saab 900 clutch weird behaviour

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Sun 25 Jun 2006 22:32
saab 900 clutch weird behaviour - horse
My 1985 saab 900 has recently started acting unusually.

The clutch appears to be not working when its cold. If you start in gear with the clutch down, it wants to inch forward when its in 1st (though doesnt seem to do it in reverse), so the gear is already engaged. If you start it in neutral, the gears dont want to engage. After a few minutes of warming up though, its fine, and the gears change as smoothly as they ever did. Whenever I've had a clutch go before, its just gone... Does it ever happen like this, or could it be something else thats causing the problem?
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Mon 26 Jun 2006 00:01
saab 900 clutch weird behaviour - 659FBE
This is an oddity of the co-axial hydraulic slave cylinder fitted to these cars. When a little wear occurs in the seal, air is drawn in when the power unit cools, leading to clutch drag with a cold engine. Increased pedal free play is the give away here. When the engine heats up, the air is expelled and normal operation is restored.

Before delving too deeply, change the clutch fluid and pressure bleed the system. These cylinders don't always bleed easily if you pump the pedal. Do not exceed 1 Bar reservoir pressure. This "fix" is surprisingly long lasting - I have a 1982 SAAB on its original seals and find the clutch needs bleeding about every 2 years.

Modifications were made to these cylinders, including a version with 2 'O' ring seals in staggered grooves, but they seem to be little better. The very hot location of this cylinder probably doesn't help. I hope bleeding cures the problem as seal kits are difficult to obtain now and clutch drag is hard on the transmission.

659.
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Mon 26 Jun 2006 00:38
saab 900 clutch weird behaviour - horse
Thanks for clearing up the mystery!
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Sat 7 Jun 2014 20:26
saab 900 clutch weird behaviour - Saab Addict

Good Afternoon,

I have a problem which may or may not have to do with this discussion item. My Saab 900i of 1986 has been standing still for 12 years now and I am in the process of reactivating it. Surprise, the clutch doesn't work. In my Saab this means that the gears DO NOT ENGAGE AT ALL. I have always thought that when the clutch fails, that would mean that the gearbox is permanently engaged and the clutch will not separate. The contrary seems to be true here. I also see sort of a gap between the discs in the little watchhole on top of the clutch bell. Pressing the clutch pedal does nothing, nothing at all. The fluid reservoir is full. Would bleeding the system help? I have never before had any problem with the clutch, I mean back then when the car was regularly used.

Thank you.

John M.Voss

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Mon 26 Jun 2006 11:11
saab 900 clutch weird behaviour - John S
Had a similar experience years ago on RWD Escort. Terrible clutch drag when cold, unable to select gears from neutral, bit of drive with clutch pedal down. It eased when hot - didn't go away completely though. I ended up removing the gearbox to check it out. The problem was the clutch friction plate sticking on the splines of the gearbox input shaft, so it stayed in contact with the flywheel enough to spin the gearbox and the synchro prevented the gears engaging. Seemed to be a build up of clutch dust causing the problem.

JS
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