Clutch Cable failure

[MadCat52]

Was enjoying a socially distant day at Petworth House today - just as I arrived, bang ... clutch cable snapped. Luckily had a spare and enough tools to fit replacement 'in the field'.

 

Two questions to the wise POBC:

a) the cable snapped at the clutch fork and I'm assuming the nipple on the end of the cable fell into the bell housing. I intend to have a ferret with a magnetic probe, but how worried should I be that the end of the cable is in there?

b) when removing the cable from the clutch fork, I noticed a small plastic tie fastened on the cable hole in the fork, which I can only surmise was their to prevent the cable end dropping and unattaching itself from the fork. Is that common practice?

Car is 05 Roadsport with 1.8 K series.

 

Thanks

Bob

[Wrightpayne]

My build ('98 vintage) included a grommet to go in the hole aside the cable end in the clutch fork.

[SM25T]

If the cable broke at the nipple, it probably won't go anywhere from the bottom of the bell housing. You might find it with a magnet on a stick ... if you can get it past the other steel components of the clutch.

[John Vine]

...magnet on a stick...

I use a Draper pick-up tool.   Invaluable.

JV

 

 

[Piers300]

Over the last 34 years, I have had to replace the clutch cable three times on my first 7 and 3 times on the one I have now. I have two spare clutch cables in the car. Every time, except the first, it has failed at the clutch fork. Very poor design I think.

 

Piers

[Bricol]

Same design as Ford,used in Cortinas, Escorts, Sierras, Granadas, Scorpios.

Same cable since build in my 2001 seven.  Same replacement cable in my Dutton trials car for the last 12 years.  When I bought it, the cable was badly set-up and on its last few strands.  A bit of time making sure the cable was aligned, adjusted so it wasn't too light or too loose - and fitted correctly into the clutch fork and it works just fine.

[EEK]

I think your summation on the plastic tie is correct. I did manage to unhook my clutch cable from the fork whilst driving once. Quite surreal to wonder why the clutch pedal has just "disappeared". Remedy at the time was a cable tie on end of clutch fork to keep cable in. Car is an earlier 1.6 K series.

[Bricol]

Cable end should drop into a dimple in the clutch fork from memory.  There should not be any free play in the arm/fork relative to the cable - there should be enough tension in the cable to hold the fork, and the release bearing, against the clutch to keep the bearing in contact and spinning - that tension keeps the cable in place.  

If its loose, ie the outer is adjust incorrectly, it will move, probably fret against the arm and chew through the cable unless it simply comes un-hooked.

 

 

[SM25T]

Check no sharp burrs on the notch in the fork where the cable sits. Add another clutch return spring as per John Vine (?) post a few years ago.

[Wrightpayne]

I think its odd that some cars eat clutch cables and others dont? Mine is the original @ 22 years old and 22k miles.

Must be pedal position, position of the cable end in the pedal box (2 big locknuts) and cable adjustment? 

[John Vine]

...there should be enough tension in the cable to hold the fork, and the release bearing, against the clutch to keep the bearing in contact and spinning...

Exactly so.

...Add another clutch return spring as per John Vine (?) post a few years ago.

This guide.  (Thanks for the plug, Ian!)

JV

[Drumster]

It is strange as I bought my 7 in 1999 (it was 6 years old) and only changed the cable when the operation of the clutch became stiff. It transpired that the inner 'plastic' sheath had become rucked up, no sign of fraying. New cable fitted in March 2006 (51,300 miles) currently on 92,000 miles with the same cable.

 

 

[SM25T]

KOD there Chris. For the same reason I am not commenting, but replaced my cable in I think 2009 when gearbox was being serviced and clutch replaced. Probably 70k miles since.

[Dave_P]

Does not prevent the fork end breakage but I run a little engine oil between the cable and the outer from the top end. I know the liner is probably low friction but the oil does make for a very smooth push. Don't know if it increases longevity but ok up to date. But carry a spare anyway.

[MadCat52]

Has anyone fitted a clutch pedal stop ... I suspect part of the problem is over-travel of the pedal putting a strain on the cable ends.  Any thoughts on the best way to fit a stop/pictures appreciated.  Thanks

Bob

[Wrightpayne]

What, like this.....

https://caterhamparts.co.uk/pedals/1472-clutch-pedal-stop-race.html

[MadCat52]

... yes, thanks.  That looks like it fits in the footwell bulkhead.  Does anyone have a photo of a stop at the top of the pedal box that works on the top of the pedal?

[Wrightpayne]

Thats a good idea a always thought the stop fitted in an ally floor not ideal. That said the cable end of the clutch pedal has a lot of mechanical advantage.

On the caterham parts website there are other clutch stop parts (CSR Race) but I couldnt figure out how they work?

[Bricol]

I fitted a stop through the end of the footwell - simply a long bolt, a large washer inside to spread the load, a bit smaller on e outside, a nut each side to set position and secure it.  No deformation after a good few years and lots of gear changes.

One fitted at the top end, as already mentioned, would have to a lot stronger to resist the considerable mechanical advantage the pedal creates.  

[Bricol]

CSR is hydraulically operated, so I guess that that threaded metal disc screws on the master cylinder pushrod and physically stops the pushrod entering any further into the master cylinder.  

 

[Wrightpayne]

Thanks Bricol, that makes sense.