High biting point

[tapav]

Hi,

I have read a lot of contradicting info high clutch biting points.. I would like some advice/opinions before forking out on a new clutch. My biting point is approx. 10mm from the top of the pedal and i'd say it's probably been getting worse over last thousand miles. Clutch doesn't feel heavier and does not slip. Any suggestions?

I'm not sure whether its connected, but hydraulic fluid ran dry about a year ago, which was topped up and has not gone down or leaked since. Clutch has not been replaced and car is on 105k miles.

Thomas

[Kaz-kzukNA1]

Hi, Thomas.

If the CL is not slipping, I would check your CL Hyd system first and won’t replace the CL.
When the CL disc (your signature states that it's 98 model so I believe you have 97+ single disc CL) is on its way to the end of its life, the CL pedal gets heavier and heavier.

When your CL reservoir went dry, did you bleed the air, change anything or check where the fluid was leaking from? CL fluid won’t just evaporate and disappear.


I was going to recommend you checking the pushrod and piston free play at the CL master cyl but if it is leaking from there, not much point as you will need to check it again after replacing the CL master/slave/hose as a set.

For your reference, this is what I will recommend after checking where the fluid was leaking from.

http://www.nsxcb.co.uk/entry.php?1165-CL-Master-Cyl-Pushrod-Free-Play

http://www.nsxprime.com/forum/showthread.php/178420-Clutch-issues-weird-problem?p=1753619&viewfull=1#post1753619

Kaz

[tapav]

Hi Kaz,

Thanks, I have previously read your links after searching all clutch related issues on here, but wasn't sure that was my issue and I was a bit sceptical about adjusting the push rod.

I did check in the footwell and definitely no moisture. At the clutch end, i couldn't really tell. I had never checked the levels before this happened, so kinda presumed it just happened over last several years, before my ownership.
It was bled after filling, although starting to suspect possibly not completely and no parts changed. As I say the level has not dropped at all since, so haven't checked again for leaks. There is some kind of debris in the reservoir, almost looks like a swirl of dye in the fluid. I will get someone to pump the pedal and while I check for leaks again. Followed by push rod play and possibly a flush.

Thanks again.. you're a legend!

[tapav]

Right there is a slight weep from the master cylinder in the footwell. Free play seems to be about right.. So new master cylinder for me (+ slave & hose)

On the friction disc.. would it be a good idea to change the friction disc and pressure plate now, to prevent damage to the flywheel and having to replace that as well?

[Kaz-kzukNA1]

Depends on the condition of your flywheel and other parts.

As I wrote in the past, it’s hard to judge the condition of one’s CL by just the mileage.
For example, in Japan, I used to replace my CL every 30K – 35K miles because the traffic was always like stop and go everywhere and there were so many traffic lights and no roundabout.
Since I moved to UK, I can easily cover more than 100K miles (but mine is twin disc type) using the same driving style.

One thing for sure. You will never experience the ‘out of factory’ feeling without replacing the flywheel. This was especially true with twin disc type CL because the friction coefficient is massively high with the OEM twin disc package that it will wear the flywheel contact surface as well. Very unlikely to happen on majority of other Japanese cars and some of them are still with their original flywheel and very likely to last for the life of the car.

For single disc type like on your NSX, the OEM flywheel is mega-expensive.
Not much saving by sourcing it through Japan or US unless you can use surface mail.
I know several owners had their single disc CL replaced at very low mileage and for the ones that I test driven, as far as I know, all of them re-used the flywheel.
The CL pedal was much lighter after replacing the CL and it felt similar to factory spec although they acted at very early stage and at low/mid mileage like 20-30K miles.

As you already covered more than 100K miles and as mentioned above, I won’t be able to judge the status but if the surface of the flywheel is just about light blue with no heavy marking, you may be able to re-use it.
I recommend replacing not only the friction disc but also the pressure plate/basket for your case.

Unless you request it, following parts won’t be replaced but I normally recommend replacing them for any CL service.
CL release fork, saddle and the spring.
CL release bearing guide

I assume you are replacing the bearings any way as a standard procedure and if so, get the release bearing from HUK.
Much cheaper than Japan or US.
Keep the used one as it could become handy when installing many different type of shaft seals.

While the gbox is off, I strongly recommend replacing the crank end seal at the Eng block side.
Several eng showed oil seepage from there and while it may look like from the oil sump gasket, it’s not and in order to stop it, you have no option but to remove the gbox and flywheel so best to do it while you have access there.


Regarding your bite point….
Small leakage at the master cyl should not affect your bite point. In fact, if you can’t push the plunger far enough at the slave cyl, you will have difficulty in selecting the gear.
It seems that this was not the case for you.

When the disc got worn, the release bearing moves towards the flywheel and thus, the spring of the CL basket will create deeper angle. This will result in much heavy pedal feeling and with the lever effect at the release fork, you may feel the bite point getting higher but only when the wear was really-really excessive.


If you are saying that the ‘free play seems to be about right…’ then your bite point can’t be ‘approx. 10mm from the top of the pedal’ like in your OP as you should have about 15mm of free play.

Double check the CL pedal height based on the Workshop manual as well.

From what you wrote, there is a chance that you may have very worn CL disc as well.

Kaz

[tapav]

Great info, thanks.. I wouldn't say my clutch is heavy at all, but maybe i've never had a light clutch!

I have bitten the bullet and ordered the whole lot.. Flywheel will depend on inspection. Just hope its all sorted for end of July!