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 Clutch problems. Pedal travel too short?
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andydeans3
V4 Guru

United Kingdom
1550 Posts

Posted - 17 Jan 2020 :  12:14:50 Show Profile Reply with Quote
I've just fitted a refurbished gearbox in my car.Since the engine was out, I also fitted a relined clutch plate.(Standard clutch, not a diaphragm clutch.)
The older 4 spring clutchplate that does not have problems with things being rivetedround the wrong way. They fitted 3.2mm thick lining, overall thickness from one side to other around 8.4mm, though there was one small section, where it was near 9 mm to 9.2mm.

Also fitted a new release bearing.

Having got it all together now, I only seem to have 50mm of clutch pedal travel, way, way short of the floor of the car. At the window, where you can see the clutch arm moving on the gearbox bell housing, the arm is moving about 12mm. The back edge is only "just" disappearing into the bell housing, Hitting something very solid, bottoming out I guess, but why?

I never touched the clutch hydraulics. Just unbolted the slave and tied it to the side.

Crunching like hell trying to get it into reverse, and hard to get it into first.I haven't got the front on the car yet, so have not been out on the road.Something is not clearly not right.

I'm pretty sure the engine will have to come out again, but I'll hold back on that till I get some advice.

Maybe I should bite the bullet, and convert to a diaphragm!

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 17 Jan 2020 12:15:12

Betsy67
V4 Fanatic

United Kingdom
397 Posts

Posted - 17 Jan 2020 :  12:51:29 Show Profile Reply with Quote
Did you set the free travel correctly on the arm/pushrod ? 4mm springs to mind.
I had a similar problem on Betsy - cured by putting some shims between the flywheel and pressure plate. Bought them from Spalding Fasteners.
If you search my posts in projects there will hopefully still be some pictures available to look at ?
Could be caused by a different thickness on the release bearing-the new one being narrower?
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andydeans3
V4 Guru

United Kingdom
1550 Posts

Posted - 17 Jan 2020 :  13:06:42 Show Profile Reply with Quote
Yes the free play was set at around 3 - 4 mm.
As a quick attempt to alleviate the problem, I tightened the free play up to close to zero, but it made no difference.

It's the lack of pedal stroke I can't quite understand.
The clutch is certainly not "clearing", and is also bottoming out, after 50 mm pedal travel, so to say.

One thing I did not do (note for next time), was check the relative thickness of the old and new thrust bearing.
It was bought from a well known, very reputable, supplier.

I am aware of the trick to shim out the whole assembly from the flywheel. I am acquainted with a retired SAAB mechanic, who tells me that back in the 70s, there were official SAAB, slotted shims, that could be dropped in behind pressure plate, through the little inspection window, to alleviate dragging clutches, which were common at the time.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 17 Jan 2020 13:12:00
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V4saab1966
V4 Fanatic

United Kingdom
238 Posts

Posted - 17 Jan 2020 :  13:45:45 Show Profile Reply with Quote
Hi Andy I had a similar problem I made a spacer and moved the slave forward 5 mm helped a lot but Ive been told a easier fix with the engine out is to weld a washer on the pressure plate where the thrust bearing meets it , havent tried it but apparently it works ??
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chris steeden
V4 Fan

United Kingdom
147 Posts

Posted - 17 Jan 2020 :  16:24:24 Show Profile Reply with Quote
Is it anything to do with the screw with locknut in the RHS of the bell housing? Maybe wind it anti clockwise a turn.
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stevebod
V4 Fanatic

United Kingdom
357 Posts

Posted - 17 Jan 2020 :  16:32:34 Show Profile Reply with Quote
Hi.
For what it's worth. When I had a similar symptom, I shimmed the clutch off the flywheel and all was well. Like you say it can be done through the inspection whole with some patience and a mirror on a stick.

This shimming is new to me. I've had 96's from time to time over the last 30 years but only recently started shimming clutches.
You only have to shim the clutch off the flywheel by 0.5mm and it moves the thrust bearing quite a lot further back. Then everything makes sense. You need less or no packing behind the slave cylinder, the free-play adjuster returns to the mid point and best of all you can get full clutch travel without the clutch arm clattering against the spinning clutch.

