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Gearbox tailshaft bush

Posted: Wed Jan 21, 2015 8:18 pm
by biomed32uk
My gearbox rebuild is progressng well, as is the manual I am writing.

I can't find any referernce in any manual about fitting the tailshaft bush into the housing.

It has a split in, and it has a groove in it for oil. My old one came out with the split at about 12 o clock, is there a prefered way of fitting the bush, mainly where the groove for oil should be.

Not happy assuming the old one was correct, I have asked the question in my gearbox thread but its hiding in there, so bringing it as a separate question.

Re: Gearbox tailshaft bush

Posted: Wed Jan 21, 2015 9:36 pm
by les
If there is no info available, The position of the split is not an issue but I'd put the groove at 6 o'clock. Theory being the oil would settle there and get carried around to a certain degree. Tap the bush in with a piece of hardwood (beech) or if you felt you wanted to-- turn up a stepped brass mandrill and knock the bush home. Either way will no doubt burr the end slightly, as that bush gets tighter the further in it goes!

Re: Gearbox tailshaft bush

Posted: Wed Jan 21, 2015 10:11 pm
by biomed32uk
Thanks for that, I will go with that, I am not sure how much oil ends up down that end. Theres a hole in the casting at 6 o'clock, which I presume is to let oil to and from the seal end.

I agree that the bush is tight, I turned up a mandrel to draw the old one out, along with a piece of studding and some pipe.

I may even reverse that process to draw it in, I would probably heat the casing up with a heat gun, its ally and just a slight increase in size helps.

Re: Gearbox tailshaft bush

Posted: Wed Jan 21, 2015 10:21 pm
by les
If you could draw it in, that would be favourite, and heating the casting is a plan! :D

Re: Gearbox tailshaft bush

Posted: Fri Jan 23, 2015 10:15 am
by biomed32uk
Casting heated with the hot air gun, bush in the freezer for half an hour, wipe of grease round it and I almost pushed it all the way in by hand, had to drift the last 1/4" in with a 1lb hammer behind it.

Just to prove a point let it all go cold and stabilise, and using my drawing out tool tried to pull it and its as tight as the old one now coming out.

The hot and cold method works so well. I fit bearings like this if I can, no hammering the hell out of anything, all my gearbox bearings went in / on like this.

Adjustable reamer ordered so I can now ream it to size with a running clearance.