Lube new clutch cable?

S

stangn99

Well-known member
My clutch cable seems to have stretched a bit. Well, maybe more than a bit. I first noticed it around 10k and have finally decided to do something about it (at 15k).
I was not able to eliminate enough slack with the adjuster on the clutch lever. BMW recommend 0.5mm of slack on a cold engine. In order to achieve this I adjusted the clutch cable via the adjuster nut under the fuel tank (PITA), which allowed me to then fine tune with the adjuster on the lever.

I've ordered a new OEM cable and curious to know if I should add any sort of lubrication to the cable? Will doing so make the cable last longer? At $150 (and hopefully no duties to pay) I'd like to do whatever I can to make it last longer than 10k.

Edit: crap. I posted in the wrong forum. Meant to post in technical.
 
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This is what I used to lube the clutch cable:


08-0182.jpg
 
Control cables are designed to run dry, lubing cables has pros and cons. Once you lube a cable, it will need regular lubrication thereafter.

Lubed cables may last longer, need less adjustment, and feel smoother but they might not. Many OE and better quality cables are Teflon lined, most lubes will degrade Teflon. Lubes can also trap grit and form gunky paste as they dry, some stiffen in colder weather.

Personally I only lube cables as a stopgap measure - once you start lubing a cable, you’re on the hook for doing it regularly. And I’m not convinced you extend the cable life.

In the case noted above, 15k stretched out OE cable may indicate some other problem. In 40 years I can’t recall an OE cable stretching out. Perhaps the cable was misadjusted from new, it should be under zero tension when released.
 
I'm a hydraulic guy myself, but do maintenance on our school's cable-clutch bikes. Agree with MM, typically change them out because they've frayed and snapped, not stretched beyond the point that the coarse adjustment nuts at the bottom of the bike can't compensate for.

BTW, is it 0.5mm free play or 5mm? 0.5mm seems really, really low. Like almost 0 free play... I'd be concerned with your clutch slipping at operating temps with that little free play.
 
Hydraulic conversions are easy.
 
Thank you all for the feedback. Still waiting for the OEM cable to arrive and will compare them side by side to see if there's any visible stretch.

@Lightcycle that's 0.5mm with a cold engine.
The slack (free play) increases as the engine reaches operating temperature. It's the strangest thing to me, but apparently that's how BMW has designed it.

So I've basically set my clutch lever to no free play, and when the temps reach about 60 degrees, I can feel a slight amount of free play. Once temperatures reach 90 to 100 degrees the free play is around 5-7mm.

1755888356769.png


*Edit*: I ran the question of free play expanding in GPT and wondering if this has something to do with it:

Cable Expansion/Stretch
  • On cable clutches, the cable itself expands when hot, adding slack.
  • Heat from the engine/radiator in traffic can cause the outer sheath to soften/expand, increasing free play.
  • This is more noticeable on bikes with the cable routed close to the engine.
Click to expand...

My bike does indeed have the cable routed along the engine. The clutch side adjustment is actually resting on the engine, under the seat (which is a pain to get to, by the way).

Perhaps an interesting test would be to wrap the portion of cable that is in contact (or very close to) the engine in some heat shielding tape to see if it makes a difference.

Something like this: https://a.co/d/dRRx9YJ
 
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