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JamesR

Marina gearbox stripping

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I'm trying to get the input shaft out of a marina gearbox. It's come out a bit. basically the back end won't come off so I can't push the layshaft through.

Firstly does the layshaft and laygears have to come off to remove the input shaft?

I 've undone the back plate and its about 1/2 from the box, but won't come off all the way. Is there likely to be anything stopping this? Anything else to remove or undo?

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Input shaft won't come out until the layshaft is out and the laygear cluster has dropped down out of the way.

 

I take it you have removed the output flange?  May need to remove the speedo gear from the casing too - can't remember for sure - haven't done one since about 1991.... ( :o)

 

Nick

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I think Nick's right.  The speedo gear will be in the shaft helix.  It must come out.  When the tailshaft is free you'll see a flat plate and a single screw retaining layshaft and reverse shaft.  You may want to take a few digital pics at the stage to help you remember the orientation of the reverse gear and such.

 

After the retainer plate is off you can pull out the layshaft allowing the laygear to drop into the bottom of the case, then the input shaft will be free.

 

When it's time to remove the mainshaft you'll find it quite awkward and it won't quite clear the front of the case.  Either set it in the hot sun for an hour or warm the case with a 500W halogen lamp to expand the alloy enough to clear.  Same trick makes reassembly immensely easier as well...

 

Good Luck, Steve

 

 

edit:  Oops, is the Marina box the same as the Saloon box or TR box as we call it? :B

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edit:  Oops, is the Marina box the same as the Saloon box or TR box as we call it? :B

 

Not quite - more or less identical to the original GT6 box.  No retainer plate, just a roll pin through the layshaft which sits in a groove in the tailshaft housing to stop the shaft spinning in the casing.  Low cost engineering ...  :P

 

(Mind you, having had cause to get close up and personal with a VW 020 FWD box recently, they are not exactly over-engineered either  ::) - no wonder the bloody things break!)

 

Nick

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Ahh, now that's a box I am WAY too familiar with.  I used to turn that layshaft over to get a new surface for the needle bearings.  Horrid little thing ;D

 

So every thing I wrote above is rubbish... :P

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Thanks guys, you are just tremendous.

It kinda makes living a life of bullshit worthwhile for people to be able to tell you how to take apart some old gearbox.

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Do I need to remove the rear flange. For the mkiv box (only manual I have) your supposed to stick it first and remove a pin. This is one tough bugger.

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Do I need to remove the rear flange. For the mkiv box (only manual I have) your supposed to stick it first and remove a pin. This is one tough bugger.

 

Yes, rear casing (tailshaft housing) on a non-OD box cannot come off with the flange fitted as it is bolted onto the mainshaft.

 

Nick

 

 

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You can lock the gearbox by selecting 2 gears (say 1st and third) at the same time (you can do this by levering the synchro hubs across with a screwdriver).

 

Note that you can't select 1st and 2nd at the same time or 3rd and 4th at the same time as they are on the same synchro hubs  :P.

 

Alternatively, drill a couple of holes in a piece of suitable scrap metal and bolt it to the flange.

 

Nick

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