Lexus Toyota Strut Bump Stop 48331-21030: OEM and Custom Polyurethane Replacement Parts from China Factory

Lexus Toyota Strut Bump Stop 48331-21030: The Front Jounce Bumper Explained

The Lexus Toyota strut bump stop with OE number 48331-21030 is the front axle spring bumper, also listed in the manufacturer catalogue as Bumper, Front Spring and in the trade as a jounce bumper or bump stop. It is a moulded elastomer sleeve that sits on the piston rod of the front shock absorber, inside the coil spring. Under everyday driving it works quietly in the background. When a pothole, a speed hump or a full load drives the strut deep into its travel, this small part is what stops metal from striking metal.

Our production unit carries Bonpora No. 4110159. It is a direct replacement for the original part, moulded in engineering polyurethane with a 21 mm bore, a 60.2 mm outer diameter and a free height of 82.5 mm. Buyers who arrive from a search for the OEM number, for a Prius front bump stop, for a Lexus HS250h strut bumper or for a custom suspension bump stop supplier are usually looking for the same three things: correct dimensions, consistent batch quality, and a factory that can quote a custom mould without a long wait.

48331-21030 Specifications and Material Data

The 21 mm bore is the first dimension to check. It is sized for the original Toyota piston rod diameter, so a bumper intended for an aftermarket damper with a thicker rod may need a different bore. Where a car has been converted to adjustable suspension, measure the rod before ordering and tell us the value, because we can mould a range of bore sizes on the same outer profile.

Vehicle Fitment: Prius, Prius V, Sai and Lexus HS250h

The manufacturer lists this part as Bumper, Front Spring with position Front, and aftermarket catalogues cross reference it across the following applications. All of them sit on the same front MacPherson strut layout and share the front spring and shock absorber family.

Engine coverage reported for these applications runs from the 1.8 litre 2ZR-FXE hybrid unit in the Prius family, through the 2.4 litre 2AZ-FXE hybrid in the Lexus HS250h, to the 2.5 litre 2AR-FE petrol engine in the tC and Zelas. Because the bumper is a chassis component rather than an engine component, one reference covers all of them.

Why the model year matters more than the model name

The name Prius has been used on four different platforms, and the front bump stop changed with each of them. The second generation NHW20 uses a different front spring bumper from this one, and the fourth generation ZVW50 moved to another number again. A part sold online as a generic Prius bump stop may therefore not match the strut on the car in front of you. Model year and chassis code, not the model name alone, decide which moulding is correct.

The supersession from 48331-75010

Catalogues list 48331-75010 as the number this part replaced. The two references are interchangeable, and a stock check on either number should be treated as the same item. Note that 48331-75010 belongs to the same Toyota group as the rear spring bumper 48341-75010 used on the Prius and the HS250h, so it is worth reading the full code rather than the first five digits when picking from a parts diagram.

Reading the Toyota Number Structure

Decoding the number is the quickest way to avoid buying the wrong moulding.

In the Toyota system the first group, 48331, identifies a front spring bumper. The same block with a 41 in place of the 31 identifies the rear spring bumper, so 48331 and 48341 are opposite ends of the car and are not interchangeable. The remaining digits identify the platform the part was released for, which is why two bumpers that look similar can carry different codes and different free heights.

Polyurethane Versus Original Rubber

The factory part is a rubber moulding. Rubber performs well when new, but it takes a compression set over time, absorbs oil and road salt, and eventually cracks or crumbles. Once the bumper has lost height, the strut bottoms out earlier on every compression and the driver feels it as a hard knock over speed humps and broken asphalt.

Polyurethane is not automatically better in every respect, and we do not claim that it is. It is stiffer for the same shape, which changes how the suspension behaves in the last part of its travel. On a daily driven hybrid the difference is small and most drivers notice only that the knock over sharp bumps has gone. On a car that is regularly loaded or driven on poor roads, the longer service life is the main benefit. Hardness can be specified to suit the application.

Common Symptoms of a Worn Front Bump Stop

A collapsed or missing front bumper rarely fails suddenly. The signs build up over months.

• Heavy knocking or a dull thud from the front when crossing speed humps or sharp ridges.
• A metallic bottoming out sensation under compression that was not present when the car was newer.
• Crumbs of rubber or polyurethane on the shock absorber rod or in the strut tower area.
• A bumper that has lost height, or that has cracked around the bore, when inspected with the strut removed.
• A noticeably harsher ride over broken surfaces even though the shock absorbers still pass a bounce test.
• Uneven wear on the upper spring seat or the dust cover, caused by a collapsed bumper letting the strut travel further than designed.

Bump stops are usually replaced as part of a strut overhaul rather than on their own, because the labour to reach them is the same either way. If the strut is already apart, fitting a new bumper costs very little extra. It is also the natural moment to check the dust cover for splits, since a torn boot lets grit reach the piston rod seal and is a common cause of damper leaks later on.

Custom and OEM Production for Wholesale Buyers

For distributors and workshops that purchase in volume, the standard 48331-21030 profile is only the starting point. We produce suspension bump stops for passenger car and light commercial applications across a wide size range, and the same tooling approach applies here.

• Hardness selection from 70A to 95A to match the ride you want.
• Custom bore, outer diameter and free height, including progressive and multi rate internal profiles.
• Moulded or laser marked part numbers, and private label packaging.
• Neutral export packaging as standard, with brand packaging available on request.

Tooling for a new profile usually needs a drawing or a sample. If you have a worn original bumper to hand, sending it to us is often the quickest way to start, because we can measure the free height and the bore directly and work from the failure mode as well as from the drawing. Our wider range of shock absorber parts is built around the same strut assembly, and the full programme of polyurethane bump stops covers both standard and custom profiles.

Quality Control Before Shipment

Every batch is inspected before it leaves the factory. Dimensional checks cover the bore, the outer diameter and the free height against the drawing tolerance. A compression test confirms the load curve of the moulding. A visual inspection looks for flow lines, voids and short fills around the inner bore, which is the area most likely to show a moulding defect.

FAQ

Is 48331-21030 the correct front bump stop for my Prius?

It is the front axle spring bumper for the third generation Prius ZVW30 and ZVW35 plug-in, the Prius V and Prius Plus ZVW40 and ZVW41, the Toyota Sai and the Lexus HS250h, with one per side. Other Prius generations use different numbers. Confirm by VIN or by reading the number on the part you are replacing.

Are 48331-21030 and 48331-75010 the same part?

Yes. Catalogues list 48331-75010 as the number that 48331-21030 replaced, so the two references are interchangeable. Note that 48341-75010 is a different part: it is the rear spring bumper used on the same vehicles and it is not a substitute for this front moulding.

Can you make this bumper in a different height or hardness?

Yes. The bore, outer diameter and free height can all be adjusted, and hardness can be specified from 70A to 95A. Custom work is quoted from a drawing or a physical sample, and a first article sample can be supplied for fitting checks before mass production begins.

What is the minimum order and delivery time?

Delivery time for standard production is 15 to 30 days. The minimum order quantity depends on whether the profile already exists in our tooling or needs a new mould, so please send the specification and the volume you plan to buy and we will confirm both figures.

Request a Quotation for 48331-21030

Send us the OEM number, the quantity you need and the market you serve, and we will reply with price, tooling status and lead time. Full contact details are on our contact information page, and you can also send a drawing or a sample photo for a technical review before you commit to an order.