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“J” clutch - type by date?


gbclive

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I’ve been contemplating buying a “project” J3 for spares for my J2.

My J2 is number is 23759 dated between 1948 and 1949.

The J3 number is 29506 dated between 1958 and 1959.

 

My J2 has a clutch of the unlined variety.

Does anyone have any idea what type of clutch the newer J3 is likely to have?

Was there a year when the type of clutch changed?

Presumably the original was unlined and was updated to the lined version?

 

Also, if necessary, could my entire unlined clutch be swapped out for a lined version?

 

As always - thank you.

Clive.

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My J2 is nominally Oct 1946, but has a lined clutch.  The date being based on the engine number on the crankcase plate does not though mean that the current gearbox was attached when the case left the factory.   Certainly several of the other bigger bits are not originals- they are numbered  '3' or '4' !   

The newer engine is likely to have originally had a lined clutch because, as you surmise, unlined clutches were the original design; but again your 'project'  engine may not have the original box.  The unlined clutches were available from the factory until 1982, according to my factory annotated spares list.

Nominally the J3 and 4 have a different (larger diameter) clutch shaft than the J2 but this is only on the section that the shaft coupling clamps to.  The internal diameters and bearing seats are the same.  Other than that I don't know of any reason why the lined gearbox would not fit the unlined engine.  There is only one crankshaft type, only one gear casing type and only one type for each of the bearings though all of the clutches and shafts are different.   You would need to remove the ahead clutch and change that so you will need new bolts ( the ends are usually well peened over once the nuts are on ) and lead key stops (and to pray that they were fitted last time the clutch was off).  They are easily made but if they are not there when removing the clutch life can be difficult.  DAMHIKT.

If you do remove the ahead clutch it is well worth checking the condition of the ahead thrust bearing (the big bugger in front of the clutch in the crankcase) as this is the only way to get at it.  The gearbox to crankcase gasket is also trapped behind the oil seal IIRC.

N

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Thanks for the usual comprehensive explanation BEngo, that’s given me plenty to think about ;)

How about the two types of governor and two types of water pump - do you think they would also be interchangeable?

Cheers.

 

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Yes.

You should check the alignment of the governor of you change it. This is the same procedure as aligning an engine to its shaft. The adjustment is by screws in the pump stool. Not many bother and few disasters seem to occur though.

The fuel pump is a  diffrent matter. That MUST be aligned.

N

PS The water pump inlet pipework may need to be modified.

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OK - thanks again BEngo.

Is such aligning skill or skill + tools critical?

And are any tools required available?

I just need to persuade my wife that our garage is better suited to storing a Kelvin, than as a home for her car :rolleyes:

That and agreeing a mutually agreeable price of course ......and relocating it from Daventry to Surrey :(

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It's easiest with a DTI or a dial gauge but can be done with feeler gauges.  Like all alignments it pays to think very carefully what is going on, and what else will happen when you move things.

Apart from that no special tools required- the adjusters in the pump stool are (were originally)  slotted grubscrews so a suitable screwdriver is needed.  The grubscrews will not have been moved for years of course and may even have been sprayed with salty water.  That (and the natural slack in the original hex tube drive)  is why I doubt if many bother much with governor alignment.

Suck it and see - There are very few tales of serious woe.  The worst case is wear in the gland follower and/or the governor input shaft.  Both can readily be sorted.

N

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