Assembly of gearbox to engine

[mangocrazy]

I wasn't sure whether to add this post to my engine rebuild thread in Members Cars or start a fresh thread in this section. As it may assist other owners, and seeing as the question logically belongs here, here is where it is...

I'm gearing up (see what I did there?) to re-fit my overhauled gearbox to my refurbished engine and I'm on the look out for hints and tips on general practice but specifically how to reattach the thin pressed metal parts that sit between engine and gearbox. I'm aware of two pieces - an upper and a lower. As far as I can see the upper piece (larger and more complex of the two) has to be fitted (or at least offered up) prior to flywheel and clutch installation. The lower (smaller) piece looks as if it needs to be fitted during the course of the gearbox and bell housing being bolted up to the engine. There are four M6 holes in the lower piece that enable fixing to the lower part of the bell housing. The photo below should indicate the parts I'm referring to.

My question is this - is the lower piece fixed to the bell housing before, during or after the gearbox is mated to the engine? I'm also interested to know how folks approach this operation. Do you elevate the gearbox using an engine hoist and slowly manoeuvre it into position, or are other methods employed?

Thanks in advance for all suggestions and responses.

[Nigel]

Graham,

The large plate should sit and stay on the dowels while you fit the box, but it sometimes
falls. I tied it up through the dowel holes using tooth floss [!]. Strong enough but so thin it doesn't get in the way of anything.

The small lower section is fitted after you've mounted the gearbox to the engine as it bolts
to the bell housing.

Cheers
Nigel

[mangocrazy]

Hi Nigel,

Nice one! Thanks for the tips. How on earth did you figure out the tooth floss idea?

Graham

[Nigel]

Graham,

I think it was after the plate had dislodged about 5 times while trying
to balance the gearbox on a jack, me on my back, struggling a bit, and wishing
the subframe was some place else.

[mangocrazy]

Graham,

I think it was after the plate had dislodged about 5 times while trying
to balance the gearbox on a jack, me on my back, struggling a bit, and wishing
the subframe was some place else.

I can think of plenty of other thoughts that would have gone through my head in that situation... 

[WestonE]

Hi Graham

I have a trolley jack gearbox cradle. But to be honest it is a phaff to use. A Piece of thick plywood bolted to the jack in place of the jack pad with some extra bits of wood to prop the gearbox at the right angle would do as well. Possibly better. You want to roll the gearbox in with it at the right angle and height.

Height is what the jack is for. The angle is about how the GB is balanced/propped on the Jack.

If I have help (preferred option) a pair of us lift the gearbox to the engine wiggle it swear a bit wiggle some more. One holds it the other puts the bolts in.  This assumes the engine it not in the car.

Eric 

[mangocrazy]

Thanks Eric. I was thinking of using a trolley jack in something like the manner you describe, but the shape of the underside of the GB/bell housing is far from helpful, with no level surfaces to work with as a jacking point. This will of course be evident to anyone who has tried this operation...

I was hoping to find a way of getting the GB propped at the correct angle/height and then just sliding it on, using the platform of the dolly as a base, but so far I haven't come up with a workable method. I need to take some accurate measurements of relative heights of mounting points on engine and GB and then try and figure out suitable chock sizes. I don't really have the option of extra pairs of hands as the close friends I used to call upon have rather unsportingly moved out of my immediate neighbourhood. One even went as far as the South coast to escape...

Graham

[SanRemo78]

Gearbox fitting... Get a couple of spare long bolts with cleaned thread and a hacksaw. Cut the hex off and cut a slot in the exposed surface. Chamfer the raw edges. Screw the resulting studs into the block and use as guides to help take the weight of the box and align the spigot in the clutch. Fit the remaining bolts, unscrew the guides and put the correct bolts in. Bag and label the guide screws for next time.
Sit back with a cup of tea whilst contemplating how easy that was compared to every other time you've done it.

This will also help locating the steel plate between the block and the 'box.
Guy

[mangocrazy]

Gearbox fitting... Get a couple of spare long bolts with cleaned thread and a hacksaw. Cut the hex off and cut a slot in the exposed surface. Chamfer the raw edges. Screw the resulting studs into the block and use as guides to help take the weight of the box and align the spigot in the clutch. Fit the remaining bolts, unscrew the guides and put the correct bolts in. Bag and label the guide screws for next time.
Sit back with a cup of tea whilst contemplating how easy that was compared to every other time you've done it.

This will also help locating the steel plate between the block and the 'box.
Guy

Excellent stuff, Guy. That should work, and work well. Pretty sure I've got some spare long bolts of the correct (fine) thread pitch, so that certainly equates to A Plan.

Cheers!

Graham

<edit> - just a thought - do you use any instant gasket on the mating surfaces, or assemble dry?

[SanRemo78]

There are no fluids there to stop leaking out... Unless one of you main seals lets go in which case, containing it would only lead to rapid clutch contamination and failure. Assemble dry!
Guy

[mangocrazy]

Thanks Guy. Assemble dry it is. Easier that way, anyway.