I got the R50-6/5 and now what?

[Hawk Medicine]

A bang?

What kinda bang are we talkin about here? The kinda bang thats like a big backfire or the kinda bang that says that a connecting rod broke?

BMW's aren't known to go bang very often...

[rudolf35]

Originally Posted by mymindsok

A bang?

What kinda bang are we talkin about here? The kinda bang thats like a big backfire or the kinda bang that says that a connecting rod broke?

BMW's aren't known to go bang very often...

Not the good kind of BANG! A BANG that points to connecting rod or digested valve. I will perform the "Grand Opening" some time this week, with pictures, then the "fat lady will sing".

[rudolf35]

Tonight, with nothing better to do, it was time to see what the bang was all about.

Since the fuel and carbs have already been emptied, it was a simple matter to remove them and get down to the good stuff. As usual, the muffler to head stars gave a fit; but nothing a bit of 2 x 4 and a rubber mallet could not cure. Once the headers where free it was a simple matter of unbolting the heads.

As each head was opened up I was reciting all sorts of "hail Mary's" and "our Mother of blessed valves" not to find mangled valves or pistons.


R side opening


R head


R cylinder


R cylinder interior


R piston


L opening


L head


L cylinder interior


L cylinder interior off angle


L piston

So, what does all this mean? Besides the basic cleaning, new rings and honing - also media blast the cylinders and heads (outside) - there is no real damage done. But, the culprit was found. The L side big end is almost frozen. It turns just sufficiently to be able to remove it but it is dead as far as using it; at leas in this state.

So, knowing what is amiss, it is time to get the ducks in a row and start working up the parts list - ah, the never ending story of keeping old iron alive.

[Hawk Medicine]

I was afraid of that...

Well, at least when you're working on an Airhead, the bikes almost always worth fixing!

Lets have a beer and then write up that parts order!

[rusty44]

I am the "least common denominator",so what does

Cylinder interior off angle mean?

I'm just trying to learn....Thanks,Al

[rudolf35]

Originally Posted by rusty44

I am the "least common denominator",so what does
Cylinder interior off angle mean?
I'm just trying to learn....Thanks,Al

"Off angle" was just a title for the image; attempting to show more of the interior of the cylinder.

As to the damage - it is the left rod for sure that is bound up. Talking to a airhead mechanic we brain stormed that the cause for the failure might be lack of oil. Not that the bike was low on oil, just not getting the oil to the right spot. As I am slowly taking the motor out of the /5 I am inspecting every part of the oil delivery system. The real "tell all" will be the oil pump. If it is "aged" or the opening worn down we have our culprit for sure. If there is no pump damage or age issues, it was a simple bearing failure - which I seriously doubt; my money is on the oil pump. Along the same line, it could also be the oil pickup, but again that one I doubt. We shall see when I get down to it.

As to the repair, I lucked out in that I have a good short block coming (via a friend for free). Between the old block and the good used one a new case will be built up. The idea is, that if the old block did not have any damage (oil pump housing and barring supports), then I can use the old block. Keep the frame and motor numbers the same. If the old block is damaged, I will just use the good use one and have fun - it is a rider not a show bike. Needless to say, all the bearings and seals will be renewed; will also have a look see as to the heads and if there is any need to work them over. The pistons, cylinders and rings look good and all they need is a good clean up and carbon removal.

More pictures will follow as I dig in.

[rudolf35]

Knowing that the cylinders and pistons are fine, it was time to get after taking the motor out of the frame. I was about to start in on the motor removal, when I was contacted by fellow ADV inmate Rusty44. He is the proud new owner of two airheads and wanted to see/learn what is inside of the /5 motors (I think his airheads are 75/5's). Great, extra hands.

So Sunday came and Rusty44 and I faced the demon.

