Chevrolet/GMC Strut Bump Stop 523065 - Polyurethane OEM & Wholesale Supplier from China

Chevrolet/GMC Strut Bump Stop 523065 Overview

The 523065 strut bump stop is a large-format progressive compression buffer produced for Chevrolet and GMC suspension assemblies and supplied by Bonpora under reference 4110131. Mounted on the damper piston rod behind the dust cover, the buffer stays out of the work for most of the travel and comes into play only at the end of the stroke: when a loaded truck drops into a deep pothole or crosses rough yard ground, the spring reaches the limit of its travel and the buffer compresses progressively, converting the remaining energy into elastic resistance so the strut never lands metal on metal. With a 148 mm free height and an 84 mm seating base, this reference belongs to the heavy-duty end of the bump stop range, where the load difference between an empty vehicle and a fully loaded or towing one is widest and the energy left to absorb is greatest.

Technical Specifications

Reading the 523065 Reference Number

The reference 523065 is a compact six-digit numeric code without dashes, spaces or letter prefixes. Buyers who work mainly with modern GM catalogues will notice that it does not follow the longer dash-separated format used there, and that is not unusual: replacement-market listings and service catalogues frequently carry shortened codes for fast-moving suspension hardware. A short code still identifies one defined buffer - one bore, one seating diameter, one free height and one compound - but it does not tell the buyer which model families it covers, and printed fitment lists are not always complete for paired brands such as Chevrolet and GMC. Professional buyers therefore work in three steps: match the number first, verify the three measured dimensions second, and confirm the model year and VIN third. Where the number and the dimensions disagree, the dimensions and the VIN take priority.

Chevrolet and GMC: Sister Brands on Shared Platforms

Chevrolet and GMC are sister brands inside the General Motors line-up, and several of their best-known model families are built as paired lines on shared architectures - the full-size pickup pair and the full-size SUV pair are the classic examples. Vehicles engineered this way routinely share suspension hardware, so the same buffer appearing in both brand catalogues is normal rather than exceptional. Trim level, towing package and market can still change springs, dampers and bump stop dimensions within one family, so a brand match alone is not a fitment guarantee. Confirm the reference in your parts catalogue and measure the buffer removed from the vehicle against the checklist below before releasing a bulk order.

Dimension Checklist for This Large-Format Buffer

• Inner bore (Φ24.5 mm) - the central hole that locates the buffer over the damper rod or locating spigot. A bore that is too tight binds and tears during compression; one that is too loose drifts, scuffs and loses alignment under side loads.
• Base outer diameter (Φ84 mm) - the wide seating diameter that spreads the final impact across the mount recess or dust cover base. An undersized base can punch through its seat; an oversized one never sits flat and risks cracking at the edge.
• Free height (148 mm) - the unloaded length, which sets the point in the travel where the buffer starts to work and how much protected travel remains before the strut bottoms out. This is a tall, long-travel profile typical of heavy-duty suspension, and it must never be replaced by a shorter universal block.

Measure all three values on the buffer taken off the vehicle and compare them with the table above. If any value differs, stop and re-check the application: close is not close enough on a part that defines the end of the suspension stroke.

Why Polyurethane Suits Truck Duty Cycles

Original buffers in this weight class are commonly cellular foam or microcellular rubber. The material works well when new, but truck duty cycles punish it: high load factors, trailer towing, heat radiated from loaded brakes and years of full compression eventually oxidise the foam until it powders or takes a permanent set. Cast polyurethane is specified for reference 4110131 because it keeps its profile through repeated full compressions, tolerates oil mist, road salt and ozone, and can be tuned across a wide hardness band so the compression curve matches the axle load instead of leaving the mould as a fixed compromise.

Importers building a mixed GM suspension programme can consolidate further references from the polyurethane bump stops range in the same material grade, which improves freight efficiency per unit and simplifies incoming inspection.

When to Inspect and Replace the Buffer

A worn buffer rarely announces itself at an early stage; workshops usually find it through secondary damage. The following signs justify pulling back the dust cover for an inspection:

• A hard metallic knock over potholes, speed ramps or yard obstacles where a damped stop used to be.
• Cracked, powdered, torn or visibly flattened material on the removed buffer.
• A buffer that has slipped down the rod or separated from its seat.
• Accelerated wear of the strut mount, spring seat or dust cover.
• New clunk noises after an impact, combined with harsher rebound comfort.

