CRB-The FINAL post (I promise)!

[Nick Green]

JR, I meant to refer to Rob's post before the one before Steve's, where he said the forces were N, not Nm. Therefore not torque...

 

Thanks for the lever info! I shall see what I can come up with over the weekend.

 

Cheers!

[Rob Board]

JR- "There ain't half been some clever b******s". Cheers, I remember doing that in the classroom some years ago. Like everthing you never use again in one ear out the other. Thanks anyway will save me looking it up. Hopefully Nick will come up with an answer before I can.(Too cold in the garage and PS2 beckons)

Thanks again. Rob(PS my HNC came free with 2 packs of cornflakes)

[Nick Green]

oops. double post

 

Edited by - nick green on 23 Dec 2002 11:04:26

[Nick Green]

If been checking things out on the clutch lever over the weekend. I wasn't able to pull the lever back exactly in line with the (relatively horizontal) clutch cable. I was having to pull upwards at an angle of about 45 degrees.

 

I was wondering if anyone knows the fiddle factor (if any) to be applied to a force acting in this way ?

[Nick Green]

To save myself a wade through the deluge of replies to my last question, I shall assume cos, as in Fcos(angle from horizontal), until otherwise enlightened

 

So, assuming the above, how does the following stack up ?

 

80-120N translates (via division by 9.81 and multiplication by 2.2, I've been advised) to 18-27 lbs of pressure needing to be exerted by the CRB onto the clutch pressure plate.

 

Allowing for the 2.25 lever ratio previously suggested (I cannot measure this on my car as it is still installed, but judging from photographs I have, it looks about right), that gives the force to be generated at the top of the release arm as 8-12 lbs...

 

I put the clutch pedal spring back on to my car, fixed a cable tie around the release arm to allow more convenient hooking-on of the spring balance, and measured ~5lbs off the balance scale. I was having to pull the balance up at an angle of around 45 degrees to clear the bulkhead, so 5cos45 = ~3.5 lbs. Not enough, given our newly gained technical knowledge.

 

On my clutch pedal, the hole in which the spring fixes, is halfway between the pivot bolt of the pedal and the point where the cable attaches. To cut the ramble down, I shortened the spring slightly and hooked it into the hole normally occupied by the R clip holding the clutch cable location pin in place on the pedal, to increase the spring's mechanical effectiveness.

 

The force then measured was about 13 lbs, which tweaked as before, gives just over 9 lbs. Assuming the angle was closer to 30 degrees, the force is about 11lbs. The release lever was definitely putting up more resistance when moved directly by hand too.

 

I plan to double-check the readings and angles I've been using, and the angle the spring might be put into when the clutch is depressed might not be good for its long term health; want to double-check that too. Unless my maths is way out (and I'm happy to be corrected, BTW), it would seem to indicate that a simple remedy might be possible.

 

Edited by - nick green on 23 Dec 2002 14:28:16

[Rob Board]

Nick E-mailed off line.

Rob.

[John Vine]

Rob (Board),

 

Did you get any feedback from Caterham about the need for a pre-load? In particular, did they comment on whether the standard cable-tensioning spring does this job adequately?

 

I recently e-mailed Simon Lambert at the factory for his opinion on whether or not the CRB needs to be in permanent contact with the diaphragm fingers. I'll post his response when I receive it.

 

JV