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JohnD

Gearbox to engine assembly advice, please!

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I'm assembling - trying to assemble! - my gearbox to the new engine.     Both are out of the car, so best possible situation.

 I can get the splines engaged with the friction plate, but I cannot get the gearbox input shaft nose to engage in the bronze bush in the flywheel.  it will not go the last 10mm as the nose goes into the bush.

 I have :-

1/ Tried with the engine on a hoist, with a load leveller, so I can adjust it for height and angle, with the gearbox on a Workbench, chocked to be level

2/ Tried with the engine fixed on the Workbench, and me holding the gearbox - hard work, but I can do it for long enough.

3/ Established that the friction plate is central.

4/ Checked that the bush is the right diameter for the shaft nose.

5/ Used Engineer's Blue on the nose tip, to see where it holds up.  The blue appears on the face of the bush.  It's just missing the hole, but not in a consistent direction.    A millimeter would enter it, and when holding the gearbox, I can 'wiggle' it in all directions, to no avail.   When I've done this before, it's fiddly and then ultimately it goes in.     But not this time!

Any advice/ideas, please?   I've been trying for two days!

John

 

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Do you have an old input shaft to check clutch alignment? They are the best tool for the job!

However, had to spend more time than I liked refitting gearboxes this year, and my best tip is to use a pair of long bolts with teh heads cut off, ideally one a tad longer than the other. Screwed into the two tapped holes in teh block that normally have short studs or even bolts? (memory failing me here, but teh principle is sound)

They enable you to hang the gearbox securely and in ideal alignment, you can easily fiddle the other end of the box so it all slots together. Makes fitting in the car so much easier.

 

A question though, has anything been changed with all this? same box, clutch. flywheel etc as before?? Or anything new?

 

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Thanks, zetecspit!

Hoh, no!   This is my fancy lightweight flywheel, with Tilton clutch and sintered metal friction plate!     But none of that can be preventing me getting that nose in the bush.    I can even get the normal studs engaged - its just the last 10mm, as the nose fidgits about on the bush.

It occurs to me that an old, worn bush I have is slightly chamfered at the entry.    The nose has a chamfer too.  The one I fitted is not chamfered.    If I took it all apart and gave it a chamfer, would the two slide togther?      Would that reduce the bearing surface too much?   I don't think there's much load on the bush, is there?  It's just to keep it centered.

J.

Edited by JohnD

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The gearbox input shaft is chamfered - you shouldn't need to do the bush as well.  My feeling is that the friction plate isn't quite centred right.  They are much fussier about this when the spigot bush is new and tight (worse still when you you have a ball race there instead!).  If it's been done with an actual spare input shaft then it ought to be good - if that is a smooth easy fit.  If you have one, have you tried it in there and is it an easy sliding fit?

Only other thought is whether it's being held off by the slave assembly (though presumably you have measured this several times already!) or even if the clutch pressure plate is contacting the bell housing - there is not alot of spare space in there.......

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What worked for me in the past was to put it in gear and have someone rotate the output shaft as you wiggle the gearbox onto the engine.

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Thinking out loud, did you try the bush on teh nose of teh input shaft before fitting? Likewise the clutch plate? You never know....

If you have, or can beg/borrow/steal a spare input shaft that would really help

 

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Yes, input shaft fits friction plate and bush.

No spare input shaft, but centered with clutch centering tool.

I have an output shaft 'wiggler', been using it!

And been shining a torch into the bell to see if the clutch is fouling anything - don't think so.

So I have dismantled the clutch and the flywheel, renoved th bush and given it a chamfer, but I'm off to bed now!.

Try again in morning!

Thanks for the ideas!  Wish me luck!

John

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Clutch centring tools vary in accuracy and years ago I resolved never to buy one as, after using other people’s a few times, I reckoned I could do just as well with random bits of bar and sockets, or even by eye. The tools tend not to be rigid enough to prevent the friction plate from dropping a little as you tighten the pressure plate bolts, but if you are aware of this you can watch for it and correct it.

the gold standard is a spare input shaft - all very well if you have one.  I do have one for the coarse splined 6 cylinder input shaft and used it gratefully on the GT6. I don’t have one for the W58 but I do own a socket that is a near perfect fit and does the job provide I watch out for gravities little trick.....

Good luck tomorrow!

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Meant to add that these days you can buy plastic copies of the input shafts for this very purpose. Seems like a great idea if they are good enough dimensionally.  Not tried one myself though I’d like a W58 one.

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Dunnit!

I bevelled the entry to the bush's bore, and re-assembled.     Because the Tilton clutch cover allows access to the edge of the friction plate, I was able to measure how central it was on the flywheel, and make some minute corrections, fractions of a millimeter, using my plastic input shaft, whihc I found at the back of a drawer.     It then slotted in!   YeeeeeHa!

I did it with the engine fixed and holding the gearbox in my arms.  Exhausting but maybe easier to 'wiggle'.

Thanks for the discussion!

John

Edited by JohnD

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