Bruintje technical

It came with worn out headstock bearings, play on the rubber of the steering, so it was loose a bit. Rear fork play. And because it has sat for so long without care, it needs some other stuff too. New tires (I didn´t like them in the first place, and always planned to use new tires on it.), brake overhaul, as the whole system clogs up. Hey - I´ll figure it all out as I go along, and document with pictures. Needs to be a good, safe, and easy to maintain ride. I´m not gonna clean it up - yet. You know - the usual stuff, wheels alu totally oxidated with that white crap, spokes rusty, frame paint here and there chipped, ... I´ll see, I´m just concentrating on giving it a spin :)

I did the headstock bearings the quick and dirty way. Just remove what is in the way, and to work safely. Unfortunately I sorta forgot to take a couple of snapshots of the process. But this pic should give you the general idea!

The T-thingie was so ugly and rusty I did a (real quick) spraypaint job on it. Unfortunately I´m kinda lazy and I did not degrease it very well, so the paint came all weird. Oh well - better than it was!

Here after a coat of primer.

I had to make a little tool to get the pistons out. They were stuck as hell. I used the tool to block one piston, using the original pump pressed the other piston (almost) out. Then you switch the tool to the other piston holding it just in, and you press out the other piston. Now - if you are lucky - the other piston will come easely out.

A soft wooden block protects the caliper from damage. Just 2 4mm plates and a bit of M8 wire and nuts. Nothing fancy.

A word of warning. However you try to get the pistons out - with air pressure or with hydraulic oil pressure, like I did with this one ...
Wear gloves - safety goggles and make sure - if the piston comes flying out, that nothing is in its path. I had one hit the ceiling first time I ever did a thing like this, with air pressure.

The problem with the steering being kinda loose, is because some jerk thought you need to use grease on the rubber. Grease has a acid compound in it, it will eat up o-rings, rubber, and the likes. If you do have to use something on rubber, use vaseline, that is just grease without the acid compound. Of course you do not have to use any lubricant here, in this case! So I degreased the whole, and the stem, and used some spare rubbers. Steering is back to it´s normal solid state. The whole little job is done. I know ... more pics next time, I promise!

The Bronze bushings on the left I´m gonna use. Second to the left an original plastic bishing and the home-made tool to get them out.

Right the hollow axle and the bolt, luckily for me they can be reused, as they are quite expensive. But then - everything is if you´re on a budget!

I make a groove in the hollow axle, as I hope this will help the lubrication. As we all know it clogs up over the years, and the bushings wear out due to lack of lubrication!

I made it on the lathe, but you can probably use an angle grinder too. It does not have to be deep, just enough so the grease can pass.

As you can see the bronze bushings have a groove, but it does not necessarely line up with the holes where the grease comes out. I hope the new cut groove will help - only time will tell.

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Coming up - pictures of how I put the bronze bushings in without problems - stay tuned!

Pulling the Bronze bushings in with a long threaded rod and a couple of pieces I made up on the lathe.

Here you can see more clearly the things needed if you want to do it this way. I used a bar of M12, it is up to the task. (M8 is not - tried that many years ago and stripped the bar of thread.

If the bronze bushings are wider than the hollow axle, you got to take a bit off. Luckely bronze is pretty soft, so that should not be too difficult.Otherwise it wont work correctly.

I was not happy with the fit of the hollow axle, I had to beat it in with a hammer. I checked and it seems the bronze bushing are deliberately made too big. The inner hole is too big (just try them on the hollow axle - a very loose fit) and the outer diameter is way too big. (22.10 mm to be exact) So it seems that they are meant to shrink when you put them in, so the hollow axle is a better fit.

Getting them out is a difficult job. I use a special hacksaw to make an incission, eing very carefull not to touch the metal of the rear fork.

I got some spare bronze bushings, so I did some measuring. The outer diameter is 22.10 mm, I decided to take a little off on the lathe. To keep it centered as best as possible, I made a piece with the exact inner diameter of the bushes, and a threaded hole to secure them.

If you want to do this sort of stuff - precission is everything. I don´t have a digital display on the lathe, but this works equally good. Just remember, moving 1 mm in on the dial is 2mm off the diameter of the piece!

I took off 5 hundreds off a millimeter, bringing it down to 22.05mm Even with the piece I made to make sure they would be perfectly centered, it turned out that they were not. So I can nly guess these things are not really manufactured with great precision.

These are the original shims yamaha provides.

They are meant to shim out the free side play. They are 0.3 mm thick. In my case, I needed 1. They fit snugly into the dust seals that come over the bronze bushes.

The fit is now a lot better, the hollow axle fits without force. Once the whole was bolted down, could not feel any free play.