Clutch weirdness - advice needed

[rpost77]

1990 NA6 with 183K

Clutch was replaced in March 2004 @ 128K (currently @ 183K so 55K with this clutch) - no idea what clutch was installed (presume standard - I knew less about the MX5 and cars in general then but am more involved and clued up now (I think )).

Slave cylinder was rebuilt in September 2004 @ 128K.

Master Cylinder replaced in August 2006 @ 152K.

My problem:-

Clutch has been fine up until around 2-3 months ago (was not driving regularly and been using as Daily Driver since).

On cold start, the clutch slips - after warming engine for a couple minutes, I drive off and the clutch does't bite cleanly and judders and slips - really noticeable when I'm leaving work - turn out of work and there's a steep hill - if I get caught at the lights at the top it slips and I have to rev it etc.

After everything has warmed up nicely (say around 10 mins) - the clutch behaviour is absolutely normal - no slippage.

The clutch pedal pressure feels fine at all times (same pressure - doesn't get harder or softer). The "bite" point when slipping and when normal appears to be the same.

I have the car booked in to Mania next week (suspension and some other work) and also booked a clutch replacement (going with the Exedy Sport Tuff as this has good reviews and apparently the pedal pressure is similar to standard).

Thinking about it since, I would have expected the clutch to last longer than 55K (I got 128K from the original and I am definitely kind to clutches).

The behaviour seems odd - I would have expected the opposite (i.e. more slippage as things warm up).

Anyone had this kind of issue before?

Any advice on whether I should actually replace the clutch or maybe just the Master/Slave if that is likely to be the issue?

Obviously if I can nail down what might be the issue and avoid replacing the clutch (presuming it is OK) I would prefer (assuming discovering the issue/fix is cheaper than replacing).

Any ideas would be appreciated - I will take on board and discuss with Mania when I take the car in.

Thanks in advance for any help/advice

[Mr Morlock]

you cannot avoid it -if the clutch is slipping due to fault in the pressure or clutch plate. Agree it should last much longer. If the actuation is ok and adjustment on free play it should not be hard for a mechanic to diagnose clutch slippage . Standard oem clutches work fine. It will be interesting to learn the reason for the problem,

[NitroDann]

Big fluid leak onto the friction surface? Rear main?

Dann

[rpost77]

Big fluid leak onto the friction surface? Rear main?

Dann

I guess if this is the case that it can only be accurately diagnosed by unbolting the gearbox/clutch assembly bits?

I guess (not having replaced a clutch myself) if you get to that point to diagnose I might as well have the job completed and replace the clutch (as I imagine the cost of labour to remove gearbox etc. and re-attach would be the greater part of labour costs for the whole thing including clutch replacement).

If it is a fluid leak as you suggest - why would it stop after warming up (maybe the heat/friction burning off the fluid?).

[de Bounce]

As others have said, it is probably a fluid leak getting onto the friction surfaces.
When the clutch is slipping, it progressively cleaning the surfaces until the fluid is removed and the clutch will functions normally.

My guess is the previous owner didn't replace the rear main crank seal when they replaced the clutch.

I believe the only way to correctly diagnose the problem is to drop the gearbox and look at the clutch assembly.
While you have it apart, might as well replace the clutch and seal.

[rpost77]

My guess is the previous owner didn't replace the rear main crank seal when they replaced the clutch.

In this case I am the "previous owner" (had the car now for 18 years).

Just rechecked my paperwork from when the clutch was done and no mention of the seal being changed (or charged for).

I had the clutch done via Just MX-5 in Kirrawee (they had Autosport Engineering in Kirawee do the work - guessing they didn't know to replace the seal when doing the clutch and I didn't know better at the time).

Rechecking my paperwork - I had my Timing belt changed at 100K (AMR Mazda) but there is no mention of the ancillary items that usually get changed when this is done (tensioner pulleys etc) and no charges for the same.

WTF!!!

The water pump was done at 128K (when the clutch was done) as, obviously, it wasn't done when the timing belt was done @ 100K.

I'm worried now re: the timing belt service etc. - what should have been done but hasn't (really hating more and more the service depts of car manufacturers and dodgy mechanics).

My car is @ 183K and (theoretically) doesn't need a new timing belt, water pump etc. until 200K - but considering the facts as above and it has been 10 years (83K) since the last belt change (and the car is 21 this month), I'm thinking I will bite the bullet and get Mania to do the timing belt & water pump as well as the clutch.

Going to be an expensive exercise but I have had this car for 18 years and will never part with it - worth it in the long run (would like to have a crack at some of this myself but I am without garage currently - I have dealt with Mania before and have confidence in their expertise and service).

Many thanks for the replies re: the clutch - I concur that it sounds like a fluid leak as described - I'll update with the diagnosis once the clutch is replaced.

[JBT]

If there is a big oil leak from the rear of the engine there should be some evidence of leakage under the car and/or on the garage/parking place floor.

[zossy1]

If there was this much fluid coming out the rear main onto the friction plate, there would be CLOUDS of smoke and a burning oil stench.

I take it you don't see/smell either of these?

My money is on a sticky thrust/release bearing. Grease on the shaft dries out and they get sticky until they warm up.

[NitroDann]

My money is on a sticky thrust/release bearing. Grease on the shaft dries out and they get sticky until they warm up.

Never heard of this... But its a well thought out call.

Dann

[aviper4u]

are you losing fluid from the clutch reservoir?