Clutch pedal fell to floor, then fine?

OK, got my tranny rebuilt about a month ago, have probably put 700 miles on it since. Had to have the slave cylinder replaced at the same time. Did not have the clutch replaced, as there was over 50% left. Babied it for 600 miles, and still have not done too many redline shifts. Tonight, a buddy of mine with a 375 HP WRX (turbo, 25+ lbs of boost) and I were out playing around, and after doing a nice launch and redline shift to second, I let off, as we were coming up to a light. As soon as I touched the clutch pedal, it FELL to the back of the firewall. I panicked and pulled the pedal back up to the top of it's travel with my foot. Lo and behold, everything worked great after that. I know it can't be a figment of my imagination that this happened, but I can't figure it out. Is there some type of linkage that could have popped off, but then popped back on when I brought the pedal back up? There was absolutely no pressure against my foot when I pushed and it fell. Has anyone had this happen to them before? I really hate to just let it go, as now I am worried that it may happen again, although there has been absolutely no indication of any problems the rest of the way home.

Have you checked for leakage around the master and slave cylinders? You might also want to check your clutch fluid reservoir to see if you are losing fluid.

No signs of leakage and level is fine.

you know what, my clutch did that once, and came back up. And it has been fine ever since. 20k miles later and it never happened again. I guess cars jsut does things some times.

Re: Clutch pedal fell to floor, then fine?????

Might be air in the system...next time you go for service get them to bleed it.....Piece of mind

Mike

Clutch pedal magic

Must be a ghost in the machine... mine did same thing about a year ago- I rode around with a bottle of brake fluid in the trunk for a while, no further problems. While in for my 45K service I did have all hydraulics bled, so well see if it happens again.

Almost certainly sign of failing master or slave cylinder - (in Tomc...'s case the master since the slave was already replaced recently)
Co-incidentally went into the car today & noticed an odd feel on the pedal as I de-pressed it to start the car: then it would not go into gear, clutch was not dis-engaging. I noticed the pedal was about half-way down from its typical position. After pumping a few times, the clutch disengaged but was engaging almost immediately off the bottom (my clutch normally engages close to the top). This was a sudden change from the previous day when it was "normal"
I checked the fluid which was full but very dark in colour. I decided right there & then to replace both cylinders (master & slave) rather than screw around - $98 & $84 respectively from Niello with NSXCA discount.
Incidentally, I was surprised by the number of clutch hydraulic issues I found with a search on Prime - seems like a pretty common problem.
I'll update tomorrow on the outcome after replacement.

Glad to know it's not just me. Air in the line was the only rational solution I could come up with, but that still seems weird. Will hold on to the hope that the car ius just possessed, instead of more stuff going bad....

I can't believe some air in the line would cause it to go to the floor - the seal probably suddenly gave & let the fluid slip by it. I imagine that once the seal was wet all the way around, it would swell enough to hold pressure again. Thats a possible theory of course no way of really knowing - I just wouldn't risk it personally - hate to be stranded somewhere for sake of $100 part.
Incidentally the Niello parts guy said that is the third cylinder he's sold in last week - he said it always happens in the hot weather (it was 102 in Sacramento & 100 at my house last few days - maybe even hotter in my garage!) I'm not sure how the heat would affect it to that degree however?
As to the job - got the master cylinder done - what a royal PITA!!!!!!
By the way - the fluid was really dark & after I siphoned most of it out with the turkey baster, there was a lot of dark crud at the bottom of the reservoir.
It is so cramped working on either side of the firewall - every single step was awkward - getting the clevis pin out; the nut on the cylinder closest to the steering column; the fluid line into the top of the master cylinder - every one of them nasty! Couldn't really get a socket on anything other than the lower MC nut - everything else was a box wrench with a minimal turn each time.
Putting back together not much fun either - trying to get the fluid line back on was no joy, then had to get the missus to push on the cylinder (with all her might, bless her) so I can get the nut started on the inside! Now the worst part of all - getting that damn clevis pin back in - I ended up taking the seat out (should have done that to begin with!) - that allowed me to lay on my back with my legs up the engine firewall - only way I could get two hands in there by the pedal box to pull up on the pedal & push the pin in. That made all the difference. Still, found a nickel under the seat for all my trouble
So, finally however, front end (master) is done - here's hoping the slave goes a whole lot more efficiently. Stay tuned for the next exciting (?) installment!
Hope I'm not scaring anyone off this as a home project - it's not technically challenging in the slightest, just awkward to get to everything. Definitely take seat out at the outset - its worth the exta 20 mins to give you better accesibility & much easier on your back!

