Royal Enfield Gearbox Layshaft Case-End Bush | 111051/11 | Bullet 350 / Machismo A350 (4-Speed)

Royal Enfield 111051/11 is a genuine OEM BUSH used in the gearbox/4-speed transmission assembly—commonly referred to by sellers as the “layshaft case-end bush” (case end support bush). This small part plays a big role: it supports alignment of internal gearbox components, helps reduce play, and prevents premature wear/noise that can develop in older 4-speed setups. The official listing identifies it as BUSH (111051/11). 

If your bike has a classic 4-speed gearbox and you’re rebuilding the transmission, addressing shaft play, or doing a restoration, replacing worn bushes is a smart preventative job. Aftermarket bushes often vary in tolerance and finish; a genuine-spec replacement helps maintain factory-like fit.

Confirmed fitment (public dealer listings): Bullet 350 (legacy/old) and Machismo A350. 
Important: This part is frequently grouped under “4-speed models,” but not every Royal Enfield variant shares the same gearbox—please match part number 111051/11 before ordering. 

Key Features 

• Genuine Royal Enfield part number 111051/11 – BUSH 

• Common market naming: gearbox end case / layshaft case-end bush 

• Helps control internal play and supports gearbox component alignment (critical for smooth shifting)

• Ideal for gearbox rebuilds, restorations, and preventive maintenance on older platforms

• Single piece replacement (buy quantity as per your mechanic’s rebuild requirement) 

• “Fits 4-speed models except Thunderbird” is commonly stated by specialist sellers (verify model) 

• OEM-spec fitment reduces return risk vs generic aftermarket bushes

• Durable metal bush construction as per OEM design intent (no cosmetic variants)

Compatibility Table 

✅ Confirmed

❓ Mentioned by one source + “4-speed models” claim (verify before purchase)

PLEASE CHECK PART NUMBER BEFORE PURCHASE 

Variants

• No LH/RH / color variants (functional bush).

• Sold as single piece; some rebuild kits may bundle it with related bushes (e.g., 111074) depending on seller. 

FAQs 

1) What exactly is 111051/11?
It is a Royal Enfield OEM BUSH used in the gearbox assembly; commonly sold/understood as a layshaft case-end bush. 

2) Will this fit all Royal Enfield models?
No. It’s typically associated with older 4-speed gearboxes; confirm via part number on your bike’s microfiche/parts list before ordering. 

3) My mechanic says “4-speed models except Thunderbird.” Is that correct?
That statement is commonly published by specialist sellers, but it’s still best practice to match 111051/11 on your exact model/gearbox. 

4) When should I replace this bush?
During gearbox overhaul, when correcting shaft play, noisy gearbox operation, or inconsistent shifting on older setups.

5) Is this a cosmetic (black/chrome) part?
No—this is an internal functional bush (no finish variants).