Clutch or Gearbox issue?

[TomGaval]

Had the car on track yesterday, 2000 superlight, RoverK 1.8L Drysumped Caterham bell housing, Hydraulic clutch and external slave cyl. 6 speed gearbox.

 

Had some trouble getting into first a couple of weeks ago and with a couple of pumps of the clutch pedal, went in and was fine. Third seemed a bit baulky when downshifting and there is a whine when downshifting into fourth. (at least when I'm heading back to pit and not at full throttle so I can hear it)

 

Changed and bled the clutch fluid before yesterdays session, still had a bit of trouble downshifting into third, but was fine otherwise. Then during the third session, had trouble getting down into 5th at the end of the straight. Worked fine for the rest of the session, (6 or so more laps) then while coming into pit, It wouldn't go into gear.

 

Coasted into the gargage, Fluid level is fine, can't see any leaks and Clutch pedal feels normal. Will go into gear with engine off, won't with car running.

Original clutch, MC, slave. I built it 12 years ago and never had an issue before. I've done about 20 trackdays this year and about 15 last year. Maybe 50 total in the past 3 years.

 

Any thoughts? Gearbox? weak clutch cover? I did have to use spacers to get the slave to pull enough when I first assembled it. Actually feels about ilke that. As the clutch wears could I need to space it out more to get the proper disengagement?

 

Thanks in advance.

Tom

 

Edited by - tomgaval on 11 Nov 2012 16:41:04

 

Edited by - tomgaval on 11 Nov 2012 18:17:44

[tin duck dave]

I would be thinking clutch plate, release bearing or spigot bearing. gearbox out time unfortunately.

[elie boone]

Tom, yes it could be that you needs more spacers to have full disengagement of the clutch

but it also could be that your release arm start to bent, they do have a reputation.

 

I would first try to adjust the clutch if it improves, good but if you soon find the same symptoms it could be the release arm that is if the hydraulic pressure does'n go off then it's either the slave or mastercil.

[manningpaul]

 

I know that there have been issues with the clutch fork bending on dry sump systems, the other likely culprit is the spigot bearing, which is what happened to my wet sump K. Gave the symptoms you describe, only a few pounds for the bearing but engine out job to fix ☹️

 

 

 

 

 

[Stationary M25 Traveller]

If it is the master or slave cylinder failing, junk the whole hydraulic system and fit a cable. Takes about 15 minutes. Best thing I ever did on mine

 

Cable cost about £25.

[TomGaval]

Thanks, guys! I have a new clutch kit and CRB on order I'll add the spigot bearing and clutch arm to the order. Good thing is there is only next weekend left in the trackday season. Unfortunately it was to be a 7's gathering with about 5 or 6 of us which is always a fun time baiting the Corvettes, GTR's and Porkers. 😬

 

Tom

 

Edited by - TomGaval on 11 Nov 2012 18:16:50

[charlie_pank]

Sorry to be the bearer of bad news, but from your described symptoms, none of the things you're planning to replace will fix it. The fact that you can pump the pedal to temporarily avoid the problem, yet there are no leaks points to fluid getting past the master cylinder seal. You may be able to fix this with a new seal, but in my experience it was the cylinder bore that was scored and only a new cylinder would fix it. I can't think of any other problem that would match ALL of the symptoms you describe, if it were a bent component or some spacers required, pumping the pedal wouldn't solve it.

[Stationary M25 Traveller]

Go cable - quicker, cheaper and nicer to use.

[TomGaval]

Thanks Charlie, I plan to replace both the Clutch master and slave cylinders as well and have the parts at hand. I'll try those first, but I think I'll also do the clutch over the winter.

Just curious, If the cable is so much cheaper and easier, why are the LHD cars specced with the hydraulic system?

 

Tom

 

Edited by - TomGaval on 11 Nov 2012 20:42:02

[charlie_pank]

If you're planning on taking the engine out anyway then by all means replace the clutch while you're at it, but if it is displaying all the symptoms you described, I'm certain it will make no difference. If the fluid were leaking past the seal in the slave cylinder it would be leaking out of the cylinder, I recommend replacing the master cylinder and piston and then seeing if you still have a problem before bothering with anything else. I'll bet you £5 to NTL that fixes your problem...

[Stationary M25 Traveller]

Quoting TomGaval: 

Thanks Charlie, I plan to replace both the Clutch master and slave cylinders as well and have the parts at hand. I'll try those first, but I think I'll also do the clutch over the winter.

Just curious, If the cable is so much cheaper and easier, why are the LHD cars specced with the hydraulic system?

 

Tom

 

Edited by - TomGaval on 11 Nov 2012 20:42:02

Don't know - but hydraulic was standard for VVC engine too. Parts very expensive. Changing to a cable has made my clutch operation much nicer - I hadn't realised how bad the hydraulics had become !

[TomGaval]

Quoting charlie_pank: 

I recommend replacing the master cylinder and piston and then seeing if you still have a problem before bothering with anything else. I'll bet you £5 to NTL that fixes your problem...

 

Deal!

 

Tom

[TomGaval]

Problem solved. 😬 Turns out that the slave cylinder needed to be spaced a bit more to get the pull lenght correct to disengage the clutch. I guess the clutch is wearing down and a little slack had occured. The yellow bush in the bellhousing had also deformed and trimmed that up to give a little more clearance too. I did replace the clutch MC and slave since I had the spares at hand. Will probably do the clutch over the winter. Last two trackdays of the season are this weekend, and we have 5 Caterhams signed up, Weather looks to be clear and chilly. I'll send the contribution to NTL along with my membership renewal. Thanks again all for your support.

 

Tom