D'Ecosse said:

Incidentally, I was surprised by the number of clutch hydraulic issues I found with a search on Prime - seems like a pretty common problem.
I'll update tomorrow on the outcome after replacement.

Click to expand...

I think it is a Honda/Acura thing. My clutch slave and master on my 6-Speed Legend Coupe failed as well, 40K for the slave and 85K for the master. Everyone I know who has Honda/Acuras and hydrolic clutches had to replace one or the other part at sometime during their ownership. The good thing is that the parts are not that expensive even at the dealer and its as good as new once replced.

ChrisK said:

I think it is a Honda/Acura thing. My clutch slave and master on my 6-Speed Legend Coupe failed as well, 40K for the slave and 85K for the master. Everyone I know who has Honda/Acuras and hydrolic clutches had to replace one or the other part at sometime during their ownership.

Click to expand...

I've never had to replace either the slave or the master, on my NSX or on the three other Honda/Acuras I've had, all purchased new and driven over 100K miles.

And a few reports on NSXprime doesn't make it common, when you consider how many NSX owners are here.

good for you, nsxtasy
I'm not going to debate you on definition of common, but do a search & you will see plenty of instances to warrant this is certainly not atypical failure.

As to the job, the slave replacement certainly much easier than the master - I got some excellent pre-install advice from master technician Gerry Johnson (who also has had his slave cylinder go out, if we're counting occurrences) that it would be much simpler process to drop the gear linkage first - that was a simple task & certainly allowed much more access.
The only awkward part was getting the piston rod from the slave cylinder lined up into the clutch lever cup - after I got that figured out after an initial mis-alignment, it was staraight forward. Bleeding is different to brakes in that the pedal does not come up for you - so you need to pump it up & down manually by hand - Mrs Scott to the rescue again, while I opened/closed the nipple. After final down-stroke the pedal will still lay on the floor till you bring it back up then it is suddenly rock hard!
Here's a few pics:
First the parts (actually the old master & the new slave)

The gear linkage before doing anything -

Take off the bottom cover,

Then pull the cotter pins on top of each actuator, remove the couplers & pull the cable assembly out of the way -

Then remove the top cover to gain clear access to the slave cylinder

Then, remove the 2 bolts securing the fluid line & the two bolts securing the slave in place & remove the assembly. I removed the entire rubber boot assembly surrounding the clutch lever at the same time, so it all came off in one piece. I also took the trouble to pump some fluid through the lines at this stage until it ran clear before going any further.
During re-assembly, it is easier to slip the boot over the piston rod, then line the rod up with the cup in the lever before securing the bolts for the slave; then re-install the rubber boot (like a grommet) after you are certain the piston rod is seated correctly. Don't install the fluid line until after this step as you will need to compress the rod against the internal spring in the cylinder as you line it up with the cup & the bolt-holes.
Lastly, re-install the fluid line, bleed it, then re-install the gear-shift linkage assembly.
Here's how my fluid looks after its all done

edited for a couple of typos 12-30-03

Final result? Clutch feels really smooth now - glad I did this.

It's not a part failure

Last year I had a new clutch tossed in at the dealer. On the way home, the "clutch fell to the floor" deal happened to me. I reached down, pulled the pedal back up with my hand with a kind of "clunk" sound. I got home, called the service manager who said it's happened to at least 3 cars he knows of and they have yet to find out what causes it.

