Time for a new clutch?

[ChrisMK3]

Morning all,

Took the MX5 out to work for the first time since owning it yesterday as it gave me a good opportunity to really get used to it in some mixed driving environments.

When I got the car a couple of months ago I thought that the biting point was a perhaps a bit low to the floor and so I adjusted the pedal accordingly… The shift improved slightly but nothing groundbreaking.

Long and short of it, I’ve messed about with the pedal loads to try and find the right balance between not having the bite too high, and what will aid the smoothest shift.

So yesterday when I went to a meeting in Manchester (130 mile round trip), I opted to take a 12mm spanner with me so I could adjust it on the fly… Made a couple of adjustments before setting off home, all was well.

When I got home I pulled into the driveway and was about to reverse into the garage and when I put it into reverse the whole transmission and propshaft effectively slammed into gear… i.e. the clutch wasn’t properly disengaging, so the GB input shaft was still spinning and so yeah… Little bit of a grind, not a smooth engagement into reverse… No biggie… I adjusted the pedal again accordingly, the bite point raises, the clunking into reverse went away.

However prior to this on the drive home the pedal movement and bite were spot on and just how I like them, of course, using the forward gears only.

Now I know that reverse gears seldom have a synchro on them so a little bit of awkwardness is always to be expected, but I’m now considering whether it might be time to give it a new clutch… My reasoning being that although I’m confident the bite point was spot on yesterday on the way home and the changes were all as expected, the aforementioned reverse engagement isn’t ideal and I suspect that the clutch itself hasn’t quite got enough meat and grip to stop the GB input shaft spinning completely, hence the grind and clunk.

I’ve also noticed that the shifts aren’t particularly supple at all if I change gear below 3000rpm, more so when the transmission is cold… It’s always a little bit notchy, basically… though I can’t remember my last NC being like this most of the time.

A new clutch is -/+ £400 so I’m trying to decide whether to splurge on it or not, or whether it’s just a characteristic of this particular car and to just live with the higher bite point.

As a side note, there’s a minimal amount of judder when the car is cold, but this goes away almost completely when up to temperature after a couple of miles and changes.

What’s everyones thoughts on this?

2006 MK3 NC1, 67k. Has had a transmission oil change in the last 1k miles.

Cheers! (sorry for the essay, but detail is always key)

[Scarletpimpernel]

Just my opinion.
Could it be that “Maybe” you have lost your reference point from the start?
As you say you have messed about with it loads, adjusting it up and down etc etc.
The main symptoms (plus others) of a worn out clutch are that it will slip under load/acceleration.
If yours is not doing that, its perhaps the time to go back to the basics.
From what I know and have read the NC clutches are quite robust.

Also plenty of threads on here about topping/checking the gearbox turret oil which seems to solve some of the issues. Mctrucky posted an “Excellent” thread on here yesterday.
His car is a 2008 2.0 and basically the same as yours. (Can’t remember the mileage).

Notchy gear change - selector limit plate wear on NC 6 Speed

I appreciate there is an other thread I created where this is talked about, titled “Gear Lever Rubbing Surfaces”, but thought worth posting this as a ‘How To’ which is the conclusion of the other thread. I am not sure if this is applicable to other models, my car is a 2008 NC 2.0 Sport. The problem was a horrible 2nd gear engagement on a cold gearbox. The solution was a replacement of the the ‘Reverse Lock Out Plate’ which limits how far the gear lever can move left to right. This plate is m…

[mk375]

I would be inclined to replace brake fluid, bleed through brakes and clutch( they share same reservoir) and reset the freeplay and pedal travel before replacing the clutch. If it’s still not right you could replace the clutch as a last resort knowing everything else is right.
Clutches on mk3 seem from general reading to be reliable and long lasting on all but boosted engines but far more issues are noted around slave cylinder and low bite issues.It’s probably fair to say that the clutch fluid is rarely renewed / bled on most cars

[ChrisMK3]

Hi all,

Yep I should have included, I have topped up the turret oil, I have bled the clutch too - no real difference and the turret actually had plenty of oil in it too so no issues there.

When I adjusted it yesterday before setting off home the bite point is where I would say it was when I bought it (though there’s ofc no way to be absolutely sure of this at this point).

Yeah I’m also not familiar with them having clutch issues in general, particularly at 67k unless they’ve really been abused, but anything is possible!

The clutch itself is also reasonable heavy (a symptom of wear I suppose).

At this point it’s not really causing me an issue, I just feel that it could be better… The ultimate question regarding a new clutch is, ‘is the juice worth the squeeze?’

[ChrisMK3]

I’m also wondering if changing the selector limit plate is a worthwhile exercise

[IanHP]

I would check that the clutch slave cylinder isn’t leaking.

[ChrisMK3]

It isn’t!

On the surface, everything is all correct!

[RichardFX]

In theory, the clutch system is self adjusting. The release bearing just runs on the clutch and the slave settles to the correct place.
So the only adjustment is the relationship between the pedal movement and the master.
Here it is important that there is just enough free play in the pedal before it contacts the master when the master piston is at full extension out.