Just before Rusty44 showed up I removed the swing arm. Now since I am a cheap guy I refused to pay upwards of $12 for a socket that I can make myself. Making the day before a trip to Northern Tool, I picked up a 27mm socket; all of $3.00. Once home I took a 1/2" extension and faced the socket to give it a flat surface so there is more "purchase" on the swing arm nut. Having done that (with the 8" round sander off my beltsander), I then slowly ground off material from the outside of the socket until it fit into the recess of the frame and got a good purchase on the swing arm nut.


Moded 27mm socket


Demon as it sat

Our first order of business was to disconnect all the electrical connections. Since the battery was out, there was no danger to the diode board and that was the first item to be removed.


Diode board and marked wires.

The diode board came out without issues and the rest of the alternator connections proved no challenge either. Next item on the list was the starter - not much to slow us down there either; had to find the right socket and spanner combination but the rest was a simple bolt off job.

Having the motor free of electrical connections it was time to remove the transmission. The hardest part of that was removing the pin from the clutch arm. After a bit of oil and some very gentle tapping with a punch and hammer the pin slid right out. At that point we removed all the top bolts of the transmission and I fitted, in the right spots, some studs I made to rest the R1150GS's transmission on when I did it's spline lube. Having the studs in place we slid the transmission back so I could reach in and make sure the clutch push rod was well buried in the transmission (do not want to bend one of them $$). After that the transmission came right out on the left side.


Farm fresh /5 transmission

The splines on the transmission looked good. Also noted that the housing was dry and no hint of oil or other debris.


Input splines

Now one thing I did note was a "rumble" when I rotated the coupling for the drive shaft. I noted a long time ago, in this post, that I have a very faint rubbing noise when I move the bike - needless to say, it is the output shaft bearing. Rusty44 noted that he might know someone who has a puller for the drive shaft coupler (it seems that Rusty44 attended a BOMA transmission workshop some time ago). Great, might tackle that myself with Rusty44's help.

At this point we had the motor on the work table and where ready to get after the removal of all that we could.


Alternator

OK, Houston we have a problem! Having not had the time to order tools I did not have a puller for the alternator rotor, #$^*%%$##@!! Thinking to myself "well we will go as far as we can and then pick up when the tools come in", we proceeded to remove from the alternator what we could. The cable was removed, the springs moved back and the brushes moved out of their holders. Then we removed the bolts holding the stator and I thought that is as far as we could go - WRONG!!

Another case of two heads are better than one. Rusty44 asked what the rotor removal bolt does. I explained that the bolt is 80 to 90mm long with no threads on the end allowing it to bottom out on the crank thus forcing the rotor off. At that point Rusty44 had a light blub come on: "why do we not take a hard pin, that has no threads and is of sufficient length to make 80 to 90mm total length?". I sat for a second and could not think of a reason. So off we went and rummaged through my hardened bolt collections to find a suitable candidate. Having located one, we removed the head with a cut off wheel and dry fitted it into the opening on the rotor. It fit and WTF? Let us do it.

I pushed the home made pin further into the opening of the rotor and then hand screwed the rotor bolt in as far as I could. Now, still having a case of no "warm fuzzies", I opted not to use a ratchet mounted allen but instead used a T-handle one (hoping that I can not put as much torque on the T-handle as I could on the ratchet). After a agonizing 1/2 turn by 1/2 turn we heard the sound we where waiting for: a nice "pop" and the rotor almost jumped into my hands.


Rotor, pin and rotor bolt

Just to make sure that the crank threads where not buggered (thinking back, who cares - this crank is a dead issue anyway) I ran the stock rotor bolt back into the crank and all was well.

Having the rotor off opened a whole new can of worms for us. We removed the front of the motor and at that point decided that this is as far as we shall go on the front; not knowing what the "good used short block" will bring. The timing chain looked good, not to much slack with the tensioner removed and the tensioner shoe looked GREAT - no groves.


Timing case off

Now our attention was turned to the back of the motor - clutch/oil pump time. Noting that we need some bolts to take the clutch off we made a quick trip to ACE and picked up the right size nuts and bolts.