I think there are a variety of thrust bearings out there too, which add some variation to how the clutch operates.
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OWEN
V4 Fanatic

United Kingdom
313 Posts

Posted - 17 Jan 2020 :  17:03:45 Show Profile Reply with Quote
Yes, shimming should work and it's doable from the inspection hole without removing the engine. I think the cause of this is wear on the fork/yoke which holds the release bearing. If the lower hole is oval shaped then it needs to be welded at the back to make is circular again with similar welding at the top to keep the bearing square to the clutch. Shimming will get over this but if you do remove the engine check the release bearing fork.
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andydeans3
V4 Guru

United Kingdom
1550 Posts

Posted - 17 Jan 2020 :  20:26:29 Show Profile Reply with Quote
Chris.
Tried adjusting the free play, but it made no difference.

Stevbod/Owen
This is exactly what I am going to try. Slotted washers through the inspection hatch. I have a mate who's a retired SAAB mechanic, and he says that this was an official SAAB operation back in the day. The slotted washers even, apparently, had a SAAB part number.
I did check the fork holes for ovality before fitting, and they seemed fine.

I will report back!

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 17 Jan 2020 20:42:08
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V4saab1966
V4 Fanatic

United Kingdom
238 Posts

Posted - 17 Jan 2020 :  21:26:33 Show Profile Reply with Quote
Andy I think any method is worth a try and at the end of the day its what works for you , like I said my method worked and it was a easy job to do I can make you a spacer if needed ok, just ask if needed.
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andydeans3
V4 Guru

United Kingdom
1550 Posts

Posted - 18 Jan 2020 :  16:09:56 Show Profile Reply with Quote
Problem solved.
Clutch slave cylinder piston bottoming out against the circlip at the end, before enough forward clutch movement had been achieved.
As Paul above suggested, spaced the slave cylinder forward with a circa 3 mm thick nut, job done, though I did get a bit of a nasty noise at the end of pedal travel, probably the actuating arm coming into contact with the flywheel, until a re-set the free play.
All good now.

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 18 Jan 2020 16:13:03
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melle
V4 Guru

United Kingdom
3388 Posts

Posted - 18 Jan 2020 :  20:20:44 Show Profile Reply with Quote
quote:
Originally posted by andydeans3
Clutch slave cylinder piston bottoming out against the circlip at the end, before enough forward clutch movement had been achieved.
I'm not exactly sure I understand what you're saying here. Is there something wrong with the hydraulics?

In my opinion spacing the slave forward is a bodge; the release arm will likely be hitting the clutch cover (not the flywheel) again in no time. I always make sure the release plate is about 0.5-1.0mm above the clutch cover by spacing the pressure plate assembly off the flywheel with 0.1-0.5mm shims. Sometimes the thickness of the shims needed varies per bolt (use a straight edge on the release plate to check) and most of the time 0.1-0.2mm shims do the job.

I'm happy to believe shimming the pressure plate assy can be done with the engine in situ, but I would definitely take it out because I imagine it'll be a real pain to do it through the inspection hole. Apart from that, it's impossible to check if the release plate lies nice and parallel to the flywheel. This may not be a very big deal because the springs and the release bearing will to a certain extent allow for it not being parallel, but because these clutches are tricky enough to get right I'd rather take no chances.

I used to use slotted M8 shims in the past, but my usual supplier for this kind of stuff (Brammer in NL) no longer stocks them and I haven't found them anywhere else so far. I now use regular shim washers, which are a pain in the arse to work with because you have to completely remove the bolt to install them. If anyone knows where I can get some U-shims, let me know!

www.saabv4.com
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andydeans3
V4 Guru

United Kingdom
1550 Posts

Posted - 19 Jan 2020 :  00:13:26 Show Profile Reply with Quote
Melle

Sorry, wrong word, not the flywheel, of course the release arm was fouling the clutch cover, very slightly. I suppose, I was sort of using the word "flywheel" as a generic term for the whole assembly.

It's too late now to shim the clutch assembly because I had a look at doing it through the inspection window and it would as you say, be very, very difficult. Not impossible, but very difficult. SAAB used to apparently do it "officially" in the 70s.

I'm happy with the "bodge". I really do not want to haul this engine out again!

The pedal now goes to the floor, instead of moving only circa 50 mm.
If I'm not wrong, as the clutch wears, the contact plate moves away from release bearing, and free play will increase slowly....I think....

