Astralpool / Zodiac Motor Foot Bolt M10 x 25 Hex Washer Head 40173
Astralpool / Zodiac Motor Foot Bolt M10 x 25 Hex Washer Head 40173 is temporarily out of stock and will ship as soon as it's available.
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Don't Guess - Ask Us!
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Astralpool / Zodiac Motor Foot Bolt M10 x 25 Hex Washer Head 40173
Astralpool / Zodiac Motor Foot Bolt M10 x 25 Hex Washer Head 40173 is temporarily out of stock and will ship as soon as it's available.
Astralpool / Zodiac Motor Foot Bolt M10 x 25 Hex Washer Head 40173
Genuine Fluidra M10 x 25mm hex washer head bolt, part number 40173. This is the current motor hold-down bolt, and it is the listed replacement for the superseded 40156. Sold individually.
- Physically Stocked, unlike most "drop-shipping" websites.
- Shipped from VIC, NSW, WA, QLD
Supersedes 40156
If your parts diagram or older paperwork calls for 40156, this is the part to order. Astralpool discontinued 40156 and directs to 40173 in its place.
What It Does
These bolts hold the motor down onto the motor foot, clamping through the rubber anti-vibration inserts. The integral washer head spreads the load so the bolt does not pull through the mount.
When To Replace
- The head has corroded and no longer takes a socket cleanly
- The bolt is seized, or snapped during removal
- Fitting a new motor, foot or rubber inserts and refreshing the fasteners as a set
Fitting Notes
Snug only. These clamp through rubber inserts, and winding them down hard crushes the rubber solid, which removes the vibration isolation the mounts exist to provide — the result is a pump that suddenly sounds much louder on the pad. Tighten until the motor is stable and stop there.
Related Parts
- 4005002 — motor foot, graphite pearl (buy here)
- 40056 — V2 rubber insert (buy here)
- 40272 — M8 brass hex nut (buy here)
- 78772 — M8 x 50mm seal plate bolt (buy here)
Fits These Pumps
- Astralpool CTX — CTX 180, 280, 360, 400, 500 (including MkII)
- Astralpool E-Series — E 140, E 170, E 230
- Astralpool Viron XT — P320 XT, P520 XT
- Astralpool XP range
Common search terms: Astralpool 40173, 40156 replacement bolt, M10 x 25 motor bolt, CTX motor hold down bolt, pump motor foot bolt.
Manufacturer Catalogues, Diagrams & Part Numbers
Need exploded views, spare part numbers, product numbers or diagrams? See the manufacturer catalogue: Astralpool Catalogue 2026 | Zodiac Catalogue 2026
Before ordering: confirm this part is correct for your pump. Use the catalogue above, seek professional assistance, or contact us with photos of your existing part, model details, serial numbers and any labels. As with all products, this must be diagnosed and fitted by a qualified and experienced person. This is a special-order item.
To the layperson, plumbing sizes and their names can be confusing due to the nominal sizes and naming conventions used.
This is not something we made up. Plumbers and manufacturers have used nominal (meaning ‘by name only’) sizing for decades.
Simply put, in plumbing, named sizes are often not the actual measurements of the pipe, fitting, or part. A PVC pipe called “50mm” or “2"” does not measure 50 mm anywhere. Instead, it follows nominal sizing, an internationally-standardised naming system.
Almost all fittings we use in the pool & spa industry use “pressure PVC” pipe & fittings. Do not confuse with “DWV” or other pipe & fittings and their names and sizes.
Use the Outside Diameter (OD) to check your pipe against fittings. Below is a quick reference for common spa & pool pipe sizes:
| Imperial Name | Metric Name | Pipe Diameter (OD) |
|---|---|---|
| 1/2" | 15mm | ~21.2–21.5 mm |
| 3/4" | 20mm | ~26.6–26.9 mm |
| 1" | 25 mm | ~33.4–33.7 mm |
| 1.5" | 40 mm | ~48.1–48.4 mm |
| 2" | 50 mm | ~60.2–60.8 mm |
| 2.5" | 65 mm | ~75.2–75.5 mm |
To reiterate, these are nominal sizes and are designed to fit matching fittings — not to measure what their name suggests. These are based on PVC Pressure Pipe AS/NZ 1477 Dimensions1.
- º Internal diameters vary slightly by manufacturer and class.
- 1 Not all pool/spa fittings match these dimensions exactly. Some do not follow Australian or international standards. Chinese spas may use proprietary fittings.
Understanding Plumbing Sizes & Nominal Measurements
Plumbing sizes can be confusing. PVC and many other pipe systems use nominal sizes—the size is a name, not the exact measured dimension. This convention is used across most pool and spa systems and other plumbing areas so that pipes and fittings remain compatible.
Why pipe sizes don’t match the measurements
The Nominal Pipe Size (NPS) system standardises pipe dimensions so that pipes, fittings, valves, and accessories interoperate.
Plumbers work with these nominal names every day, but DIYers can be tripped up if they try to match by a tape-measure alone.
How to Measure Pipe Correctly
-
Pipe size is identified by:
- The pipe’s Outside Diameter (OD).
- The fitting’s Inside Diameter (ID) (socket opening).
- Pipe Class / Schedule (e.g., Class 9, 12, 18 or Sch 40) relates to wall thickness and therefore the Internal Diameter (ID) and pressure rating.
- The outside diameter of a fitting is not useful (wall thickness varies by manufacturer).
Hose & Tube Dimensions
Common flexible hose sizes used in pool/spa systems (approximate IDs).
| Imperial Name | Metric Name | Inside Diameter (ID) |
|---|---|---|
| 3/8" | 9–10 mm | ~9 mm |
| 3/4" | 19 mm | ~19 mm |
BSP – British Standard Pipe Thread Sizes
BSP thread names are also nominal. The thread OD will not equal the nominal name.
| BSP Thread Size Naming | Outside Diameter (mm / inch) | TPI |
|---|---|---|
| 1/16" BSP | 7.7 mm / 0.304" | 28 |
| 1/8" BSP | 9.7 mm / 0.383" | 28 |
| 1/4" BSP | 13.16 mm / 0.518" | 19 |
| 3/8" BSP | 16.66 mm / 0.656" | 19 |
| 1/2" BSP / 15 mm | 20.99 mm / 0.825" | 14 |
| 5/8" BSP | 22.99 mm / 0.902" | 14 |
| 3/4" BSP / 20 mm | 26.44 mm / 1.041" | 14 |
| 7/8" BSP | 30.20 mm / 1.189" | 14 |
| 1" BSP / 25 mm | 33.25 mm / 1.309" | 11 |
| 1-1/4" BSP | 41.91 mm / 1.650" | 11 |
| 1-1/2" BSP / 40 mm | 47.80 mm / 1.882" | 11 |
| 2" BSP / 50 mm | 59.61 mm / 2.347" | 11 |
| 2-1/4" BSP | 65.71 mm / 2.587" | 11 |
| 2-1/2" BSP | 75.18 mm / 2.960" | 11 |
| 3" BSP | 87.88 mm / 3.460" | 11 |
| 4" BSP | 113.03 mm / 4.450" | 11 |
| 5" BSP | 138.43 mm / 5.450" | 11 |
| 6" BSP | 163.83 mm / 6.450" | 11 |
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