Manual NC (Series 2) 1st gear selection & clutch issues in heavy traffic

[Jester_j70]

Hi All,

I have a manual 2009 NC (Series 2) with almost 100,000 Kms and have found issues with the clutch and selecting 1st gear when driving in heavy traffic.

When driving in heavy stop start traffic for about 30-45 mins, first gear becomes increasingly hard to engage to the point that sometimes I cannot engage it. Further, the clutch take up point gets closer and closer to the firewall to the point that when I have the clutch completely pinned to the firewall , have 1st gear selected, and barely ease it off (1-2 mm), the clutch friction point is reached. In normal driving situations the clutch take up point is probably about 1/3 of the pedal travel away from the firewall and although 1st gear selection can sometimes be a little difficult, it’s rare and generally works well. The clutch does not slip and nor does it make any unusual noises.

I have read the NC is prone to having issues in relation to finding first gear (http://www.mx5parts.com.au/tips-and-tri ... ard-select ) however I am not sure whether the clutch issue I describe above is common. If it is not common, keen for any feedback on what the likely issue may be and whether it could signal a failing clutch.

Thanks.

[JBT]

The NC gearbox is pretty bullet proof, despite the agricultural noises it makes at lower engine revs when hot. Haven't had a problem with the shifter collar on ours yet - 110,000 km and is also tracked.

Your symptoms sound like hydraulics problems. Check the master cylinder level. You may have a fluid leak at the slave cylinder or elsewhere. When was the fluid last flushed?

[1600Dave]

Clutch hydraulic issue.

Is the master cylinder fluid level OK ? Has it been low enough at some stage to allow air into the sustem ?

Is there evidence of leaking from the slave cylinder (wetness around cylinder / fluid on ground under car) ?

Is there evidence of leaking from master cylinder (wetness / fluid on the inside of the firewall / in the driver's footwell where the pushrod connecting the clutch pedal to master cylinder comes through) ?

Have you tried bleeding the clutch hydraulics ?

A take up point 1/3 of the way from the firewall is still not good.

[Jester_j70]

Thanks for all the feedback.

I’ve checked the fluid reservoir tank and it is bang on the “F” line (Not above it).

No obvious signs of leaking around the master cylinder, including fluid on the inside of the firewall.

I have not visually inspected the slave cylinder however the car has a dedicated car space and there is definitely no fluid on the ground under the car.

When I last got the car serviced (about 9 months ago at MX5 Mania, I’ll be getting it serviced again soon), the mechanic mentioned the clutch did not feel quite right. He had inspected both the master and slave cylinder and had not noticed any leak. He bled the clutch hydraulics but even after doing so did comment that the improvement was very minor. I did not think too much of it at the time as the clutch felt OK to me. However, since having the clutch take up point issue in heavy traffic that I described in my earlier post (It’s not an intermittent issue, it happens every time I am in heavy traffic for more than 30 mins), it’s become something that I’m eager to get fixed. Further, when driving today I paid particularly close attention at the clutch take up point in normal driving conditions and it’s more like ¼ (or potentially as much as 1/5) of the pedal travel away from the firewall.

As the car is due for another service soon I’ll get the guys to have a closer look and try bleeding it again.

[JBT]

There could be an internal seal problem with the master or slave allowing the fluid to bypass - or the clutch hydraulic line is full of air. What happens if you pump the clutch pedal - do you get better response?

The only way to check the hydraulic system is to observe how much the clutch release lever physically moves when the clutch pedal is depressed. If that's working correctly, then the problem lies with the clutch mechanical system e.g. pressure plate.

[Regie]

Still running the stock clutch or has it been replaced?

Those were the exact same symptoms I had when I was running a xtreme heavy duty.

Have gone back to an exert clutch and the problem has gone

[1600Dave]

Further, when driving today I paid particularly close attention at the clutch take up point in normal driving conditions and it’s more like ¼ (or potentially as much as 1/5) of the pedal travel away from the firewall.

As the car is due for another service soon I’ll get the guys to have a closer look and try bleeding it again.

Sounding more and more like an internal issue within the master cylinder to me. Take up point should be closer to the top of the pedal travel, not the bottom (firewall). Possibly the master cylinder piston isn't fully returning when you take your foot off the pedal (broken internal spring / dirt or contamination / scratches due to wear / etc) ? It may be hard to tell if you've gotten used to the pedal feel as it currently is, but does the pedal feel very "soft" when initially depressing it until it gets to the point where the clutch starts to disengage ? ie could you be pressing against the pressure of the pedal return spring only, not against hydraulic pressure ? Can you depress the clutch pedal for at least part of its travel by hand (fairly easily) rather than using your foot ?

[Mr Morlock]

You get the advice but in the end you are probably going to save time by asking the local Clutch/ brake service. Like the others I would say its nothing to do with the gearbox. If the cr has done 100K there is no guarantee if the clutch has not been given a hard time and clutches / pressure plate clutch plate etc wear out. My bet is that if the fitter cannot detect anything obvious including perhaps some clutch slip under a stress test then they will suggest replacing the clutch.

