A33‑1266‑100 vs A33‑1266‑100BP: TheLast T680 Fairing BracketHolding the Panel

Summary. The A33-1266-100 is the longer of the two understep fairing reinforcements on the Kenworth T680 Next Gen. Each panel is held by two of them together with one shorter A33-1268. On the trucks we have documented with a failing panel the brackets do not let go at once, but in sequence: the A33-1268 goes first, one A33-1266-100 follows, and the second A33-1266-100 is left carrying the panel on its own. The OEM part is injection molded from 40% glass filled polypropylene and is a hollow shell with no internal ribs. The A33-1266-100BP replaces it on the factory mounting points, adds a full internal rib structure, and is manufactured from carbon fiber reinforced plastic. It is priced at $30.00, compared with $88.91 to $111.13 for the OEM part at the retailers surveyed. Where warranty terms, fleet policy or same day availability require a genuine Kenworth part, the OEM bracket remains the appropriate choice.

Bushido Performance manufactures the A33-1266-100BP. The findings on this page are drawn from photographs and video of trucks in service, the molded markings on the OEM part and published material data, and inference is identified as such throughout. Bushido Performance is not affiliated with Kenworth or PACCAR.

Readers still diagnosing a lower fairing that sits out of level should begin with our diagnostic guide to T680 fairing bracket failure. The A33-1268 is covered in the A33-1268 comparison. This page addresses the A33-1266-100.

Comparison at a glance

The last bracket holding the panel

Each understep fairing panel hangs from three brackets, two A33-1266-100 and one A33-1268, and while all three are intact they share the load between them. On the trucks we have observed with a failing panel they do not release together, and the sequence follows the same order each time. The A33-1268 goes first, at which point the panel drops at that end and its weight shifts onto the two A33-1266-100 reinforcements. One of those follows, leaving the remaining A33-1266-100 to carry the panel on its own until it too releases.

The two frames below were recorded on different Kenworth T680 Next Gen trucks, both from outside the vehicle and in daylight. They establish where the panel and the remaining bracket sit rather than the condition of the bracket itself, and the circle in Figure 1 marks the part under discussion.

On both trucks a single bracket remained in place after the others had released, and in each case its position and dimensions identify it as an A33-1266-100. These are observations rather than a failure study, so they establish no failure rate, and the detached brackets were not recovered for examination. They do, however, describe the same end state on two separate vehicles, and that end state places the whole of the panel on one bracket.

Why the A33-1266-100 is the last to fail

The reasoning below is drawn from the geometry of the parts and the order in which they release, rather than from fracture analysis.

• Load is redistributed, not removed. When the A33-1268 releases, the panel weight and the wind load it was carrying transfer to the two A33-1266-100 reinforcements, each of which then carries a share it was never intended to take alone.
• The load arrives off axis. With one end of the panel dropped, the panel twists on the mounts that remain, so the remaining reinforcements are loaded in torsion as well as in the direction they were shaped to support.
• The OEM section is a shell. Molded as an open channel with thin walls and no internal ribs, the OEM A33-1266-100 is stiff in the direction the panel normally loads it while offering little material to resist that twisting.
• The clips work against the part. The panel is retained by spring steel clips pressed over the bracket ends, and a panel that has begun to move rubs those clips against the plastic on every cycle. The wear is gradual and gives no outward sign until the clip seat has loosened.

A bracket still holding a hanging panel is therefore a bracket that has already been overloaded. When one A33-1266-100 is found in that condition, the others have either released or carried the same load, which is why all three should be replaced together.

What is molded into the OEM part

The OEM bracket carries its own specification. A new part photographed on the Big Rig World listing reads KENWORTH, A33-1266-100 A33-1266-200, REV C and PP-GF40. PP-GF40 is polypropylene with 40% glass fill, the same designation molded into the OEM A33-1268, and a standard specification for an injection molded component in this position. The same photographs show the interior as an open channel without ribs, with the spring steel clips fitted over each end.

Carrying both part numbers on a single part is consistent with the Kenworth dealer catalog, which directs orders for A33-1266-200 to A33-1266-100, and the A33-1266-300 listing at Big Rig World is illustrated with that same molding. Owners searching under any of the three numbers are therefore looking for the same bracket.

Design changes in the A33-1266-100BP

Each change addresses a specific weakness identified above.

