1972 R75/5 |
Read on or fast-forward to May 25 ...
Now that the temperatures are bearable in Southern Ontario, it is time
to start working on the R75/5. During the last years 3000km I noticed
a couple of things I wanted to check:
Shopping for parts
I went shopping for most parts at Motorworks in the UK:
Disassembly
It took me just 2 afternooons to disassemble the bike down to the bare
frame. I took a couple of pictures of the
inside of the headlight shell to be able to get everything back
together to function
as it was before. I considered that most of the
body parts including the frame needed
a new dress, so I will gather everyhing up and have it powdercoated, most
probably at MES in Stoney Creek, Southern Ontario.
Initial findings after examination of all parts
You can see that the lower of the two upper tube is out of line, the two front downtubes are convex/concav and the motormounts don't line up anymore, both rear motormount spacers were badly crushed which tells another story about the accident, explains why the bike was seeping in certain areas. But bear in mind: the bike was tracking straight, free-handed at any speed! So although I sort of figured something was wrong, I was comfortable riding it
Bruno, an Austrian, owning a couple of beemers himself, did a beautiful job on the two splines as you can see. Thanks Bruno.
Frame related work
I brought the frame to a guy near Buffalo, NY who was recommended
to me my a fellow BMW rider. Once the work is done and the genius
agrees to have his name and email published, I'll let you know.
Update: apparently somebody had already tried to straighten it
and obviously failed. So it might not even be possible to straighten
it after all and the expert has suggested not to throw good money
after bad! So Plan B is in effect: use of a
03/73 R60/5 frame which I already purchased.
Gearbox related work
One seal and a boot need to be replaced in the clutch rod line up.
Timing Chain
Getting access to the timing chain is described in various articles at the know Beemer sites.
The procedure in short: get access to chain, remove old chain, fit new chain and get everything back together ;-) . The long version is described e.g. here and here.
Oilpan
Cleaning the pan and replacing the gasket are the two things to be done here.
Removing the clutch is described here. The seals and gaskets on the oil pump behind the clutch seem to seep a bit, therefore I will remove the clutch and replace all accessible seals.
In preparation, I secured the crankshaft with some cardboard between the front cover and the alternator rotor and produced a tool to prevent the flywheel from turning when removing the bolts.
Cylinder heads, barrels and pistons
If I remember correctly, one of the cylinders was weeping at the base and maybe at the pushrod seal. But really, that is only an excuse to open up and use all new seals and gaskets. So from here on, I know what is done and when.
Both pistons are Grade B pistons, 81.975mm diameter with matching barrels.
The exhaust valve relief of the LH piston is damaged. It looks like as if the exhaust valve had previously hammered on the relief. The exhaust valve looks brandnew so the previous owner seems to have corrected the problem.
Clutch installation
Installation of the clutch is decribed here. I have bought a secondhand pressure plate and pressure ring with only little wear and combined that with a stock diaphragm spring (18mm) in good condition and a brandnew friction disc (thanks Rob @ The Five Workshop). Couple of minutes work (ok, half an hour) and it was done.
Tapered bearings
After having removed and cleaned the headstock and rear wheel
bearings I have examined them closely. They show signs of pitting
on the rollers and the races of the rear wheel bearing look
as if installed with too much preload, they have notches.
I have ordered some
additional shims to correct the preload error and am buying
the bearings at a local bearing supply.
The rear wheel single row tapered bearings are marked "SKF 30203
Germany N+Z", the headstock single row tapered bearing is
marked "SKF 320/28 X Germany-S M".
I have checked the front
wheel bearings, they are in good shape with no signs of pitting.
But since I could not access them for regrease, I decided to change
them, they are only $32 Canadian. Here are two excellent articles on wheel bearings:
Duane Ausherman's suggestions
and Section 54 of Snowbum's technical articles.
In Section 42, Snowbum elaborates on headstock and swingarm bearings.
Re-assembly
I follow a few simple rules when reassemblying that bike:
Stainless steel nuts and bolts:Wherever nuts and bolts are structurally important
(shear or tractive forces at shock mounts, engine mounts, handlebar mounts, foot peg mounts, pinch bolts etc) I
don't use stainless steel material for their material characteristics.
If they are used for cosmetic reasons (just about anywhere else such
as wheel covers, fender mounts etc), I always use copper-based antiseize
to not get into trouble later with stainless steel bolts stuck in
aluminium threads due to chemical reactions.
Rubber pieces:I have a shop locally which sells all sorts of rubbers,
nuts and bolts (stainless too), even set crews for the tranny neutral
switch fo a couple of cents etc (Spaenaur).
I bought the majority of grommets and rubber pieces there as well. Even
the ones on the batterie holder, the seat pan and thick M6 rubber
washers for the fenders etc.
Things are coming together and I picked up all the parts form the paint shop. I will post pictures of the progress as I go along:
I had a bit of a problem when I started thinking about the wiring, namely about routing and connections on the ignition board.I found some very good information on the 5United group on Yahoo (thanks Nate, slash2nut and nsgreear) and have quickly summarized that on this webpage.
May 25, 2005: here is the result of my nearly 2 months restoration:
Bike has been warmed up, so far no leaks anywhere, a longer trip will reveal any problems. Basically, everything is done, remains to have the VIN changed on the registration document.
