clutch play? (c900)

Likely that your clutch master has a small leak. Have you had to top up the brake/clutch fluid lately?

Take a look at the clutch master, where it connects to the pedal linkage. Any signs of hydraulic fluid?

Sounds like a master cylinder problem. Went through that about 4 month ago. Last week changed the clutch and slave cylinder. sorry

dave

Last I looked, the reservoir was quite full, but I'll take another peek.

I'll have to take a look.

The Bentley manual doesn't mention my specific problem as a failure mode. Rather, it talks mostly about a so-called "spongy" feel, which I'm honestly not sure what they mean exactly.

Thanks, John

If you have to do the master cyl, put a kit through the slave cyl as well - saves it going out in sympathy 4 wks later! Cheers

Listen to the man - this happens very often. Many theories as to why it happens, most likely it's the new fluid that does it.

It's just that - a soft pedal, which results in a very low-to-the-floor biting point. Caused by air in the hydraulics (master/slave/pipe). Air is very compressible.

Yeah, I have that symptom too on my daughter's '98 900SE. It had a new clutch and slave cyl. installed just before we bought it. I'm pretty sure that it has some trapped air in the clutch line somewhere, but from everything I have seen, bleeding the clutch hydraulics is a tricky situation. I think you may have to remove the slave cylinder (which means the trans has to be pulled) to really get all the air out completely.

Any comments?

-Fred W

Not sufficiently familiar with NG900s to comment with confidence, but they are very similar to 9k clutches, which I am familiar with.

Pressure bleeding will remove the air. It works very well on 9ks and C900s. Either buy a pressure bleeding kit, or make one out of a £10 garden sprayer. Great for brakes too.

Thanks, I do have one (home-made) already. I'll investigate that possibility. My assumption was that the slave cylinder, being so low would not allow the air to pass out. But maybe if the flushing is done fast enough it will. I'll let you know after I give it a try this weekend.

-Fred W

I checked it out, and there is no drop in hydraulic fluid-- the reservoir is filled right up to the line.

I haven't had a chance to check that out yet. But from my symptoms, I'm wondering if perhaps the piston in the master cylinder is somehow being prevented from returning all the way when the clutch is released. That might explain the lack of missing fluid, plus also the intermittent nature of the problem. If this were the problem, replacing the master cylinder would do the trick. Looks like that might be an annoying job (car w/ ABS). Fortunately still drives ok so far.

John

Could be the piston return spring, which is inside the cylinder. Either way, a new cylinder is a good idea.

Nah, not that bad even with abs. Lots of skin left behind :-(

I'm having some weird problem with my news server that prevented me from seeing some key articles in this thread; just caught up via Google.

So Grunff, it sounds like you're saying that air is entering the system via a leak in the master cylinder, or perhaps the return spring is somehow fouled. I assume that if a leak is the problem, bleeding the clutch will only temporarily remedy the problem. And so I suppose I should replace the master.

New master cylinders seem to run around $116 (US). However, eEuroparts.com seems to sell a clutch master cylinder "rebuild kit" for $6.90. From the picture, it seems to consist primarily of an assortment of seals. Have you any experience with a rebuild kit? Would I be better off to shell out 20x more for the new cylinder?

Any/all input appreciated.

Thanks,

John

Yup.

I've rebuilt a few, yes. The standard answer is "if the bore is good, and the piston is good, the new seals is fine". The problem is, you won't know until you take the cylinder apart!

If you can have the car out of service for a while, then by all means, remove the cylinder, strip it down and check it. Most of the time they're fine. If the bore or piston are at all scored, buy a new one. If not, put new seals and a new return spring (usually in the kit) in and it'll be great.

BTW, you can do the same with brake masters. Just make sure you check really carefully. It's a real PITA having to redo the cylinder a few weeks later.

Ok, one more question:

I'm ordering some parts for this project, and the Bentley manual suggests replacing the self-locking nuts (or was it bolts?) that hold the master cylinder. These are on the interior footwell side. Do I really need to get new ones, or can they be re-used? If I wanted new ones, where would I find them?

Thanks,

John

Nuts.

I've always reused, with a bit of threadlock on them.

As for new ones, any Saab dealer, or any nuts and bolts supplier.

Likely they wore out at the same time. The seals on the master and slave cylinders should age at roughly the same rate. I rebuilt the master cylinder without removing it from the car. Had to be careful about the brake fluid dribbling about though. Took me about 2 hours. In retrospect I probably should have used a brake hone in the cylinder bore and cleaned things up a bit better, but I was in a hurry. I knew it would be clutch time soon, and was trying to stretch things out a bit.

dave

My own theory is that the system adjusts to the gradual line pressure loss (ditto brakes) and then a sudden restoration sends it into shock - final straw syndrome! - either way it's affected most things I've owned over the last 30 years at some point. Cheers

Hi,

I took the clutch master out of the car on Saturday. Not a very tough job, though I highly recommend taking the coolant hoses to the heater core off-- it's much easier to add back a little coolant than it is to re-grow skin :)

Anyway, the seals on the cylinder seem fine, although there was a fair amount of gunk built up inside. I was able to locate the problem rather easily: the piston return spring was broken into 3 pieces. And of course my rebuild kit doesn't include a spring. So the car is currently out of commission until I can get a new spring (about $9 US from a Saab dealer, special order). So this is turning out to be a relatively cheap and straightforward repair.

I'm ignoring everyone's advice about fixing the slave simultaneously, much to my peril I'm sure. What will be the symptoms of the slave failling?

Thanks,

John

I finally finished the job yesterday morning, installing the master cylinder with all new seals and the replacement piston return spring. That circlip was quite a pain to get on and off without the proper tool!

This was my first time bleeding the clutch, and I have a few recommendations for anyone doing this for the first time. I used a pressure bleeder (purchased from eEuroparts.com), which I used to pump air instead of fluid since I couldn't be bothered to clean out the tank afterward. Pointers:

1. Don't bleed the clutch outside in pouring rain in 45 F (7 C) weather, especially when wearing a T-shirt. By the time I was done, my tools were wet and slippery, I couldn't tell what was water and what was spilled brake fluid or coolant, my clothes were totally soaked, and I was shivering so badly I could barely do anything. Plus it took extra effort to keep any water from contaminating the brake fluid, as you might imagine. But when one has no garage and must get the car to go in order to drive to work, options are limited.

1. The brake fluid reservoir must always be FULL. I spent way too much time pumping air into the clutch and having it come clear through the bleeder. Why? Because the fluid level had fallen down to around the "Max" level. Although it seems like this should be plenty to keep the clutch fed with fluid, it evidently is not. Thanks to the quasimotors.com site for enlightening me. (See
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   point #2)

1. There was lots of nasty black dirt in the brake fluid when I first started bleeding it out. Although I'm sure the reverse-gravity-turkey-baster bleeding method would work well, it seems like it would end up flushing lots of dirt into the reservoir.

Despite the adverse weather conditions and missteps, I prevailed. The clutch feels like new, and I am a happy man.

As always thanks to everyone for the advice.

John