Friday, May 1, 2015

Transfer Housing Idler Bearing Extraction

<This post is part of the 'Winter Project 2014/15 - (Gearbox Refurb)' project>

In the previous post I managed to come up with a quite frankly genius (by genius, I mean free) method of extracting the idler bearing from the gearbox. Unfortunately the corresponding idler bearing in the transfer housing seemed stubbornly immune to my thrifty tinkerings, leaving me in perilous danger of having to buy a special tool for the job! Just when all hope seemed lost, I had a brainwave.

The idler bearing stubbornly remains in place,
but not for long...
Unlike the idler bearing in the gearbox, the problem with the transfer housing idler bearing is that there's just no way to get a good grip on it. Having searched around the workshop for something that might work, I found nothing of use. It's worth pointing out that I've already had several previous failed attempts at this, one of which involved removing the rollers and cage.

Chatting with a few people online about the problem, a fellow Mini fan called Tom sparked an idea in my head. If I could somehow get a nut wedged inside the bearing, it might just give me something to pull on. The problem is though, how do I get the nut inside the bearing?

I thought about maybe finding a nut that was just slightly larger than the hole in the bearing and then tap the nut through the hole with a hammer. The problem is though, even if I were able to somehow whack the nut inside the bearing, it would probably just pull back out again when I applied any tension to it.

Then I thought, rather than trying to bash a nut inside the bearing, it might be easier to use a washer with a nut behind it instead. Then the nut could pull on the washer which would pull on the bearing and hey-presto. At this point, anything was worth a try!

Measuring the inside diameter across the hole in the idler bearing, it was a little over 26mm, so I thought that if I could somehow get a 27mm washer inside the bearing, it would might just do the job. But how exactly do you get a 27mm washer through a 26mm hole?



When you think about it the answer is remarkably simple, just file off half a millimetre from the top and half a millimetre from the bottom like so...



The distance across the filed edges is now about 26mm, so when angled correctly it should just fit through the hole in the bearing. Once inside, because the washer is bigger than the hole in the bearing, when it's pulled up flat against the inside face, it shouldn't be possible to pull it back out. As long as nothing bends or snaps, in theory this should work. It had to work as quite frankly I was out of ideas and was only one failure away from having to buy the 'proper' tool and do it the 'proper' way which isn't the 'have a go hooligan way'. It's the boring way.


Time to put the theory to the test. In order to give myself as much room as possible to manoeuvre the washers through the hole on the bearing, I used a half height nut instead of the one that came with the cone compression tool. (Lucky I live fairly close to a nut and bolt shop to find such things.)



Using a broken transfer housing I had kicking about the place for practice, the first thing to go in is the half height nut.



Followed by as many filed washers as possible. I managed to fit three in.



Now the shaft from the cone compressor can go through the washers and be bolted into the half nut. A quick pull confirms that the washers are indeed locked in place.



Now the crappy bit of pipe with old baulk rings taped to it which I made in the previous post goes on next. Of course, I only use the highest quality tools available! Sadly this was the highest quality tool I had available! It does the job though so hey-ho. The baulk rings have a larger diameter than the bearing, so allow space for the bearing to move into as it's extracted from the housing.



Next to go on is the outside of the cone compression tool.



Lastly the top washers and nut and it's ready to turn.



Slowly and hopefully I started to turn. The first few turns required quite a hefty effort, but it became easier after that and I was beginning to realise that it was working as I could feel the bearing being lifted. A few more turns later and... sweet victory!!!!!!!



Here is the accompanying video for this post showing the moment of success...




Conclusions
After three weeks of trying, I am finally at the point where both the idler bearings are free from their housings and ready to be replaced. I could easily have bought the correct tool for the job and to be honest I probably should have, but I wanted to set myself the challenge of doing it without. If you've read my blog in the past, you may have picked up that I have an aversion to buying tools that are very specific to one job, favouring a home brew method instead.

This approach, although frustrating and slow tends to lead me up some interesting paths and yields some of the best learning opportunities as the problem is slowly solved. Also there is that 'I have beaten the system' feeling that is well worth the extra time, effort and frustration that it takes to work these problems out.

Now once the actual transfer housing I am planning to use comes back from the soda-blasters, I finally have a workable method to get the bearing out.



<This Post> - 'Transfer Housing Idler Bearing Extraction'
<Previous Post> - 'Gearbox Idler Bearing Extraction'

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