lame final drive question

[ISAMEMON]

fixing a friends leaking final drive. Mono-lever BMW.

IS there a problem with running a final drive up to "speed" for a few minutes with the wheel off and the brakes off, but the other side of the drive bolted up. so we an open it up again, and look for leakes without ruining new shoes.

I was told that a yahoo, putting a helicoil into the overflow plug drilled into the brake tube that the brake arn goes through the final drive with. They told him, 2 weks later when he went back with a big oil leak, that he needed a new final drive case, and wanted big $$$$$$$$ I told him, that if it were me, adn they put a helicoil in and screwed up the case, it should cost him nothing, but them the big $$$$$

so now I wonder if he did the helicoil and wont admit it, I havent pushed , nor will I , ask the shop who he said did the work.

thus brought to me

by the time we opened it up, it was late and it was a giant oil soaked mess. It looked like the main seal was leaking. ( at ring gear) After I lerft he did a very nice job ( anal) of cleaning everything up.( even cleaned the old oil soaked shoes) I would have prefered to take a closer look at everything as I carefully cleaned things to see where else oil might be leaking.

thus my idea of running it for a bit, without the brakes and wheel on, besides, if it still has a leak someplace , I dont want to oil soak new shoes

but I m not that familiar with the mono-shock final drive

The tranny is not loosing fluid , nor is the shaft, so I do beleive it was the main seal and maybe the brake tube ( as he was told)

my other thought is that possibally during or shortly after the helicoil was put in the final drive, that the breather got blocked, thus causing excessive pressure blowing the final seal. Or could have all been a co-incidink ( 3 stooges quote)

sorry for the long thread

 

[NEALART]

Would it be possible to put it back together with no shoes in it and ride it around just using the front brakes for 100 miles or so?

 

[ISAMEMON]

Probabally. Its was riding with oil soaked brakes. guess I could put the old one sback on, they wont be any worse, and better then nothing

 

[pglaves]

Assuming some parts of his tale of woe are true - they make sense. The rod the brake actuating lever is on passes from one side of the case to the other. On some models (I forget which - my K75T comes to mind though) the rod runs through a tube sealed to the case at both ends. On other models (my /5 comes to mind) the rod itself is sealed at each side of the case with a simple O ring.

So, first step is take the lever off the actuating rod and remove the cam and shaft towards the shoe side. Now if you find two O rings the wheel side one is probably the culprit. But if you find a tube running from one side to the other, then that is what they would have (might have) drilled into. And if so, there ought to be a visible hole in that tube.

And if there is a hole in that tube then oil will flow a bit freely past the brake cam and soil the shoes.

Take a look.

Added: I looked in the fiche for a late model R100. The tube is called a "pipe" by BMW and has a part number of 33 11 2 301 699. It will be an interference fit (to seal tightly) so removal will require heating the case and cover, and reassembly will also require heating the case and cover. But it is in the fiche so must be a replaceable part.

 

[ISAMEMON]

PGlaves

you are 100% right on.
the "pipe" was drilled through
the independent shop here in *&^**&^ is not standing behind it, ( protecting name dont need a slander lawsuit on me)

My nearest dealer (Eugene) thinks that if I replace the o-rings and felt seal on the brake cam shaft that it will stop the leak, as the final drive is not under pressure.

I guess that this is not that totally uncomon, as the parts person said that another person has had the same issue and fixed it with the new O-rings.

While I dont see that as a permanent fix, it might get the bike through the summer or until he sells it...the owner of the bike is loosing all interest and in HIS opinion, the bikes are expensive to repair

to a point I agree....if your paying someone 85 an hour and $8ea for float bowl gaskets and $49 for an airfilter ( square ) ( his other recent repair) , and they dont stand behind their work then yes they are expensive

 

[pglaves]

From distant memory:

The pipe pulls loose when the cover is heated and removed. Then warming the case on the other side at the pipe and the pipe pulls out of the case. Reverse the process with a new pipe. Re-install the cover just as if you had been in the case for whatever other reason.

I'd fix it right - not much harder than a temporary fix.

 

[ISAMEMON]

thanks
order parts this morning to fix it right