Gearbox overhaul

[bmcecosse]

The main 'fun' is still to come - getting all the little interlock slugs and balls back in the right holes.......

[biomed32uk]

I presume that the interlocks make sure only one selector rod can be out of neutral at one time, any more than that would be kind of bad.

Apart from the blindingly obvious test of making sure that all the gears can be selected cleanly are there any other tests to be made on the bench, that's the place to find a problem.

[bmcecosse]

I guess not - I have a box lying in bits myself (waiting for the weather to improve) and then I will be assembling it - but of course I have completely forgotten now what goes where!

[biomed32uk]

No problem, I'll do a step by step rebuild guide...

[bmcecosse]

If you can - it would make a v useful 'sticky'.

[biomed32uk]

Thats a good idea, its happening. I have a camera with me and I will do a picture and word blow by blow account of re assembly. My contribution for others.

[don58van]

I'll do a step by step rebuild guide...

It will be a lot of extra work for you to do the guide, but I am another one who would greatly appreciate the opportunity of studying it.

Thanks for your helpfulness.

Don

[biomed32uk]

It's probably going to end up as a pdf, as there are lots of pictures, hopefully it could be stored here for download somewhere. I rebuilt the 3rd motion shaft tonight so I have made a start. I actually quite enjoy writing manuals, and do it for work occasionally.

[M25VAN]

Well I have learned from your rebuild why my gearbox that I rebuilt years ago won't go into 2nd.
There is a definite skill to manual writing and your work would be appreciated by many. If I try writing up anything I might as well try tying knots with sticky tape, it just ends up a mess.

[biomed32uk]

Well I have been busy this afernoon, reassembled the core of the box and taken lots of photos. It all seems to work as well, well pleased with that. Manual is being crafted.

I have had to pull the tail shaft bush out, the play is excessive on the prop yoke and bush, its probably the horrible vibration I can hear under my seat, so hopefully a new replacement will be good, and have enough bronze in to allow fitting to the prop diameter.

Gearbox so far.[frame][/frame]

[bmcecosse]

Looking good ! The bronze bush will need reaming to size....... I'll be interested in your 'Manual' - since I stripped out a box many months ago to renew the front bearing, and have long since forgotten which interlock ball/slug goes where......

[les]

I renewed the bronze bush in the last gearbox rebuild, and found the reamer broke through to the steel back when the right size was reached! I had a replacement sent, which although ok, could have been better.

[biomed32uk]

The often inferior quality of some parts then, I think I read your post on another thread about this, if I could have left it alone I would have done so but it was seriously excessive the slop, and the bush looks like a ploughed field inside. Strange that this is the end of the prop that a UJ was also bad on, flats on the bearings, not loose but I feel the two working together on making themselves worse.

Not sure whether I will just press a new one in and pop down the engineering shop and get them to ream it, or I buy an adjustable reamer and do it myself in the vertical mill, should be possible once I centre it up, low speed, plenty of coolant and fraction at a time.

The box is a joy to rebuild, totally enjoyed that job and it feels a million times better now.

[biomed32uk]

The often inferior quality of some parts then, I think I read your post on another thread about this, if I could have left it alone I would have done so but it was seriously excessive the slop, and the bush looks like a ploughed field inside. Strange that this is the end of the prop that a UJ was also bad on, flats on the bearings, not loose but I feel the two working together on making themselves worse.

Not sure whether I will just press a new one in and pop down the engineering shop and get them to ream it, or I buy an adjustable reamer and do it myself in the vertical mill, should be possible once I centre it up, low speed, plenty of coolant and fraction at a time.

The box is a joy to rebuild, totally enjoyed that job and it feels a million times better now.

[les]

If you take your time and have a vertical mill, you should be ok. with a lot of wear you have no choice but to replace. It's quite a tall assembly, so will need a decent clearance under the miller. Good luck. Although for a one off job and the price of a reamer I dare say if you know a decent engineering company that might be the way to go.

[bmcecosse]

You'll be buying up old boxes and reconditioning them next!

[les]

He wouldn't be the only one! I've got two sorted and stored for any future mishap. I did think of carrying on but getting decent parts etc, plus what folk would be prepared to pay for one, brought me back down to earth!

[katy]

Check the OD of the new bushing and the ID of the housing before you press the new bushing in.
Seems to me I read on here somewhere that some of the new bushings are oversize on the OD and will crack the housing if pressed in w/out checking/adjusting the OD before pressing in.

[bmcecosse]

Maybe an idea to make a suitable bush in brass - or something like Nylatron/UHMW-PE/PEEK - for those lucky enough to have access to a lathe..

[biomed32uk]

The bush that I drew out was a split bush, steel backed, so not sure what the new ones are like.

From what I can see from the pic on ESM the bush they sell looks solid bronze.

Where should the oil groove sit, looking up the end mine was at the top, is this right as I wouldnt have thought much oil would have got down it at the top.

Has anyone else tried the Nylatron bush.

I did wonder about getting a piece of bronze tubing and turning one up, I can run the slit down as I have some slitting saws for the mill and put the oil groove down.