Author Topic: Mk 4 Gearbox refurb  (Read 2806 times)

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Offline dragonmk5

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Mk 4 Gearbox refurb
« on: 13 Feb 2012 at 09:34 »
Good morning one and all.
Ideally I would like to remove the coupling and spinner from the gearbox main shaft.  I have 2 assemblies - the orig one which is quite worn, and a spare.   Looks like it might be a bit of a swine as there isn't enough room to get my puller to work, and as it's on a taper and key I don't think belting it is an option!!
One way or another I can get one off by a bit of jiggery pokery, but the best one I need to remove  without damaging it
Is there a special tool or specific method to achieve this?
Any and all options considered!

Thanks

George

Offline eddie

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Re: Mk 4 Gearbox refurb
« Reply #1 on: 13 Feb 2012 at 12:23 »
George,
             The front coupling doesn't have much of a lip to hook a puller behind, so the easiest way of dealing with it is to remove the '8' plate complete with the input shaft. Inside the box, the input shaft has the dogs relieved on one side to clear the layshaft gear, so you will have to turn it until the relief is at the bottom (easiest seen with the side cover removed) before the '8' plate will come completely clear. With the input shaft gear held in the vice, undo the coupling nut a couple of turns, then grip the coupling in the vice and release it. Keep working your way around the 6 splines (it takes a bit of patience!) until the coupling gives up and frees from the taper. The couplings can be very stubborn, but I haven't found one that doesn't give up eventually!
       Even if you do manage to get a puller onto it, be reluctant to apply the hammer to shock it off - this usually results in damage to the oil retaining lip on the '8' plate (it's behind the thrower, so you cant see the damage you are doing!).

       Regards,
                     Eddie.

Offline dragonmk5

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Re: Mk 4 Gearbox refurb
« Reply #2 on: 13 Feb 2012 at 13:24 »
Hi Eddie
Have removed both couplings by grinding my puller to suit. It's now a bit thin so probably won't be strong enough for much else!  Naturally, I did this before reading your advice / method, but I had removed the 8 plate prior to attempting surgery.
Fortunately the oil retaining lips on both plates are still intact.  Have asked spares dept if gaskets are available, but have made one anyway but from 0.015 material as opposed to the correct 0.010 joint.  Will buy the proper joint if available, but I don't think 5 thou will be crucial in the scheme of things. Sods law of course, is that the layshaft bearing in the 8 plate I want to use is not as good quality as the one in the spare, but I intend to leave it as it is because I hope to rebuild the spare box to a decent standard - parts availability permitting.
As always, thanks for the help Eddie.
George