Clutch pedal 'buzz'

[thompster]

My K-series clutch pedal has developed an annoying buzz / vibration above a certain engine speed.  If I lift the pedal or put pressure on to tension the cable it goes away.  If I only touch it lightly it amplifies the vibration.

The pedal has an awful lot of end float on the shaft and a small amount of play in the bush.  Is this likely to be the problem and if so what do people do to fix it?   Shim the pedal/shaft?  Live with it?

[Wrightpayne]

You can get new a new bush from caterham. Have you done the pre-load mod devised by John Vine?

[John Vine]

Have you done the pre-load mod devised by John Vine?

http://i405.photobucket.com/albums/pp140/trog65/Supersport-R/CRB/DSCN0081.jpg

More info here.

JV

[Domus]

Had this on my Sigma, very annoying.

 

"Grease is the word"

[thompster]

Thanks all.

Domus - you're right, v. annoying.

Those extra springs look useful although I think I'd still get a brief rattle each time I loaded the pedal.   I found the bush on CC parts so will start with that.  I initially thought it was impending crb failure but there's no other symptoms so hopefully just the pedal.

[John Vine]

Those extra springs look useful...

Just to clarify...

The springs are there to increase the pre-load on the CRB.  Any anti-buzz benefit is entirely fortuitous!

And as you say, you could try packing the pedal bush out with washers or shims.

JV

[thompster]

Hi JV.  I read the word doc you kindly linked to.  I get the aim of it, but wasn't sure why a 7 would be a special case when 'normal' cars don't need the CRB under slight load.  I'll read it again later and see what I missed.  For my particular problem I'm sure some downward tension would help - though fixing the root cause (hopefully just the bush) would be better!

[John Vine]

Well, the answer is that modern cars have CRBs that run in constant contact with the clutch diaphragm fingers, held that way by a pre-load. This is true of hydraulic clutches (like, say, the Mondeo) and cable clutches (like, say, the Sierra). In the Sierra, the pre-load is applied by a cable-tensioning quadrant on the clutch pedal. That tension is what's missing in cable-clutch 7s, and is what my mod supplies.

JV