Rocker Arm Shaft

Function of the Rocker Arm Shaft:

1. Supports Rocker Arms – The shaft holds the rocker arms in place, allowing them to pivot smoothly.

2. Reduces Friction – Often includes lubrication holes to deliver oil to the rocker arm bushings or bearings.

3. Maintains Alignment – Ensures proper valve timing by keeping rocker arms correctly positioned over the valves.

Construction & Features:

• Material: Typically made from hardened steel or alloy for durability.

• Hollow Design: Often hollow to allow oil flow for lubrication.

• Mounting: Bolted to the cylinder head or valve cover, depending on engine design.

• Bushings/Bearings: Some designs use bushings or needle bearings for smoother operation.

Common Issues with Rocker Arm Shafts:

1. Wear & Scoring – Over time, friction can cause wear on the shaft or rocker arm contact points.

2. Oil Starvation – Clogged oil passages can lead to poor lubrication, causing excessive wear or failure.

3. Bending or Damage – Can occur due to valve train malfunctions (e.g., stuck valves, over-revving).

4. Loose Mounting – May cause misalignment, leading to improper valve operation.

Maintenance & Replacement:

• Inspect Regularly: Check for wear, scoring, or oil passage blockages.

• Proper Lubrication: Ensure oil passages are clean and oil pressure is adequate.

• Torque Specifications: When reinstalling, follow manufacturer torque specs to avoid distortion.

• Alignment Check: Verify that rocker arms move freely without binding.

Applications:

• Common in OHV (Overhead Valve) and some OHC (Overhead Cam) engines.

• Found in both automotive and motorcycle engines.

Specification Of Rocker Arm Shaft

NO.	PHOTO	MODEL	DESCRIPTION	SIZE	OE NO.
1		DAIHATSU	CB/S-75 370/376 S88	16×9.5×284.5	13901-87702
			CB/S-75 370/376 S88	16×9.5×279.5	13902-87702
2		DAIHATSU	HC/S-89	19.5×8×375	13902-87101
			HC/S-89	19.5×8×375	13901-87105
3		SUZUKI	ST-100	15×8×307	12860-73004
4		CHANGAN	FUTURA 472 SF413	16×8.5×355.5	12860-82600
			FUTURA 472 SF413	16×8.5×357.5	12870-82600
5		CHANGAN	SA310	16×9×270	12860-82001
			SA310	16×9×272	12870-82001
6		CHANGAN	474	16×6.5×406.5	1007091-01
7		ALTO	308/368	15×8.5×242	12860-78102
8		DAEWOO HYUNDAI	CIELO/G15 AUTOS	17×6.5×313	24510-02500
9		DAEWOO	MATIZ F8/1.1 MANTIS EXH.	17×8×259.5	96316351
			MATIZ F8/1.1 MANTIS INT.	17×8×259.5	96352715
10		DAEWOO	MATIZ F8/0.8 ANCHI INT.	15×8×259.5	94581480 12860A-78B01-000
			MATIZ F8/0.8 MANTIS EXH.	15×8×259.5	94581482 12860A-78B01-000