To me it seemed like a mechanical - not fluid - related problem, but I make no wild claims.

I have over 10k miles and 6 track events under my belt since it happened and everything is working great.

Now do what you want, but I wouldn't go replacing parts looking to fix a problem that may not be there. If your clutch system is actually failing, you or the dealer should be able to tell instantly, and the problem will be constant, not a "one time" issue as this thread is discussing.

-ed
www.nsxbuilder.com

It has to be hydraulic - if it was mechanical it surely wouldn't recover when the pedal was raised
Let me ask a question for those with the "pedal-on-the-floor" situation (mine wasn't like that - just wouldn't disengage the clutch)
Was the clutch engaged or disengaged with the pedal on the floor?
If it was engaged, then that means the lever on the clutch was still in its "normal" position - for that to happen the only possibility is that the pedal goes in & no hydraulic fluid transfers that pressure to the lever - has to be failure of either the master or the slave piston seals.
Failures don't heal themselves - it is certainly strange that this happens once & then never again for 10's of K's of miles (I'm certainly not disputing - it's been reported several times this way)
I ask those who ignore it, hoping it won't come back - if this was your braking system would you ignore it like that??? I suppose it is not necessarily a question of safety, more of potentially being stranded. When something isn't right, I personally prefer to fix it.
I think you can equate what happens as you bleed the system: if you stop with the pedal in the down position and close the nipple, the pedal will still lay on the floor - you have to manually pull it back up & then it becomes immediately hard. This sounds exactly like what is happenning - instead of the fluid exiting through the nipple however it has to be by-passing either seal.

Originally posted by D'Ecosse
Failures don't heal themselves - it is certainly strange that this happens once & then never again for 10's of K's of miles (I'm certainly not disputing - it's been reported several times this way)
I ask those who ignore it, hoping it won't come back - if this was your braking system would you ignore it like that??? I suppose it is not necessarily a question of safety, more of potentially being stranded. When something isn't right, I personally prefer to fix it.

Click to expand...

When something isn't right, I personally prefer to fix it, too; I like my cars to be perfect, with no known problems. However, if something happens once, and then doesn't happen again, I don't immediately take it to get fixed. I've tried that in the past, many times (not just on the cars, but on various appliances, etc) and I've learned that if something isn't happening with any consistency and repeatability, it's going to be impossible to diagnose and fix. So now, I will keep going, and wait for it to happen again, and try to identify a pattern of causation, something that I can pass along to the experts, to help them figure out what is causing the problem, so they can fix it. Usually, the problem occurs again, in a pattern I can identify or with enough frequency that I can take it to be fixed with some confidence that it will manifest itself. Occasionally, a problem won't occur again, in which case I will shrug and move on.

Ditto nsxtacy.

Re: Clutch pedal fell to floor, then fine?????

D'Ecosse:

I found it extremely hard getting those cotter pins out! Maybe because they're likely 15 years old... the rear one broke into pieces when I tried straightening it and I eventually used a dremel to cut it off (I know, you're shuddering...)

Re: Clutch pedal fell to floor, then fine?????

Got notified that this thread resurfaced, and 2 years pretty close to my original post date, and I have had no further issues. Everything has worked fine since that one original incident, with no parts replaced. Must have been a ghost in the machine. Just wanted to update anyone that cared....

Course now I am going to go down to find every seal leaking....

Re: Clutch pedal fell to floor, then fine?????

I replaced the slave cylinder today. (The master had started to leak,
and I replaced both at the same time.) Thanks to D'Ecosse for the
step-by-step instructions and pics. :biggrin:

Like bjmills, I found the cotter pins a pain to take out (and not
a delight to put back in, either). Maybe it's easier with the car
on a lift, I did it lying on my back underneath the car. I'm
wondering if the pros have any tips on how to get the cotter
pins out. I grabbed them with



while holding



behind them so I could see what I was doing.