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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts |  Posted - 17 Apr 2021 : 15:31:01  
| OK, I've spent a few hours on the 96 over the last couple of weeks, moving slowly towards getting the car roadworthy.
I had a new clutch master cylinder which looked identical to that which was on the car when I bought it, only difference being it had a 3/8" female pipe thread rather than 7/16". I suspect it is for a Mini. Anyway I found that a Stag master to slave pipe is a 3/8 to 7/16 fitting so bought one and connected up the lot. The slave bled easily and on taking a little drive all seemed well though I thought the clutch travel seemed rather short. Getting into reverse proved a crunchy business though.
I set up the slave rod to the exact same length when I refurbed it with new seals and the rod on the master was measured and found to be the same length as the old master too.
I wonder the if the swept volume of the new master is a little smaller? Perhaps I just need to take the master off and wind out the rod a few turns to give myself a little more clutch.
Otherwise the forward gears select very nicely so I wonder if the gears linkage might instead be the issue?
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 17 Apr 2021 : 20:29:39
| I peeled back the rubber gaiter at the end of the clutch slave this evening and found the clutch fork to be barely visible. So I jammed a screwdriver into the hole where the gaiter sits and was able to push back the fork and with it the slave piston.
Having done that the clutch fork sprung to and fro fine, there's evidently something wrong with the clutch slave, which is not retracting when the pedal is released. I refurbished that slave, admittedly several years ago so expected it to operate fine....
There appears to be a wee bit of fluid leaking from the rear end of it, where it bolts to the gearbox.
Now.... I presume the default, sprung position of the slave is with it's piston withdrawn and hence the clutch not operating?
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 19 Apr 2021 : 20:16:14
| OK, well, I removed the clutch slave today and took it apart; it looked good inside but nonetheless I cleaned it out and ran a rotary wire brush through it, cleaned with carb cleaner and re-assembled with some brake fluid.
Now I did notice that the bolt hole to which the cylinder is mounted to the gearbox has a helicoil in it...I also noted the slight leak from the rear of the cylinder. Should there be a gasket there?
Even so, a wee leak like that should not affect the movement of the piston in the cylinder.
So I wonder now if the fault lies with the master cylinder. I shall replace it with the original one that worked when I bought the car. Means I shall have to purchase another pipe with 7/16" fittings at either end.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 19 Apr 2021 : 20:20:11
| I wonder too if the clutch diaphragm is simply not exerting enough force on the clutch release bearing and fork to push the piston of the slave back? Pushing the end of the clutch fork with a screwdriver seemed to take a reasonable amount of force and it sprang back well enough. Hardly like a truck clutch but commensurate with a small car.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Woody
V4 Guru
United Kingdom
2764 Posts | Posted - 20 Apr 2021 : 21:05:15
| The heli-coil is put in to the slave cylinder to lengthen service as a thread in the alloy housing would soon fail.
There shouldn't be a leak at the rear. I wonder if in the past a bolt too long has been used and caused a crack in the housing inside. This will allow air into the system.
To be safe I would change the slave cylinder. | |
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 20 Apr 2021 : 23:15:41
| OK, the new clutch kit I fitted to the car was a Sachs type, I am not certain but I think the old clutch may have been the diaphragm type...
From a little research it seems that the overall depth from flywheel to rear of clutch may be somewhat smaller with the Sachs type clutch.... So it may be that the movement of the clutch fork I was getting was actually just it's sprung return and not even operating the clutch at all, that's why it seemed so light...
With a shallower clutch the end of the clutch fork and the pin that fits into the slave will be operating when they are further into the bell housing than before.
So I will have to move the slave cylinder forward using washers and possibly extending the bolt, or weld an extension onto the pin that fits into the end of the slave.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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melle
V4 Guru
United Kingdom
3833 Posts | |
Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 21 Apr 2021 : 20:57:03
| OK, I've made a little progress this evening, the movement of the clutch fork that I was producing using a heavy screwdriver was not the clutch operating but the backlash in the system. So I wound the clutch fork progressively inwards until the backlash was around the 4mm its supposed to be, I did this with the car running, much further and the bearing could be heard squeaking a little against the clutch.
Then I tried selecting gears and was able to get them all apart from reverse. It does appear that the slave is about at its maximum extension so I have made up a steel sleeve which fits over the end of the clutch pin and will gain another 8 to 10mm of extension, hopefully enough to consistently get all gears to function.
I am also suspicious of the master cylinder, which as stated earlier has a 3/8" fitting rather than 7/16" and I believe is for a Mini. I wonder if despite looking identical it has a lower swept volume than it should and hence is unable to push the slave piston as far as it needs to. So tomorrow I shall try the original master in combination with a lengthened slave pin and see what occurs. I am certain now of a small leak at the rear of the slave, why this should be I don't know.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 21 Apr 2021 : 20:57:18
| OK, I've made a little progress this evening, the movement of the clutch fork that I was producing using a heavy screwdriver was not the clutch operating but the backlash in the system. So I wound the clutch fork progressively inwards until the backlash was around the 4mm its supposed to be, I did this with the car running, much further and the bearing could be heard squeaking a little against the clutch.
