Found the problem!

From Zero 250611

So new bigger master cylinder in (can see in the photo how much bigger the new one is), while the engine was out we checked carefully that we were getting full travel on the slave cylinder. I pushed slowly on the pedal while Mike held the thrust bearing pushed back as far as it would go. The full 1 inch of travel was achieved with the pedal on its highest ratio (there's three holes drilled to allow us to vary the pedal ratio). We thought we'd need to get more extension against the clutch cover to spaced out the cylinder with a few washers. Engine back in, still no luck disengaging clutch. Pushed pedal again and 'POP', fluid all over the floor... No option for it but to get engine out. How depressing.

With the engine out it seemed the slave had only slightly over-extended and pushed fluid out as the slave cylinder had gone back into the slave housing. Then after a bit of searching on Locost Builders I thought I'd take another look at the clutch plate. It had witness marks around the outside of the splined bit, it seems the fixed guide tube in the slave was permanently holding the friction disc hard against the flywheel. Some measurements taken, and without the washers we just added, there was only 0.3mm clearance between guide tube and cluth plate...

So, the spacer we had made is too thick. Looking at the clutch cover plate, the pressure ring can only come out 4mm, so we thought we'd skim 4.5mm off the spacer to give a bit of clearance. Just trying to track down a local lathe person today then hopefull we'll be back in business.

From Zero 250611

This is the guide tube.

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Pink arrow shows the marks from the end of the guide tube
Green arrows show depth of plate from finger. Engine face to fingers = 60mm, fingers to plate = 19.3, so engine face to plate = 60-19.3= 40.7

From Zero 250611

Blue arrows show guide tube to mounting face. With the slave spacer in, depth = 41mm
This gives just 0.3mm clearance.

From Zero 250611

So clearance needed to allow plate to move away from flywheel, max movement would appear to be 4mm (yellow arrows).

More bad times..

Disaster after disaster. We realised that due to the Omega originally running a Dual Mass flywheel which is very thick, and we are using the saab one which is thin, we'd need a spacer behind the clutch slave to make up the distance. Using our previous measurements where we thought all would be fine, we realised that when clutch and gearbox are mated the thrust bearing is pushed back against the spring around the clutch slave (this should make sense if you're looking at it). The thrust bearing is always pre-loaded against the clutch fingers.

Measuring it extended and fully depressed came to 25mm ish, so we had a spacer bought from SBDEV, part ref CLT-HCS-30, lathed down to 24mm.

Fitting it all back together, we bled it through to get what felt like a firm pedal. However depressing the pedal the full travel of the 3/4" bore Land Rover Clutch Master didn'r release the wheels from the engine. Some head scratching and it seems we just aren't shifting enough fluid to fully extend the the slave. So we found a single port 1" dia brake reservoir for a Series 3 Land Rover on ebay and ordered that plus a reservoir. Waiting for delivery to see if we can finally get a break with this build!

Disaster!!!

So with the engine in and all wired up we started to fill it with fluids. Water went in, leaked from various places, tightened things up, water stopped leaking. Realised that you have to have almost perfect size matches i.e. you can't get away with putting a 40mm hose on a 38mm pipe - it'll leak! No matter how tight you tighten it.

Oil filled up, leaked everywhere - forgot to tighten the oil unions in a couple of places which seems pretty basic but it's easily done!! Also the oil filter leaked slightly as there's so little chassis clearance you can't get a good hold.

Put clutch fluid in, spend ages bleeding it but no pressure in the pedal. Eventually found the fluid dripping out of the gearbox bellhousing... NOOOooooo...

So it appears that the seals are gone on the slave cylinder, so engine out again. This is very depressing - the car looks a mess again and it almost looks the same as it did a year ago. These things happen I guess - the lesson here is don't trust anything, check it before fitting; a few minutes saved can prevent days of misery later.

From Zero 050611

From Zero 050611

One concern is the actual use of the Saab flywheel and Omega clutch. When we put the engine and g'box together we measured clutch face to engine block, and slave cylinder to bellhousing mounting face. These appeared to match so all was thought ok. But its possible the slave cylinder had been locked in the out position from being over-extended. Reading up more, it seems that as we're using a normal saab flywheel, not the thicker dual mass omega flywheel, we have some extra space to take up. This means we might need a spacer under the slave cylinder.