There's nothing wrong with the hydraulics, the slave cylinder is simply sitting too far back. This means that once the rod is in place , the piston is already part way along the bore. Push the pedal, and the piston moves along the bore, and comes up against the circlip, before the clutch is fully extended,(because the piston didn't start from the back end of cylinder)
Shim it forward slightly, and the piston moves back closer to the nipple end of the cylinder. I've probably shimmed it a little too far, which is why the release arm, initially fouled the clutch cover.
I might experiment a bit more with thinner spacers.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 19 Jan 2020 10:15:40
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deggsie
V4 Fanatic

United Kingdom
403 Posts

Posted - 19 Jan 2020 :  16:16:36 Show Profile Reply with Quote
I've been following this thread with great interest ... since my engine rebuild and re-installation, I have had arguably the opposite problem, the clutch only operates with the pedal right down by the floor.
Initially it wouldn't release at all, so shimmed the slave forward a bit (2mm) and it worked fine on all forward (synchromeshed) gears, but graunched into reverse. Had the symptom of the release arm fouling the clutch cover when the engine was warm and the clutch pedal was pressed hard.
Shimmed the slave a bit more (another 2mm = 4mm in total) and adjusted the free play, now works reasonably OK but can still be noisy into reverse when hot.
The guy who rebuilt the engine for me mentioned there were "washers on the heads of the pressure plate bolts" that he didn't think should be there and so omitted on rebuild, but I suspect that they were actually spacers between the pressure plate and the flywheel (we didn't replace any of the clutch parts as it worked fine before the engine problems - probably false economy).
It's too cold in the garage for any lengthy work at the mo, but may try to reinsert some spacers when the weather improves.
Jack Ashcraft's "Transmission Survival Guide" (p. 47 - may be a copy on Melle's website ?) shows a diagram of 'trouser' shims with a hole in the bent tab to aid installation/removal), anyone familiar with these ?

___________________________
Saab - beyond the conventional !
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melle
V4 Guru

United Kingdom
3388 Posts

Posted - 19 Jan 2020 :  19:19:35 Show Profile Reply with Quote
quote:
Originally posted by andydeans3
There's nothing wrong with the hydraulics, the slave cylinder is simply sitting too far back.
But it's designed to sit all the way back?

quote:
Originally posted by andydeans3
This means that once the rod is in place , the piston is already part way along the bore. Push the pedal, and the piston moves along the bore, and comes up against the circlip, before the clutch is fully extended,(because the piston didn't start from the back end of cylinder)
If the piston in the slave doesn't fully retract the spring is probably broken?

quote:
Originally posted by deggsie
may be a copy on Melle's website ?
No, this is copyrighted material so I can't publish it on my website.

www.saabv4.com
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andydeans3
V4 Guru

United Kingdom
1550 Posts

Posted - 19 Jan 2020 :  20:31:29 Show Profile Reply with Quote
Melle
Aye, the slave cylinder is supposed to sit "all the way back", but due to the vagaries of the clutch pressure plate set up, it would seem that it's sometimes necessary to shim it forward slightly.
My mechanic friend was a SAAB mechanic from the late 60s, through to the early 2000s, and tells me it was standard practice at the time, among other bodges. (Like dropping slotted washers through the inspection window!). This was at a main SAAB dealer, not a back street bodge shop!

The spring on the clutch assembly is not broken.
When the system is at rest, and the slave piston is "relaxed", the position of the piston in the bore will be dependent on the relative position of the slave cylinder to the operating rod.
Shim the slave cylinder forward, and the piston will move back, and therefore give more "stroke" so to say.

Before I shimmed the slave cylinder forward by 2 or 3 mm, the pedal only moved about 50 mm, because the piston was coming up against the circlip at the end, ie it had run out of travel.
The clutch was not clearing, could not get the car into reverse without a lot of crunching.
Shimmed the cylinder forward 2 or 3 mm, ( I didn't measure it, but it's about 2 or 3 mm) and hey presto, pedal goes to the floor, and all gears are smooth. I may have shimmed it too far, because the rod was just fouling the clutch cover. Re-setting the free play fixed that.
I'm going to experiment again tomorrow because when everything has expanded at full temperature the fouling might come back

It's quite hard to explain this all in words. Maybe some cartoons would help

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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melle
V4 Guru

United Kingdom
3388 Posts

Posted - 19 Jan 2020 :  20:55:45 Show Profile Reply with Quote
We'll have a look at it next time you're in Bath; tea and cake at the ready. :D

www.saabv4.com
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