Then I tried selecting gears and was able to get them all apart from reverse. It does appear that the slave is about at its maximum extension so I have made up a steel sleeve which fits over the end of the clutch pin and will gain another 8 to 10mm of extension, hopefully enough to consistently get all gears to function.
I am also suspicious of the master cylinder, which as stated earlier has a 3/8" fitting rather than 7/16" and I believe is for a Mini. I wonder if despite looking identical it has a lower swept volume than it should and hence is unable to push the slave piston as far as it needs to. So tomorrow I shall try the original master in combination with a lengthened slave pin and see what occurs. I am certain now of a small leak at the rear of the slave, why this should be I don't know.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 21 Apr 2021 : 20:57:37
| OK, I've made a little progress this evening, the movement of the clutch fork that I was producing using a heavy screwdriver was not the clutch operating but the backlash in the system. So I wound the clutch fork progressively inwards until the backlash was around the 4mm its supposed to be, I did this with the car running, much further and the bearing could be heard squeaking a little against the clutch.
Then I tried selecting gears and was able to get them all apart from reverse. It does appear that the slave is about at its maximum extension so I have made up a steel sleeve which fits over the end of the clutch pin and will gain another 8 to 10mm of extension, hopefully enough to consistently get all gears to function.
I am also suspicious of the master cylinder, which as stated earlier has a 3/8" fitting rather than 7/16" and I believe is for a Mini. I wonder if despite looking identical it has a lower swept volume than it should and hence is unable to push the slave piston as far as it needs to. So tomorrow I shall try the original master in combination with a lengthened slave pin and see what occurs. I am certain now of a small leak at the rear of the slave, why this should be I don't know.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 21 Apr 2021 : 20:58:09
| OK, I've made a little progress this evening, the movement of the clutch fork that I was producing using a heavy screwdriver was not the clutch operating but the backlash in the system. So I wound the clutch fork progressively inwards until the backlash was around the 4mm its supposed to be, I did this with the car running, much further and the bearing could be heard squeaking a little against the clutch.
Then I tried selecting gears and was able to get them all apart from reverse. It does appear that the slave is about at its maximum extension so I have made up a steel sleeve which fits over the end of the clutch pin and will gain another 8 to 10mm of extension, hopefully enough to consistently get all gears to function.
I am also suspicious of the master cylinder, which as stated earlier has a 3/8" fitting rather than 7/16" and I believe is for a Mini. I wonder if despite looking identical it has a lower swept volume than it should and hence is unable to push the slave piston as far as it needs to. So tomorrow I shall try the original master in combination with a lengthened slave pin and see what occurs. I am certain now of a small leak at the rear of the slave, why this should be I don't know.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 22 Apr 2021 : 13:42:40
| | Looks like you are a victim of the upload gremlin. Post your message and then forget about for a while. Getting the "thank you for posting" is a luxury here! | |
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mettersl
V4 Fan
United Kingdom
126 Posts | Posted - 22 Apr 2021 : 18:18:37
| When I took apart our supplied new 1967 car 40 years ago, there were a lot of washers behind the slave...Saab dealer serviced all its life, one new clutch (and gearbox) so this must have been a standard bodge at the time. They are still on the back of the slave 40 years later, one day I hope to put it all back, you cant take these projects too quickly.
North West Es*ex,Cambs/Suffolk/Herts borders | |
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 23 Apr 2021 : 18:18:20
| Yes, I think you just have to experiment as best you can with some elderly cars, especially if you don't know anything about an individual car's history.
This afternoon I removed the master cylinder and replaced with the original that came with the car. Then I added a thick copper washer to the base of the slave cylinder, that cured the leak around that spot and together doing those two things gave me a working clutch.
The gear action is stiff but I think that may be more down to the linkage. I shall clean the old grease off it and put some new on. I shall also purchase a repair kit for the old master cylinder which is weeping very slightly around it's rubber gaiter. I'm hoping that will allow for easier selection of forward gears.
However, reverse will not select, as I bring the lever back the gears begin to baulk. If I switch off the engine I can depress the clutch, select reverse easily and then, with the clutch down, turn the engine over again and proceed to shift the clutch to and fro to manouever the car backwards...what is the problem?
Not quite enough clutch throw? Or is it a problem with that side gearbox mount?
I see that the reverse position involves sliding the linkage laterally, quite a long way, up against a stop on the steel rod. Now, on a RHD car, if the gearbox is wound a little towards the nearside inner arch, using the threaded rod of the mount, the distance that the linkage has to move in order to select reverse lessens...just a thought.
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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Jimmys old Saab
V4 Beginner
United Kingdom
98 Posts | Posted - 25 Apr 2021 : 16:23:36
| OK, well I wound both the mounts out a bit, moving the engine and gearbox towards the offside wing. Doing that got me 3rd and 4th gear, plus I am not able to just about get reverse. I shall refurb the steering linkages in the future...
Saab 96 1971
Datsun 120y coupe 1975
Saab 9000 CSE turbo 1993
VW T5 LWB 2012
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| | Topic | |
Clutch issues
