924Board.org

[F924T]

Hi all;
The clutch pedal on my 1980 931 is almost on the floor; it has been getting lower and lower and now is getting difficult to drive; I know is a hydraulic clutch, so I thought the car might be loosing fluid, but I don't see a clutch reservoir in the engine compartment...I did the cluch test and I believe that the clutch disc has good life in it....Has anybody had this problem before?

Thanks for you help.

[cs]

the clutch master cylinder gets its fluid from the brake master cylinder. it's really not a good set up, probably wouldn't be a bad idea to rig something up so they had seperate containers.

[kevrl]

The UK spec cars (RHD) have a seperate clutch reservoir for the clutch cylinder mounted on the bulkhead, maybe you could use this. The clutch fluid does get very dirty.

I have had the exact same problem in my 931, the clutch pedal sinks to the floor over a period of time. I have changed the slave and master cylinder and the flexihose, then pressure bled the whole system. The threaded rod from the pedal to the master cylinder also needed adjusted. Now it works just fine, except for after i've done a hot run in cold weather, the clutch pedal will be slightly lower the next morning. All you have to do then is re-prime the master cylinder. (i.e. hook your foot under the pedal and pull it up as far as it will go, then press it down again) 'Apparently' this is because on RHD cars the master cylinder is above the exhaust manifold, so it gets hot and expands the fluid slightly, then when it cools, the fluid and cylinder contract and draw the pedal down - apparently ?

Hope this helps,

Kevin

[numbers]

I have an '80, and several years ago, I noticed some oil on the hose from the reservoir to the slave cylinder line. The hose was perforated with small cracks. Replaced it with some fuel line hose, and haven't had another problem.

[RobDumoulin]

First thing to check is to make sure the master cylinder fluid level is well above the feed line to the clutch master cylinder. If it is below that mark, you have air in your system and you need to bleed it. Next thing to check is for a leaking clutch master cylinder. Run your hand along the connecting rod between your clutch pedal and the firewall. If you have brake fluid on your hand, it is leaking. Rebuild or replace the clutch master (be careful not to drop the nuts when you take the old clutch mc off. they are a pain to find down there in the wheel well).

I just went through this and found that with the better pressure of my new master cylinder, I blew the slave. That will be replaced this weekend.

[Smoothie]

Actually, having both the brakes and clutch drawing fluid from the same reservoir might provide a safety feature. The clutch gets fluid through a hose connected to the side of the reservoir and therefor from a point higher up than where the brakes get fluid - from an opening in the bottom of the reservoir, so; if the brake system starts leaking fluid, the clutch looses its' source of fluid before the brakes do. My only problem with this is: Will the clutch start to act up at this point or will it continue to function normally if it's only lost its' source of fluid and it itself isn't leaking? Then on the other hand, if the clutch system is leaking, you only loose fluid down to the point where that hose comes out the side of the reservoir, so; the brakes still have fluid.

Anyway, I had hydraulic clutch problems too. I went through 2 slave cylinders, neither of which solved the problem I was having, but; I thought I was seeing a slight improvement with each replacement and blamed the fact that the problem wasn't being completely fixed on the assumption that I was just the worlds worst hydraulic system bleeder. Anyway, I was getting fooled by the fact that fluid was leaking through the slave cylinder down at the bell housing. That's why I went for new slave cylinders. I drove it for longer than I'd like to admit in this condition where I had to keep lifting the clutch pedal off the floor with my toes and pump furiously, not only when first starting out, but; many times while driving. Also, it (the clutch pedal) would drop on a higher rpm acceleration. Finally, I went for a new clutch master cylinder and that was what it needed. No more leaking through the slave and no more retreiving the clutch pedal from the floor while driving.

[kyhm]

FSCK!

Just went out for a drive, to find my clutch pedal wants so sink into the floor, it has that same soft feeling as when the slave cyl went last year... And I look, it's rusty on the outside of the cylinder body, inside the firewall, brake fluid on the rubber boot, on the floor...

I dunno, did I miss a fscking meeting on the clutch cylinders? Are they an expendable item like oil and fuel, that have to be replaced yearly?

Sorry for the rant, this just is so damn frustrating.

Now, to try to make this post constructive, anybody know of a better way? I mean, if I'm gonna fix the thing, are there any updated replacements?

[Smoothie]

KYHM,
I think you'll be alright for a good while once the master cylinder is rebuilt or replaced. I took a look through my replaced parts collection in the garage and got reminded that I didn't actually replace my master cylinder - only rebuilt it. I used a NAPA kit. It says "NAPA - United Brake Parts #1899 Clutch Master Kit". As far as the slave cylinder - I replaced it the first time and rebuilt it the second time. The procedure is similar to rebuilding a drum brake cylinder. I used a brake cylinder hone on a variable speed drill. Removing and replacing the nuts that hold the master cylinder to the firewall can be a bstch. I used one of those extension magnet things to retrieve the nuts each time they were dropped and to hold them in place while re-attaching. Don't know of any extra high quality parts to use. The rebuild kits were just standard replacement parts from NAPA (both were made in Germany) and the new slave cylinder that I used, I got by mail from either Tweeks, Automotion, Performance, Zims or PAR in Yonkers, NY. It has the name "FAG Vehicle Hydraulics" on it and also came from Germany.

[ This Message was edited by: Smoothie on 2001-11-22 05:17 ]

[F924T]

Problem gone on my baby, it was the hose from the master to slave cylinder, it cost around $35 from the stealers, a couple of bruised knucles and some swearing and sweet talking and now the clutch is back to normal.

[larso]

Did the hose have a hole in it?

[F924T]

It was cracked...not too big, which explains how it deteriarated so slowly.

[TonyMechanic]

Just wanted to let you all know, if you have problems with your clutch hydraulics after it gets hot, switch to Ford Heavy Duty brake fluid. It is made to stand up to the abuse that 24 Hours of Le Mans/Daytona racers subject them to. Believe me, my last boss built and raced a car at 24 hours of Daytona here in the states, he says that %90 of the teams were using Ford Heavy Duty Brake Fluid. You might only be able to buy it at Ford though