• Internal rib structure. Transverse ribs along the full length of the channel, joined by a central spine, add section where the OEM shell is open and give the part resistance to the twisting load it carries once the panel has shifted.
• Controlled flex. The bracket is stiff vertically, where it supports the panel and the load of a driver on the step, while allowing a small amount of lateral movement so that panel motion is absorbed by the bracket rather than worked into the clip seats.
• Carbon fiber reinforced plastic. Selected for dimensional stability under sustained load and for thermal margin behind the panel, with a published heat deflection temperature of 194 °C against approximately 150 °C for the OEM material class.
• Factory interface. Mounting points and clip seats match the OEM part, so the bracket installs with the existing clips and no modification.

When the OEM A33-1266-100 is the appropriate choice

• The vehicle is under factory warranty and the repair is being performed by a dealer.
• Fleet or lease requirements specify genuine parts.
• Same day availability is required and a local dealer has the part in stock.

The A33-1266-100BP is an aftermarket part. Only a part supplied through Kenworth is OEM, and a listing that describes a non-dealer bracket as genuine is inaccurate.

Pricing and availability

OEM prices reflect online listings on 17 September 2026, excluding shipping. A complete panel takes two A33-1266-100 and one A33-1268, so the OEM cost of a full replacement is roughly three times the single bracket price. Pricing varies by retailer and over time and should be confirmed at the point of purchase.

Methodology and disclosure

Bushido Performance manufactures the A33-1266-100BP and therefore has a commercial interest in this comparison. The evidence consists of video of a parked T680 Next Gen recorded on 28 August 2026, from which Figure 1 is drawn; a photograph of a second T680 Next Gen, from which Figure 2 is cropped; the molded markings and interior of a new OEM part as photographed by Big Rig World; and our own part, shown in Figure 3. The order in which the brackets release is our field observation across the trucks we have examined and has not been measured. The identification of the remaining bracket is based on its position and size. Figures 1 to 3 were taken by Bushido Performance. Figure 1 has been rotated to horizontal and carries a red circle marking the remaining bracket; Figure 2 is cropped to remove carrier markings. Neither image has been altered in any other way. Neither part has undergone laboratory testing.

Sources

• OEM material and part numbers. Molded marking on the OEM part, as shown in the product photographs at Big Rig World, accessed 17 September 2026.
• Supersession of A33-1266-200. Kenworth dealer catalog at Rihm Kenworth, which directs A33-1266-200 to A33-1266-100.
• Heat deflection temperature. ISO 75. The A33-1266-100BP figure is the published technical data sheet value for the material grade used: 194 °C at 0.45 MPa and 170 °C at 1.8 MPa. The OEM figure is a representative published value for glass filled polypropylene and not the specification of any single product. See Figure 7 of the diagnostic guide.
• OEM pricing. Big Rig World, Rihm Kenworth and BuyParts.Online, accessed 17 September 2026.

Frequently asked questions

Is the A33-1266-100BP better than the OEM A33-1266-100?

The OEM part is an open glass filled polypropylene shell. The A33-1266-100BP fills that shell with a full length rib structure, is made from carbon fiber reinforced plastic with a higher published heat deflection temperature, and is designed to absorb lateral panel movement rather than pass it to the clip seats. It is priced at $30.00 against $88.91 to $111.13 for the OEM part. The OEM part remains the appropriate choice where warranty or fleet requirements call for genuine Kenworth parts.

Are A33-1266-200 and A33-1266-300 the same part?

They are earlier numbers for the same bracket. The OEM part carries both A33-1266-100 and A33-1266-200 in its molding, and the Kenworth dealer catalog directs A33-1266-200 to A33-1266-100. The A33-1266-100BP replaces all three.

How many A33-1266-100 brackets does a panel need?

Two per panel, together with one A33-1268 at the narrow end, which is why the set is supplied as two A33-1266-100BP and one A33-1268BP for $85.00.

One bracket is still holding the panel. Can it stay?

No. A bracket found carrying the panel alone has already taken load it was not designed to carry, and the other two have released ahead of it, so all three should be replaced and the clips inspected at the same time. Inspection steps are covered in the diagnostic guide.

What material is the OEM A33-1266-100 made from?

PP-GF40, a polypropylene with 40% glass fill, injection molded. The designation is molded into the part together with the revision level, REV C.

What warranty is provided?

The A33-1266-100BP carries a 90 day warranty from delivery covering defects in materials and workmanship. The warranty does not cover damage resulting from improper installation, collision or misuse. Claims require proof of purchase and photographs of the defect.