S2 Clutch Issue after full rebuild

[colinevans]

Hi all, need some help with a clutch issue please.
2 years after starting a full rebuild I have just done my first shakedown miles, 7.5 to be exact. 3 identical trips of 2.5 miles each, with the same issue occurring at exactly the same point (about 2 miles). When I get to this point I can’t select first gear. It hasn’t baulked prior to this point and selection has been smooth enough. I can get the other gears so I end up pulling away in second and driving back. I would estimate forty gear changes until the problem hits, but I can’t replicate it in the garage, cold or warm.
The box was reconditioned as part of the rebuild and its a new clutch, release bearing and slave cylinder.
I re-bled each time and after this last run I did get one bubble, but none on the previous times. I guess it could be a stubborn bit of air that took 2 miles to work down to a problem position but I’m not convinced, why is it only affecting first? I haven’t been out since the last bleed as its an OTS and I haven’t got a roof yet- its a bit chilly at night!
If any of you helpful guys has any idea what could be happening I’d be very grateful as it’s starting to get frustrating!
One more thing, the new thrust bearing is correct for an S2 but I don’t think it’s as deep as the old one, this then pushes the fork extremely close to the back of the slot in the casing. But there is clearance, and as I say the clutch is working properly when I set out so I don’t think this is the issue.
Cheers, Colin

[Gfhug]

Colin, is selecting first from stationary or changing down? If from stationary, out of interest can you select first by selecting second gear then first? An old trick that works sometimes, into second then slide straight into first. There is good value in getting help to bleed the clutch such that when the pedal is fully down a final push forward of the slave rod by hand or with a lever will expel an extra bubble of air or two.

Those are a couple of points that might help and the more knowledgable will put forward other ideas.

Geoff

[colinevans]

Hi Geoff, cheers for the tips.
It’s both actually, changing down and stationary. It’s really odd. So generally I’m approaching the junction, crawling in second and trying to find first. No joy, so at rest I’m into neutral and then trying again, no luck.
Re the bleeding there were two of us. I held the slave rod in place but to be fair I didn’t try actually levering it back. I’ll give it a go.
Thanks again, Colin.

[DWW]

I am not a great expert but after the troubles I had with my clutch after the restoration and the fact your travel is at max I tend to lean towards the release bearing especially since you mentioned that it is thinner than the original.....I hope I am wrong and that it is only a hydraulic issue .

[MarekH]

The clutch doesn't know which gear is being changed. You are looking at a mechanical issue to do with gear selection and/or engagement. Narrow down the search by working out what you can do and when, e.g. engine not running, selecting reverse first, engine warm, engine cold, double declutch, what might be rubbing against what, etc. If you can move through all of the gears when the car isn't even running or when the car isn't warmed up, then you have clues to work with.

The first clue is that this is freshly rebuilt box with no miles on it.

kind regards
Marek

[mgcjag]

Hi Colin...as Geoff mentioned above when bleading the slave cylinder on the final press down of the pedal hold it down and push the pushrod of the slave fully in untill it bottoms out...typically air will be expelled...... ....are you useing an external spring on your slave.....is the pushrod adjusted correctly with a 1/16 inch gap....Steve

[colinevans]

Thanks guys. Steve, yes an external spring on the slave. I have lengthened the pushrod to ensure it can still bottoming out in the cylinder with the shallower thrust bearing fitted and adjusted to the 1/16 free play, but I’ll double check just in case it wasn’t fully in. I’ll also try the bleed trick.
Cheers, Colin.