Clutch removal tools - the ACE Hardware way

Having removed three of the clutch holding bolts (in a star shape pattern) we sunk the ACE bolts in as far as they would go and then spun the nuts down until they made contact with the clutch housing. Having the nuts spun down we removed the remaining stock bolts that held the clutch together. Then the fun started - 1/2 a turn at a time, I started to back the nuts off making sure the bolts did not move. This bit of wrenching took the better part of 5 minutes but I played it safe - did not have the desire to eat a clutch. After 5 minutes of wrenching and spring popping we where rewarded with the clutch in our hands.


Clutch out

At this point curiosity got the better of me and I just had to mic the friction plate. #$%$%&^#$$ - the friction plate is within 0.05mm of being at the lower end of usability. OK fine, a new friction disc to add to the parts list (sure as heck do not want to go back for that; once it is back and running).

Now, since the crank is almost seized, I thought why not take the flywheel off and get into the oil pump (Boxer Bruce mentioned that lack of oil/bad oil pump could be a reason for the L rod going south)? So, ingenuity again comes to the rescue: we shoved a wooden block under the almost frozen L rod and made sure the rod pressed on the wood and that it pushed on the case. Then with a 17mm socket and ratchet we removed the bolts and flywheel.


OK, it was the handle of a brush - who is counting?

Anyway, with the flywheel off we broke out the impact driver and with a few taps the oil pump screws where spinning free and the cover came of the oil pump.


Oil pump cover - new gasket for sure

Having the cover off the we measured the oil pump clearances we where quite happy - the oil pump came in on the tighter end of all clearances. Then we removed the rotors, mistake.


Gouged oil pump shaft

Now, I did not find a corresponding metal piece in the the sump or any where near it. I think this damage happened some time ago. To be honest, I can see not reason the change the cam since the key is holding fast and no scoring on the pump - I could be wrong! Anyway, with the "good used short block" I should also get a cam; that would solve that issue.

At this point, Rusty44 and I called it a day. We where "good" tired and he had to get back to the casa - Mrs. Rusty44 does not let him out after dark - LOL!!

[rusty44]

Thanks, for having me over !!

I had a blast and I learned alot!!

I'd never done anything like that before!....Al

[cycleman2]

good post & I plan on watching.

[rudolf35]

While I am waiting to hook up with the "good" used motor I got board. So, since this motor might be to far south I might as well sharpen my Airhead skills on it. So, with nothing to loose I started to take the studs, timing chain, oil pump, cam follower, cam and front bearing off the motor.

The studs where taken off by double nutting them and spinning them off. I did note that several where quite loose - no clue if it was the head removal that loosened them or if they where loose from the go (chances are they loosened during head removal).

The timing chain took a special tool - Dremel with a cutoff wheel. After the chain was off I went after cam followers, oil pump and cam. The followers where no match for a rare earth magnet. They popped right out and looked very good. The oil pump was also no issue since I had already loosened the phillips screws with a impact driver (only way to loosen them without buggering up the lot). Since I decided the cam sprocket looked good I simply used a allen through the openings in the cam sprocket to remove the whole thing as a unit. The race looked good as well as the lobes on the cam.

So no it is time for the front crank bearing - fun. After a smoke and coffee to mull things over I dug out the three arm puller and my propane torch. Running a short bolt into the tip of the crank (to protect the tip) I mounted the three arm puller and put some tension on it. Then fired up to propane torch and heated the bearing; trying to keep most of the blue flame on the inner bearing race.

Now my thought was to heat the bearing, while the puller was under tension, thus causing it to "pop" loose. I spent a good 10 minutes of heating the bearing and was just about to loose faith in my methodology when I was rewarded with a small pop and the puller hitting the workbench. Sucess! The bearing was hot, the crank tip unmolested and my methodology validated - might not be BMW's way but it worked.


