How do you ream a bushing?

[Ozmadman]

Hi Clanger, you have 2 critical dimensions here - the bore of the bush and its outer diameter. The bush inner diameter will close up to an extent dependant on the the interference fit, as it is pressed in. I find the best way of fitting bushes is to get the inner diameter right - you have the reamer to achieve this, although I would bore it in a lathe, as reamers can 'smear' the metal. It is easier to get the bore right before inserting the bush as reaming it in situ can be tricky. The outer diameter is then turned to be a push fit in its housing, and it is secured in place with retaining compound ( e.g. Loctite or 3M) - the bore will then not close in on insertion. Hope this helps, Andy

Yes, just to add, mine was an easy tap fit into the casing and hadn't "closed up" at all on fitting but I did use some Loctite 603 bearing fit on it just to be sure as they do have a habit of coming loose

[Steve S]

This thread is very timely as after a 6 month search for a revised sleeve gear and sliding gear with dogs, I'm about to reassemble my 1960 G5 box.

Ozmadman has been extremely helpful in advising throughout this period and the last challenge is the tight layshaft bush issue that Clanger has raised.

I bought mine from Andrew Engineering as well after wasting my money on the Club one and have eased off the inner diameter with wet and dry (wrapped around a 15mm copper pipe) so that it runs (not spins) on the layshaft end.

However the fit into the case is very tight and I imagine it will contract the inner diameter to an extent that it will need easing again, which will be very difficult in situ using the same method.

I am therefore considering rubbing down the outside of the bush with wet and dry so that it is a tight push fit and fixing it with Loctite. I am hoping that any slight eccentricity or misalignment will be insignificant!

Steve S.

[clanger9]

Hi Steve,

Have you removed the end plug from the casing? Without the plug in place, it should be possible to ream or hone it.

I was planning to ream the bush in-situ, because I expect it'll close up slightly when pressed into the gearbox casing.
It seems AMC expected this bush to run with a decent clearance: the manual says the bush should be reamed to 0.6255-0.6260". The layshaft measures up at 0.6235", so by my reckoning that's a running clearance of at least 2 thou.

My new bush from Andrew Engineering is 0.6200", so it needs to be enlarged by 5-6 thou.

[Steve S]

That's a good suggestion Clanger although I was hoping to avoid removing the plug as at present it is oil tight. I plan to borrow my son's vernier gauge later today to measure it up and then decide how to proceed, Steve S.

[clanger9]

Ah, if the plug is still in then it will make honing the bush more difficult. I had to remove the plug on mine to tap the old bush out.
The plug drifted out easily enough. I'm assuming it'll go back in oil-tight (probably with a bit of Loctite to make sure...)

[Ozmadman]

Interesting that two members have had to ream their bushes purchased from Andrews! I purchased two spares when I discovered that at some point Andrews were closing but they are just spares so maybe that is what I will have to do if or when I need to use them. Yes, removing that plug makes things easier and when I replaced mine I just sealed the circumference with a bit of JB Weld. Bear in mind, the manual lists two different part numbers for those two plugs so presumably they are not interchangeable.

[Steve S]

Well I have the layshaft bush in nicely now and the shaft turns freely and so the bush didn't close up much at all.

Now I have dropped the main output bearing in after freezing it and heating the case but it doesn't allow the sleeve gear to bear up against the ring part 041391 such that this ring doesn't protrude from the oil seal as it should.

Have I failed to seat the output bearing fully into the case? I drifted it home with a block of wood and it appears flush with the casing. I am going to remove it tomorrow to have a look but would be grateful if others could advise?

Steve S.

[clanger9]

The bearing recess in the gearbox casing is the same depth as the bearing, so if it's flush then it should be fully home.
Have you got the seal the right way round? There's nothing I can see that would stop the spacer properly engaging with the bearing.

Here's what the sleeve gear, bearing, spacer and seal look like when assembled on the bench (old part, but you get the idea):

IMG_1100.jpg

Here's what they look like when spread out:

IMG_1101.jpg

[Ozmadman]

I presume you have fitted the correct bearing? If you try to avoid the expense of the proper one and use a pattern example you will find that the i.d is fractionally out and the output gear won't go through the bearing properly. If you have the correct beating then TBH there is nothing that can go wrong. When I have done mine the bearing literally dropped in and no tapping needed. Clangers picture is spot on ( just ignore the position of that bronze bush!) Is the bearing surface on the gear seating properly in the bearing rollers? And have you got the correct sleeve for the seal? Or is the seal pushed fully home?

[Steve S]

Thanks to you both for the rapid advice.

Looking at it again this morning I am sure I have the bearing fully pressed home but perhaps I have not pushed the oil seal fully into the casing from outside.

It has been so long since I disassembled the box that I have perhaps forgotten its position - I presumed it would fit flush to the case.

I attach some photos and would appreciate your opinions, Steve S.