Aids to help the reassemble of 3 speed clutch and gearbox.

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garagiste
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Joined: Wed Jun 15, 2011 8:22 pm

Aids to help the reassemble of 3 speed clutch and gearbox.

Post by garagiste »

The two pins shown in the photo made life a lot easier when replacing the clutch and gearbox with the engine in the car.

They are made from 5/16th BSF bolts, the heads being turned off to form a blunt cone.

With the clutch the pins are screwed into the flywheel, the engine side of the clutch is hung on the pins. It is then possible to place the clutch plate and a dummy to align the splines without having to support the weight of the whole assembly. Then the bolts may be put in place and tightened, the two pins being replaced by retaining bolts.

Another tip is to have secured the clutch springs in the alloy carrier with a little silicone glue, This saves the frustration of a spring dropping out during assembly.

When replacing the bellhousing/gearbox the pins are screwed onto two of the threaded holes on the back of the crankcase. Again it allows the weight to be taken whilst the unit is being bolted up.

I hope this tip will help someone faced with task which, without the pins is very heavy work.

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PeterWHills
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Re: Aids to help the reassemble of 3 speed clutch and gearbo

Post by PeterWHills »

Actually fitting the gearbox is a one man dream job if you have a spare spigot shaft to ensure the clutch plate is in place if that is replaced. I have found that the standard mandrel is not sufficiently precision to align the clutch plate perfectly.

First check that the spigot shaft is a perfect fit to the bearing in the flywheel. I have found that past bodgers (including me) have had great difficulty removing and then refitting the gearbox with the consequent dammed to the end of the spigot shaft. Fitting should be simple but if not then the spigot shaft has been plastically deformed and a hence more than interference fit into the spigot bearing, it is so tight that some break the Bell Housing using tyre levers.

Spigot bearings are as cheap as chips so replace it with a sealed type, use the old one to ensure the spigot shaft fits it easily.
Ian Grace
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Re: Aids to help the reassemble of 3 speed clutch and gearbo

Post by Ian Grace »

Many years ago I bought a clutch centre plate aligning tool from Mike Dowley that is designed to do the job. I have used it many times over the years. I'm sure he still stocks them.
PeterWHills
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Re: Aids to help the reassemble of 3 speed clutch and gearbox.

Post by PeterWHills »

Last time I refitted the gearbox I cleaned the spigot shaft so that it easily slid into its mating bearing. Yesterday I removed my gearbox and it came out like a dream, just pressed the clutch pedal and out it popped. The best approach is to obtain a redundant spigot shaft for precise alignment. Another reason why the Spigot end may be distorted if it is hammered to remove its associate bearing.
Ian Grace
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Re: Aids to help the reassemble of 3 speed clutch and gearbox.

Post by Ian Grace »

As mentioned above, I have in my tool box a clutch driven plate alignment tool that I bought from Mike Dowley over forty years ago. It is a copy of the clutch spigot shaft, but without the splines. When inserted into the spigot bearing through the driven plate, it make sure that both are concentric. Very easy to knock one up on a lathe. It has paid for itself many times over.

I suspect that Sports & Vintage still have the tool listed.

I think the trick to removing the gearbox is to remove the top bolt last, thereby helping to support the box so as to ensure that it isn't allowed to sag and seize the spigot in the bearing. That and keeping the splines in good, unworn condition so that they don't snag the driven plate when pulling the gearbox backwards. This can happen if the shaft splines are badly worn.

Oh, and you have to remove the prop shaft first! :-)
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