Honda Strut Bump Stop 51722-SMG-E04: OEM and Custom Polyurethane Replacement Parts from China Factory

Honda Strut Bump Stop 51722-SMG-E04: The Front Jounce Bumper Explained

The Honda strut bump stop with OE number 51722-SMG-E04 is the front axle spring bumper of the eighth generation Civic hatchback family. In the manufacturer catalogue the part is listed under the shock absorber group as a bumper for the front spring, and in the trade it is usually called a jounce bumper or bump stop. It is a moulded elastomer sleeve that slides over the piston rod of the front shock absorber, inside the coil spring. 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. 4110156. It is a direct replacement for the original part, moulded in engineering polyurethane with a 25.5 mm bore, a 68.2 mm outer diameter and a free height of 71.8 mm. Buyers who arrive from a search for the OEM number, for a Civic front bump stop or for a custom suspension bump stop factory are usually looking for the same three things: correct dimensions, consistent batch quality, and a supplier that can quote a custom mould without a long wait.

51722-SMG-E04 Specifications and Material Data

The dimensions match the reference data published for this position: the leading European aftermarket catalogue lists its equivalent front bump stop for the Civic VIII at 71 mm in length and 68 mm in width, in line with the 71.8 mm free height and 68.2 mm outer diameter of this moulding. The 25.5 mm bore is the first dimension to check. It is sized for the original Honda piston rod diameter, so a bumper 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, because we can mould a range of bore sizes on the same outer profile.

Vehicle Fitment: Civic FN and FK Front Axles

Aftermarket catalogues cross reference 51722-SMG-E04 across the European eighth generation Civic range and, in some references, into the early ninth generation. All of these applications share the same front MacPherson strut layout and service group.

Engine coverage reported for these applications runs from the 1.3 litre IMA hybrid and the 1.4 and 1.8 i-VTEC petrol units through the 2.2 i-CTDi diesel to the 2.0 litre Type R engine. Because the bumper is a chassis component, one reference covers all of them.

Why the revision suffix matters

The E01, E02, E03 and E04 suffixes are successive revisions of the same front bump stop. The major aftermarket catalogues treat them as interchangeable references and list them on the same product page. A stock check on any of the four numbers should therefore be treated as the same item, but the number moulded on the removed part remains the safest starting point for a match.

Companion references in the same strut group

Catalogue suppliers also group two related Honda references with this bumper: 51686-SMG-ZS00 (SK1) and 51610-SMG-305 (SK2), plates and seats that sit above the bump stop in the front spring assembly. One European catalogue describes a single aftermarket item as replacing all of these references together, and FEBEST adds 51722-TV0-E02 to the same list. Because the 51722, 51686 and 51610 prefixes stand for different components in the Honda numbering system, confirm the exact component by the number on the removed part and by the three dimensions above.

Reading the Honda Number Structure

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

In the Honda system the 51722 prefix identifies a front bump stopper, which is why both this part and the sedan number 51722-SNA-904 begin the same way. The middle block ties the part to a platform family: SMG stands for the European hatchback family of the eighth generation Civic, while the SNA block is catalogued for the sedan variants. Similar looking bumpers can therefore carry different codes and different dimensions, so match the full number rather than the first five digits.

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 at the end of its travel. On a daily driven Civic most drivers notice only that the knock over sharp bumps has gone, while on a car that is regularly loaded 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, and uneven wear on the upper spring seat caused by a collapsed bumper.

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. When the strut is already apart, fitting a new bumper costs little extra, and the dust cover should be checked at the same time, since a torn boot lets grit reach the 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 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. 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 shipment. Dimensional checks cover bore, outer diameter and free height against the drawing tolerance, a compression test confirms the load curve of the moulding, and a visual inspection looks for flow lines, voids and short fills around the inner bore, the area most likely to show a moulding defect.

FAQ

Is 51722-SMG-E04 the correct front bump stop for my Civic?

It is the front axle spring bumper for the eighth generation Civic hatchback and related body styles in the FN and FK families, built from 2005 to 2011, with one per side. Some catalogues extend coverage into the early ninth generation FK. Confirm by VIN or by the number on the removed part.

Are 51722-SMG-E01 to E04 the same part?

Yes. Catalogues list them as successive revisions of the same front bump stop and group them on one cross reference list, so any of the four can be ordered against the same specification. Check the bore, outer diameter and free height as well, in case an earlier revision was fitted before your car reached you.

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 51722-SMG-E04

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.