Clutches and hot weather

[S Works]

Do Mk1's suffer from issues with clutch fluid pipes expanding in hot weather, causing gear selection notchiness and a low biting point?

Symptoms:
- engine running, in neutral, I can hear an occasional 'twittering' sound which disappears when clutch pedal is depressed
- clutch bite 'seems' very low, literally just off the floor - can't remember what it was like before I noticed this tho, so could be placebo
- engaging gears can feel notch, especially 1st to 2nd, 2nd to 3rd and back down again

The notchiness has previously been noticeable in cold weather but disappeared when fluids warmed up. I've recent had a new MX5parts s/s manifold fitted, maybe this is causing more heat in engine bay?

I've seen a braided clutch hose on MX5parts and wonder if this is a known issue.

Final Q, is the clutch fluid separate to brakes or on a shared circuit? Recent had brake fluid changed so trying to eliminate possible causes.

Edited by S Works on Saturday 23 April 16:29

[Aizletree]

I can't add much.

That twittering noise sounds like the clutch release bearing. Mine does it too, 43k 04 plate and my fiesta has done it for about 25k with no problems.

[snotrag]

Clutch fluid is totally seperate circut.

Clutch slave cylinder is notorious.

You can just about see it through the OSF wheel-well. I bet its leaking (which also explains notchiness). About £15 from MX5 parts.

If you squidge the rubber boot I bet loads of manky fluid will come out. If you replace the cylinder, and re-bleed, then you'll find a much more 'positive' clutch action and it will disengage much higher in the pedal stroke. The leak will mean the pistons not moving fully, and clutch is probably dragging a bit, hence the hard gear change.

Edited by snotrag on Saturday 23 April 15:41

[S Works]

Aizletree said:

That twittering noise sounds like the clutch release bearing. Mine does it too, 43k 04 plate and my fiesta has done it for about 25k with no problems.

Makes sense, you get the same in Elise's. Thanks for posting.

snotrag said:

Clutch fluid is totally seperate circut.

Clutch slave cylinder is notorious.

You can just about see it through the OSF wheel-well. I bet its leaking (which also explains notchiness). About £15 from MX5 parts.

If you squidge the rubber boot I bet loads of manky fluid will come out. If you replace the cylinder, and re-bleed, then you'll find a much more 'positive' clutch action and it will disengage much higher in the pedal stroke. The leak will mean the pistons not moving fully, and clutch is probably dragging a bit, hence the hard gear change.

Gotcha, thanks snotrag. I'll take a look tomorrow and try what you suggest. Everything points to it not being the clutch being shagged (as it'll stall if I put it in gear, handbrake on and take it beyond biting point - no judder), so I was hoping someone would educate me more on how the circuit works. Here's hoping it's that - should be an easy fix for my local garage if it's a replace and bleed. Would you recommend the braided line too?

[Munter]

Sounds just like my clutch when the slave cylinder was failing.

[MX-5 Lazza]

Slave cylinder is very easy to DIY. 2 bolts and the fluid hose. I wouldn't bother swapping the hose - I don't know why you'd need to do that unless the old hose is perished.