Gearbox dismantling question

Post by **ndevans** » Sun Oct 19, 2008 8:36 pm

bmcecosse wrote:I have a note in my manual saying 1.118" is the size for the bush - but not sure where I got that from. 1 1/8" is obviously 1.125" - so measure the prop shaft first to make sure you don't ream the bush too large - although 7 thou on the diameter may well be a good running clearance!

Ta gents, I will make sure the workshop know that.

Progress update-got the remote control off without incident, no lost plungers, springs etc

cheers,
Neil

Post by **bmcecosse** » Sun Oct 19, 2008 8:39 pm

It's the next bit where things may go flying! The remote is just that - a lever system to put the gear stick within reach.

Post by **les** » Mon Oct 20, 2008 9:18 pm

If you are getting others to do the job, maybe take the prop end with you , they can then ream to suit. It will be more than 1.125, (although not much, and need no more than 2 thou clearance, otherwise you will end up with another worn bush!

Post by **ndevans** » Mon Oct 20, 2008 10:14 pm

les wrote:If you are getting others to do the job, maybe take the prop end with you , they can then ream to suit. It will be more than 1.125, (although not much, and need no more than 2 thou clearance, otherwise you will end up with another worn bush!

Thanks again, was planning on taking the prop shaft end along so thay can measure directly from it.

Post by **ndevans** » Mon Oct 20, 2008 10:33 pm

OK folks, time for the next installment!

Couple of pics for you. The first two are of the rear of the gearbox, showing the tailshaft & selector rods poking out.

The next is of the front of the extension.

I have a couple of questions for the more experienced amongst you.

1 looking at the rear of the gearbox, does it look like all is ok, ie no parts missing, nothing looking like it's fallen into the gearbox?

2 looking at the front of the extension, I'm a bit concerned at the small pool of "sludge" in the bottom. This is oil plus small fine pieces of metal. Is this normal in a gearbox?

3 the tailshaft turns very easily and smoothly by hand, but there is a small amount of lateral play. Difficult to judge how much, but I'd say less than 1/16".

4 there is a shim hanging on the tailshaft. Not sure where it normally hides, it appeared as I pulled the extension off. It's got a bit damaged as you can just make out. Any idea what size a replacement should be?

Thanks for your help,
Neil

(also on the other board)

Post by **bmcecosse** » Mon Oct 20, 2008 11:38 pm

Difficult to tell Neil - the box looks ok - study that bearing very closely to see if the cage is all complete and any sign of roughness on the ball race ? The extension - the machining shown just at the top of the pic looks a bit rough - but maybe just the angle of the pic. The shim will have been determined during the build - so if you can't re-use it I think all you can do is get another of same thickness! the oil/sludge/metal bits is normal for a box with crash first and reverse - and poor syncromesh at the best of times !

Post by **les** » Tue Oct 21, 2008 9:17 pm

Over the length of the tailshaft with no support at the end 1/16'' sounds reasonable, so if bearing is smooth I think personally you should be happy. The shim thickness is determined by the difference between the depth of the recess in the extension plus the gasket thickness minus the amount the bearing protrudes from its housing, but as suggested and assuming it was right in the first place and also the new gasket compresses as the old one, just duplicate the damaged shim. The shim, as you may now have gathered, sits on the bearing and is sandwiched between it and the recess in the extension. As the box is in situ, you will need to hold the shim in place with a little grease, as it must locate properly. Just as an afterthought you can often tell if the box has been tampered with in the past by the state of the lockwashers, not many people fold them over nicely, but beat the hell out of them!