Because dampers and buffers age as a set, review the complete range of shock absorber parts on the axle before ordering; fitting a new buffer onto a worn damper shortens the life of both.

Supply Terms for Importers and Fleet Buyers

Bonpora manufactures reference 4110131 in China and ships it in neutral export packaging, so cartons arrive unbranded and ready for relabelling under your own programme. Standard lead time is 15-30 days depending on order volume and production scheduling, and a 1-year warranty applies under normal installation and service conditions. Fleet operators running mixed Chevrolet and GMC vans, pickups and SUVs can consolidate this reference with related axle hardware to fill containers efficiently.

Information to Send With Your RFQ

1. The complete reference 523065.
2. Measured bore, base outer diameter and free height, or simply the Bonpora number 4110131.
3. Vehicle brand, model, model year and, where available, the VIN.
4. Quantity per shipment and any rolling forecast for production planning.
5. Target hardness if you are converting an original foam programme to polyurethane.

OEM Customisation and Private Label

Programmes that need a private-label buffer, a different hardness band, a modified flange or a replacement for a discontinued reference can be routed through the custom parts channel. The process is sample-driven: send a drawing or a removed buffer, the target compression curve is agreed from measurements, first-off samples are produced for fitment approval, and batch production is released only after sign-off. This route is used regularly for heavy-duty applications where the original foam buffer is no longer listed but the vehicle population still supports steady replacement demand.

Factory Quality Assurance Process

Every batch passes three gates before packing. Dimensional inspection verifies bore, seating diameter and free height against the approved master sample. Visual inspection screens for flash, voids, cracks and bonding defects around the base. A sampled compression and rebound test confirms the hardness grade and that the buffer recovers to free height without measurable permanent set. Batch records are retained so each shipment can be traced back to its production lot whenever documentation is requested.

Fitting Tips for Heavy-Duty Applications

• Replace buffers in axle pairs so both sides engage at the same point of travel.
• Inspect the dust cover and strut mount while the strut is open; on trucks these parts age together with the buffer.
• Clean the damper rod before fitting and keep grit out of the bore.
• Use a silicone-based or PU-compatible grease where lubrication is needed; petroleum grease can attack the compound.
• After assembly, confirm clearance between the Φ84 mm base and the dust cover so the buffer seats without rubbing.
• Never cut a buffer shorter to change ride height; ride height belongs to the springs, not to the buffer.

Frequently Asked Questions

Does 523065 fit both Chevrolet and GMC models?

Both brands sit inside the GM line-up and several model families are built on shared architectures, so cross-listed hardware between Chevrolet and GMC catalogues is common. Which exact models and years carry this reference varies by trim, market and towing package, so treat the number as the starting filter: verify the 24.5 mm bore, 84 mm base and 148 mm free height against the removed buffer and confirm the VIN where doubt remains.

Why is the free height as much as 148 mm?

Free height is a design value, not a quality feature. A 148 mm buffer engages early enough in the stroke to protect a long-travel, heavily loaded suspension, which is typical for full-size truck applications where the load difference between empty and maximum is large. The replacement must match the removed part in all three dimensions so the engagement point stays where the suspension was engineered to place it; a shorter universal block would leave the damper exposed to metal-to-metal contact.

Can I order by dimensions alone without the reference number?

Yes. Send the measured inner bore, base outer diameter and free height, plus the Bonpora reference 4110131 if you have it. Dimensions are the decisive filter for a compression buffer; the number mainly speeds up catalogue matching and adds a second cross-check before dispatch.

What are the lead time, packaging and sample options?

Standard production lead time is 15-30 days depending on volume, and goods leave the factory in neutral export packaging suitable for relabelling. Samples of reference 4110131 can be arranged before a production order so fitment can be proven on an actual vehicle, and a 1-year warranty covers the part under normal installation and service conditions.

Request a Quotation for 523065

Send the reference number, your measured dimensions and the target model year, and the sales team will confirm availability, hardness grade, packaging and lead time for 4110131. Samples can be shipped before a production order so the fitment can be checked on a real vehicle first.