Clutch pedal to the floor

[PeterW]

Yesterday I had the often reported clutch-pedal-to-the-floor experience. I was able to get home by lifting the pedal up and down a few times, after which it worked fine. Kaz has given advice on this in the past, and it worked. The level in the reservoir is fine, but I know I have a very slightly leaking master cylinder. I haven't checked the slave cylinder or the flexible hose yet, other than a quick look from the top and without peeling back the two rubber covers on the slave cylinder. Anyway, my question is, does anybody have experience of overhauling the master cylinder rather than replacing it? The piston assembly is listed as a separate and significantly cheaper part than the complete cylinder. Maybe the cup seals are even available as separate parts, although I don't see them listed on the Ling's site.

Anybody have experience of this?

Thanks
Peter

[Pride]

I had exactly the same experience about 2 years ago. It turned out to be the slave cylinder, quite common by all accounts, at least according to Yeomans Honda, Chichester.
It will be interesting to know what you find.

[NSXGB]

I believe there was a thread on Prime about this not so long ago. It can be done as long as the bore is fine. Rock auto used to sell the seals but not sure if they still do. Unfortunately RA only sell the LHD master cylinder which is different to the RHD, but I'd wager that the internals are the same, otherwise the complete unit would be pretty cheap from them anyway.

[drmikey]

Complete unit is recommended.

New seals in an old rusty and worn bore/cylinder wont last long

[goldnsx]

Always replace both, master AND slave.

[Kaz-kzukNA1]

Hi, Peter.

In Japan, we used to be forced to overhaul/replace many parts on the car at the specified interval by the government law so in the Japanese workshop manual, you will find so many extra instructions that you won’t find in other language versions.
For example, the overhaul method on the brake master cyl, classic ABS modulator/solenoids, CL master/slave cyl, brake booster, etc.

I used to overhaul brake master cyl and brake callipers every 2 years as required by the law.

However, for the CL master cyl, despite the availability of the parts and instruction manual, unless it failed prematurely (I must admit, the CL master cyl on other Japanese production cars won’t fail so frequently like our NSX even used under the same conditions), it’s not worth it.
Just replace the whole cyl for the following reason.

The CL master/slave cyl are significantly used more frequently than the brake master cyl that by the time it started leaking, the internal bore wall could be worn.
Therefore, you could overhaul it once but not recommended the next time.

I normally simply replace the CL master/slave/hose as a set because they went through the same number of CL pedal strokes even just one of them failed.

If doing overhaul, just get the piston, return spring, valve guide, valve spring, stem, etc as the ‘piston assy’ and replace the whole lot.
Otherwise, you need to lift the notch at the spring retainer to release the piston body but there is nothing to service apart from replacing the parts so again, not worth it.

Kaz

[duncan]

IMO [for what that may be worth, or not], neither the clutch master or slave are particularly complicated, subject to their bores being OK, it's easy enough to replace the seals and is no more difficult than a Girling unit, it's just that the seals have to be purchased individually rather than as a set.
As ever, the joy is working upside down in the footwell.
For the master cylinder, the main internal part is PISTON ASSY 46926-SF1-003 plus maybe the dust seal BOOT, MASTER 46184-611-000
For the slave cylinder, PISTON, S/C 46932-SL0-003; the seals CUP A, PISTON 46933-SL0-003 and CUP B 46934-SD4-901 and maybe the dust seal BOOT, S/C 46937-SD4-003
A check on page 12-7 and page 12-10 of the service manual [marked as Canada only] will show what's where.
When as a routine replacement in 2010 I replaced both sets of seals the total cost of 6 parts above from HUK was £73 compared to the then listed price of £348 for a new master and slave.
It is possible to have the cylinders rebored and sleeved back with a stainless steel liner, these people
http://www.pastparts.co.uk
provide such a service within the classic car world, I know others who have used them and are happy to recommend them.

[PeterW]

Thanks all for the good advice.

I'm going to check the bores of both cylinders and if they look smooth I'll overhaul them with the parts Duncan kindly listed. Excluding the hose, boots, O ring and split pin, according to the prices on the Ling's web site, overhauling both cylinders will cost £69.96 compared to £497.15 for replacements. I'm comfortable that this is technically acceptable, especially since the clutch isn't safety critical. If it was somebody else's car and I was charging for the work, it might well be a different equation and not make sense to spend time on the overhaul.

I overhauled leaking brake cylinders on Ford Escorts in the 1970s and that worked out OK!;)

Thanks
Peter

[PeterW]

Just to round this off ...

I replaced the slave cylinder rather than overhaul it with new seals. The bore was a bit rusty, and the price from Rock Auto was very reasonable - thanks NSXGB for the Rock Auto tip. The cylinder from Rock Auto is almost indistinguishable to the old (assumed to be original Honda) one, even down to casting markings.
I reused the hose. I wanted to use a new O ring but the delivery was weeks, so I reused the old one. It's not leaking, happily.
The bore of the master cylinder was fine so I just replaced the piston assembly (46926-SF1-003) which was a £200 saving compared to the Honda UK price for a complete master cylinder. Since then though, I saw the post from Tegiwa Imports and their price for a master cylinder looks very good.
I used SKF LGEV2 grease in the pocket of the clutch actuating arm ... but annoyingly it now creaks! Perhaps I'll put the old pushrod back on if it doesn't quieten down.
Key learning though, is that before doing the work on the master cylinder in the foot well, you need to prepare ... here's something you should try a few times before you start that job :) https://www.youtube.com/watch?v=2eBzkpvt-II

Thanks for all the advice.
Peter