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3 synchro GB strip down


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Hi Folks,

I am working my way through the process of stripping a 3 synchro GB.

I have found problems at each step of the way.

However I think I am down to my last problem (and this is only the strip down)

I was under the impression that when the main gear cluster was removed then the gears on the bottom shaft (1st Gear) should simply (Huh) lift out.   Mine are loose in so far that they can move slightly but as for lifting out it's a no no.

Any tips please.

 

Roger 

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Hi Roger

                Have you taken out the thrust washers, a fiddly job but should solve your problem.

                Cheers Richard

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Hi Richard,

 the rear one came out quite easily followed by the gear cluster.

The rear mainshaft bearing was a devil to pull off but it came off eventually.

It should be interesting putting it all back.

I will do a 'dry' run to make sure I can do it then I'll do it again measuring and fitting the correct gaps etc.  I will not buy the two big bearings as they can fitted at any time afterwards - and they are expensive for a whim.

 

Roger

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Roger,

Whenever I look at exploded parts diagrams for the gearbox I think how little there is actually in there. I took one apart about 30 years ago and now all the pieces are scattered around in various parts of the garage and attic…

Have you been really careful to lay out all the parts in the order they came off or did you just drop them all into a cleaning bath?
I would guess that the best way would be to take a piece off, thread it onto the end of a ¼” rod, then take the next bit off, do the same etc.


I think it’s far better to follow the antics of someone who has never done it before, rather than hear how an expert did it. The expert never gets stuck, so the watcher never knows what the real problems are.

I will follow with interest.

Charlie.

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Hi Charlie,

I have kept the main gear cluster on its shaft but other pieces are on a big tray in no order.

Most things only go in one place and hopefully the WSM exploded diagram and the Moss pars diagram will assist where other bits go.

As I mentioned above the 'dry' will be to see where parts go rather than have a working GB.

 

Roger

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Hi Roger,

When I removed gears, rings ect I used a large tie-wrap to stick them in the correct order, and took pictures off course.

Waldi

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Have you made a dummy layshaft 

You may well find (or have already found) that the layshaft is worn, & possibly the inside of the laygear. this is usually the cause of a noisy gearbox in all but top gear.

Bob.

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Hi Bob,

no, not yet.

I have not really bothered with keeping the parts in order. I'll find where they go by  using the 'jigsaw' method

The small reverse gear cluster have seen some serious gear changing - the edges of the teeth on one side are quite badly worn as it the gear it links with.

However there is still plenty of teeth remaining so would probably do a job.

Should be fun assembling it after it is completely clean and I have recovered from an op next week.

 

Roger

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Hi Roger

                You can cut down an old layshaft to use as a dummy or just use grease to stick the needle rollers in place. The layshaft is usually the first place to see wear on the TR box.

                Cheers Richard

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Roger

When you get new needle bearings get the caged type it will save no end of grief, if you need a dummy lay shaft you can get away with a bit of plastic pipe and use a long (12"+) screwdriver to manipulate the bits into place while you insert the layshaft

When I did mine I used Overdrive Repair Services in Sheffield for the bits and advice, which was offered very willingly 

George

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Hi George,

This GB has loose needle rollers. I read  somewhere the other day that there are three varieties of roller assembly -

Loose, shell type and in a cage.  The early boxes used the first two.  They commented that the latter cage type gave most wear issues.

I'll put the original loose needles back simply to see what happens.  If at some time I decide to build it properly then I can get all new user parts.

 

Roger

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If the needles, layshaft, & laygear are all unmarked, then I can only assume that the box has had a relatively recent re-build, or simply has not done many miles.

how much slop is the in the ball bearings, & the 1st motion shaft spigot bearing ?

Bob.

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Hi Bob,

I do not know the history but this is what I do know.

The inside of the box had a seriously thick layer of black gunge with 'Matmos' styled silver streaks. The clutch fork taper pin was in two halves.

It hadn't been used for at least 10 years - but this does not add to wear etc.

The little reverse gear had bad wear on one edge where it clattered into its associated gear. Its associated gear had serious wear due to being clattered.

The first speed hub has got some bad marks on its rear face but not wear as such.

The lay shaft looks good and all the needles were in one piece.

The front and rear main shaft bearings feel knackered

 

Roger

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