MACH7

Clutch pedal goes to the floor and stays not engaging the clutch, is this a failed master cylinder?

As I pulled into my driveway last night, I depressed the clutch pedal and it stayed on the floor. I suppose the clutch master cylinder has failed? If the master cylinder, is it better to replace or rebuild it? And if replace, what experience is there with rebuilt ones vs. new ones? And where is a good place to buy one? Or buy parts if a rebuilt one is recommended? Any other insight would be welcome.

Also the repair manual says to use a nut expander to remove the master cylinder. Is this necessary? And if yes, were do you get one?

tmking66

Could also be the slave cylinder. Replace both with new ones. If one is bad the other is not far behind. Rebuilds in my experience do not hold up and since new ones are not that expensive I would not waste my money on rebuilds or rebuild kits. Any auto parts store will carry them. Victoria British actually has the best price that I have found anywhere.

No special tools are required to remove the master. Just remove the two 12mm nuts behind the clutch pedal and disconnect the linkage to the pedal, remove the fluid line and pull the master cylinder loose.

spot_skater

i'm not too sure about clutch master's, but on brakes it's usually best to replace if the bore is scratched or scored in any way

before you go replacing things and spending cash, check for fluid leaks and all that stuff, it may be something like a seal

troubleshoot...best of luck

Brianhsval

Whats wrong with the re-build kits? I have never had any trouble with one, and comparing $55 for a new master cylinder vs $10 and some change for a kit I can't see where you could go wrong. Unless you make a mistake with the re-build. Although it is so easy to do I don't see how you could. It isn't like it is rocket science.

anthrax

You could have just run it out of fluid...

Like spot_skater said check for leakes

But if it is hardware failure do replace both the Master and Slave, I did not do that when the master failed in my first RX-7 and sure enough the slave failed shortly there after as I was driving throught town...

RotaryRyan

My clutch did the same thing. It was the rubber line -it had busted, and the thread on the slave were all screwed up. Like all the others have said. it sounds like a fluid prob.

At least it happened pulling into your driveway

sgieldon

Bleed it First before you go and spend money you may not need to!
My Clutch Pedal did the same thing when I changed my Clutch setup to the RB HD Clutch. I was about to shell out the Cash for Both.
Hayes Manuel has the process in detail.
Doesn't cost anything to bleed it first!
At least you will know for sure.

If you have never Bled the Clutch before than there is a good chance that the Fluid is in pretty bad shape.
You should Bleed the System out anyway so that if you have to replace the Master and Slave you will start out with Clean Fluid and not contaminate the new components.

And Yes: Do replace both units at the same time!!!
sgieldon
steve

tmking66

As far as the rebuild kits go it MAY work depending on the condition of the master cylinder. If it has excessive wear or scratches in the bore the rebuild kit will not work. I have done two of these. One is still going strong after a couple of years. The other, lasted 4 months and the failed. For parts under $60 I would rather have a new part that I know will hold up than to take a chance wasting money on a rebuild kit. I guess that is why I am not a professional gambler.

Tom

Definately change fluids and bleed- see if that fixes it first.
If not, pull the slave cylinder off, actuate the clutch and see if its' leaking. If not, assume the master is bad. If you replace the master, you might as well replace the slave for good measure.
(At least this is how I determined my slave was bad when it did this same thing)

Manntis

You're describing the symptoms I encountered when my master cylinder went.

Tom

Either one. If the slave leaks and loses pressure = no pedal rebound. I thought it was my master at first too, but verified the slave when I pulled it off and pumped the pedal.

coldy13

Take off the master and slave cylinders. Take them apart and inspect the bore of each. If the bore is smooth and clean, rebuild them. If there is any scratches or gouges in the bore, get a new cylinder.

red_blast

Replace the slave and master cylinders as well as the line. Its better in the long run to replace them all at the same time.

MACH7

Thanks guys,
The Mazda manual talks about needing a "nut expander" and it gives a part number, is that needed to take either the master cylinder or slave off? Is there anything I should pay particular attention to when changing them?

