No clutch

[lil_red_roadster]

Re: No clutch

Looks like Alan called it right several posts upstream.
That looks very much like a Marina slave bolted to an MGB gearbox...

[mark westbrookwhite]

Re: No clutch

I am wondering if this is an MGB gearbox and someone has bodged the Marina slave cylinder to fit on to it! looking in the Marina Haynes manual this cylinder looks right for the 1800 TC.

[stevejgreen]

Re: No clutch

I am wondering if this is an MGB gearbox and someone has bodged the Marina slave cylinder to fit on to it! looking in the Marina Haynes manual this cylinder looks right for the 1800 TC.

Could be. It certainly looks like an MGB gearbox casting.

So where to now? I think you would be best off fitting an MGB clutch slave, about £20 from that auction site.

Assuming you have a Marina Pedal Box fitted, I would like to check the relative bore and travel both the Marina and MGB Master and Slave Cylinders for comparison. Hopefully the Marina master will shift enough fluid to move the MGB slave cyliner far enough to operate the clutch arm.

It could be that you have an internal problem with the MGB clutch, but best to eliminate everything possible on the outside before going to the trouble of seperating gearbox and engine.

[mark westbrookwhite]

Re: No clutch

Thanks Steve sounds like a plan as really don't want to take out the engine again (twice this year already)

[b_caswell]

Re: No clutch

Was it working before the bracket broke? If so it should work now, try turning the slave round so the bleed nipple is at the very top or even better take it out of its bracket and tip the operating end down and the bleed it again.
Is it possible that some of the throw is being lost, the release arm looks longer when compared with the MGB one in Steves pic.(maybe just the angle and no grommet)

[dogoncrazy]

Re: No clutch

I'm sure this problem has cropped up before but can't find it on the forum. The marina master cylinder has I think aa different bore size to the MGB but again I think it has same bolt centres. My opinion is that using the Marina set up on a MGB box won't work properly.You need to change the slave for an MGB one and likewise the Master cylinder.

[lil_red_roadster]

Re: No clutch

MGB clutch master fits the Marina pedal box bolt centres.
However the base is a bit smaller so you may need to make a thin spacer out of ally to get it to sit neatly and prevent daylight & water finding its way in (which is what I've done).

[stevejgreen]

Re: No clutch

That's interesting Jez.
Do you have a record of the relative bores and strokes?

I presume tha club's database does not hold records of cars built with MGB transmissions. That would give Mark an extra guide.
Like Dogoncrazy I think it's been covered before, but where?

Added: Courtesy of Fastmarina

I have some info that might help.

Relative bore sizes for Marina and MGB
Marina m/c = 15 .9mm
Marina slave = 22.2mm

MGB m/c = 19mm
MGB slave = 32mm

For a comparison of relative ratios of diameter between master and slave cylinder
MGB = 0.594:1
Marina = 0.716:1

[mark westbrookwhite]

Re: No clutch

Yes Ben It was working perfectly well then after sitting in the barn for a week (to dry out my son was caught out in a torrential storm) I could not drive it out, the bracket disintegrated as we dismantled the slave cylinder I can only assume that the problem occurred whilst it was standing. I can't see any leakage at either end but must have a problem somewhere perhaps a total stripdown and new seals to start of with.

[cameronfurnival]

Re: No clutch

I would just check its moving first. If it pushes the clutch arm then the clutch is at fault. If it doesnt move it then it might be leaking seals, collapsed pipe internally or master cyl probs similar.
Release bearing could have become dislodged and is jamming it all up or the clutch centre may have sheared (its happened to me before). I would just say get another pair of eyes to have alook before you go to the trouble of dismantling too much though.

[mark westbrookwhite]

Re: No clutch

All working again I bled the existing cylinder with the bleed nipple right at the top this did the trick although when I have saved some pennies up I think I will convert the system over to an MG set up.
Thank you all for your suggestions!!!!!!