Goodies I removed


Crank sprocket view

My plan now is to attack the crank sprocket with the same methodology - puller under tension and propane torch. We shall see how comes out. After that, I will pull the rods and then the crank.

[rudolf35]

After removing some of the extra bits, it was time to get serious about the crank. Having procured a two arm puller, it was put to use in attempting to remove the crank timing sprocket.


Two arm puller on crank timing sprocket

As in the removal of the front crank bearing I put the puller on the sprocket and then while it was under tension I heated the sprocket with a propane torch. This went on for the better part of an hour without any result; with the exception that the puller slipped several times. At that point it became quite clear that the PO had done something not right and that the crank timing sprocket was not going to budge with the setup I was applying. Now, since the crank is done for I thought I might as well remove the rods and then pull the bugger out with the timing sprocket still on it.

OK, the decision to remove the crank has been made; now how do I do it? I had the triple square 10mm driver for the rod bolts and with the aid of a impact driver (hammer driven) I loosened the right side bolts. After a good tap from a hammer and impact tool the right side bolts yielded without a issue.


Right side connecting rod

The one thing that did strike me, was that the connecting rod bolts did not seem as tight as they should be. I am not talking loose but not feeling as tight as they should be. After closer inspection of the rod's big end I could see some very light scoring - matter of time until that side would have gone south.


Closeup of right rod's big end

Having the right connecting rod out it was time to go after the partially seized left rod. This is where the real fun started! Again, with the impact driver and a hammer, I attempted to loosen and remove the left connecting rod bolts. The bolts started to loosen so I switched the triple square driver to a ratchet and attempted to wrench them out. NO GO! The bolts would turn about 1.5 turns and just stop - needless to say, something was bent! Taking a very close look at the rods big end I could see metal debris protruding out from under it. Yeah, when I kill something I really kill it - LOL!

Anyway, the let connecting rod and the crank are dead so WTF I might as well cut the rod off. After making sure that I did not suffer from some kind of brain-fart, by consulting with a fellow inmate, I started to cut the left rod off as close as I could to the crank.


Cutting the left connecting rod

I was very surprised, how fast the Dremel, with a cutoff wheel, got the rod cut.


Crank less left connecting rod


Carnage aftermath

OK, that went as well as it could. Now let me rotate the crank and see if I can start getting it out of the case - wrong! It seems, that these is just the right amount, of non rotating, left rod remaining to prevent the cranks removal. Now what? First thing I did is to take off the front carrier; I have no clue what the PO had done but needless to say the cranks front race is buggered - I would really like to meet that PO. OK fine, now what in the name of Hades am I going to do?

It has become quite clear that all I can salvage from the motor was the case; exception being the outer bolt on bits. With that as a given, I again broke out the Dremel with a cutoff wheel.


Target for the next cut


Partial cut into left connecting rod's big end

The Dremel did a good job cutting into the split between the connecting rod's upper and lower junction but I soon ran out of cutting wheel size. Being late in the evening I could not obtain any new cutoff wheels so I switched to my air powered cutoff wheel. It also did a good job cutting into the rod and soon I had one end of the rod, connecting bolt, cut. After some prying it became clear that I have to also cut the other side. Now this is where things will get interesting. The crank can only turn about 270 degrees, that is just insufficient to get a clear shot at the remaining connecting bolt.

At this point it was late and I had better think this through a bit more. I do want to salvage the case at all cost; no clue why with a good low mileage long block coming my way - I guess just a personal thing.


As things sit now

[scrannel]

Love these bikes. Leave it stock it's got a great touring position as is... IMHO. I drove a stock R60/5 from Berlin to Australia in 1972 -- when I was a kid! Here we are at the dead sea. (Well, I did mount fog lights...)

[rudolf35]

Originally Posted by scrannel

Love these bikes. Leave it stock it's got a great touring position as is... IMHO. I drove a stock R60/5 from Berlin to Australia in 1972 -- when I was a kid! Here we are at the dead sea. (Well, I did mount fog lights...)