If you overdo raising the bite point to the extent of losing the pedal free play and even eating into master piston extension, then you will have the symptoms you describe. You mention the 12mm spanner, you need two different sized spanners, 12mm is for the lock nut to prevent the adjustment slipping, 10mm makes the adjustment. I had fun with this last year.

What have you done to your MX-5 today? (Part 1)

Today I learnt how to adjust the push-rod that operates the NC clutch master cylinder. Check the clutch pedal travel is 130mm.  Bare foot on the pedal with end of tape measure held between the toes, note the difference in readings against the stitching on the steering wheel while operating the clutch. In specification, so the top adjustment is not needed. Recharge the inspection lamp. (And have lunch.) Adjust the seat base so far back it jams on the runners. Place the Bathroom Stool …

If there is still a bit of pedal free play, and the clutch is not slipping, then the problem is in the hydraulics, slave or master, or hoses.

You say you’ve bled the system, then the next most easy thing to change is the slave cylinder. But if this is not leaking then it is most likely OK.

If not the slave then maybe the hose to it is weak and bulging, usually more pronounced when the engine is hot.

If not these, then the master!

If you’ve not already done so have a read here. Alas they want might money now.

clutch.pdf

[ChrisMK3]

Yeah I found that I didn’t need a 10mm spanner for the actual push rod itself - I was able to turn it by hand by gripping it tightly with my thumb and forefinger!

Clearly there’s a bit more science to this than I thought, though getting a spanner over the free play adjuster was a nightmare, I gave up, couldn’t do it, namely because I couldn’t figure out how to remove the sensor switch that presses in when the clutch is disengaged.

I’ll be having another go tonight!

[Mad_Malc]

If you pump the clutch pedal 2/3 times quickly before you change gear does it improve? Particularly when selecting reverse. If reverse engages smoothly after the 2/3 pumps then it is an indication of air in the system.

[Keat63]

If the friction plate has worn, then eventually, you’ll be able to get it in and out of gear without using the clutch pedal at all.
There will be no friction between the engine and the input shaft.
If engaging gear is gridning, then either the pressure plate is failing, or there is not enough pressure on the hydraulic side.
Could be an air lock, or failing slave/master cylinder.
I guess there is also the possibility if you’ve adjusted the pedal too much, that the hydraulic system is never at rest (always under some load), which could in theory allow the pressure the drop, making your pedal travel worse.

A couple of pumps before changing gear would prove this theory.
60,000 miles used to be about the going rate for a daily stop/start commuter car for a clutch years ago, but clutches are better made these days.

As for pedal adjustment, from my experience there’s nothing in it.
Any adjustment doesn’t really make any huge difference.

Slcken the lock nut, rotate the rod until you feel it starting to bind, back it off a turn or two, nip up the lock nut.

[1954]

Adjusting the rod by 3/4 turn on my car made a big difference to the bite point and has remained consistent for the last year,

[GeriAtric]

If you are using finger and thumb to rotate the rod how are you managing to tighten the lock nut effectively without a second spanner?

[ChrisMK3]

Right I’ve just had another go…

Adjusted the free play bolt, slight improvement…

Messed about with the actuator rod itself a few times with multiple test drives and ricking back and forth on the driveway (neighbours must think I’ve lost the plot)… And it seems to be better already!

So later on when the missus has calmed down about me not doing the dishes when she asked me to (oops), I’ll ask her to help me bleed the clutch properly and see where we’re at.

@GeriAtric - You’re right. As much as I was able to adjust the rod without a spanner, tightening the lock nut up mean’t that the rod was moving out of position after I’d adjusted it… I’ve done it properly this time and it seems better.

So yeah - it seems better all in all… Just need to keep an eye on it!

[mk375]

Have a google miata clutch pedal assembly and the first result “Clutch Pedal assembly repair” on the miata.net forum. It discusses problems with the clutch pedal bracket which can affect gear selection.

[ChrisMK3]

Quick update: she’s better than she’s ever been!

Completely bled the clutch earlier and removed nearly 600ml of fluid before it ran clean, readjusted the pedal as described accordingly and she’s now lovely and smooth!

The pedal is also noticeably lighter which really makes long journeys a bit better!

Also fitted my shiny new roll bar covers, courtesy of @Davy_F (thank you!!)

[Davy_F]

Looks soooo much better. Thanks for the trust, Chris.

[ChrisMK3]

It really does!!

Never doubted you for a minute

[ChrisMK3]

Well I’ve just about given up on trying to get the clutch pedal right.

Bleeding it completely and fresh fluid has definitely made the biggest difference overall but its still not quite right. The weirdest thing seems to be that everytime I adjust it, it seems to go through something of a settling process so when I think it feels just right, it seems to settle/self-adjust itself somewhat and then my adjustments seems to always be a mile off.

I’ve tried following the guides (the one linked above, and the mazda service sheet), but I still just can’t see to get it right

I don’t suppose anyone is in Yorkshire and fancies doing it properly for me?

Outside of this, I’m going to see if MX5 City are up to the job of resetting it to factory spec! It’s really starting to ruin my love affair with the car now!

[mk375]

Are you sure the pedal assembly mounting hasn’t cracked?
You can google and read the post on the US miata forum
Clutch pedal assembly repair