Harley-Davidson X440 / X440T Rear Brake Disc HDH43251RAA000S | Genuine 240mm Rear Rotor

Harley-Davidson X440 / X440T Rear Brake Disc – HDH43251RAA000S

Replace a worn, scored, warped, heat-damaged or accident-damaged rear brake rotor with the correct genuine Harley-Davidson rear brake disc. Part number HDH43251RAA000S is identified in the supplied parts catalogues as DISC RR BRAKE / rear brake disc. In buyer-friendly terminology, this is the rear brake disc, rear brake rotor, or rear disc plate used on the Harley-Davidson X440 family applications confirmed below.

This listing is written around the terms owners and workshops are most likely to search for, including Harley X440 rear brake disc, X440 rear brake rotor, Harley X440T rear disc, X440T rear brake rotor, 240mm rear brake disc X440, and the exact OEM part number HDH43251RAA000S.

Product Identity

• Brand: Harley-Davidson
• Part Number: HDH43251RAA000S
• Official Catalogue Description: DISC RR BRAKE
• Common Name: Rear Brake Disc / Rear Brake Rotor / Rear Disc Plate
• Position: Rear wheel
• Brake Type: Disc brake
• Nominal Rear Disc Size: 240 mm
• Quantity: 1 piece

Confirmed Compatibility

• Harley-Davidson X440 – September 2023
• Harley-Davidson X440T – January 2026 / R4AA

Compatibility note: the same exact part number appears in both the supplied September 2023 X440 catalogue and the January 2026 X440T catalogue, confirming cross-model fitment for these two applications. Fitment to any other model or generation should still be checked by exact OEM part number before ordering.

Rear Brake Disc Specification Context

Harley-Davidson / Hero published specifications for both the X440 and X440T list a 240 mm rear disc brake. This makes the catalogue identification consistent with the factory chassis specification for these models.

What This Part Does

The rear brake disc is the rotating braking surface attached to the rear wheel. When the rear brake is applied, the brake pads clamp the disc through the caliper to create braking force. Because the disc is a critical friction surface, correct thickness, flatness, mounting and surface condition are essential for predictable braking performance.

Common Reasons for Replacement

• Brake disc is warped or causing pulsation
• Rotor has deep scoring or grooves
• Disc is below service thickness
• Surface has been damaged by worn brake pads
• Disc is bent after an accident or wheel impact
• Heat spots, cracking or severe discoloration are present
• Rear brake overhaul requires replacement of a damaged rotor

Symptoms of a Damaged Rear Brake Disc

• Pulsation or uneven braking at the rear wheel
• Scraping or grinding noise during braking
• Visible scoring, grooves or impact damage
• Brake pads wearing unevenly
• Rear brake lever / pedal feel becoming inconsistent
• Disc visibly running out of true when the wheel rotates

Important – Disc Only

HDH43251RAA000S is the rear brake disc / rotor only. It is not a complete rear brake kit.

Do not confuse this item with:

• Rear brake caliper
• Rear brake pads
• Rear ABS sensor ring / tone ring
• Rear wheel-speed sensor
• Rear brake hose
• Rear master cylinder
• Complete rear wheel assembly

Related Rear-Brake Components

• HDH43250ACJ000S – Caliper Sub Assy
• HDH43251RAA000S – Disc RR Brake – this product
• HDH43252ACD000S – Sensor Ring Rear / ABS tone ring
• HDH43301AABA00S – Clip, Brake Line
• HDH43310ACJ000023S – Clamper A RR Brake
• HDH43331AACJ000S – Rear Brake Hose Sub Assembly

Why Exact Part-Number Matching Matters

• Brake discs can share similar diameters but differ in bolt pattern, offset or carrier geometry
• Incorrect rotor offset can affect caliper alignment
• ABS-equipped motorcycles require correct relationship between brake and wheel-speed components
• Exact OEM part-number matching reduces fitment risk
• Correct genuine replacement avoids modification or spacer improvisation

What’s in the Box

• 1 x Genuine Harley-Davidson Rear Brake Disc / Rotor
• Part number: HDH43251RAA000S

Not Included Unless Specifically Supplied

• Brake pads
• Caliper
• ABS sensor ring
• Wheel-speed sensor
• Disc mounting bolts
• Rear wheel
• Brake hose or master cylinder

Installation & Inspection Notes

• Inspect rear brake pads when replacing the disc
• Check the caliper slides / movement and pad contact pattern
• Inspect the rear ABS sensor ring and sensor for damage
• Clean the new braking surface before use
• Ensure the disc mounting face is clean and free from debris
• Tighten mounting fasteners to the correct workshop specification
• Check disc runout after installation
• Bed in new pads / disc correctly where required
• Brake-system work should be performed by a competent technician

Brake Safety Note

The brake disc is a safety-critical component. Do not continue using a rotor that is cracked, severely warped, below minimum service thickness or otherwise structurally damaged. If the cause of abnormal brake wear is unclear, inspect the full rear brake system before replacing parts.

Return Prevention Note

Please verify that you need the REAR BRAKE DISC / DISC RR BRAKE and not the rear ABS sensor ring. The two parts sit close to each other in the rear-wheel assembly but serve completely different functions.

FAQs

1. What is HDH43251RAA000S?
It is the genuine rear brake disc / rear brake rotor used in the confirmed Harley-Davidson X440 and X440T applications.

2. Which models are confirmed?
The supplied catalogues confirm Harley-Davidson X440 – September 2023 and Harley-Davidson X440T – January 2026 / R4AA.

3. What size is the rear brake disc?
Harley-Davidson / Hero specifications for the X440 and X440T list a 240 mm rear disc brake.

4. Is this the rear ABS sensor ring?
No. The ABS sensor ring is a separate part. HDH43251RAA000S is the brake rotor itself.

5. Does the disc include brake pads?
No. Brake pads are separate service parts.

6. Can a warped rear disc cause pulsation?
Yes. Excessive disc runout or distortion can cause uneven braking and pulsation.

7. Should pads be checked when replacing the disc?
Yes. Worn, glazed or uneven pads can damage a new disc or prevent proper bedding-in.

8. Does it fit X440 OBDII?
The supplied screenshots directly confirm the September 2023 X440 and January 2026 X440T. X440 OBDII fitment should be confirmed separately by exact catalogue reference before ordering.

Search Keywords

Harley X440 rear brake disc, X440 rear brake rotor, Harley X440T rear brake disc, X440T rear rotor, 240mm rear brake disc X440, rear disc plate Harley X440, DISC RR BRAKE, HDH43251RAA000S.