30 | x19x1.6 to x72x5.0 (14 lengths) | 14 |
| Mudguard | 316 Stainless | M5, M6, M8, M10, M12, M16 | x15.0x1.2, x18.0x1.6, x24.0x2.0, x30.0x2.5, x30.5x2.7, x37.0x3.0, x38.0x3.2, x50.0x3.0 | 11 |
| Mudguard | 304 Stainless | M5, M6, M8, M10, M12, M16, M20 | x15.0x1.2, x18.0x1.6, x24.0x2.0, x30.0x2.5, x37.0x3.0, x50.0x3.0, x60.0x4.0 | 7 |
| Mudguard | Nylon Natural | M3, M4, M5, M6, M8, M10, M12 | x9.0x0.8, x12.0x1.0, x15.0x1.2, x18.0x1.6, x24.0x2.0, x30.0x2.5, x37.0x3.0 | 7 |
| Mudguard | Nylon Black UV Stable | M5, M6, M8, M10, M12, M16, M20 | x15.0x1.2, x18.0x1.6, x24.0x2.0, x30.0x2.5, x37.0x3.0, x50.0x3.0, x60.0x4.0 | 7 |
| Standard | Smo 254 | M4, M6, M8(5/16), M10, M12, M16(5/8) | x9.0x2.2, x13.5x2.0, x16.6x2.0, x21.0x2.0, x25.4x3.0, x30.7x3.2 | 6 |
| Standard | 316L Stainless | 1/4, 3/8, 1/2, 3/4, 1 | x13.5x2.2, x21.0x2.0, x25.4x3.2, x39.0x3.2, x48.5x3.2 | 5 |
| Standard | Delta Protekt | 1/4, 3/8, 1/2, 3/4, 1 | x13.5x2.5, x21.0x2.5, x25.4x3.4, x39.0x3.4, x48.5x4.6 | 5 |
| Mudguard | Zinc Flake Silver | M10, M12, M16 | - | 3 |
| Standard | 304 Stainless | M12, M16 | x44x5.0, x50x5.0 | 2 |
| Standard | 316 Stainless | M12, M16 | x44.5x6.0, x57.2x6.0 | 2 |
| Mudguard, bulk carton | Nylon Natural | M6 | x18.0x1.6 | 1 |
| Mudguard | Zinc Plated | M10 | x38x3 | 1 |
| Mudguard | 304 Stainless | 5/16 | x2x16g | 1 |
Data sheets and documents
The documents for the product you choose are listed with the selector above. Here is every Mudguard / Penny Washer document from Hobson Engineering.
All Mudguard / Penny Washer documents (34)
Data sheets and technical data (15)
- A4-70 vs BUMAX 88 in Ammonium Nitrate Environment
- BUMAX 88 and BUMAX 109
- BUMAX Grades
- BUMAX Definitions
- Breaking Strength
- Product Finish Comparison
- Junker Test Principle
- Vibration Test Diagram
- Hardness Tables
- Nylon Resistance Chart
- Nylon Properties
- Nylon Types
- Types of Washers
- Washer Gauge Conversion Chart
- Nord-Lock Washers - User Manual
Approvals (ETA, DoP) (1)
Did You Know flyers (6)
Guides and articles (12)
- A different shade of grey
- Common Misconceptions About Stainless Steel
- Prevent Zinc Whiskers with HDG Products
- What is Stainless Steel?
- Why does rust occur?
- Zinc Flake Coating
- Anti-Vibration Paper
- Zinc Flake Coating Delta Protekt
- Bumax Product Guide
- Nord-Lock Product Guide
- Nylon Product Guide
- Washers Product Guide
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Add the sizes you need to your quote, or send us your list and we’ll price the lot and supply it with the rest of your order.
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