BMW Motorcycle Clutch Cable Removal Guide

Maintaining the control cables on your BMW motorcycle is crucial for a smooth and safe riding experience. The clutch cable, in particular, plays a vital role in gear changes and overall operation. This guide will delve into the intricacies of removing, replacing, and adjusting these essential components, focusing on BMW models from the /2 series through to the /7 and beyond. Understanding the nuances of these cables can save you time, effort, and prevent potential roadside issues.

Understanding BMW Control Cables

BMW motorcycles, especially the older /2, /5, and /6 series, utilize robust yet sometimes intricate cable systems. These cables, often referred to as "Bowden cables" after their inventor, consist of an outer sheath, a spiralled metal casing, and an inner wire. Modern cables may also feature a Teflon liner to reduce friction, which means they should not be lubricated. Proper storage is key; cables stored hanging vertically are less prone to developing a "set" or stretching, which can compromise their performance and lead to synchronisation issues, particularly with throttle cables.

Castings and Levers: The Foundation of Control

The control castings for both throttle and clutch on these BMW models are typically made from cast aluminium, often finished in gloss black. They are designed for 22mm handlebars, and attempting to fit them onto American 7/8" bars (which are slightly larger) will likely result in breakage. Always ensure the handlebar is clean and free of nicks. The perch wedge, a small but critical component, prevents the casting from rotating on the bar; ensure it's present and correctly seated. Levers themselves, often high-quality Magura units, can sometimes be straightened if bent, though caution is advised to avoid snapping the metal.

Lever Positioning for Comfort and Safety

Correct lever positioning is paramount. A good rule of thumb is to align the lever with a line drawn from your shoulder through the handlebar. This ensures you can pull the lever smoothly towards your shoulder, minimising strain and maximising control, especially in stop-start traffic. Proper positioning reduces fatigue and improves reaction time in emergency situations.

Clutch Cable Removal: A Step-by-Step Approach

Removing the /2 Clutch Cable

The removal process for the /2 series is relatively straightforward:

1. Locate the clutch lever at the handlebar. Loosen the lock nut and run the adjuster all the way in.
2. Align the cut-out sections of the adjuster with the slot in the casting.
3. Pull the clutch lever all the way back towards the grip.
4. With your right hand, grasp the outer sheath of the cable and pull it away from the adjuster as you slowly release the lever.
5. Once sufficient slack is created, the cable can be guided out through the aligned slots.
6. Finally, remove the cable by letting it drop downwards out of the barrel pivot hole.

Installation is the reverse, ensuring the cable sheath is hooked onto the adjuster locking nut and the lever is pulled to allow the wire to be threaded back through the slot.

Removing the /5 and Later Clutch Cable

The /5 and subsequent models feature a more enclosed system, offering better protection but a slightly more involved removal:

1. Begin by addressing the lower end of the cable, where it connects to the clutch arm on the transmission.
2. You can create slack by loosening the adjustment bolt and locking nut (typically 13mm nut and 10mm adjuster) or by levering the clutch arm forward to create enough space to detach the cable end from the arm.
3. With the lower end disconnected, push the inner wire fully into the sheath towards the upper end. This provides enough slack at the handlebar lever.
4. Carefully remove the barrel retainer from the clutch lever assembly. This retainer is what holds the cable end in place within the lever.
5. With the cable loose at both ends, it can be carefully routed out of the motorcycle frame.

Installing a new cable requires careful routing, especially around the transmission housing "boss," and ensuring the barrel retainer is correctly seated.

Clutch Cable Adjustment

Proper adjustment is critical for clutch operation. The goal is to achieve a small amount of free play at the lever, typically around 1/4" to 3/8" (1 cm). There are two adjustment points: a "gross" adjustment at the transmission end and a "fine" adjustment at the handlebar lever. One turn at the lower adjustment is roughly equivalent to six turns at the upper adjustment.

Recommended Procedure:

• Set the upper adjustment (at the lever) to have about 2-3 turns exposed. This allows for future adjustments due to cable stretch or heat expansion.
• Make the gross adjustment at the transmission end, running the bolt in by hand until slight resistance is felt, then locking the nut.
• Check for the correct free play at the lever. Adjust as needed, prioritising enough play to prevent slipping but not so much that it hinders full disengagement.

A properly functioning clutch should begin engagement about halfway through the lever's travel.

Throttle Cables and Controls

Throttle cable maintenance shares similarities with the clutch. Synchronization is key for smooth engine performance. Issues like stretched cables or a "springy" feel can make achieving proper sync impossible. Always replace throttle cables in pairs. The unique bevel gear drive system on many BMWs provides precise low-end control but requires specific adjustment procedures. Ensure the throttle tube and bevel gear mechanism are kept well-greased.

Throttle Cable Adjustment Steps

1. Adjust the cable adjusters at the carbs to ensure an equal amount of thread is showing on both, aiming for approximately one thread of play showing at the adjuster.
2. Carefully disassemble the throttle cap to access the bevel gear mechanism.
3. Ensure the bevel gear area is clean and lubricated.
4. Re-mesh the bevel gears, ensuring minimal play at the grip. The goal is to take up slack without making the throttle stiff.
5. Re-synchronise the cables at the carburetor adjusters, aiming for both slides to lift simultaneously.
6. Test for any idle speed changes when turning the handlebars lock-to-lock and adjust cable routing or slack as needed.

Other Cables and Considerations

Speedometer and tachometer cables require occasional lubrication to prevent needle flutter and ensure smooth operation. Pay close attention to the speedometer cable boot at the transmission, as a damaged boot can allow water ingress, leading to gearbox bearing damage. Always ensure the upper end of the speedometer cable is correctly seated to avoid damaging the instrument itself.

Choke cables (fuel enrichener) and timing retard cables also benefit from periodic lubrication.

Perch Wedge: The Unsung Hero

The perch wedge is a small, serrated metal piece that fits into a triangular space within the control casting. Its purpose is to bite into the handlebar, preventing the clutch and throttle controls from rotating. Despite its small size, it's a critical component for maintaining stable control positioning. Many owners are unaware of its existence, and its absence can lead to controls shifting during use.

Troubleshooting and Maintenance Tips

• Cable Inspection: Regularly inspect cables for signs of wear, fraying, or stiffness. The inner wire should move freely within the sheath.
• Lubrication: Lubricate non-Teflon lined cables periodically. For Teflon-lined cables, do not lubricate.
• Spare Cables: Carry spare clutch and throttle cables, especially on longer journeys. Storing them alongside the existing cables can facilitate quick replacement.
• Lever Feel: A hard-to-pull clutch lever on later models (/6 onwards) may indicate a need for adjustment or a different approach, such as the Vech modification.
• Riding Without a Clutch: In an emergency, it's possible to ride without a clutch cable by carefully timing gear changes with engine RPMs. However, this is a skill best learned and practiced in a safe environment, and it underscores the importance of maintaining the clutch cable.

By understanding these components and following proper maintenance procedures, you can ensure your BMW motorcycle's controls remain responsive and reliable, providing a safer and more enjoyable riding experience.