Oh no worries! The bike will stay stock. First of all it is to close to dead on stock and second I can not get into the Cafe scene; besides that I have the thought of a Scrambled HD Sportster in mind after the /5 is up and running.

The plan is to get the motor and transmission up to scratch. Assemble the whole thing, run it until winter, take it down and work on the "look good" parts.

[rudolf35]

Had a busy weekend these last two days. Received a call on Friday that my replacement short block was ready to be retrieved. Great, I can start heading toward the assembly again.


Farm fresh used short block

The block was everything I hoped it would be. It is dirty (mostly dust and oxidation) but nothing a wire brush and some kerosene can not cure (followed by some etching mag polish a old time air head wrench recommended).


Short block front

Looking at the block a bit closer I noticed that there was oil coming out from under the flywheel. It is either the rear main seal or the oil pump seal; neither one a big issue since I plan to remove the clutch to see what shape it is in (might be a good friction plate thus saving me a few bucks).


Rear main seal or oil pump leak

The plan now is to clean the outside without tearing into the motor to deep (as in stripping the case of all parts and starting fresh). Once I have it reasonably clean, I will go after the clutch and the oil leak and then start the assembly of the motor. After the motor, Rusty44 and I will attempt the rear main bearing replacement on the transmission - see how that will pan out. But then again, nothing ventured nothing learned. This whole project is a learning experience with the benefit of being able to ride it when done.

Gratuitous i-Phone photo of R50-60/5 about 45 minutes before the motor went "bang".


Sunday, February 9th 2012

The never ending story carries on!

[rudolf35]

Having some time on my hands, it was time to get after the "new" short block. To say it is dirty, dusty and oxidized is a understatement. The first thing to come off was the alternator. The brushes looked very used and the alternator had a lot of oxidation on it.


Hard to see oxidation but the white powder is there


Corroded stator

Having pulled the stator off I found the rotor to be in worse shape than the stator. There was sufficient rust to make a persons worth of hemoglobin.


Hemoglobin anyone

No issues, I have the stator and rotor from the original motor; besides that, the corroded stator and rotor can be cleaned up and reused if and when the need arises.

Next on the take off list was the front timing cover. Now it does not show well in the images, but there was sufficient white oxidation on the cover to fill a bag of flower. But all was not bad. The seals seemed to have held so there was no oil seepage (new seals will be mounted). The bolts and funny nuts came off without a issue and after a tap with the rubber mallet it popped loose to reveal a nice oily chain and sprocket set. After removing the timing chain tension shoe, it became evident that the motor has been in operation for some time. The shoe was not worn bad, just more than the original shoe.


Timing cover off

At this point I took a old inner tube and cut some sleeves for the connecting rods - do not want them to bang around the opening cutting notches. Having protected the rods it was time to look at the clutch and flywheel. With the rods protected each clutch bolt was loosened with a T-handle allen - not very tight, a surprise to me.


Protected rods


Taking clutch off

After the clutch was removed, I again was facing a bumper crop off rust. It seems to me, that this case has been sitting for some time but the internals, crank, was protected with oil. The clutch of the "new" short block will be a machine shop cleaning job. but not all is lost, I still have the original motors clutch parts and a new friction plate was a given anyway.


Flywheel of "new" short block

Now I do have a quandary! Checking the rods there is no discernible up and down play, but there is some side to side play - as in the slide left to right on the crank (just a bit not sloppy). Having never taken a functioning airhead down this far I do not know what "normal" is.

As a parting shot this is another image of the dirt on the case.


Dirty case

Another good thing that happened, is that I received word, that Rusty44 and I will have use of the tools needed to rebuild the transmission. The tools are in use in Denver and in about two weeks they will head our way for us to use and pass on. I just love the support of the BMW airhead community - our Congress could learn a thing or two from that; but that is another never ending story.