Clutch slip...

[guitarguy]

After a successful (for me!) day's sprinting at Curborough I noticed a little clutch slip on the drive home.... (rev increase only really noticeable pushing hard in a high gear...). Didn't spot anything competing, don't think it slowed me down.... No chance to properly investigate yet...

Is that just an adjustment job, or a sign that a new clutch is needed? How do I tell? Fearing the worst, do people recommend the 'leave box in' or 'lift it all out' approach to do the clutch.... (done similar jobs in a previous life on other cars, but nothing this big on the seven.... Is it easy enough??)

('05 K 1.6 120, 31,000 mainly road miles, 2 track days, 6 sprints, 2 sprint test days.... in my ownership, so not had a bashing...)

Thoughts welcome...

[Jonathan Kay]

I don't think you can tell yet. I'd start by having a good look at the cable for wear, especially where they fail in the pedal box. Then I'd adjust it (let us know if you need the instructions). The slip will either disappear or not.

As far as I can tell you'll get different opinions on where you want the engine and gearbox when you split them... I'd take them out together.

Remember that there are some generous members with cranes and balance bars.

Some suggestions on what else to do while the engine is out.

Jonathan

[Mark Durrant]

Mark

I would start by sleckening off the clutch cable and if it still slips then the clutch will need replacing. I leave the gearbox in the car supported by a trolley jack and take the engine out. I remove the exhaust, alternator and engine mounts but leave the induction and Apollo installed. I use a crane plus it is easier when installing to have someone else to operate the crane whist you guide the engine into place. Well done yesterday a great improvement.

Mark

[Paul Richards]

Make sure there's slack in the cable. If there is it is pointing to new clutch. To help identify, try setting off in third gear. If the clutch is slipping this will often tell you.

[guitarguy]

Thanks guys. Think I'm being a total numpty here (think I might need those adjust instructions Jonathan!).

Clutch cable looks healthy - the parts of it I can see that is. Had the pedal box cover and the rubber 'gaiter' cover on the bellhousing off to examine. Mark/Paul, I have a clutch cable with two adjusters on the outer, one at the pedal box and one at the bellhousing - if I adjust either I'm surely just moving the pedal lower or higher...? I don't see how I can get slack on the cable as it's taken up by the return spring at the pedal box and translated into pedal height (I assume the adjusters are there to set the pedal at the required/prefered height?).

 I'm also assume I'm just checking that the clutch is fully releasing when the pedal is released... (I guess this needs adjusting as the clutch friction disc wears down??).  Can't see quite how to do it mind and still maintain a decent pedal position.

Sorry to be a bit blonde.... (oh the joys of Caterham ownership on the cheap - buy one 'prepared earlier' and you lose all that knowledge and experience you get sticking it together in the first place...!).

*******************

Thanks Mark - I'm now where I should of been this time last year!  Was a really good day....!

[Jonathan Kay]

You're not missing anything: how to adjust clutch cable.

If i understand your current problem... we're really only checking that the cable isn't binding and for some other reason isn't slightly declutching. A good look and play while it's disconnected and then standard adjustment will eliminate that  possibility.

(A related issue is that if you adjust at the wrong end you can get a bad run for the cable as it exits the outer in the pedal box. This is widely believed to be a cause of failure of the inner cable.)

Jonathan

 

[elie boone]

To test if your  clutch is fine : put it in first gear foot firmly on the brake heel just on the trottle to give 1500rpm and slowly let the clutch come up, if it stalls direct your clutch is fine,

[Mark Durrant]

Mark

YHM

Mark

[guitarguy]

Thanks for the help on this everyone...

In typical fashion took it ot last night and could not induce any clutch slip symptoms at all! (swift starts, accelerating hard in high gear up long fast hill, tried the 'letting clutch out in first with foot on the brake' (promptly stalled)... etc). Not sure what is going on, whether it was just a figment of my imagination or whether my fiddling with the adjusters (and flapping the arm under the rubber cover) has freed something up?!?!   I'll run it around a bit and if I get nothing I'm gonna leave it for now.

Forgot to try the 'pull away in 3rd'..... will give that a go later... If I get nothing I think I am going to leave it be and just keep an eye on it....

Thanks again

Mark

[Paul Richards]

When we say slack in cable we mean just making sure the clutch release arm is free to return and nothing jammed to prevent this. There will be some slack in the cable which is taken up by the lightweight return spring. 

Setting off in third gear is similar test to starting in first with brake on but easier to execute. If clutch is sound, car should stall. 

Just a thought. It wasn't just a bit of wheel spin you experienced was it? 

[Nigel Riches]

Perhaps the clutch got lightly toasted on your sprinting session, not enough to be permanent damage, but enough to glaze the friction material, and now, after several cycles of the clutch under road use that has been removed, just a thought. Perhaps fanciful, but if the problem is now gone, better than hauling the engine and gearbox out. 

Nigel. 

[guitarguy]

You know what, Nigel, that is exactly what I was thinking......

2 or 3 quite aggressive spins per warm up, plus the start, all x 6 is a far bit of action!  (plus a few practice starts out of quiet laybys down the A38 on the way there!) - all a bit much maybe.

I'm kind of hoping that that is what it is, I feel I need some sort of explanation just to maintain my sanity and feel I'm not becoming hopelessly delusional!