POST 16: The Orange bike - rear wheel brakes, bearing and oil seal

 Turning my attention to the rear wheel- I removed the mudguard (cracked and needs a plastic repair) and exhaust. 

Rear mudguard and exhaust removed

Removing the rear wheel is a case of removing the split pin and undoing the nut- can be tight- this one wasn't.

Remove split pin and castellated nut and washer

The rear wheel then just pulls off to the left after the brakes have been slackened- if necessary. Removing the wheel showed the brake linings were contaminated and dirty. The inside of the hub was also oily with corrosion around the surfaces. This was removed and cleaned and the "brake mounting surface" also cleaned.

    

I don't think the brake shoes are salvageable, but the springs can be reused. Lift the shoes into a "V" shape to remove.

Cleaned up brake mounting surface- no sign of leaking here and bearing looks in good condition.

This raises the question of where all this oily stuff has come from - the obvious place being a damaged drive shaft oil seal, but there is no sign of leakage around the bearing which is tightly fitted and seems to be in good condition. However, I decided that I couldn't leave it without checking the seal on the inside so case separation coming up! The transmission on this bike seemed in good condition and still contained nice-looking oil. I hadn't intended to strip it and I'm only doing so now in view of the contamination on the brake  shoes. I'm going to try and keep the job as simple as possible without removing the motor or stripping out clutch and alternator- naturally I don't want to separate the crankcase halves as both big-end and main bearings seem fine. Anyway, I started by draining the oil before removing the kickstart...

...  (actually best to leave this). I removed the case screws and separated the cases using a rubber mallet to ease them apart. Remove this forward filler plug to help oil drain. The oil that came out looked pretty clean.

Case separation was very difficult and the PO had used some super-strength jointing compound. I did eventually get the separation started and held the kickstart shaft in position whilst easing all the other contents back into the rhs case as the lhs came away. In fact the kickstart spring still disengaged and ran down and will need to be re-tensioned on refitting. Hence my remark - leave the kickstart in position! Looking inside the lhs cover with the kickstart mechanism still inside...

Kickstart spring still engaged in quadrant- there is no tension so the other end of the spring has rotated round behind the quadrant- if tension had been maintained it would still be forced against the "stop" moulding in the case. Note this case is upside down and the forward direction is to the right, final drive location on the left.

The kickstart had run down its tension and although the spring was still hooked into the starter quadrant and in place against the case moulding- it had no tension in it. 

Looking into the rhs the transmission was still in place- note the thrust washers and roller washer still in place on the final drive slave shaft pinion- tensioners also still engaged with the chain and their tension spring.

I removed and cleaned the thrust washer assembly

Thrust washers and roller washer removed.

I'm not intending to remove the clutch but these pics of the transmission system are for reference in case anything changes.

Final drive shaft in position

The final drive shaft pulled out of the seal and bearing behind it- apologies for the lack of pictures but I went ahead and removed the seal with a lever and then the bearing. That sucker was tight!  When I've done this job previously I've separated the cases and could use the bench press- which made the job easy! This time however I couldn't do that and the bearing simply wouldn't tap out. I eventually removed it by heating the cases with a hot air gun and then using a blind bearing puller inserted from the transmission side to pull it backwards with the slide hammer. It was a struggle but I succeeded eventually. I can say that I do not believe that this job was necessary at all as both bearing and seal looked to be in excellent condition. 

One oddity though was the presence of a bored hole connecting the bearing land to a shelf like exit below the rear wheel hub. This puzzled me greatly but Im informed its a "weep hole" that allows oil in the event of seal failure to exit below the brakes and avoid contaminating the linings. Not sure why this should be neded here, but maybe the exit of oil at this point could be catastrophically rapid? Also not sure how this fits in with the contamination on my own brake shoes when the seal appeared intact anyway? The hole and exit shelf are visible below.

Bearing and oil seal removed

Reassembly required putting the new bearing in the freezer over night before heating up the case the next day with the hot air gun. It was still a tight fit but the bearing could be tapped back into the housing using a suitably sized socket.

The reassembly process went well although cleaning the old gasket material off the case sides was a nightmare. It released a lot of debris that had to be carefully cleaned from the case internals; my recommendation- if doing this again - remove the motor and transmission internals! I used Permatex gasket sealant to stick the gasket to only one side of the case (the LHS). This is in case I need to separate the cases again and I want to avoid this cleaning nightmare. The case flanges are in good condition and I'm hoping will still be oil tight.

I rebuilt the brake assembly with new shoes.