NC Clutch Issue

[bruce]

Are you losing any fluid? Reservoir dropping?

[JBT]

You have an after market exhaust system there.

Does it include a different header system?
Could the exhaust be causing overheating of an hydraulic line to cause symptoms like hot/boiling fluid?
Was the exhaust put on at the same time as the other mods or was it there before and OK?

[JBT]

Despite the advice regarding the exhaust, I'd have a look to see where it passes close to any clutch hydraulic lines and wrap a few layers of foil around that pipe or put in a temporary foil barrier and see if things improve.

[manga_blue]

I had something similar in a Fiat once which I couldn't solve until the whole master cylinder and a piece of firewall with it flew into the engine bay on a snap 1-2 gearchange. Firewall metal fatigue.

Try checking that the master cylinder does body not move and that there's no unusual deflection in the firewall when your depress the pedal. Similarly check the slave cylinder body and the clutch pedal box for any movement.

[Mr Morlock]

It seems odd that the fitter did not guarantee the job but I guess you went down that track . If you are not planning to increase the power of the engine I would be re fitting all standard clutch equipment and it will work. An inspection of the partially functional clutch assembly including the pressure plate may reveal some obvious fault- this can be done before returning to standard. Bite the bullet and put back what Mazda designed and specifed.

[JBT]

I agree it sounds like a hydraulic problem - most likely localised hot/boiling fluid between the master cyl and slave cyl.

Is it worse in stop start traffic or after a long slow climb i.e. hotter than normal under bonnet temps?

"RunMax Stainless Clutch Line" - could this have anything to do with it?

[Mr Morlock]

Hydraulic does sound a candidate- eg leakage of air but once it leaks you would expect consistent poor engagement. Boiling does not ring true to me - if the lines are run as designed ( JBT noted ss clutch lines??) what would account for this extreme situation. A faulty pressure plate say with spring components not properly heat treated can give inconsistent results. I am an untrained amateur but logic tells me a standard system with tried and proven components must work. You might need to engage a clutch specialist.

[Mr Morlock]

If you have a trained automotive engineer some of them are familiar with formal problem solving techniques. Ford for example use 8D. This brings a discipline to the problem solving - not just a random approach of trying this and that. I suggest that you look up 8D and start outlining on a big sheet of paper- it costs nothing except a little time to organise what you know. Fish bone diagrams are another way of zeroing in on the problem.
I would have thought a clutch specialist will nail the prob and part of that process would be good if they drive it from cold and observe the exact symptoms.

[NMX516]

The slave could be getting too hot and boiling the fluid inside it... I'm not familiar with the layout of the NC though. Is the pedal adjusted properly? How soon moving the pedal off the floor does the clutch bite? Was there any heat shielding removed when the exhaust was done? Is the ID of the ss clutch line the same as the standard Mazda item?

One of the local guys here had problems like this in his NB and it turned out to be the clutch. One of the springs had broken and jammed the full clutch movement on occasions. It was stuck in there and would just float around getting in the way every now and then. Was an intermittent and inconsistent problem.

[Charlie Brown]

OK, I’m coming from left field here but your clutch problem sound very much like one I had after the dealer serviced my NC for a worn pin that clicked every so often when I depressed my clutch. It never felt right from the time I drove it out of the service bay and gradually got worse on the drive home so I did some investigating.

If you dive under the dash and have a look where the rod from the master cylinder joins the clutch pedal you will see that it is threaded and has a lock nut. If that lock nut is not tightened the master cylinder rod is free to rotate and therefore move in and out. This changes the throw of the piston in the master cylinder and therefore the amount of fluid that gets to the slave cylinder.

You can be driving along and everything works fine but a bit further down the road the rod has rotated in through engine & road vibration and the next time you hit the clutch pedal it’s all soft and gooey and won’t disengage the clutch. You curse and swear, head home only to find that the clutch works fine as the rod has now vibrated out and given you back some clutch feel.

So before you rip out all those parts have a look at this connection. Adjust the rod so when you push on the clutch pedal there is about 15 – 20mm of free travel and then lock the nut off.

And by the way the nut is a bitch to get to. You may need a mirror to locate it first up and then go on feel to do the tightening. Another way that I didn’t try was to remove the circlip which would make it easier to tighten the nut.

[de Bounce]

Another way that I didn’t try was to remove the circlip which would make it easier to tighten the nut.

IMHO I found the pin and circlip was a bigger problem to get back in then tightening the locknut in my NB. Might be different for a NC

If the locknut is loose on incorrectly adjusted as Charlie Brown states, unless you are a contortionist, start by removing the drivers seat to get some room.