[TrackAttack]

Have you looked at the shifter cover bolted onto the gearbox? The plastic wears out and can cause issues selecting gears... From memory, the 4 M8 fasteners holding the shifter turret on also come loose...

[JBT]

The OP's issue is the clutch system and not a selection problem. If the clutch won't disengage properly, then all the shifter bits are of academic interest only.

[Jester_j70]

Really grateful for everyone taking the time to read the post and provide continued feedback, thank you.

@ JBT – I tried pumping the clutch pedal a few times and there was no discernible difference. If there was, I could not feel it. Unfortunately unable to comment on the clutch release lever as I’m unable to inspect it whilst pressing in the clutch.

@ Regie – I can’t categorically confirm whether it’s a stock clutch or not as I’m the second owner of the car. However, the guy I bought it off kept meticulous records and had every service invoice since new. He had not made any modifications to the car (except for fluro blue lug nuts and antenna, which I promptly changed to RAYS charcoal coloured lug nuts and a Cravenspeed black stubby antenna as I prefer a more subtle look ). With this in mind I’d say it’s highly likely to still have the original clutch.

@ 1600Dave – I think you may be onto something… Based on your comments I paid particular attention to the clutch resistance and yes, the clutch pedal is indeed very soft for about the first 1/3 of travel. It does feel as if it could be the pedal spring as the resistance is minimal. I can press the clutch pedal down fairly easily with a single finger for the first 1/3 travel and then the resistance becomes much harder to the point that I can no longer press it with just one finger. Assuming it’s the master cylinder, would it be a matter of simply replacing it with a new one? How long would the process take given brake/clutch fluid would need to be drained?

@ Mr Morlock – Fair comment and I agree that having a specialist look at it is a good idea. When I made the original post I was not sure if it was something obvious that would be simple to asses by those on the forum who have experience. If it was not, I was keen to get feedback on what the potential issues could be so I could do some additional research and have a (somewhat) informed discussion with the mechanic.

@ TrackAttack – I’m finding the issue to be with the clutch which is then leading to having a hard time selecting gear. However, I have bought an IL Motorsport short-shifter which I intend to install soon. I have also purchased a new gear stick base plate to replace the current one. I’ll check the fasteners and torque them to spec when I install the short-shifter.

[1600Dave]

I've not done a master cylinder on an NC (or an MX5 for that matter), but the usual process is :

1. In driver's footwell, disconnect master cylinder pushrod from clutch pedal. Often just a split pin through a clevis pin or similar. Normal car, a few minutes work. MX5 maybe a bit more, unless you have a small child to do it for you or are some sort of contortionist

2. Under the car, disconnect the hydraulic line from the slave cylinder and let the brake fluid drain out.

3. In engine bay, disconnect hydraulic pipe from master cylinder. A strategically placed rag helps to catch any stray brake fluid which has the potential to damage paintwork.

4. In engine bay, remove a few nuts that hold the cylinder in place and remove master cylinder from car.

5. Reverse the process for installation.

5. Fill master cylinder with brake fluid, and bleed clutch hydraulic system.

Should be less than an hour to do.

If it were me, if you end up replacing the master cylinder, I would get a price on replacing the slave cylinder as well. They are usually fairly cheap, should take around 5 minutes to replace, and you will need to bleed the system regardless so no extra labour cost there. More so if you find evidence of dirt / contamination in the master as this may have ended up in the slave as well.

[93_Clubman]

If not clutch slave &/ or master cylinder then clutch thrust/throw out bearing might be on the way out.

[Aiming Faster]

I just did an NA8 and NB8a clutch master/slave recon, cost $20 for the bits to rebuild those 4 units.
You'll need a pump pack with meths to flush the cylinders, and a small amount of rubber grease (or just use brake fluid) to lube the new seals too.
I got Super DOT 4 brake fluid from Supercheap (2 for 1 deal), and made a simple hone.
After reading this forum, I also removed the steel/rubber/steel lines and rebent the longer steel line to fit (with flexibility) between master and slave. Metho rinse this too.
Either line will work, no cost! The first one I did even self bled perfectly when I opened the bleed bolt and pumped the pedal 3x!

[shortSteve]

I had an ongoing issue with the clutch on my NC1, after a autotest or heavy clutch use, clutch "freeplay" would increase, and "take up point" would get closer to the carpet, as a result 1st and reverse were difficult to engage from neutral. Had the brake fluid drained and bled at service, problem persisted, so when hot and not performing, bled from clutch slave end and fluid was black. After getting clean fluid back through, clutch behaved as fine. Of note, take up point can be as low as 25mm from carpet and still be within spec (25-50mm on a 130mm stroke with 5-15mm freeplay). After 2 more trackdays, it occurred again (but no-where near as bad, was just noticeable) after parking up from a long session, bled again and definitely blackened/burnt looking fluid again. Once bled to clean, was all good again. So my issue either relates to poor bleed through of new fluid or severe heat build up in slave or lines too, I also run DBA rotors and Winmax pads and have a full exhaust system, so unsure if residual heat in brakes (same fluid) or from headers are making it more noticeable/worse. Seems after 10km of easy driving, or an hour parked up, problem goes away again, hence putting it down to heat soak. Car has standard clutch still.
Keep us informed on how it all goes.

sS