Saturday, June 6, 2015

Three "Special Tools": Final Drive

For the past months, I'm completely stuck in a research-read-hit an obstacle loop. On top of that, it seems that my shopping frenzy of tools is still going on and there is no sign that it will be over in the near future.

Speaking of shopping, although lot of the parts of the Beemer can be handled using everyday tools, quite a few tricky points require rather extraordinary stuff. Furthermore, some important parts can only be removed using "special tools", literally specific to the brand and model. You'd better get used to this term - you'll hear it very often.

I sort of broke down the bike into four major "systems", while I'm stuck to one or more "special tool" needs. These four systems are the engine, transmission, final drive and the front forks. Although I found possible solutions for all four, it will be very stupid to attack all at once. I should start with the relatively easy one - the final drive.

Now, these special tools are not things you can buy at a hardware store, I decided to adapt the most critical ones myself. As, unfortunately, my skills with design tools do not quite exceed MS Paint, I asked a friend of mine from Istanbul, who designs and manufactures stainless steel products, for expert support. I don't want to turn this blog into a collection of "Zen and the Art of Motorcycle Maintenance" type of philosophical essays, but I should say I find it really amazing how the motorcycling bring together so different people from different professions, profiles, even cities. Just this alone, makes it such a special and valuable hobby. 

So my friend Ünsal converted my beautiful hand made in MS Paint designs into proper CAD format, and got them laser cut and sent me. The first one you'll read about is a kind of wrench for removing the big dented bolt which keeps the final drive together. You can see the "before and after" in the picture, my fancy design and how it should look in the CAD drawing.
The result looks perfect. The internal diameter is just the way it should be, and the dents are right where they are supposed to be. Well, here comes the "but" part - I've just overlooked a small detail...
This is what the beautiful tool turned into, in just a few tries. So can you guess what this tiny little detail was? That it's been sitting there without being touchede for ages! Oil, grease, dirt mud, collected in decades makes it stiff as concrete. My petty tool did not even tickle it.
So I went shopping again and bought this hook wrench. It serves the same purpose, with a more generic shape. In my opinion, it is not as elegantly designed as my tool, but far stronger.

Well then, what did this one do? Nada! The bolt did not move even the tiniest bit, even the edge of the dents on the bolt got slightly deformed. I got confused, perhaps it is not the right way to open it up. So back to the computer, for more and more research. But the outcome only confirms it. That bolt must be removed.

So there's only one way out. I'll use everything that can help and attack the "problem" with sheer brute force. I heated the body with the hot air gun, until it can't be touched with bare hands. Then, attached the hook wrench as good as possible and literally started jumping on the damn thing. After a few very disappointing tries, in the fourth or fifth, the bolt finally gave up and started to move. 

Note for the young enthusiasts: Your most precious assets are the hot air gun and patience...

Result is good. The input shaft joint looks pretty nice and clean. The bearings are intact. I left it aside as there's nothing to replace or service here. 
The output joint looks the same. They are immersed in oil anyway, so no need even for cleaning. 
And the body. The large gear in the above photo sits onto the big bearing in the middle. The input shaft then slides into the hole at the right side. It is how the axial movement is rotated by 90 degrees and directed to the rear wheel.

The photo makes it look very dirty, but it's just the remains of the paper gasket. I'll clean the surface before putting a brand new one.
This is the inner side of the body. The big bolt and the hole is where the brake pads sit. The dirt is just the remains of brake pads over time. Nothing important.
Of course, this doesn't mean that I won't touch it at all. So back to the bucket. No matter how "clean" it looks, remains of oil and dirt is very significant. The water was crystal clear the day before, when I immersed the final drive.

Next step is to buy brand new bolts and put together now cleaned final drive with brand new gaskets and oil seals. This will leave me with just three "systems" to go.