And on the rebuild vs. buy new, the car has 58K on it, thus its probably failing from age and lack of use vs. over use - given the low mileage would you recommend a rebuild if it looks OK once taken apart or reduce risk and go with a new one? Are the new ones really new or factory rebuilt ones?
Thanks for the information and help

Brianhsval

Depends on where you get it. 58k milage is low! I agree with coldy13, take it apart inspect. Clean it with alcohol and then FEEL the inside. Smooth is a re-build, scratched is replace. I know nothing about a nut expander. An 8mm, for the bleeder valve,( be sure to prime the re-build, or the replacement), I think the line is a 10mm, and a 12mm for the mounting bolts.

MACH7

also, the reservoir is full and fluid is clean - and I do not see any leaks - up to now everything has been working as it should - I am assuming that its either the master or slave - I have been expecting to be stranded somewhere some rainy night with a failed master, so it is no surprise that it went given that car is approaching 20 years old (though only 58K miles) - feel lucky that it failed just as I was pulling into my driveway!!!

Issue now is whether to chance a rebuild given that the car only has 58K or reduce the risk by purchasing a new one

hanman

For the money I always go with new. I have had to replace four sets of hydraulics in my cars in the last two years. I figure since they lasted for twenty years, the $100 bucks or so, is worth it.

Brianhsval

20 yrs or not. It is a closed system, therefore unless there has been trash allowed to get in there should be no reason it would be damaged. Chances are it is fine, but again take it off and inspect it. I am not there to look at it myself therefore use your best judgment. Everyone is intitled to their own opinion, you asked and I gave mine. I personally do not see a reason for throwing money away on a new master or slave if the old one is re-buildable. Some people enjoy buying new stuff and that is fine, I enjoy the challenge of re-building as long as it is in good enough shape to do so.

JLIU

Pull the rubber boot off the slave and see if it is wet. If it is wet, your slave is leaking. Look under the dash to see if you see any signs of leakage from the master. I totally agreed with the comments on replacing both the salve and master at the same time. My slave went out a while back. I only replaced the slave and sure enough about 8,000 miles later, there was a very small leak in my master. I would have save a little bit of time had I replaced both at the same time. For the money, get new parts. MY 2 cents!

fast50

my clutch pedal stuck to the floor before in my 5.0 it was just the clutch quadrant

pjr

iTrader: (8)

My SE is doing the same thing... when the car is cold the clutch feels soft and doesn't come up. After a minute or so I can shift, but it is real soft... make I should add some Viagra to the fluid?

Until I saw this thread, I assumed the clutch was crappin' out... thanks folks for the tip!

MACH7

Well to close this thread out, I pulled the MC off and took it apart - it looked OK to rebuild, but after struggling with getting it off and then the slave (could not get my hand on the nuts/bolts to remove them easily), I went with all new vs. risk the rebuild only worked for a short while and I would have to go through the removal/install again - rebuild looked easy enough for those who have smaller hands and longer arms [or who otherwise can deal with the frustration with getting the MC and slave out and back in] - best prices I found were Olympus (www.forparts.com) & nopi.com - also, changed the flexible line while I was at it

Thanks to all who commented, it helped

RotoHead

LOL No clutch quadrant on first generation RX-7s.... They use a hydrolic clutch system as opposed to the cable system that is in your 5.0.

I'm currently having the same problem.. I had JUST replaced the master/slave cylinders too. Wondering if I did something wrong on the Master Cylinder end though. So I'm going to bleed and make sure that isn't my problem. Then I'll pull my master and slave to see if there is any failure... Seems like that is the general concesus around here.

P.S. Does anyone know if the FC or FD RX-7s had a cable system? And if so, do their clutch systems swap with the First Gen counterparts? I don't have my Victoria British catalog on me.

RotoHead

I've pulled the MC before, but haven't pulled the slave yet. So I'm hoping bleeding the system works well. Otherwise, I'll figure out how to get into and pull out a slave cylinder.